Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Papa Jim on December 04, 2015, 01:05:35 pm
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Newbie question. Is there a any tips you can share when it comes to select 12AX7 or other tube when so many choices exist. Brands, NOS, and price. Also a ton of other tubes that will replace a 12AX7???? From what I have seen so far Electro-Harmonix is at the low end of price. Are they o.k. Does it make a big difference in sound?
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Regarding used tubes:
I would suggest that the biggest differences lie in condition of the particular tube (life left, strength, triodes balanced? , microphonic)
Some of the subs have more or less gain, some are special low noise versions for sensitive preamp applications
like the 7025 or the 12AD7
New tubes are probably mostly good. I've had what people consider to be cheap Chinese tubes sound just as good as strong tested vintage telefunkens, bugle boys or Mullards.
As far as sound goes, I guess I don't have dog ears, though I have been playing professionally on and off for 25 years, and I'm something of a recording engineer as well.
I have had pretty well all the most coveted 12AX7 come through my hands and I've tried most in my amps with little or no difference in sound.
I say get good strong tested and or new tubes...and practice your instrument :icon_biggrin:
IMHO You are the biggest influence on your sound, then your instrument, then your amp and speaker. Tubes come after all that, probably after your amps transformers, if they have a discernible effect at all.
Many people hold a completely different view, I'm sure they will chime in as well.
It is fun to play around with tubes though!!
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Thanks. Kinda what I was thinking but just looking for some kind of verification. I plan on always buying new for sure. As far as price unless someone can convince me, I think I will just kinda get an average of the cost and then pay somewhere between it and the lowest priced ones. At least for right now that's what I'm thinking. As long as we're talking amp building costs I assume it is probably worth the small extra to purchase Metal Film Resistors vs Carbon. Also Film capacitors vs Ceramic. What ya'll think about that.
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Resistors and caps are just as debatable points as tubes
I fall into somewhat the same camp
With components, buy new, not vintage. vintage components are past their due dates (except for maybe transformers)
Even if you have a vintage amp, think of it this way; you don't want to put 50 year old tires on your 50 year hot rod....
I use metal film flameproof resistors wherever I can, as they are safer and don't cost significantly more (cents)
For Capacitors I have used Sprague Orange drops, Solens (German)silver mica, and then most lately cheap brown small polyester caps
They all worked great and sounded fine with no discernible difference
One thing to consider, The big amp makers of yore that people love and often copy were businessmen who usually used the cheapest parts they could get that would do the job. I'm pretty sure they weren't sitting around trying different capacitors, resistors or tubes in their amps to see which sounded best. They were small components in a larger circuit.
Get decent parts but use what you can afford, especially for a new /experimental build
Put your money into transformers and if it's a combo a good speaker(s)
Speakers have large impact on sound, once again in my opinion it's largely about quality and condition, don't be fooled by nostalgia.
Once again there will be other viewpoints
Check out Doug's store. He has a large variety of parts and price points, pretty well everything you could want or need.
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I tried swapping different 12ax7s in a tube amp a few years ago. I remember that I didn't notice much of any difference when played clean. When the tube was heavily distorting, the tubes sounded way different. Some sounded absolutely killer, and some sounded kind of lifeless. I don't remember exactly what they all were, but they pretty much lined up with new manufactured tubes sounding unimpressive and the vintage tubes sounding amazing. I'm pretty sure I had a JJ and EH for newer tubes and RCA, Amperex for vintage tubes.
I'm sure there are other people here who have done much more of this than I have.
The best thing to do is get some and try it.
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To Toxophilite's comment. Yep, I've been doing some pricing today and have pretty much come to the conclusion that Dougs prices are very economical and I will go exclusively with him once I discovered that. Besides I started a cart on his site and it works so awesome, creating amp documentation as you go, along with even photos of each part included. Awesome.
dmp. Good observation and I will keep that in mind if I don't like the sound. I will probably stick with my tube buying plan for this first build, play thru it, then purchase a few others and test again. Heck I feel like I will probably be getting hooked on this hobby and can use anything I buy eventually. :l2:
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This is my "I've had good luck with ........" snippet. I've had good luck with EH 12AX7 Guitar Center on sale sometimes for $10. If you have a small smattering of amps, you are going to use 4 or 6 or 8 or 12 or 24 12AX7 over the next year....so buying a dozen if they can give you an even better price is not the worst idea ever. Is there an Xmas sale on TOOBS? I have not looked. Point being, if you save $3-5 on each of a dozen tubes, you can go pay $10 or $20 too much for one or two elsewhere. If you are paying $100 for multiple vintage RCA NOS 7025 I will withhold my opinion.
You never know with used tubes. There are very low emission RCA, GE, Mullard etc; tubes everywhere. I like to try to buy used test equipment which can have 12AX7s and very often 5751's in them. SOME, only SOME organs can yield a treasure trove of used tubes but only a few use more than a few 12AX7..Most use 12 or 24 or 36 12AU7, much less useful a tube. (tho everybody needs one)
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Funny you mentioned EH eleventeen, I was just reading this below on AMP FIX website.
The Russian Sovtek company manufacture a range of quality valves, and sell them in their thousands to the likes of Mesa Engineering (Boogie) and Fender, Groove Tubes, Electro Harmonics, etc. With the individual company logo's printed on them, and at hugely discounted prices. They are then marketed by those companies and sold on to the the likes of you an I in some cases at greatly over inflated prices. To be fair the exception would be Electro Harmonics. These do retail at a fair market price. No amplifier manufacturer makes their own valves, they all buy from the major factories.
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Sounds sensible, build an amp get it working, then if you want to monkey with more expensive/fancy tubes to see if it turns your crank, it's an easy enough thing to swap tubes in and out
Most of all
Have fun!
and don't get electrocuted...or see the magic smoke..at least not the electrical kind :icon_biggrin:
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Have fun!
and don't get electrocuted...or see the magic smoke..at least not the electrical kind :icon_biggrin:
Do you speak from experience. :l2: :l2: :l2:
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Yes for all the above! :icon_biggrin: though I've only been indulging in accidental electrocution in recent years..
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So are you saying you did it on purpose in prior years?
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yeah but after a while I began to find it reVOLTing! :icon_biggrin:
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you did it on purpose in prior years
I thought everyone tried it...once :icon_biggrin:
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... any tips you can share when it comes to select 12AX7 or other tube when so many choices exist. Brands, NOS, and price. ...
Overall, no. I can't share tips because in the end your opinion is the only one that matters for your amp. Use what works best for you.
That said, my experience has been that of the preamp tubes, the one directly connected to the input jack makes the most impact (because a change there is amplified by the rest of the amp).
I've also found that some amps seems to have very noticeable changes with a tube change, while others seem to sound the same no matter what s in the socket. So it's up to you to find what works best for you.
In the early 2000's, I went into a well-stocked music store and bought one of every 12AX7 they hand (8-10 brands). I tried each in one of the amps I had, and most sounded the same to me. Years earlier, I had tried several different old-production 12AX7's (RCA, G.E. Telefunken) in a '67 Princeton Reverb. I heard some subtle, but noticeable differences. That said, having tinkered amps since the late-90's, my opinion is you'll get a bigger change of amp tone by changing parts values in the amp circuit than by a tube swap or a resistor-/cap-type swap. The latter are icing on the cake, and may get lost if you're not listening to the amp/guitar by itself.
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I have been experimenting with this recently.
Unless you have gotten vintage tubes like I have, scoring premium tubes salvaged from other junk gear, this is too expensive to test.
There is definitely a difference in your amps sound when you put a sweet premium tube in the V1 spot. It is subtle, though.
Many people will not notice this subtle difference. You might be one of them.
Many places charge like 10x the cost of a regular 12AX7 for a premium Mullard or Bugleboy. Is it worth it?
Not to me, but I guess there is a sucker born every minute.
I do prefer the sound of premium tubes, but I would never pay retail prices to use them.
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One of the things that I read early in my state of tube curiosity was the first page of this pdf from Merlin's preamp book: http://www.valvewizard.co.uk/Common_Gain_Stage.pdf (http://www.valvewizard.co.uk/Common_Gain_Stage.pdf)
I took this to say that it would serve me well to expend more energy concentrating on all of the components and circuit structure that affect overall "tone" instead of focusing on specific tube types/brands as the be all, end all of tone shaping.
I found this theory to be helpful in every aspect of tube amp building and it has afforded me the clarity to look beyond folklore and lose less sleep wondering what a "better" preamp tube might sound like. (or "better" capacitor, transformer, resistor, etc., etc., etc., etc.)....so I figured I'd share that "idea" with you.
That said....
Here are 2 reference forms that someone (much more knowledgeable and experienced than I will ever be) spent time putting together. There was a time when these descriptions offered me some form of mental comfort and direction. But now it seems that I am at the mercy of the specific circuit I am putzing around with, and wind up just subbing in tubes until I find one that gets me closer to the tone I am searching for.
One of my favorite authors once wrote "TONE is found somewhere between the ear and the beers" (or something like that.....you get the picture).
http://www.thetubestore.com/12AX7-Tube-Reviews (http://www.thetubestore.com/12AX7-Tube-Reviews)
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I always like what I read once where a fellow pointed out that nowhere in the marketing of tubes or capacitors etc in the 50s and early 60s did anyone talk about tonal qualities and or sound. They all talked about ruggedness, longevity and staying in spec. There was no mention of tubes sounding like British tweed jackets.....This was the heyday of tube technology when everything required them and marketers were no slouches either. If marketers knew of any quality that would sell their products better they certainly wouldn't neglect to mention it.
Individual capacitor and tube tonal qualities seems to be a comparatively recent concept
Still it's fun and the electrocutions are way better than with weak solid state gear!
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... nowhere in the marketing of tubes or capacitors etc in the 50s and early 60s did anyone talk about tonal qualities and or sound. They all talked about ruggedness, longevity and staying in spec. ... If marketers knew of any quality that would sell their products better they certainly wouldn't neglect to mention it.
Individual capacitor and tube tonal qualities seems to be a comparatively recent concept
In some ways this is because today the marketing is aimed at mostly non-tech folks. Anyone can pull a 12AX7 from the socket and install a new one as "a mod."
Most of the old marketing was in publications targeting knowledgeable DIY folks (like the Ham who builds his own transmitter/receiver) and repair personnel. The DIY guy wants to spend his relatively limited budget on tubes that aren't noisy and will last, giving economy in measured useful lifespan. The repairman wants a replacement tube that won't quickly turn faulty and have him called back to re-fix his work (often for free), so that he can build/maintain his reputation and keep the one-time labor charge in his pocket.
If you pay close attention, the magazines that target the repairman repeatedly talk about "avoiding callbacks" on almost all tube and cap ads.
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Sounds good to me! Something that is reliable and works show after show, rehearsal after rehearsal, session after session!
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I've had some fun substituting different tubes in a few amps. +1 to the idea that the first preamp stages are the most important. Especially in terms of the noise floor because any noise at the front end gets amplified further.
New tube fabrication doesn't seem to be especially precise. With a really simple circuit like a 5F2-A, sometimes I can hear differences between tubes with the same label. There do seem to be trends between different labels. EH 12AX7s are my starting point. Consistently low noise and an absence of ice pick high end. But I've found new Tung Sols and even some Chinese tubes that sound really good.
I've also had good luck with a few "almost new old stock" 12AX7s. Only worth it in the V1 spot, but worth it in some amps.
Power tubes vary a fair amount too. Chinese 6L6s don't sound the same as "winged C" Svetlanas. At least not in the Super Reverb I built. The amp's owner preferred the Sveltlanas too - and I didn't tell him which were which. (And yes I re-biased when changing tubes)
I got a pair of JJ EL84s for my Blues Jr. Harsh, brittle and unpleasant in that amp. A pair of Ei power tubes made that amp sing. Fixed up a couple of issues in a Peavey for a young friend and tried all of the EL84s I had on hand. To my surprise, the JJs sounded great in that amp. Again, I had the owner pick his favorite pair out of three choices and he liked the JJs hands down.
I guess my point is that tubes are not consistent like transistors which either work or they don't. If you have a modern amp with multiple channels and lots of tone tweaking, maybe the cheapest tubes that are quiet make sense. OTOH with simpler circuits, tubes can make a difference. Certainly as much as capacitor choices IMHO.
Nothing close to speaker choice though!
Respectfully,
Chip
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... a fellow pointed out that nowhere in the marketing of tubes or capacitors ...
... the magazines that target the repairman repeatedly talk about "avoiding callbacks" on almost all tube and cap ads.
Sounds good to me! Something that is reliable and works ...
It just occurred to me that marketing, whether today or 60 years ago, has little to do with the product being sold. The product could be good, bad, be anything really. Successful marketing reflects the psychology of the target audience, and what they're worried about. It then tells them (truthfully or not) that the product will make everything better, and keep them from having cause to worry.
I never took marketing in school, but I bet that "insight" on my part i covered in the intro to marketing class...
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I think the point I had read (and shared) was that marketers are generally very tenacious and exploitive of any quality they can use to flog something on the unsuspecting public. I was under the impression that they will often invent a dilemma or 'fear' (like governments often do!) and then seemingly provide the solution.(This is REALLY 'successful' marketing) so the dilemma doesn't actually have to reflect the current mindset of the populace it just has to be believably presented.
I thought it was a humourous and enjoyed the connection as marketing is EVERYWHERE and it's very hard to avoid. Generally I am not keen on it as it is rarely aimed at making people feel good.
Out of curiousity, as you seem very well informed,(and I say this with NO mockery)
Has there has been any scientific, peer reviewed, factual literature published regarding the 'tone' or ' sound' of amplifier components like tubes and capacitors?
It would be very interesting to read
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This is REALLY 'successful' marketing
I worked for a sub company of J&J, as a service engineer on CAT scanners, the *real* engineers were in final stages of a truly new scanner that blew away anything out there. The sales team and marketing was wetting their pants over the new homes and boats they were gonna buy, so they sold the scanners before they were released from engineering. my company sold out to GE a year later because of all the down-side bugs and cost over-runs etc, but the marketing & sales guys made their money!
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Has there has been any scientific, peer reviewed, factual literature published regarding the 'tone' or ' sound' of amplifier components like tubes and capacitors?
It would be very interesting to read
I'm thinking sound is a subjective matter and does not relate well to scientific quantifiable measurements.
We can measure gain, noise levels, MTBF, shock and heat tests, but quantifying what sounds good doesn't seem to be so easily measured.
I used to think my tube tester could give me a good indication of this, but have now realized that this is not so.
Many tubes I have tested score low or even bad but sound just fine in an amp to me.
Often I have a hard time discerning the difference between tubes that score high/above specs from tubes that score low/or even bad.
I did watch a Youtube video about Mullard tube manufacturing and the growth of their operations.
It seems they made facilities to produce almost everything in house. With testing labs to control QC.
I think that is a big part of their allure. Quality inputs to the manufacturing process led to consistent quality output.
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I'm not sure about that
There is a lot of science behind audio engineering
Identifying frequencies to remove and or enhance them, isolating the sonic qualities of individual instruments to help locate them in a mix so that they don't interfere with other instruments etc etc. Finding frequencies that have a tendency to feedback, tuning PAs to particular spaces etc etc etc.
Audio engineers/ soundman could be described as people who know how to translate technical information regarding sound into something an average muscian/person would think 'sounds good'. Kind of an interface between the two worlds.
So I believe how things actually sound can be measured and defined, and there is gear readily available to do it.
Certainly there are preferences, that is subjective, but there are absolutes
If you read descriptions of what people say certain brands of tube 'sound' like. You will often find people saying the same sorts of things, which often sound like they are related to frequency response.
This could be for two reasons
1 - They are all hearing the same sonic characteristics (which would often be about EQ or frequencies represented)
2- They are all reading the same information/sources and have developed a lexicon regarding the tubes as a result
If it's the former, it should in some way be measurable, defined, or tested
However I think I'm totally off topic annnd riding a hobbyhorse!, These concepts interest me and I digressed
back to the scheduled programming.
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I think you are correct in that some of these sound characteristics should be measurable.
But that might not tell the whole story.
What sounds good to me might be very different from what sounds good to you.
Again we are back to that subjective determination of what sounds "good".
To me, the old premium 12AX7s do sound subtlely better.
But definitely not worth 10x the price of current production. :l2:
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I think there's a lot to be said about anything made when almost most electrical devices used tubes and there was vast industry and much experience in place to manufacture them to a consistent degree of quality.
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Nice discussion and thread. But I will simply only say that various tubes do in fact matter. There is a discernible difference between them especially in V1 sockets as pointed out earlier. If you don't hear it, then possibly you either have an inefficient speaker, lame amp circuit, poor set of damaged ears from years of playing too loud, dark sounding guitar and/or pickups, old strings that need changing (unless you use flat wounds), long high capacitance guitar chord, maybe your amp was made with all ceramic disc caps (oh the horror), heck maybe all of them combined? If you don't hear the differences than I feel badly for you that you can't. Do all mustard flavors or cheddar cheeses taste the same? Do all micro brews, cabernet wine's or scotch whiskey taste the same? Can you test them with signal generators & oscilloscopes? Of course not. Ha! How about the marketing angle with cryogenically treated tubes? Those are supposed to be the best?! I haven't seen anyone mention that "tube live's matter"? Maybe that's another thread? For some reason I feel like I'm channeling PRR with cynicism or Richie200 at moment? (and PRR nothing but respect for you - you have a way about keep things simple and understandable - Richie not so much (inside joke)) Peace out!
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Well don't feel sorry for me
I have a lovely amps, Excellent high efficiency speakers, Beautiful regularly maintained guitars (great acoustic tone, well set up etc etc), good quality normal length patch chords, change strings regularly, play lovely clean crisp sounds
Do not play too loud (jazz rockabilly, latin, etc etc) etc etc So NO NO NO NO NO NO to all those assumptions.
Strangers are always telling me how lovely setup sounds ( I play live a lot)
And with respect
I don't compare electrical components to organic foods , aged whiskies or fine wines .
Tubes are manufactured objects mass produced in factories developed over a matter of a few decades, not the result of thousands of years of tradition, experimentation, family recipes, complex organic processes etc.
Couldn't even begin to imagine them in the same league myself . I could compare music to those things though.
But I will NEVER begrudge you your enjoyment of them or suggest that anything you are doing, using, etc is deficient,and I certainly wouldn't pity you for enjoying them or spending extra money on them.
Please enjoy them and the differences you hear! (I say this seriously)
To me the magic is in the music, the playing of it,and to a slightly lesser degree, the instruments. Gear is tonnes of fun, but to me, ultimately an ends to a means, and a pleasurable pastime.
Best regards
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There is a lot of science behind audio engineering
I played around with single 12ax7's one time monitoring it with a scope and a spectrum analyzer borrowed from work, with single freq, or 2 freqs things were reasonable, gain, bandwidth, noise, but when you started mixing multiple freq as fast as you could strum it became totally *unmanageable* with test equipment
I told the guitar player "it looks like S*&T"
That said I am NOT a sound engineer, I would starve :icon_biggrin:
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Well obviously my opinion is an extremely popular one
Maybe it's too practical??
:icon_biggrin:
Feel free to pile on!
You could if you had tubes that had similar amounts of gain do some simple recordings with everything else being the same.
Same guitar part, same mike position etc etc and then have a very close listen and look at the actual waves forms.Perhaps something would show up.
Digital recording is pretty cool that way. And there are frequency analyzers which are pretty neat too.
However there could be little Djinn living in those little bottles :icon_biggrin:
No two tubes are the same strength and thus will always sound a little different.
I just never found it significant, it never made my day, nor wrecked it, Music was still just as enjoyable.
This is like a discussion on politics and or religion!
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One thought on tube-era marketing: it was aimed at a different market. Tube radios, TVs and maybe organs either work right or they don't. The ham radio operator doesn't care if his tone is warm or has ice pick highs. He does care if a tube is microphonic or doesn't produce gain in an acceptable range. Other than that, it works or it doesn't.
Guitar amp builders OTOH obsess over polyester vs. polypropylene caps, foil orientation, magic mojo from Mercury Magnetics transformers (now there's a lesson in marketing sizzle!), oxygen free cables, partially depleted pickup magnets, and a million other things.
Like JojoKeo, I can hear differences between different tubes. Sometimes, in some spots.
Chip
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But now it seems that I am at the mercy of the specific circuit I am putzing around with, and wind up just subbing in tubes until I find one that gets me closer to the tone I am searching for.
+1
Like SG I find myself simply rolling tubes to see what impact it has and whether I dig it or not.
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But now it seems that I am at the mercy of the specific circuit I am putzing around with, and wind up just subbing in tubes until I find one that gets me closer to the tone I am searching for.
+1
Like SG I find myself simply rolling tubes to see what impact it has and whether I dig it or not.
Precisely - which implies that we DO in fact hear various tone and gain differences between different tubes used, not to mention various artifacts and hopefully not microphonic issues also. This fact is not limited to 12ax7s but all other 12a_7 preamp tubes as well as pentodes also.
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I will give 2 brand new EH 12Ax7's for any 1 Truly NOS RCA, Tung SOl, Telefunken, Mullard, Amperex or EI. If you have some RCA, NOS large white letter black plate 12Ax7 or Bugle Boys I will give you 3 new EH 12Ax7.
Hell, I will even do NOS GE 2 to 1.
I promise to never sell them so I will not profit from you. If I do ever get rid of them I will send them back to you.
Oh hell, make it 3 to one and 4 to one on the Mullard, RCA black and TungSol. I will bet my PM box gets full now. :l2:
Oh yea, I will pay shipping both ways.
Any takers? I bet not.
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I will give 2 brand new EH 12Ax7's for any 1 Truly NOS RCA, Tung SOl, Telefunken, Mullard, Amperex or EI. If you have some RCA, NOS large white letter black plate 12Ax7 or Bugle Boys...
Ed, I have a nice box filled with 'em. I won't be running out anytime soon. I use the new production tubes for phase inverters, trems, reverb or other "worker bee" positions and save the oldie AND goodies for the important jobs. btw, you didn't mention a few others but don't say 'cause we don't need further competition than there already is in finding them. It always gives me a big :icon_biggrin: when I get lucky and my searching pays off with an excellent price. This disputes comments that they (good ol' NOS) can only be found with paying high prices and therefore not worth it. Rubbish & sour grapes both. But as you also know, even at $50+/tube, nothing can touch what a really sweet tube will give you. Not special transformers, special caps & resistors, or even the best of speakers.
Just my opinions & observations forum friends...we all know SRV didn't care anything about what tubes he used right? :laugh:
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Why doesn't anyone talk about the healing properties of tubes?
I've just been turned on to this and I find I'm leading a warmer, articulate, and more transparent life with less top end 'fizz'
My girlfriend has noticed that my middlle is more scooped and my bottom end seems a lot 'tighter' :icon_biggrin:
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Ed I'll trade you a used Bugle boy made at the Ontario Amperex plant denoted by the little 'r' in the date code etching for three Eh 12ax7. It doesn't have the little picture of the tube playing a bugle which I know makes it sound better but it's the same thing otherwise. I've sold a gazillion of these in the past 10 years and I've kept some to use, as Amperex was a good name in manufacturing. More importantly I didn't have to buy them! I'd be happy to have three new Eh tubes. That means I'd have 2 more tubes and they'd be brand new!!! How many can i get for an Amperex 7025?
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I don't compare electrical components to organic foods , aged whiskies or fine wines .
To me, tubes seem to be the only electrical components worthy of comparison to fine food or drinks.
There does seem to be some type of organic nature / personality to tubes. :icon_biggrin:
If they didn't have that, I'm pretty sure we would all use the cheaper SS guitar amps instead. :l2:
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Ed I'll trade you a used Bugle boy made at the Ontario Amperex plant denoted by the little 'r' in the date code etching for three Eh 12ax7. It doesn't have the little picture of the tube playing a bugle which I know makes it sound better but it's the same thing otherwise. I've sold a gazillion of these in the past 10 years and I've kept some to use, as Amperex was a good name in manufacturing. More importantly I didn't have to buy them! I'd be happy to have three new Eh tubes. That means I'd have 2 more tubes and they'd be brand new!!! How many can i get for an Amperex 7025?
I am not sure of why you would post this to me. I assume you know what NOS is, but in-case you do not it means a tube that has not been used. New Old Stock.
I am sure you are not thinking I am dumb.
If you missed me writing that go back, but I think you are being a straw man as it is ridiculous to even offer this to me as I know you are not so stupid to not understand what I meant.
Also, tube manufacturers certainly did and do refer to the audio quality of their tubes and some were designed to have specific characteristics like aligning the screens to remove the kink giving us the Kinkless Tetrode and enclosed to direct the electrons as in a Beam.
They also advertised having better audio quality. Look at the old ad I have posted here. I actually collect old tube ads and you would be surprised how many do refer to improved audio quality.
You have the right to you opinion, but in the future please leave me out of your debate if all you want to do is be silly. I mean why would I want an old used tube?
BTW, say what you want about the little bugle on the tube, but they are worth more money. It is not that they are guaranteed to sound better, but you can be assured they are made for audio in Holland.
So again I ask you. Did you miss the NOS part of my post or are you simply trying to make me look foolish.
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Has there has been any scientific, peer reviewed, factual literature published regarding the 'tone' or ' sound' of amplifier components like tubes and capacitors?
It would be very interesting to read
"Scientific" and "peer reviewed" suggest a scientific journal. I'm not an AES or IEEE member, but suspect there is such material in their journals, at least for component parts. Dunno about such writing for tube sonics.
There is a good article series on Capacitor Sound (http://www.scribd.com/doc/2610442/Capacitor-Sound) printed in Electronics World in 2002. I submit it is scientific, having been researched and written by a capacitor engineer and because it gives results that, while substantiating some of the general claims about cap sound, also points out notable deviations (like how different flavors of ceramic dielectric caps both represent the worst- and best-measuring samples). The author spends a great deal of space on his measurement setup to enable others to duplicate his results; result replication is important for published scientific research.
(A quick note: "PET" in the articles is polyethylene theraphthalate, also known as polyester. But there's more than one type of polyester, and Mylar is a special form of polyester. "PP" generally means polypropylene in the article. For all dielectrics, construction methods can differ, and the article suggests construction method can cause measurable distortion in some caps.)
The challenge with doing the same with tube sound is deciding what factor(s) to measure which will be indicative of in-circuit sound/performance. There aren't too many tube manufacturing engineers left to guide the choice. As an active component, there are additional dimensions to the problem compared to passive components (which are surprisingly complex when you delve into real-world components compared to theoretical ideal components).
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BTW, say what you want about the little bugle on the tube, but they are worth more money. It is not that they are guaranteed to sound better, but you can be assured they are made for audio in Holland.
I LOVE these little guys and not just for 12ax's... :thumbsup: :notworthy:
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Ed's point of real NOS tubes has me wondering. :dontknow:
This supply must be very limited and trending toward extinction every day.
I have seen sellers on Ebay selling just the premium Mullard, Amperex boxes, for very expensive prices.
I wondered why anyone would buy them. I think I can see why now.
It makes me wonder how many of the tubes sold as NOS actually are unused tubes? :w2:
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Oy yoy you Ed you sure do take this seriously
We are talking about electrical components here aren't we??
Or are we talking religion and politics??
Seriously
No-one was calling you dumb
if I had a proper shiny , just came from a vault tube , the only reason i wouldn't trade it to you is that some 'enthusiast' would pay me piles for it and then i would go buy some other perfectly useful new tubes or other things like guitars strings, food etc etc
Anyway clearly this is really important to you and I apologize if I'm making light of it
However I never think it's bad to be silly
There is enough unhappiness in the world from people taking things excessively seriously. we are witnessing it all the time, sadly
I don't want any part of this 'debate ' I was offering the original fellow an opinion and I think a reasonably sensible one
To concentrate on building and amp and not worry to much about hunting down special important parts which will make tiny differences
To me the magic is in the player, the mind the heart the soul and the music not in the glass tubes
time spent tube rolling could be better spent playing and or rehearsing
I'm sorry I'm not preaching to the prevalent choir with this concept
I had an opinion and Jojokeo told me I was deaf, I had old strings, I had crappy amps etc etc etc yeesh!
I responded with humour as I was trying not to be offended by the rudeness
I am not stopping anyone from spending any amount of time with capacitors and tubes etc
I just prefer playing music , and making amps for fun
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I prefer JAN tubes. But I will use an import if I have to. I guess. :icon_biggrin:
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I have been through many many crappy sounding preamp and poweramp tubes. As has been said here over and over there is a difference. I say huge difference - sorry, but I will have to take Jojo's angle. Either you have been weaned on inferior product and think it is the norm, or the application is flawed. If even your drummer can tell you that you sound like crap, you know your in trouble. Geez, everything from spikey to thin to horrid distortion characteristics, my gosh, I could go on and on. It's as plain as my big nose. They all check out fine electrically, but the majority of the crap I've run across ARE new manufacture. I've ranted several times here about Groove-your-wallet Tubes and my round robin with their Chinese and eastern euro crap tubes. Many new manufacturers are copying the old charts for advertising knowing full well the tube can never achieve those numbers. How do I know? I've got the dead soldiers to prove it. My goodness a good tube can change the whole dynamic character of an amp. This is not to say some old mfg stock are bad, because there where/are. However, the functional old tubes are superior. Companies that are trying to copy some of the old tubes to the molecule are outrageously expensive - for a reason. It's not in the labor or short runs. Some simply can not be replaced these days. Case in point my old stash:
Jim
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The reason I am so keen on this subject is because I've spent a lot of hard earned money with sub par results. I'd like to think I can save someone some cash based on my unfortunate experiences. I think we are all giving our opinion for the original poster. I may disagree with some folks but I have real reason and a lot of live and woodshed hours to back it up. It's all well and good to talk about the spiritual aspect of music and guitar playing. However, telling someone to practice more and roll tubes less could be considered just as rude to someone who is trying to explain what they have encountered. When the rubber meets the road, its the little differences that make a world of difference. That's why Brian May, Robin Trower, Page, Beck, SRV, etc, etc.... sound like they do and you can tell who is trying to sound like them - but not quite there. I guarantee you these guys are not using crappy tubes from Chine. After all, that's part of the reason why we are all here in the first place - to chase that tone as SG said. I happen to think the glass plays a large role. However, I am partially deaf and I do play with strings that are years old. But that doesn't matter because I have THIS :m8
Jim
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Wow, I guess the reason I thought there was only a subtle difference is because all the tubes I have are old ones salvaged from other gear.
I didn't have any of the new manufacture tubes to compare with. I guess I'm just lucky.
All the more reason for me to continue with my junk gear acquisitions then. :laugh:
I picked this one up for $21 including shipping just for the Hammond/Mullard 12AX7 and 12AU7 I could see it had. :icon_biggrin:
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I had an opinion and Jojokeo told me I was deaf, I had old strings, I had crappy amps etc etc etc yeesh!
I responded with humour as I was trying not to be offended by the rudeness
C'mon Toxo I was not speaking to you directly at all or I would've put something by you in quotes like above. And I was being humorous as well so why did you not take it as that also as you're saying above (rhetorical - no need to respond)? Something is inconsistent and amiss?
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Ed's point of real NOS tubes has me wondering.
This supply must be very limited and trending toward extinction every day.
It makes me wonder how man of the tubes sold as NOS actually are unused tubes?
In addition, most of the really good ones have been culled out over the years/decades. Every single tube that RCA or GE or Mullard made back in the vacuum tube heyday wasn't a winner. Some were noisy. Some were microphonic. Just like what we see today. Overall the quality was higher and there were likely fewer duds but there were still duds. Most of the really good ones have been sorted through. What is being hustled today is the best of the rest or sometimes not even the best of the rest. There's a lot of glass being sold simply based on the ink print or etching it has on it. Once in a while someone unearths a case of pristine unused tubes but expect to pay a car payment for them.
Case in point: I have a really nice Westinghouse branded 12AX7 that I love. Sounds great in V1 or every amp I put it in. It's a pre-war EI tube made on the old Telefunken tooling. It's basically an old Telefunken clone. Great tube. It is currently making my Soldano sing. I saw one recently online from a NOS tube dealer. $35. Not gonna break the bank so I rolled the dice since I love the one I currently have. It's an exact copy of my current tube and it is microphonic in every amp I have tried it in. It might be useful in my PRRI. I haven't tried it there yet.
Buying old tubes is a crap shoot, at best. It can be fun and rewarding but understand the risks going in and remember the old adage "If it sounds too good to be true...".
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Oy yoy you Ed you sure do take this seriously
We are talking about electrical components here aren't we??
Or are we talking religion and politics??
Seriously
No-one was calling you dumb
if I had a proper shiny , just came from a vault tube , the only reason i wouldn't trade it to you is that some 'enthusiast' would pay me piles for it and then i would go buy some other perfectly useful new tubes or other things like guitars strings, food etc etc
Anyway clearly this is really important to you and I apologize if I'm making light of it
However I never think it's bad to be silly
There is enough unhappiness in the world from people taking things excessively seriously. we are witnessing it all the time, sadly
I don't want any part of this 'debate ' I was offering the original fellow an opinion and I think a reasonably sensible one
To concentrate on building and amp and not worry to much about hunting down special important parts which will make tiny differences
To me the magic is in the player, the mind the heart the soul and the music not in the glass tubes
time spent tube rolling could be better spent playing and or rehearsing
I'm sorry I'm not preaching to the prevalent choir with this concept
I had an opinion and Jojokeo told me I was deaf, I had old strings, I had crappy amps etc etc etc yeesh!
I responded with humour as I was trying not to be offended by the rudeness
I am not stopping anyone from spending any amount of time with capacitors and tubes etc
I just prefer playing music , and making amps for fun
The OP, remember him? He asked if there are any benefits to a particular 12Ax7? This thread has 50 posts of which 15 are yours. Your first opinion was acknowledged and anyone with comprehension skills can certainly understand your position.
Do you take your investments seriously? See you overlooked one huge benefit in having a nice supply of New Old Stock tubes.
Care to even guess how much percentage gain you would have made in an investment of having held NOS tubes for even 3 years? How about the 48 matched Mullard XF2's I got in the late 80's when my friend closed his electronic shop? Just the increasing value alone makes the NOS the better choice. The reason is they are not making them anymore.
Also that old tired comment that tone comes from the hands and _______________ (insert great player here) would sound the same no matter what he is playing and that is simply not true.
Would Chet Adkins sound like Chet if he were using Eddie's tone on Eruption? Would Stanley Jordan sound like Stanley if he played a flat top with no distortion/overdrive. Of course not because he relies on the high gain to make all his taps ring out. Joe Banamassa is quoted as saying if it were not for the tones he gets from his amps and electric guitar he would probably not even play guitar.
You are right, we are talking about electronic components and not religion, but most of us are here because somewhere along the way we experienced the joy of the tone of a simple tube amp and guitar. This impact to a lot of us could be compared to religion as in the area of life changing experiences. You do not have to imagine the impact equipment like a Marshall, Fender and Vox made. Simply listen to music recorded prior to the birth of Rock and Roll which would have never existed if it were not for this unnecessary stuff like tube amps. I mean Robin Trower could have recorded the Bridge of Sighs album using a Martin D28 and it would have sounded just like it does. The tone is in the hands.
Ridiculous comment? I think it is no more ridiculous as saying tone comes from the hands. A players style comes from the hands and the Tone-Pitch-Timbre comes from the instrument. In our case vibrating strings.
Another thing about tubes. They are not very efficient and will never produce the cleanest tone compared to other methods of amplification. Tube amps take more maintenance and simply cost more and are not as reliable as other amps and are much more difficult to get high wattage from.
I have read a lot of your posts where you go to great measures to get a clean tone and use very expensive old speakers like JBL and you know there is really no difference between a JBL and a UTAH since all you have to do is practice until you can get the tone in your hands to make any piece of gear to sound like you want.
Am I serious about this stuff? Probably not as much as you may be thinking. I just simply do not agree with your first reply or the other 14 needed to expand and or explain your position. I did not call you, you called me out. Now that you have I feel obliged to explain other areas where I do not agree.
Now I am putting these things :icon_biggrin: :laugh: :l2: :w2: :dontknow: :think1: :worthy1: because I mean nothing offensive to you and that I am not being serious.
And one more for Jimbob :m8
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There's a lot of glass being sold simply based on the ink print or etching it has on it. Once in a while someone unearths a case of pristine unused tubes but expect to pay a car payment for them.
This is true for the less informed and the true collector. The better the print, clarity, clean shiny pins, and special markings <>, date codes, etc. will fetch nice prices now and even greater in the future as Ed mentioned. Especially even when taken from a pristine box or sleeve of boxes where it's fairly obvious these may have been stashed away in someone's shop or home maybe an estate sale? If you are diligent, tenacious, & lucky enough every once in a while you stumble onto something very worthwhile and get rewarded for your efforts.
Now as simply a guitar player that appreciates the finer aspects of our crafts, if you know about tube construction you don't need any printing or box to tell you what you are looking at. Like that Westinghouse of yours, this wasn't made by Westinghouse as I'm sure you know? But you know the instant of plugging that bad boy in and warming it up when you strike your first chords and hear pristine tonal bliss, the degree of headroom you like, the tight punchiness and body, the 3D sound quality permeating your senses...whatever qualities you value - you have a winner. It doesn't matter if you searched far & wide through a tube dealer or it came as a part from an old organ amplifier that was being thrown away in a junkyard near you...you have the sound, tone, and amplifier of your dreams. What did it actually cost you? And even better, did you create this for yourself? What is this all worth to you?
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This is for anyone and everyone but no one in particular:
this is a "tube" amp forum. To dismiss and/or poopoo the very crucial, critical, and important role of the tubes themselves which over and over again are so carefully biased and provided carefully filtered voltages to doesn't make any logical sense whatsoever and is entirely ignorant to this fact at best.
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Bias? So that's what happened.... :think1:
Jim
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Brah, you shred so hard you melt yo' glass! :laugh:
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Bias? So that's what happened.... :think1:
Jim
Great Playing causes that!!!!!
I thought you would know that. Seriously, I would guess flyback since those burning things are Majors.
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So from my extremely limited group of test subjects. Basically 1 of each kind.
I would rank my premium 12AX7s as follows:
1. Mullard
2. Bugleboy
3. Other Old Stock
Would any of you other premium tubers care to give your brand ranking preferences?
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Don't have a ranking preference; sometimes different 12AX7's sound different, which then makes one good for some applications and not others.
I really like the neutral, balanced sound of Telefunkens. But then the warm sound of some RCA's is sometimes the way to go, while other times the lively top of Mullard or Amperex is the ticket...
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There is a good article series on Capacitor Sound (http://www.scribd.com/doc/2610442/Capacitor-Sound) printed in Electronics World in 2002. I submit it is scientific, having been researched and written by a capacitor engineer and because it gives results that, while substantiating some of the general claims about cap sound, also points out notable deviations (like how different flavors of ceramic dielectric caps both represent the worst- and best-measuring samples). The author spends a great deal of space on his measurement setup to enable others to duplicate his results; result replication is important for published scientific research.
(A quick note: "PET" in the articles is polyethylene theraphthalate, also known as polyester. But there's more than one type of polyester, and Mylar is a special form of polyester. "PP" generally means polypropylene in the article. For all dielectrics, construction methods can differ, and the article suggests construction method can cause measurable distortion in some caps.)
I read through this and I get some of it but....... care to boil it down a little? :w2: :dontknow:
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Don't have a ranking preference; sometimes different 12AX7's sound different, which then makes one good for some applications and not others.
I really like the neutral, balanced sound of Telefunkens. But then the warm sound of some RCA's is sometimes the way to go, while other ties the lively top of Mullard or Amperex is the ticket...
+1
Jim
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.. care to boil it down a little? :w2: :dontknow:
If a cap was an ideal device and introduced zero distortion, it would have no "sound" and all caps with identical ratings would be interchangeable.
Except that almost all caps measured had at least some distortion, which seemed to follow these rules:
- The bigger the cap, the less distortion (relates to different dielectrics and construction styles), except
- Sometimes caps of a specific dielectric distort much more/less than other of the same dielectric (ceramic was notable when 2 different types exhibited the most, and almost the least, distortion of all caps tested)
- Bias (voltage) across the cap increases its measured distortion (which is bad because we use caps specifically in places where there will be d.c. across them)
- Higher voltage caps seem to exhibit less distortion than lower voltage caps of the same type (which also amounts to them being bigger), and
- The rules don't always hold up (and there are bad apples even among normally-good types) so you should measure the specific caps you want to use to see how they really perform.
So if you hear a sound change when swapping caps, you're really hearing the difference in the artifacts each cap overlays on the intended signal.
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Great breakdown of the info HBP. Thank you.
But (sorry can't read it now) does it mention anything regarding caps "breaking in" or becoming accustomed to certain voltages being placed on them to where the dielectrics sort of "form" or "settle-in" similar to e-lytics?
2nd - Does it mention anything regarding outside foil direction/placement and the related characteristics or phenomena this may have?
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Don't have a ranking preference; sometimes different 12AX7's sound different, which then makes one good for some applications and not others.
I really like the neutral, balanced sound of Telefunkens. But then the warm sound of some RCA's is sometimes the way to go, while other times the lively top of Mullard or Amperex is the ticket...
Unfortunately, I haven't scored a Telefunken 12AX7 yet.
I do have a junk Telefunken R-R with a 12AX7 in it on my watch list.
I didn't want to pay the $75+ for it.
My Hammond/Mullard junk gear came in today.
I'll have to check out both of these tubes tonight.
That will bring my Mullard 12AX7 inventory up to 2. :l2:
I do like the sound of these, not quite as bright as my Bugleboy.
Very full and warm sounding to my ears.
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Guys, so as to not hi-jack this thread I started a new thread, link below, on capacitors;
http://el34world.com/Forum/index.php?topic=19534.0 (http://el34world.com/Forum/index.php?topic=19534.0)
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I had matched pair of Bugleboy 12ax/12au7 from one of my carcasses.
I loved the sound of my paypal account filling up. :icon_biggrin:
I know what Jojo means about tubes though. I like the way 6SL7s sound as opposed to the 12ax7s. It's hard to define, but I'd say smoother, warmer, and the distortion created is even softer sounding. Which, is not what everyone might want depending on what they play.
I had bought some Russians, and they sounded really nice. Bought some more and they are almost all microphonic, and don't have the same sweetness. Bought a bunch of NOS and used from a feller, and they are awesome. Frankly, I doubt if it would show up as a huge difference on a 'scope (and I wouldn't know what I was looking at anyway) . (except for the noisy ones)
I'm still not paying $50/tube. *squeaksqueak*
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I had matched pair of Bugleboy 12ax/12au7 from one of my carcasses.
I loved the sound of my paypal account filling up. :icon_biggrin:
I'm still not paying $50/tube. *squeaksqueak*
So you sold the Boys? I don't resell any of my premium tubes.
$50 ??? many places are asking $150 for NOS Mullard/Bugleboys.
Makes me think of a Cash song. "How highs the water Mama? It's five feet high and rising".
I'm thinking that if I don't keep all my premium tubes, the others will all get washed away and I'll never have any.
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I sure did sell 'em. I drove open tractor for many years and was too young to think about ear plugs. While my hearing is still very good, I can't tell the diff between "premium" and not. I don't hear like EJ and don't play like him either. :icon_biggrin:
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Opened my Hammond package on my dinner break. Got a Hammond/Mullard 12AU7 but the tube in the 12AX7 spot turned out to be a Hammond 7247.
I was disappointed not to get another Mullard 12AX7, but I guess that 7247 tube is not all bad.
1/2 AU7 1/2 AX7 might still be useable in some guitar amp applications. :dontknow:
Both made in the Mullard factory in Great Brittan, so I'm hoping they are quality tubes.
I saw listings for more than I paid total for just the Hammond/Mullard 12AU7. I didn't even consider the other parts inside of the chassis.
A quick peek inside revealed some kind of reverb/percussion do-dad.
Almost like some kind of side by side coils/relays about the size of some swiss cake rolls. :laugh:
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I was disappointed not to get another Mullard 12AX7, but I guess that 7247 tube is not all bad.
1/2 AU7 1/2 AX7 might still be useable in some guitar amp applications. :dontknow:
No it's not bad at all.
That tube is some what rare, Ampeg among others used them.
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Great breakdown of the info HBP. Thank you.
But (sorry can't read it now) does it mention anything regarding caps "breaking in" or becoming accustomed to certain voltages being placed on them to where the dielectrics sort of "form" or "settle-in" similar to e-lytics?
2nd - Does it mention anything regarding outside foil direction/placement and the related characteristics or phenomena this may have?
The article says nothing about break-in time for any tests that I recall. It also says nothing about outer foil connection.
It's therefore unclear if the measured distortion increase (THD and/or IM distortion) with a bias voltage added is something that would settle down after a period of time to allow the dielectric to absorb all it can/will.
Unfortunately, I haven't scored a Telefunken 12AX7 yet.
I was lucky: the first good tube amp I had (a '67 Princeton Reverb) had all Telefunken preamp tubes in it when I got it. :occasion14: I played exactly 1 chord on that amp and knew it was massively better than the Peavey amp I had at the time.
Then I was lucky again years after: I bought 20 Telefunken ECC83's for $1 each at a hardware store in Nashville. :huh:
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7247=12dw7. Dual triode with a gain factor of 100 on the anode number 2 side and gain of 20 on anode number 1 side. You do find them in Ampeg's, however they are really nice to cascode in V1. It is similar to a cascode of a 12Ax7 to 12AU7. Makes a very tuby sound similar to a Octal preamp tube. Fat and warm.
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7247=12dw7. Dual triode with a gain factor of 100 on the anode number 2 side and gain of 20 on anode number 1 side. You do find them in Ampeg's, however they are really nice to cascode in V1. It is similar to a cascode of a 12Ax7 to 12AU7. Makes a very tuby sound similar to a Octal preamp tube. Fat and warm.
Now that's something I never thought of doing, thanks I'll try that. I thought old Ampegs only used that tube.... :laugh:
But that first gain stage 12Ax7 is the most important preamp tube. You can get lucky sometimes buying on ebay used old tubes but it's a crap shoot. If someone is selling one most likely the tube is beat.
Hey, JoJo want to sell any of those old tubes, just kidding but nice collection. I love the Philips Holland made eL84s, in an 18 watt.
Bottom line: tubes matter to me, only I'm not picky on rectifiers as long as the voltage is what I want.
K caps, plate resistors have a lot to do with tone but tone is subjective. One man's holy grail is another's junk....
Remember that first tube is the one to fool with as long as everything else is up to par...
PS: Don't get too sensitive, no thin skin allowed here :l2:
al
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I thought old Ampegs only used that tube
Magnatone is quite fond of that tube also. My M10A has one for the vibrato oscillator/driver. And Hammond really likes them. There are 3 in my AO-63.
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You can get lucky sometimes buying on ebay used old tubes but it's a crap shoot. If someone is selling one most likely the tube is beat.
I love the Philips Holland made eL84s, in an 18 watt.
PS: Don't get too sensitive, no thin skin allowed here :l2:
al
Got the tube lot thing covered in my junk gear thread. I have always had great luck buying the junk gear, those tubes have not been picked through.
I've got 1 Miniwatt and 1 Bugleboy EL84 made in Holland, that I want to team them up in an amp eventually.
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I thought old Ampegs only used that tube
Magnatone is quite fond of that tube also. My M10A has one for the vibrato oscillator/driver. And Hammond really likes them. There are 3 in my AO-63.
Sluckey, have you ever considered trying one in the AC15 Tremolo/Vibrato. I do not come close to understand the Vibrato circuit, but I think the AU side would then drive the tremolo and the AX side would drive the Vibrato.
Just wondering if the Vibrato would get stronger?
Now don't jump on me, I said I did not understand the Vibrato. :laugh:
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7247=12dw7. Dual triode with a gain factor of 100 on the anode number 2 side and gain of 20 on anode number 1 side. You do find them in Ampeg's, however they are really nice to cascode in V1. It is similar to a cascode of a 12Ax7 to 12AU7. Makes a very tuby sound similar to a Octal preamp tube. Fat and warm.
Now that's something I never thought of doing, thanks I'll try that. I thought old Ampegs only used that tube.... :laugh:
But that first gain stage 12Ax7 is the most important preamp tube. You can get lucky sometimes buying on ebay used old tubes but it's a crap shoot. If someone is selling one most likely the tube is beat.
Hey, JoJo want to sell any of those old tubes, just kidding but nice collection. I love the Philips Holland made eL84s, in an 18 watt.
Bottom line: tubes matter to me, only I'm not picky on rectifiers as long as the voltage is what I want.
K caps, plate resistors have a lot to do with tone but tone is subjective. One man's holy grail is another's junk....
Remember that first tube is the one to fool with as long as everything else is up to par...
PS: Don't get too sensitive, no thin skin allowed here :l2:
al
Yep Dude, it does work, but you still use a whole socket and you could use a pentode there. That is what a lot of people do, but they are cheap even in NOS which does provide a very low microphonic 12Ax7 section. I did one and made it switchable. Waste of time cause I never switch it off. :icon_biggrin:
I am adding a fun pot to the cathode of the lower gain side currently. When I tested doing it I ended up with a range of resistance from about 500 ohms to 2k. Doesn't sound very good at either end of travel, but it is still nice. You can go from warm and fat to a nice light overdrive.
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Sluckey, have you ever considered trying one in the AC15 Tremolo/Vibrato.
Yes I have, but not while I was hot and heavy on building the AC15. Too late now, at least for me, for 2 reasons... You would have to switch triodes. The oscillator needs the AX7 side (pins 6, 7, 8) and the phase inverter needs the AU7 side (pins 1, 2, 3). So you would have to rewire the socket. Also, I have a bunch of AX7s. I have no spare DW7s.
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There's a new made DW7 that they make either way, AX7a/AU7b or AU7a/AX7b.