Anyone built a rev. unit but not a fender cct

[traynor]

I was just wondering if anyone has built there own reverb unit, like the 5G15 but using a different reverb cct. I really like the reverb in Ampeg's, and I'm going to start figuring out how to do it as a standalone.
Brent

[ETR]

Yes, I have. There's a lot of good circuits that don't use a transformer to hit the tank so hard. You'll need a tank with a higher impedance input.

[Diablo]

If you'd like to share the schematic and layout you develop, I'd really like to see it posted here. I like the Ampeg reverb too - sounds better than Fender to me.

[stokes]

I built a stand alone unit using a reverb pan from a Gemini VI.Dont have a schematic,and it was over two years ago.My son has it in Bklyn right now,so I cant even open it up just yet.I remember I had to use the circuit from the Gemini for the input and a bastardized output from the G15.I started out with the stock values and did a lot of tweaking to get it just right.Had to tame the output quite a bit.It had quite a bit of hum at first so I used a dc filament supply,there is a post about it that was recently resurected,see "DC filament supply" below.Like I said,I dont have my hands on it right now,and at my age,CRS is my reality,but if I get it back I'll try to draw something up.In the meantime,if you start it,you can always post things as you go and I am sure there are more than a few here,along with myself,who would be glad to help you sort things out.

[traynor]

Thanks for the input, and yes I will post anything i think of, or find. I'm going to use the 5G15 cct as a guide and implement the Ampeg reverb in it.
Brent

[stokes]

If you go with the G15 circuit,use a tank that matches the G15.As I pointed out,I had to use the Ampeg circuit on the input side.The tank alone wont make it sound like an Ampegs rev.

[luthierwnc]

I built a stand-alone unit a couple years ago based on the Ampeg Gemini I reverb. It came out really well. I prefer it to the Fender tanks which always sound a little sproingy to me. This seems to infuse the notes rather than shaking them. It was built to sit on a homebrewed 5E5-A and they fit hand-in-glove.

I pitched the schematic in a frenzy of shop cleaning. If you are serious about making one, let me know and I'll crack it open and review my circuit. One quick note about Ampeg tanks; you need to internally ground the jacks. In the original circuits, it is grounded in their complex star ground system. If you try to go directly from the schematic, it won't work. I spent quite a while monkeying with this until Mark Norwine on Thegearpage helped me figure it out. Here's the link:

http://www.thegearpage.net/board/sho...d.php?t=347906

Good luck, Skip

[luthierwnc]

Volts are circled. Everything on the board is attached to a piece of 14 ga Romex. It and the power grounds are star grounded by the PT (except the heater reference resistors). Even some of the short runs needed to be shielded. It is pretty quiet but I may put in a 100R heater pot while it is on the bench. Parts were whatever was in the bin -- mostly Xicon MPP caps with a few Orange Drops and 150's sprinkled in.

Hope this helps. Let us know how the project is coming.

Skip

[traynor]

Thanks for all the info guys, I'm going to go through my spare parts and see if I have the right tranny for this. I'll keep you posted.
Brent

[luthierwnc]

Most any trannie will work since you're only running three preamp tubes. I think the PT on mine is actually center-tapped. I just taped it off and ran it as a FWBR for more volts. Donor choke. Don't need an OT.

If you are working off the old Fender schematic, take a look at the power supply. It is a half-wave rectifier. I don't know if he used one side of a trannie he had laying around or what. It takes more filtration to smooth the DC. The reissues and every other device I've encountered use a full wave or bridge rectifier. This is where the Duncan PSUD program comes in really handy! In a low-profile version, you could even use a flat-pak wired backwards from a 12VAC supply.

Also, the tank # is 4FB3D1B and don't forget to ground the jacks!

Skip

[traynor]

Well I've finally built a stand alone reverb unit using the ampeg design. Sounds great. I followed the schematic somewhat given by luthierwnc. The changes I made were a 250K linear dwell pot and a paralleled 12AT7 as the reverb driver.I used a reverb pan that I pulled from an old Hammond L-100 organ, seems to work good. I plan on building more in the future, It sounds that good. Thanks for the schematic to get me started Luthierwnc.

Brent

[traynor]

Just another note in case someone cares or attempts to build an Ampeg standalone reverb unit. I've made a few more changes to the amp. I removed the 220K res.and 250Pf cap going to the mix control.
I also split the plate load res. on the rev driver 33K and 68K, the dwell feed was tapped between the two. Similar to fender where they used 10K and 100K.This mod was done to stop the rev from squealing if you were to unplug your guitar or the dwell was too high. I'll see how these mods hold up and post any new changes....R&D takes time.Thanks again Luthierwnc for the schematic to get things started.
Brent