Conn organ conversion to amp

[scottpetersen]

Wow, that's an amazing amp! I used the same type of bias meter on my Citation II.

 

[richwalters]

Wow, that's an amazing amp! I used the same type of bias meter on my Citation II.

I made 3 of those amps (one sold); mechanically have to take the weight of iron which becomes a disadvantage, in having to reinforce the chassis like a ships rib..and also the heat.This wouldn't be the case with a lower wattage amp.
As a fireman I can handle the weight straight lift ~50kg, but amp certainly won't get stolen easily. Otherwise "don't bite off more than you can chew".

I'm currently revamping the specs; always alterations.... thd stuff encl. The all important phaseshift re-doing. Note the 4mm racket type bus earthing with two thick straps at the upper input end which is the tribute to the performance.This requires a large wattage iron. I used nomex tape over critical components to avoid damaging the thin insulations which is easily done these days...
4 stage B+ for the o/p stage, 200;300;400;600V all selectable A;AB for audio quality; and/or B for MI. I will do a graph of the distortion on this setting.

richy

 

[scottpetersen]

Do you hsve a topside pic of your amp? I couldn't find one.

 

[Braet]

Do you still have schematics for the Conn 541?

I know this is an old post but I just acquired the same Conn 541 organ from my inlaws.
Do you still have the schematics for the 541.

I can provide my email if you have them.

Thank you
CBraet
Ontario
Canada

I have a Schematic for a Conn 541 Organ that has a tube layout like this the chassis number is not something I know right now as my organs are stacked like cordwood(maybe 59092-7 on schem). I got the original repair manual from a source that sells the whole manual. They are organ enthusiasts so it is not a good idea to pose the proposition we are discussing.

The schematic is a 3 part fold out with parts on other pages. In a nutshell, mine uses the poweramp section to power up the amp as well as the offboard tubes that are 12au7's used as keyers(so #24 tubes using both halves one key each). There is also an output for the Leslie. The amp uses an OA3 tube for voltage regulation. By the way the Organ is 1963 with Cleveland 12" Alnico speakers.

The Two problems with the conversion I have found so far is that the amp is basically a 2 channel amp with one channel called Flute and one channel called String. The difference in the amp is non-existant. The amp is just a Stereo Amp. The second problem is the preamp for the String and Flute channels are off board in the top of the organ and it is Solid State? 1963??Solid State preamp's were cutting edge and expensive. There are transistors and the both channels are colored with different tone parts (caps etc..) to make the flute(hollow bass) and the string(high treble). Oddly there is also a tube in the preamp but it is a tremelo circuit. So in a nutshell we have a Power stereo amp needing a preamp and tone section. It would be easier to convert this to Audiophile Stereo use.... However the Power Transformer is built large to power up all the key tubes and the other tubes, so it can easily handle a couple preamp tubes.

 

[vrusso123]

please post this schematic here or send me a copy!

 

[res0i0tv]

Are you willing to email the schematic for the Conn quad 7868, dual 12AX7-power amp Sir? I kept this one out of the dump. gave away any parts that were reusable so that is the best that I could do. Thank you either way and have a good 2014. Stay Tonal, Tom

 

[vrusso123]

I have the quad 7868 amp (free dumpster find). rebuilt it with no schematic. changed all caps and a couple burnt resistors. got a quad of NOS 7868 sylvania's locally for 100.00. this amp sounds amazing. dead quiet and sings like an angel. this is my first tube amp for hi-fi, and has replaced my Luxman M-117 solid state powering Martin Logan Aerius I's. I can't imagine what the fisher 680a that I just got is gonna sound like!

 

[res0i0tv]

Conn 7868 quad, dual 12AX7 stereo

You have me on edge now! I have only listened to mine with a keyboard. WOW it was clean. I only mod my organ amps very little for guitars. R1,r2, maybe fixed bias. 1m pots for master volume. I rigged a Conn dual 6l6GC- dual12V6 and dual 12AX7s each side. Stripped the "field coil" amp out. Not needed...
Ultra clean at moderate (loud) volume BUT!!! I use in this order stomp boxes-- 1981 DOD 250 OD into a Boss 63' Fender reverb (recent release-best I have found yet) into a 1981Electro-Harmonix Clone Theory to split the single for stereo. The bypass has a little gain there. The DOD does the work for the tone and overdrive.. Man I love the Conn PTP design period. The best. It's ugly but the sound achieved is pure sweet. Kids got a hold of these amps before I could save them, bummer. Saved all parts that I could, give them to friends local. I'm east of LA. I'm getting off thread, sorry folks..
That 12AX7 on the 7868 looks like a modified split tail splitter-really different wiring. drew out the schematic but I have no values!! Mine was in %100 order, all caps just fine, lucky day.
Think that you might post a jpeg of your guts on yours? Thank you in advance. Thank you for responding too, nice Bro. More later....

 

[Braet]

Conn Organ schematic

Tom:

My Conn is a 541 so without seeing yours I'm not sure it is the same.

Here is a link to the Conn 541 schem
See Hanger-18; post 18 and 19
Organ Conversions - Guitar Preamp/Master Vol/ Tone... Help!


You can view my youtube video here:
Conn minuet 541 tube amp conversion for guitar - YouTube
Check to see if it is the same

Braet

Are you willing to email the schematic for the Conn quad 7868, dual 12AX7-power amp Sir? I kept this one out of the dump. gave away any parts that were reusable so that is the best that I could do. Thank you either way and have a good 2014. Stay Tonal, Tom

 

[res0i0tv]

Conn 7868x4, 12AX7x2, stereo

Braet,
You made my week fellow!!!!! It is the correct schematic that I need and then some. I really needed the values for safety, don't want to blow the OPT's or any tubes. Tomorrow I can't wait to study the schematic- compare it to my layout too. I did remod my two bottoms (4x12s") back to 8ohm, previously I wired them 16ohm stereo for another Conn. Anyway, i did plug my Gibson in followed by the DOD250 OD and the clone (2Xoutputs for stereo). WOW this thing sounded great even though there was minimal gain, very minimal. I'm dropping the amp and the preamp into my EPI Valve Special combo box! The hidden amp thing, lol lol. Mount the preamp to the back "door" hinged for access. It's for those jams that others seem to keep cranking theirs up for some stupid reason! The EPI is modded with MM OPT and choke- it screams tone. "OK boys, MY turn." Next is the preamp. Cloned following the EPI, I really love the layout and tone on it. As soon as I have finished this baby, I'll send you a few pix.
I want to thank you so very much. As mentioned before, I salvaged the organ best that I could. I just thank God that the kids couldn't get the back off. Oh what a hammer can do to a nice piece of gear, just plain sad. Until then, have a TONAL week and I look forward to our next contact.

Thanks Again and Respectfully,
Tom C.

 

[scottpetersen]

An externally hosted image should be here but it was not working when we last tested it.

broken link, cannot edit

 

[vrusso123]

THANK YOU so much for that schematic Braet!!!!

 

[scottpetersen]

I went through the amp and drew up the original schematic for someone if they want it.
This is for the Artist 720 (4)7027 (2)7868 (2)7199 (1)12AX7 (3 channel 100 watt amp)

 

[kc7fys]

Well, the conversion of the Conn 6026 Organ amp to Guitar amp is complete. I like it alot!! If anyone has a 6026 they want to sell let me know. I would love to have a second as a backup amp. here are a couple pics.

Is there any chance of getting any more information on this conversion? The pictures are very nice--but did the builder tell you what he did at all? DIY audio and all. Thanks!

 

[dan stevens]

conn conversion

hello, what I got is a tube less chassis,,,590907 conn organ amp, would like to use as bass guitar power amp run though a Carvin pre amp, l want to be able to run bass/treb speakers separately.