Amp discovery!

[ibanez48]

Ordered 2 of them. These Lilttle power amps are freaking awesome. I ran the line out of my Randall head into one of these and the out to my 4x12 cab to see what it would sound like. All I can say is awesome and it’s loud I could not turn it past 3 on my amp. The only thing I lost was some distortion from running the line out to this amp. But it still sounded good. Also I was running it at 21 volts. If anybody is interested this is what I’m using for the power supply. Got it from amazon u can adjust the voltage down to about 19 volts. I bought it because of the reviews. The only thing it’s really cheaply made. Other than that it works perfectly. Oh and one thing the eq on my Randall head sounded really strange with these power amps. I don’t know if that’s because my Randall has a passive tone stack. I’m going to build a active tone stack and see how it will sound with one of these amps. If your were building some kind of rack preamp this would b perfect for the power supply.

[Blackboarcult]

FWIW I've had the following TS (Gallien-Krueger 2000CPL) on my breadboard for the past two months, running in series after a Durham Sex Drive for added grit and volume boost, and it's by far the best active tonestack I've had the pleasure to test. The 4-band cut-boost gives it lots of versatility.
Absolutely great to test preamps and drive pedals, and I'm running it into a Baja Presence & Resonance (a MUST HAVE to breathe some life into dull SS stages), then to a Class D 100W poweramp. Beats most SS amps I've tried.

[ibanez48]

Thanks for the info... I remember trying out one of these in the late eighties. They sounded great and the chorus. They want to much money for them now. I guess because Iron Maiden used them on somewhere in time album lol.

[Blackboarcult]

Love that one!
I did a layout of the 250ML distortion section some time ago, I guess I'll post it once I verify it, as it's a bit messy at the moment. Getting the asymmetrical clipping working was a bit tricky... Good sounding 80's distortion, a bit sterile, but nothing a sh*tload of chorus-delay-reverb can't fix  At first I wanted to build the whole preamp + tonestack and put it in a box with a Class D amp, but I opted for modularity instead and I'm building it as I wrote above

[ibanez48]

Yes I would be interested in the layout for the 250ml.

[Blackboarcult]

Posted in the Unverified section ;-)

[thewool]

Hi, i'm about to buy an 8inch Jensen C8R speaker for the TPA3118 board.

Should I get 4ohm or 8ohm?


Any opinions or recommendations would be greatly appreciated!

[rocket88]

Since the amp is solid state it will work with either and adjust itself to the speaker wattage. The lower the wattage the speaker the more output you’ll get from the amp. The issue will be the wattage of the speaker, which needs to be higher that the amp or you risk blowing the speaker. I would spend the time to match the speaker to the wattage of the amp.

[thewool]

Cheers, thanks for the quick reply.


The amp board output power is 60W. It can accept an 4 or 8ohm speaker. up to 24V.

The Jensen speaker is 8 inches, 24W at either 4 or 8ohm.

(This is the largest speaker that will fit my cabinet.)


My understanding is that I would need to lower the amp supply voltage to not blow the 24W speaker?

So i'd need to lower it more for a 4ohm speaker than an 8ohm speaker?


I guess an 8ohm speaker sounds better, to suck more of the power? That right?

[rocket88]

You’ll want to run it at less than 24V, not sure how low though. The idea of higher impedance speakers sound better isn’t really the case, as each speaker has its own character. What I’ve found is that 2 speakers that are the same model, but one is 8ohm and the other 16ohm, the high impedance speaker will sound darker. Not better or worse, just a little different. You can always look at other speakers to see if there’s a higher wattage 8in speaker. Eminence may have one.

[thewool]

yep.

Already have a 24V 3AMP transformer, but might put a trimmer on an LM350 and test some voltages to be safe, also to hear how it affects tone, if at all.

Did a bit of reading and looked at the graphs on the data sheet. I think i'll be ok with the 8ohm Jensens. Going for a fender sound, hence the Jensens, also testing a few fenderish pre-amps ive made.

Also wanna test some different power amps, i'll also build some circuits with TDA2030 and TDA2050. See how they impact tone.

[ξεναγος νεκροπολης]

mxr mc-401 in to a dod 410 and with a switch you can add the model-T in series.
huge sound. very loud.
all in all a perfect build!

[cjonesplay]

This is rad. Is that a Hammond enclosure, or is there another brand that makes these awesome cases? They remind me of the old Shure rackmount units.

[ξεναγος νεκροπολης]

thanks.
those enclosures are common in greece i guess. every local electronics store has those

[Kinski]

Built an amp using at 3116 board, and a Catalinbread 5F6 board from PedalPCB. Power supply is a board that converts 120v AC to 24v DC (4 amps). Used the 24v DC to power the 3116 amp. And used a 7818 regulator to feed the 5F6 18v.

Everything works perfectly. Super loud and very low noise.

With two kids, I dont have much time for circuits these days, so I find using PCBs save me time. I'll get back to vero eventually.

Sorry I dont have a pic of the completed build. And I'm too lazy to open it up again to take photos. But here are some near completed photos.

[Travis]

Awesome Kinski! How does the sound compare to your 5e3 build?

[Kinski]

Whoa! Good memory, Travis!

Sadly, I can’t compare at the moment. Thanks to COVID, we are living somewhere else right now and don’t have access to my amps for a direct comparison. But I will let you know when I get the chance to do so! I don’t expect it to sound as good as my tube amps, but super impressed with this thing. Big, loud, and very “tweedy" sounding for sure. At 18v, the 5F6 preamp gets pretty clean on low settings but can really grind if you turn up the gain. And can clean up very well with the guitar volume knob. Exactly what I wanted - a small, light weight, 50w solid state version of a tweed amp.

[Frank_NH]

Very cool, Kinski.  I have a similar project underway using an available LM1875 power amp + power supply (20W - 30W output).  So, select a preamp to give you line level into your power amp.  I'm also thinking about adding a reverb circuit and possibly tremolo.  All this is built into a head cabinet, which should make for a very portable, lightweight head.  

It occurs to me that someone in the DIY PCB world should offer a solid state amp kit like this, with a selection of preamps (e.g. Fender, Vox, Marshall, Orange styles...), power amps, and additional effects modules.  Would be much less expensive than your typical tube amp kit and offer more versatility and options for customization.

[Kinski]

Looking forward to seeing your build, Frank! Why did you choose to go with the LM1875? I don’t know much about that one.

Amp kits would be a great idea. A one-stop-shop for this kind of stuff would be nice. You could get really crazy and hook a bunch of different “amp-in-box” preamps up to a rotary and have your choice of a bunch of classic amps. Would be a lot of knobs, but would be amazingly useful.

I like that the Catalinbread 5F6 has a toggle to switch to higher gain. In normal mode, the gain range is pretty much like a Bassman. Flipping the gain switch to high mode and you get into some pretty heavy territory. Not modern metal, but definitely a lot more than you’d ever get from a Bassman.

[Frank_NH]

Hey Kinski.  I found an LM1875-based SS power amp on eBay based on the github project here:

https://github.com/xform3/xfpcb-0003-amp

The amp came with the power amp board + power supply.  Of course one can source other power amps (as seen in this thread), but I wanted something with a versatile power supply so all I would have to do is supply the preamp.

I suppose all this may be overkill as you can buy a pedal-sized power amp today for about the same cost as building your own e.g. EHX 44 Magnum.  However, I kind of like the idea of an all-in-one SS head that you match with your favorite cab for gigging.

BTW, the preamp I am intending to use with this the L5 preamp from Aion Electronics.  I have an vintage Lab Series L5 (100W 2x12 combo), and the overdriven sound of the L5 on channel 2 is one of the best I've ever heard!   The problem is that the combo amp is a huge, heavy beast and not that friendly on your back, so I hatched the idea of creating a smaller power head version.   We shall see if it all comes together...