My first amp build or rework

[Yona1973]

Well I'm getting close to finishing up my first amp, I guess rework or mod is more accurate. I was given an old Hammond organ that was going to cost more to repair than it was worth. So after a bit of testing I found the amp in it was good and working properly. I started off with a lot of reserch and schematics of both this amp and other amps. Then I just set up simple input and output to test it. After that that I added a volume control and with some help from a friend who repairs amps we changed some resistors and caps to take some harshness out. We tried to hook up the reverb but ran into some noise issues with the reverb so we disconected it. After a few more days of reserch and playing around with it I got the reverb working correctly with an amazing side affect, it developed a beautiful distortion once turned up about 3/4 of the way up on the volume which it didn't have before I hooked up the reverb. I don't understand yet how hooking up the reverb effected the tube distortion but I'm not complaining. The distortion is not effected by the amount of reverb or even if it is turned all the way down till there is no reverb. I then added a power switch. After playing it for a couple of weeks I felt it would get a little dark when turning the volume down so after checking the schematics on some marshalls and remembering about Jonseys trebble bleed kits I added a 470pf cap to the volume pot, hah problem solved. Well now happy with the sound so far I turned my attention to adding a fuse and replaceing the old 2 prong cord with a new 3 prong cord, also removed some wires and plugs that are of no use anymore. I've been useing a eq pedal as of late to fine tune the sound a little more. I've been thinking of addind. A tone pot or tone stack but have very little space left in this small chasie. Oh I almost forgot I did also add a power light to it, and thinking of a standby switch, but as I said I'm running out of places to be able to put pots and switches. But most of the small tube amps I've seen around this size (about 18-20 watts) don't have a standby. Guess I'm going to have to build a case for it soon and will try and get some pics to post too.

 

[eddy999]

sounds like an interesting project, glad it's worked out for you. Now where are those pics and clips?

 

[Reaperc89]

Sounds neat, some pictures and maybe sound demos could be interesting, would have never considered converting an amplifier from an old organ.

 

[Yona1973]

here is a few pics of the amp I haven't buit a case to put in yet. It's running a 5U4GB rectifier, 2 el84 power, 2 12ax7 preamp and a 12bh7a reverb tube for the spring reverb. I'm running it into a peavey scorpion 12" which currently resides in an old dean SS amp a friend gave me ..the amp was blown but the speaker was good. as far as organ amp conversion I believe trainwreck amps started from old hammond organ amps or at least there iron

 

[Yona1973]

well got started on the cabinet today and got it close to finished. Still lack the faceplate for the amp, mounting it in the case and putting feet on the bottom. But guys the best is yet to come ....wait till you see the faceplate for the amp. I hope to have it finished by sunday night. then on to the matching speaker cab.

 

[hipofutura]

The cab looks fantastic! Curious to see your faceplate as I just had one made last week.

Nice work.

 

[Yona1973]

well I'm making my own faceplate ....if it works out it will be amazing. the wood is Boxwood I think, but the thing is it has a lot of worm holes and something about secreations from the worms has turned sections almost a red color in a way and pattern as to almost look like flames. going to take a lot of work though as I am going to have to plane it as thin as I can and then sand till I get it almost a 1/16" thick. If it works wow it's really going to turn heads.

 

[Yona1973]

OK here it is! man am I glad this is done ...but wait there's more to come the matching speaker cab. But here is my moded hammond amp for guitar in its new case ....the pics don't even come close to what it looks like in person ...but will give you a good idea. This amp is almost as basic as it gets so it makes you work your amp and guitar knobs..the knob on the left next to the light, switch, and jack is your volume. the one on the far right is reverb...yes a spring reverb that part of the reason it's so tall. somewhere between 12:00 and 2:30 is max volume for clean, after that is natural tube distortion..I like the distortion at around 3:00 maybe a touch more. will try and get sound bits soon if any cares to here them ....let me know and I will try and get over to the studio soon and record a bit.

 

[hipofutura]

Well that's pretty cool. You've done a very nice job! Definitely a "one of a kind".