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Hoffman Amps Forum image Author Topic: Finally...  (Read 3227 times)

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Offline 12AX7

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Finally...
« on: February 07, 2017, 10:45:27 am »
I've built several amps over the last 10 or 15 years, always trying to achieve a certain sound thats basically a marshall with preamp based overdrive. Most were el34 but this one which started life as a 18 watt and went thru several different incarnations even one being princeton based but ended up with the same goal as the el34 amp and with 6V6. I've tried endless variations that would probably be shocking to most because there were times i spent most of my free hours daily endlessly tweaking. But there was never perfection. There is a certain thing that happens when a amp of this type is right where it just breaks into harmonic at the drop of a hat even at low volumes. Where you can't really say the highs are bright or dark or the lows are dark or bright. Where balance is just perfection like everything fell into place and when you roll down the volume it cleans up in the exact way that it should. Theres a squawk and squish in the feel/tone thats utterly satisfying and makes you play your best. (at least if this is the type of tone u are used to) In short, not a single thing needs improvement. Perfect articulation, smooth yet crisp and defined, just perfection. Others may not care for it but i bet no one could fault it other than in a subjective sense.

I achieved that a few days ago by simply changing the ever important (seems like THE most important area to me) 2nd stage into stage 3. I have used every imaginable circuit configuration there but i think the difference this time was that i biased the first 2 stages very differently than usual. V1 and 2's cathode have 2.7k and 4.7k respectively with the same .68 bypass on both as always. But that biasing difference seems to allow me to go places with the stage 2>3 area that i couldn't go before without causing blocking or just bad tone.

Anyways, it's something that took me years to achieve and it turns out it was simple because you just have to have all the right pieces in the puzzle, and the final tweak won't work if all of the related pieces aren't in balance. This is all stuff most of you guys understand how to do in theoretically, but i'm just a player not a tech so it took me forever., But man o man did i finally nail it. This is exactly to a T what i was shooting for, the ideal mashall master volume tone thats what i have had in the past with some amps but never quite as perfect. A lot of work and endless hours of my life spent, and probably foolish since i could have bought this sound. But while i can't justify how i went about it i must say this is so satisfying !!! Every time i plug in i expect the tone to sound different and feel like it's changed for the worse, but every time it's tonal nirvana, and the perfection of tone that i feel is consistent because it so right that its relatively unaffected by the usual day to day changes you hear with gear in general. Anyways, i just had to shout it from the rooftops and this is as good a rooftop s any. The chassis went back into the combo cab for the first time in a very long time aside fro when i went to a few jams here and there, and it's staying ! :thumbsup:

Offline sluckey

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Re: Finally...
« Reply #1 on: February 07, 2017, 10:57:04 am »
Congratulations! Now for the ultimate challenge. Can you repeat those results with another build?  :icon_biggrin:
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline 12AX7

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Re: Finally...
« Reply #2 on: February 07, 2017, 11:09:41 am »
Congratulations! Now for the ultimate challenge. Can you repeat those results with another build?  :icon_biggrin:

You know, i think i could because while i know how that goes, i think it usually changes only because the design has flaws that are accentuated by slight differences in lead dress, component tolerance etc. I think that the more "right" it is the less it's affected by those things.But i have no reason to do so. Well, i WOULD like to just to have a clean build of this circuit because mine is a sloppy mess beyond anything you've likely seen. But i can't afford to do that.

Offline Ambugaton

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Re: Finally...
« Reply #3 on: February 07, 2017, 02:17:27 pm »
While it was nice to feel the excitement you must have while reading this... I can't help but wish there was some sound clips!!! Congrats

Offline 12AX7

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Re: Finally...
« Reply #4 on: February 07, 2017, 04:26:34 pm »
Put it this way....if i had sound clips of the amp today and some from just before the change, you probably wouldn't be able to tell. This is the kind of stuff thats as much if not more about the feel of the amp, and i doubt even i could tell the difference between them listening to clips, at least not easily.  Before it didn't sound bad at all, but i couldn't play well and i thought it was me. You had to work so hard to get the tones out of it you were shooting for it was hard to play. Now it plays itself. Soon as i made that change my playing shot thru the roof to where it normally was in the past. Thats not to say i'm a great player, but i'm one hell of a lot better today than i was b4 that change.

Offline Joel

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Re: Finally...
« Reply #5 on: February 07, 2017, 04:41:50 pm »
Schematic?
The mouth of a happy man is filled with beer  - Egyptian Proverb

Offline Ambugaton

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Re: Finally...
« Reply #6 on: February 07, 2017, 05:13:01 pm »
I suffer from the same dilemma, If I don't like my sound then it severely affects my playing ability. More so a problem is that we all know gear sounds different on different days/rooms/moods... for the longest time I thought I was just making excuses but then I get in that moment when I feel the amp and each note sounds sweet to my ears and it is night and day with what I can do.

Bottom line is confidence is the actual thing that makes us play better. Some people just have it, me... I need a little push to get that confidence.

Offline 12AX7

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Re: Finally...
« Reply #7 on: February 07, 2017, 05:43:37 pm »
Schematic?

Don't have one, but I can describe it. Look at a JCM800 2204 schematic and from the input on back change...

1. lose the 100pf on V1A between the plate and cathode
2. change the treble bleed cap on the gain to a 500pf
3. put another 470pf/470k treble filter on the wiper side of the gain pot (yes, i know....3 in a row but it works)
4. change V1B cathode from 10k unbypassed to 4.7k bypassed with a .68uf
5. remove the 470pf/470k between V1B and V2A and just go straight to V2A's grid from the coupling cap
6. change the 470k grid leak on V2A to 150k

From that point thru the power amp it's the same as a 2004 except....
1. 6V6 output section with trainwreck style 30w OT
2. 18 watt PT with SS rectifier
3. 10H choke between plates/screens
4. 22uf/10k nodes thru the preamp
5. Variable NFB

Thats basically it off the top of my head. Heres a 2204 schematic if you wanna compare...  http://schematicheaven.net/marshallamps/jcm800_lead_mstvol_50w_2204.pdf

Offline 12AX7

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Re: Finally...
« Reply #8 on: February 07, 2017, 05:45:04 pm »
I suffer from the same dilemma, If I don't like my sound then it severely affects my playing ability. More so a problem is that we all know gear sounds different on different days/rooms/moods... for the longest time I thought I was just making excuses but then I get in that moment when I feel the amp and each note sounds sweet to my ears and it is night and day with what I can do.

Bottom line is confidence is the actual thing that makes us play better. Some people just have it, me... I need a little push to get that confidence.

Same here, tho when i've had amps this right with this type of tone thats much less of a problem. In fact, it happened to me daily till i nailed this sound and it hasn't happened since. Every time i plug in it's the same.

Offline Joel

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Re: Finally...
« Reply #9 on: February 08, 2017, 05:02:03 am »
Thanks.  I'll save that info away for future experimentation.
The mouth of a happy man is filled with beer  - Egyptian Proverb

Offline Ed_Chambley

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Re: Finally...
« Reply #10 on: February 08, 2017, 05:18:40 am »
Just curious, what speaker(s)?

A few of us built an AC15 and we all added some mods a little differently.  It was an idea of Binwitt and Sluckey initially to rework the circuit into a Tube up Marshall 18 watt layout kind of.  Anyway, simply more logical and runs very cool.

On mine I combined the tremolo and normal channel putting the EF86 into Vib/Trem and added cap switching, I used 12 different values on a simple rotary switch.  I also slowed the trem circuit adding a resistor on a switch.  Built a single 12 cab, Celestion Blue, that can be closed back, 1/3 open and 2/3 open.  Well when building it I promised to make some sound clips and I did. I did not post any simply because they do not represent the best feature of the amp.

What I mean is if you need a Vox tone, I can get that with a computer model amp and even a pedal with a clean amp.

The amp turned out unbelievable in response, tone and feel.  After a lot of recording and listening comparing it to other it sounded as you might guess, an amp and while good sounding, the way the amp inspires cannot be recorded.  None can.

It sounds like your story and I get it.  Not the only amp I have felt about this way, but certainly is very disappointing not being able to capture this on a recording. 

Congratulations on getting your tone, it is sometimes tough to do so.  Can you buy this?  I do not think so but that just my opinion. Certainly someone else could build it for you, but I do not think anyone's idea of feel and the way an amp inspires are the same.

Offline 12AX7

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Re: Finally...
« Reply #11 on: February 08, 2017, 09:06:56 am »
Some things you can capture like the TYPE of tone. You can for example capture the fact that an amp sounds like a vox or a marshall. But the quality of the tone.....no way no how. And like i said, in large part because what makes killer tone is not the sound itself that you hear, but the way it responds, or as people often cal it, "touch sensitivity".  IMO that is what separates great from just good or mediocre.  that cannot be recorded.

Personally, whie this amp also SOUNDS great, i have never been one to be anal about the perfect tone. It's the perfect touch that i'm after, and if the sound itself is as good then i consider that the cherry on top. But if you offered me the choice of legendary tone like a dumble tone or TW or whatever, but without the touch aspect, i would take the tone of a average production amp like a peavey classic 30 or such if it had touch over the dumble ! I first noticed the importance of that aspect many years ago when i bought an amp i thought sounded amazing to replace my main amp of several yours. I tried to gig the new amp but i had mostly really bad nites where i played my worse. Eventually i realized what it was and went back to my old amp, which was a great sounding amp not not amazing like the new one, which i promptly sold. But that old amp just had touch dynamics that were great and the new one had none to speak of. Had the same thing happen once with a acoustic guitar. A larivee that sounded fabulous. It recorded great too. Just a fantastic sounding guitar. But after a while i never wanted to pick it up. Came to realize it was due to the fact it had no dynamics. It always felt and sounded like i had a compressor on whichmade it a total bore to play. I sold it and bought a recording king for $300 that was much better ! I don't recall what the larivee listed for, but it was $3000 last time i looked a few years ago.

I maintain that among guitar players the majority don't even recognize that it's touch they are after. They think it's the sound, but it's not that which allows thier playing to excel. It touch sensitivity, and when they play and amp like that they recognize how great it is, but they don't realize WHY they feel it's great. they think it's the sound. I was the same way till that incident years ago. This is why clips are so requested on guitar forums.

I remember a quote from Aspen Pittman of groove tubes many years ago that i read in a interview. He said, and i'm paraphrasing, it's not that solid state amps don't sound great, it's that they don't feel great. That stuck with me and one of the most important things i ever read about tube amps, an yet rarely do i hear people on forums speaking about that aspect when discussing amps and what is great and what isn't.

Oh, and to your question....open back with EV12L, my fav speaker in most any amp for decades. This one has gone to 100's if not 1000'sof gigs with me in many different amps. And speaking of touch, the 12L has a feel i like more than any celestion i've used which is why i love it so much. yet sound wise there are some celestions i like over the EV. I suppose a 2 speaker setup with both might be a good idea, but i also love the lightest gear possible, and one thing you DO NOT want is more weight than that EV already saddles you with.  :icon_biggrin: .
« Last Edit: February 08, 2017, 09:17:09 am by 12AX7 »

 


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