Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: ALBATROS1234 on March 05, 2018, 12:28:48 pm
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I started building amps because I am on a quest to get the guitar tone of my dreams. It's hard to describe exactly what I like about vintage amps tone though. I here the amp demos on YouTube for instance. I found I mainly like the early valco tone ,supro,national whatever from late 40s to mid 60s. I'm pretty new to tube building not tube amps though I have had and used many. I've tries to keep things simple single ended and raw but there's this scratchy scraannng that's missing. I have been using bridge rectifiers and mostly modern components except the tubes which all that I have used are old/used from the 40s thru 60s. I have tried to use octal preamp tube like supro amps although I haven't exactly miimiced a specific schematic but more so have borrowed concepts from schematics of amps I like. What can I do to get more of that vintage spank? Do I have to use only new old stock components or perfectly mimics specific circuit?or is it the rectifier? It seems to have helped to use lesser value on that caps like 33uf,10uf,10uf. My 1st and I used way to large cap values,you can strum audible chords for good few seconds after shut off before it goes quiet. The first amp definitely sounds more punchy and sterile ad well which I think is due to filter caps size. Any advice?
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Speaker has a big role how amp sounds.
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Don't know if it will solve your question, however
e-caps value and CC resistors have a particular impact on tone
Franco
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Tube rectification will smooth some of the ragged sterility you are hearing. This was certainly present in the amplifiers you mention. Time to build another one!
Jim
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Yea im always playing with stuff. This weekend I play with different preamp tubes
6sk7, 6sq7, 12ba6, 12at7 . Anyway I got a 12ax7 and el84 which i got a deal on the pair
Guess more trial and error coming my way
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Oh and regarding speaker I figured that long long time ago. Not new to playing music or tube amps, just used to buy and play thru them,lost all possessions in hurricane Katrina and having had tubes since until a few months ago when the desire to get some tone back in my life overwhelmed me. Actually I have a a couple 8" celestion a 10" celestion and a 15"eminence . The latter by far sounds the best. I mainly have played thru 4-12s most of my life. Started with a friend's Silverface quad reverb moved to a traynor head with a Marshall 4x12, then had a 70s 50watt marshall,later I got an ampeg v2b with me old Marshall 4x12.. had fun with some solid state too had a sunn concert lead and ampeg ss150. Been wanting to get more of a vintage supro/valco sound now.
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I found I mainly like the early valco tone ,supro,national whatever from late 40s to mid 60s.
Those amps, mostly used cheap ceramic disk coupling caps.
They added some grit.
There are different types of ceramic disk caps, some ceramic disk caps are very high guilty. You don't want the good sounding caps if you want some of those old amps you named grit.
There's a thread here on do caps sounds different, it has some info on this.
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IMHO a big factor is plate voltage. Modern amps tend to use hi voltages to max stated Wattage output specs. Higher amplification changes the shape of the signal wave from rounded sine > more rectangular or saw-tooth like: steeper side walls, harsher shoulders, sharper tip. Every gain stage and the power tubes produce another set of harmonics. Higher gain emphasizes odd-order harmonics. Lower gain retains more of the the roundness of the sine wave, and instead emphasizes even-order harmonics.
2X 6L6's in PP can produce up to about 20W, or up to about 60W, depending on plate voltage. The difference in perceived volume is minimal, because that's logarithmic. There's a tonal difference.
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i did hear recently that ceramic coupling caps add a touch of grit, thanks.
also plate voltage is something i had not considered,this is why i posted the question here. i havent used very high voltage yet. my first amp has a metal 6f6 with about 275vdc on the plate. the second which has a 12aq5 has less it gets more like 265vdc on the plate. i did an experiment last night coincidentally with a 12ax7/12aq5 first using a transformer with 285vdc at node 1 getting close to 260vdc on the power tube plate, triode plates got 107/114vdc . i then hooked up a back to back doorbell transformer array giving 156vdc at node 1 and ony getting 124 on the pt plate with only 54vdc on each triode plate. the volume was slightly lower but it actually didnt sound much different suprisingly. granted i only played for a minute or so on each transformer, perhaps i should revisit and check out tone more closely.thanks
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There's a tonal difference.
JJ is correct, higher plate volts does equate to a big tonal difference. I've been beating up kt88's running them as low at 340plate and as high as 440ish, hold all other variables equal and you have 2 completely different sounding amps. OT's, PI type also add flavor. one of my "twists", I use an OT rated for 80W in a 25W amp. I also use an inter-stage tranny as my PI, I've done a couple cathodyne type PI's that I would then change out for a tranny, again, enough change to think it was a different build.
The biggest thing, as you're experimenting, document WELL, next year when you're ready to "kill-it", you'll be running all over looking under the couch trying to find what it was when I did............ :laugh:
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The player :icon_biggrin:
It's all in the fingers.
Just couldn't resist :laugh:
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to a certain extent you are right dude, tone.attack is is the players fingers but i have heard the same guy sound way different with a different amp or guitar too so optimizing gear does help or else we wouldnt have a hobby we could all just buy a solid state combo amp with an 8" speaker and a boss overdrive pedal but that wouldnt be very fun now would it?