Turning a Preamp into a full solid state amp... cuz I love the sunn...

[jdoughty]

Ok, so here's mah deal... I love the sound of the Sunn amps. I've build the alcopolco gold and enjoy it, but I want something that's more interesting/versitile and I'd love to use something like that as my base amp. So I noticed there's schematics and even PCBs for PreAmp pedals based on the Sunn Model T using jfets isntead of tubes. While I could build it as a preamp and run it into an amp, I want it integrated... and then I saw on amazon that there are Class D amp modules you can purchase for like 12 bucks or so.

My question is, what do you think I'd get wiring such a 'pre-amp' pedal into one of these and use that as an amp? What considerations should I make myself aware of? I'm hoping this would let me have a small, light, Sunn Model T Amp that won't set me back thousands.

[GibsonGM]

It's hard to say 'what you'd get', JD...these projects CAN give you some good, enjoyable results.  But if you're looking to have an ACTUAL Sunn Model T, I don't think you're going to get off quite this easily, LOL.  But for the cost you might have fun with it.   It won't compare with the 'thousands of dollars' amp, no...

Personally, if taken all together the stuff isn't expensive, I'd give it a go just for having the project to do, out of curiosity and for learning.  You'd probably get a lot out of mating the 2 together and doing some mods, improving things here and there and so on.    You could build a combo, so there's some carpentry there for you too!   Only you can decide how your DIY time and money should be spent; I think many or most of us have messed around with this kind of stuff now and then, tho.   

Remember you need a capable guitar speaker...what is the power amp you're looking at? Maybe a power supply for it, too - just some things to think about. 

[mdcmdcmdc]

The TPA3118 60W power amp module is a popular choice for these kind of projects:



I haven't built one yet, but it's on my to-do list; people seem to really enjoy them. You could either keep it as a separate module and plug in whatever amp-in-a-box/preamp-style stomp box you like, or box everything together into one solid state ripper. Effects Layouts has a couple of nice-looking sunn projects available as PCBs, and Aion has some interesting stuff like a full IVP build as well as the LAB-series stuff. Heck you could even build a simple tube preamp to match.

[marcelomd]

Hi,

The idea is sound. My current setup is a TPA3118 module (plus utilities) and a preamp pedal. I thought about putting everything in the same box, but I like the option to change the preamp.

These things will work with 9V, but they need 24V for full power. In my case I added a little step down converter board to get the 9V for pedals.

I also added a simple buffer, aux in and master volume. They run from the 24V supply.

This module is very clean, very neutral, until it clips in a very ugly way. All distortion must come from the preamps, so adjust the input signal accordingly. You can add some diodes before the module, to simulate power amp distortion if you want.

[jdoughty]

Thanks so much for the thoughts and suggestions I'll look into the TPA3118 and see what I can do to get started. I'll have to look into guitar amp speakers next I suppose

[marcelomd]

Found the schematic of my simple input buffer:

[jdoughty]

Just ordered a pair of TPA3118s! fingers crossed this goes well! I just need to get some decent JFETs after discovering J111s really aren't meant for this...

[alexdestructor001]

Well, long time lurker here.
Some time ago I built a Sunn Preamp from TagBoard Fx (this one: http://tagboardeffects.blogspot.com/2016/09/sunn-model-t-1st-gen-preamp.html) it sounds amazing as a preampbut I had that exact same question: What if I build an amp using this as a preamp?
I built a solid state amp, used this as a preamp, slapped the thing inside a homemade cab, connected it to a 4x12 cab and let me tell you, sounds amazing.

[iainpunk]

the thing that makes a SUNN amp a SUNN amp isn't the sound of the preamp, which is basically a Fender Bassman, but its the insane output power. i mean, if the preamp pedal into a solid state power amp makes you happy, thats good, but it won't be what made the SUNN amps famous. i mean, 150W translates to a hell of a lot of clean headroom.

cheers

[jdoughty]

It may just be the overdriven bassman tone I really enjoy then. I know I've watched demos of Sunny model T preamp pedals and love the sludge they produce going into clean amps, so hopefully that character will translate. Koda effects had a really cool break down and video demo of the circuit they used for theirs and man, it just makes me excited!

[pacealot]

Agree with Iain; if there's an attribute that the real Sunn amps all seemed to share, be they tube or transistor, it's that they were loud. (Speaking as someone who used a Coliseum Lead as a bass head for the better part of a decade and was never accused of being too quiet on stage...  )

A guitarist friend of mine told a story once about using a Coliseum at an outdoor gig in the late '70 where he was so loud, he made the singer cry....

[jdoughty]

I'd heard a story of a band joking to a venue on being asked if they needed hooked to the PA that if they weren't an indoor venue there'd be noise complaints.

Yeah I know that's something alot of people cherish about the Sunn amps. As a guy who can't play loud after 8pm anywho though, I just want that Doom tone, the dirty cleans, and the wonderful stacking with muffs and rats. Hopefully that much will translate.

[GibsonGM]

Sometimes you just gotta make do, and try things. I'd totally do what you're proposing, I just wouldn't expect it to BE a Model T...no reason it can't be YOUR sound, though!  With some tweaking you should end up with what you need.  Punching small amps is awesome!   

[amptramp]

I'm not sure I follow the OP's request - does he want to run an amp inside a preamp case?  Even if you can find switching amps that work, you need room for a big transformer power supply (unless you want to go with switching for that as well).  That might be an interesting project - a switching amp operated form a switching supply with synchronized switching frequencies.