http://www.hammondmfg.com/pdf/EDB1760J.pdf
It is Hammond OT for Fender Pro Reverb or Vibrolux.
Can I use it for JCM800 with 6L6/5881?
(With no circuit change)
Does anyone tried this?
Can I use Hammond 1760J OT for JCM800?
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Stevem
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Re: Can I use Hammond 1760J OT for JCM800?
Yes you can , you do not even have to move the feedback wire as both Amps pull that voltage off of the 4 ohm tap!
The bolt down pattern will likely differ and you may need to drill new holes and or extend some of the wires on it.
The main issue is that your going to need more bias voltage for the 6l6 type tubes, about 10 volts more overall than what the amp has now.
The USA versions of these amps came with 6550 output tubes so the bias circuit should have the needed range, to check this yank out the outout tubes and measure the - dc voltage on pin 5 of one of the output sockets and open up the bias trim pot fully and see what you have for max voltage.
The bolt down pattern will likely differ and you may need to drill new holes and or extend some of the wires on it.
The main issue is that your going to need more bias voltage for the 6l6 type tubes, about 10 volts more overall than what the amp has now.
The USA versions of these amps came with 6550 output tubes so the bias circuit should have the needed range, to check this yank out the outout tubes and measure the - dc voltage on pin 5 of one of the output sockets and open up the bias trim pot fully and see what you have for max voltage.
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
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psychepool
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- Joined: Fri Apr 18, 2014 8:29 am
Re: Can I use Hammond 1760J OT for JCM800?
Thanks for your reply!
My plan is make a clone amp. Not modifying stock amp.
I bought the 1760J OT for make single-channel Pro Reverb, but the plan is changed with JCM800.
I don't want to throw the OT in the trash.
You mean, I can use the OT for JCM only with bias circuit(voltage) change?
My plan is make a clone amp. Not modifying stock amp.
I bought the 1760J OT for make single-channel Pro Reverb, but the plan is changed with JCM800.
I don't want to throw the OT in the trash.
You mean, I can use the OT for JCM only with bias circuit(voltage) change?
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Stevem
- Posts: 4587
- Joined: Fri Jan 24, 2014 3:01 pm
- Location: 1/3rd the way out one of the arms of the Milkyway.
Re: Can I use Hammond 1760J OT for JCM800?
No, since you are starting from scratch your good to go OT wise, but now the question is what PT are you going to use and does it have a seperate bias tap with enough voltage for the 6L6 tubes you will use, or will you have to tap voltage off of the main B+ and then lower that down for your bias voltage needs. If you are doing that latter then the dropping resistor should be a 3 watter to be on the very safe side.
If you go to Triode electronics you can look at the tube spec info for a 6L6gc and check out how much bias voltage you will in on pin 5 for a givin plate voltage and in fixed bias mode!
If you go to Triode electronics you can look at the tube spec info for a 6L6gc and check out how much bias voltage you will in on pin 5 for a givin plate voltage and in fixed bias mode!
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Re: Can I use Hammond 1760J OT for JCM800?
It's not a very Marshally OT, bit under-specd, I'm thinking Fender was still thinking their amps would be played clean at modest volumes when they designed those 2 amps. Go ahead and use it but go to some seller's site (ie Hammond 1750N) and get the foot print for a proper Marshall OT and leave yourself some room and plan around the orientation, holes, and wire runs just in case you want to swap it in the future.