Simple solid state amp to build?

[Mike K]

The long established method to emulate speaker-amp interaction with SS amps is speaker current NFB.
No additional cab simulation required.
Read teemuk's book.

Fair enough - but this does not mean that this is not a valid method. Just because you know one method, does not mean that others do not exist.

[glebert]

If you are looking for a simple SS amp to build, I would nominate the Marshall Lead 12. I have one that has been rebuilt a couple times, with semirandom parts, and it sounds amazing. The only downside of that is using Darlington output devices, but you don't have to use the metal case original type.

[Axtman]

If I remember correctly "Electric Guitar Amplifier Handbook" by Jack Darr has some solid-state guitar amp schematics. Unfortunately the free PDF copies I have found online do not have the schematics in the back. That said the PDF still has great information....and it's free!

I have not had experience in building SS amps.

[Mike K]

Read teemuk's book.

Perhaps you might want to again. Pg 237-238 show the application of the gyrator in said Marshall patent. Figure 6.45

[Mick Bailey]

I've used mixed-mode feedback in a few SS amps and it works really well. I have two Sessionette 75s, one with mixed-mode feedback and the other stock. The difference is substantial, especially in the lower frequencies where there is a lot more power and an extended lower range. The main downside is an increase in hum as a result, due to the extended lower range. It certainly sounds more tube-like compared with the stock amp.

The last SS amp I've experimented with was a cheap and small 100W class D board with a tagboard tube preamp running off a DC-DC converter to give the HT, all powered off a 24v supply. This resulted in a really good sounding amp capable of being used live and worked out really cheap to build. The flexibility is in experimenting with the preamp gain stages and tone controls, made straightforward by the use of tag board.

With SS amps I start with the power amp and power supply design and then work back. Nowadays I tend towards a minimum parts count power amp using ICs or modules because they perform so well and are relatively cheap.

Edit: Take a look at this - 14W with a versatile preamp. The link to the stereo clip works if you want to take a listen. Any preamp would be fine - essentially running a pedal into the power amp, and I particularly like the Runoffgroove stuff.

https://www.tdpri.com/threads/14-wat...da2030.144427/

[Chuck H]

I think the suggestion for the gyrator circuit seems fine for a headphone amp or headphone output since a speaker is typically NOT in use in that case. And I think the speaker derived NFB should be a good solution to correct damping when a speaker IS in use. I see no reason both circuits can't be implemented on the same amplifier.

Play nice you guys. I don't like problems.

[Helmholtz]

Perhaps you might want to again. Pg 237-238 show the application of the gyrator in said Marshall patent. Figure 6.45

Thanks, will do. Always eager to learn. That's why I asked in post #6.

[Mike K]

I think the suggestion for the gyrator circuit seems fine for a headphone amp or headphone output since a speaker is typically NOT in use in that case. And I think the speaker derived NFB should be a good solution to correct damping when a speaker IS in use. I see no reason both circuits can't be implemented on the same amplifier.

Play nice you guys. I don't like problems.

I think this is a typical application. But I don't think Marshall had that intent when they proposed it. I think it was actually meant to be used to drive a large speaker - it's pretty obvious from their patent claims. Seen as how mixed mode NFB is much simpler, I don't know that anyone, other than a hobbyist, might try this method. But I read on another forum of a person trying to develop a more sophisticated model to emulate an OT and speaker - it's probably overly complex and not very fruitful, but I'd love to hear more about the actual result before I disregard it.

Again, I came across the notion by looking at modern headphone amps. That then led me to wonder if it wouldn't work driving a large speaker, and I came to read a little about it. It seems the tradeoff, from the little that is known about actually applying it to driving loud speakers is noise and complexity. But it apparently works, to some degree.

[Mike K]

Thanks, will do. Always eager to learn. That's why I asked in post #6.

I apologize then. Your post seemed condescending to me. Perhaps just suggest an alternative and do a search before immediately criticizing. I saw your post earlier and purposely did not respond because I figured you could find the information I did. It's not an invention, I'm pulling up information based on past research. It may be useless, but it may lead to something else. Never know unless we question it.

[Axtman]

Here is the Jack Darr book I mentioned in my earlier post. It is too bad they left off the schematics in the back.

https://www.trinityamps.com/ForumGal...r_Handbook.pdf

[Tassieviking]

For a small SS amp I think the Marshall 12 watt is a great one to build, I have built 2 different ones so far.
I made a PCB that I can use to build 5 different Marshall 12watt amps on, I found 5 different schematics online so I made one PCB for all.
I also looked at the Marshall 30 watt schematic and added the differences to my PCB, so I can build 5 different 12 watt pre-amps with 12 to 30 watts output on the same PCB.
I left the Gerber files and schematics on SSGuitar.com site. https://www.ssguitar.com/index.php?topic=5164.0
You have to log in to see the files.

Another way to build a ss amp is to build one of the many pre-amps in pedal format, you can always stick the PCB in a bigger box and run wires to the pots mounted on the front.
I think Aion has the Lab L5 in pedal format in a kit as well as the SUNN Beta pedal you can build, just search pedal pre-amps and you will find lots of PCB's you can buy and build that will fit in a pedal or you can wire the pots and put it in a chassis.

I have a Sunn Beta Pedal I use on the bench and then I have a 125B pedal I stuck a mono TPA3116D2 100w amp module in that I run of an old laptop power supply.
2 pedals and I have a 100 watt amp if I want to use it, great for testing and mucking around with.

I built a full size Sunn Beta Bass pre-amp but I haven't finished it yet, same PCB for the Bass or Lead pre-amp.
I am working on getting a PCB ready for a Lab series L4 pre-amp, that one will be mated to a class D 1000w amp module that's pre-built from Ebay.
I will de-rate it to 500 watts max at 4 ohm for reliability.

[glebert]

Tassie, that is a great idea about the PCB, and great that you are sharing it. I love the idea of putting the 9v regulator into it. Seems like most of the space in a Marshall 12 is just air, it would be cool to try it get it down to pedalboard-ish size. I haven't had a chance to register to see the pics and files yet.