What circuit to mimic a raging vintage solid state amp?

[Bill Mountain]

The question is easy enough.  What circuit would make a good approximation of an old Peavey/Kustom/Road/Traynor/Sunn/Acoustic/etc.

I thought maybe something with a 386, a Rusty Box clone, or maybe just a wide open FF, or a boost driving a differential pair, or a TSF driving an old Ge tranny, etc.

I peaked at a few schematics which makes me wonder about copying the power sections but really I'm just looking for something close for those fly gigs where an old lead sled is not an option.

Any good ideas?

[Kipper4]

Take a look at the Deacy amp Bill might be what your after.
I think Dino did a thread on it.

[Gus]

Bill
I don't understand the question
Are you posting about an effects box to go into a DI?

Some solid state amps use voltage feedback This lowers the output resistance in the smaller signal output range (output voltage current drive)
This causes a different interaction with the speaker and cabinet(s)
This changes with drive level

I think most of the sound is amp speaker cabinet interaction and the volume.  Speaker cones break up different at volume

Some solid state amps use current feedback or a mix of current and voltage feedback

Some solid state amps use switching circuits(called class D)

The preamp clipping and EQ could could copied easer the output section speaker cab might be the issue

[Bill Mountain]

Take a look at the Deacy amp Bill might be what your after.
I think Dino did a thread on it.

This is a good idea.  Thanks!

[Bill Mountain]

Bill
I don't understand the question
Are you posting about an effects box to go into a DI?

Some solid state amps use voltage feedback This lowers the output resistance in the smaller signal output range (output voltage current drive)
This causes a different interaction with the speaker and cabinet(s)
This changes with drive level

I think most of the sound is amp speaker cabinet interaction and the volume.  Speaker cones break up different at volume

Some solid state amps use current feedback or a mix of current and voltage feedback

Some solid state amps use switching circuits(called class D)

The preamp clipping and EQ could could copied easier the output section speaker cab might be the issue

OK.  Here is some more details to hopefully clear things up.  I play bass.  I use to exclusively play vintage solid state rigs.  On occasion I ended having to use provided backline so I go tired of lugging around my Acoustic 370 rig only to be told not to use it.  So I sold off my Acoustic 370 & 140 and I returned a Sunn Coliseum Bass and a Traynor TS60B that was on permanent loan from a buddy.  I have owned some class D amps and I agree they do not overdrive well but I believe most of the vintage stuff was AB amps made with high power BJT's.

I realize now that I am missing that grinding solid state distortion tone in my setup.  I though a BMP or two would cover it but I'm not yet satisfied.  So...I was looking for ideas on how to replicate it.  Either with known circuits, cloning an amp, or experimenting.  I'm more interested in the sounds from SS power amp sections as the preamps usually do not over drive well (except for maybe the Traynor).

Stuff like the Deacy amp mentioned above or maybe just a highly distorted transistor boost would work.  I'm not necessarily looked for an amp in a box.  Just a good circuit with a good SS grind.

I will also state the output stage will be a LPF with a slight bass boost to mimc a cab response.  I don't intend to run it direct.  It's just more for taming high end sizzle and to keep highs out of tweeters.

[Gus]

I would try a NS chip amp like a LM3886. 
Lots of stuff of DIY the web you can even buy built boards

[Bill Mountain]

I would try a NS chip amp like a LM3886. 
Lots of stuff of DIY the web you can even buy built boards

Thanks!  Do these overdrive well?

[tca]

> Just a good circuit with a good SS grind.
You could try a 9V version of the Peavey Standard preamp. Something along these lines:



P.S.
Or a two stage PNP-NPN old school opamp (which is basically what the Peavey preamp is). I'll try and look for one.

[Gus]

I have not tried them as guitar, bass amps.  I have not built with the 3886 but I have used another NS chip for audio and it sounds fine.

If I was to build it for bass I would run it at the specs lower voltages or use higher resistance speakers to help keep the protection circuit from turning on, 

[Bill Mountain]

I have not tried them as guitar, bass amps.  I have not built with the 3886 but I have used another NS chip for audio and it sound fine.

If I was to build it for bass I would run it at the specs lower voltages or use higher resistance speakers to help keep the protection circuit from turning on,

Oh...so you mean to use this as an amp?  I guess I wasn't clear but I am looking to build a pedal that sounds like an old solid state amp.

I have some ideas I want to try.  One of them is you NPN overdrive I saved somewhere on my hard drive.

[Bill Mountain]

> Just a good circuit with a good SS grind.
You could try a 9V version of the Peavey Standard preamp. Something along these lines:



P.S.
Or a two stage PNP-NPN old school opamp (which is basically what the Peavey preamp is). I'll try and look for one for example.

This looks cool!  I like the old-school opamp idea too.  Maybe I could do a Bluesdriver without clipping diodes?  Or just cascading differential inputs.

[Gus]

OK
I would use an Opamp stage
You could try something like a 741 with its lower gain bandwidth
What voltage(s) will be available I ask so we can set the opamp load resistor value for more distortion
Drive/clip the opamp then send it to a speaker sim This might only sound good with a clean amp speaker after it.

What amp will you be using?

Have you tried any of the devices like the line 6 bass Pod?

[Bill Mountain]

I haven't used a POD recently but I do have a DM4 ( Line 6 distortion modeler) that is pretty fun to mess around with.

Voltage is negotiable.  Anything that would be easily achievable in a pedal format.  I recently built a TSF that runs at 3 volts which is pretty sludgy sounding so I'd love to experiment with starving opamps too.

Your post reminded me of a circuit I built many many many many many moons ago.

It was mainly an experiment in pre-distortion filtering that I designed for one of those builder contests.

I remember this had that throaty SS tone I've been thinking about.  Time to find my box of dead pedals.  But I know a little more about circuit design now so maybe I could stand to make a few improvements.

There exists a video of this on the breadboard.  I need to find it!

Edit: Found the video! "The Hobo Cannon" DIY bass distortion & fuzz.: https://youtu.be/0bTSpaGFItM.  This could be tweaked to get something cool sounding.

[Gus]

If you give the first stage a little gain X2 or more you can reduce the feedback resistor values of the 2nd stage for maybe a little lower noise
However you have the 1/2 voltage node getting wiggled by the first stage output so if you change the gain you will change the amount of wiggle going back to the first stage input
Did you do this on purpose or by accident?

Have you tried a 100K  and 100 ohms for the 741? increase the two cap values X10

For bass have you tried two .1uf in the tone control

[marmora]

Here is some info on replicating a Sunn Beta Lead sound:
http://www.diystompboxes.com/smfforum/index.php?topic=106487.0

CMOS inverters:
Maybe the ROG Double D?
Red Llama
22/7

Let us know what you find

[Blitz Krieg]

http://www.diystompboxes.com/smfforum/index.php?topic=101178.0