Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: basschops1528 on September 13, 2016, 11:45:24 am
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Hey all,
I have a friend who seems to really like the Jubilee. I've taken a look at the schematic and It's a little hard to decipher with the relay channel switching and such. I have a feeling that it's not much different than a counterpart from that era (JCM800?), or possibly the exact same. He's convinced we could put the preamp section to another low wattage amp. I don't see it having much of an effect regardless. I've recommended building the stout. Could someone compare the Jubilee to something like the Plexi or other amp of that era? I'd like to know how different it is and if I could pacify him with something like a "Jubilee stout", preamp+ EL84's.
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If your friend likes preamp distortion you can. A 12Ax7 distorting sounds pretty much the same regardless of the output section provided you are not overdriving the power tubes. You cannot get small bottle tubes tubes to sound like EL34's or 6L6's for that matter.
If you friend likes the Silver Jubilee clean channel running on about 3 and using a boost pedal to overdrive the preamp, which is what most do when using a 50+ watts in a small room.
In looking at the 2555 Schematic I would suggest trying the 6V6 plexi and add a hotswitch gain stage and I believe it will get as close as you can. I mean you cannot get the sound of 4 EL34's being pushed without giving something up. Also, you can always try something cheap which is purchase the Joyo British pedal. It is surprising how it makes a little fender amp sound very Marshally. Marshall and Friedman and a lot of others are beginning to use diode clipping for overdrive.
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Thanks Ed.
Diode clipping? Sounds kinda lame to me. Maybe for a cheapo distortion pedal, but for good quality tone and overdrive I'd prefer cranking a small watt amp. I did see some sort of clipping circuit in the Jubilee.
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http://el34world.com/Forum/index.php?topic=11058.msg101838#msg101838 (http://el34world.com/Forum/index.php?topic=11058.msg101838#msg101838)
More photos: http://www.fydamps.com/photo6.html (http://www.fydamps.com/photo6.html)
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Thanks Ed.
Diode clipping? Sounds kinda lame to me. Maybe for a cheapo distortion pedal, but for good quality tone and overdrive I'd prefer cranking a small watt amp. I did see some sort of clipping circuit in the Jubilee.
Yes, I know it sounds strange, but I built the same circuit from a Timmy pedal to create a third channel. When switched on I have a preamp tube and 2 additional gain stages which are mild and make a nice chunck tone for channel 2, but between the 2 additional gain stages resides the Timmy circuit. This allows me to control the gain and volume at teh last stage prior to the Phase Inverter. This all but eliminates the doide clipping's sterile sound and makes for a monster lead channel.
The reason I selected the Timmy circuit is it has a Bass Control and I can roll off still using the lead channel.
I did not make the amp for me since I am mainly a clean player, but it did bring out some old Whitesnake from my geetar. I know we shy away from Solid State Transistors ans diodes, but pedal boards are full of them. I guarantee you friend does not know he is getting his distortion via diodes and preamp in the Silver Jubilee.
That being said, I just finished a 6V6 Trainwreck and I will say for clubbing playing Classic Rock or 80's rock it is probably the best amp I have ever played using no pedals. One thng I did do is make it so I can lift a bypass cap via a footswitch which gave it a very nice clean tone very similar to teh JCM800 clean.
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Tell me more about this Timmy circuit, I've never heard of it. I also tinker with pedals so I'm always looking to learn more.
Also, Drew, would you be willing to share your build info/ schematic layout for the Jubilee? He absolutely loved the idea of a low watt Jubilee and I know for a fact he would do it.
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^ That wasn't my build; it was just one that I remembered had been posted about here, and seemed similar to what you were talking about.
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Hey mate, I built one from scratch, kinda did my head in, but well worth it.
It's now resides at a mates place where he gives it a good workout.
The two channels are very usable, but not to every ones taste.
He mainly uses the clean channel "CRANKED"
So I would suggest that you do a plexi preamp with a marster vol as well as a PPIMV with what ever output wattage you need.
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Here is the timmy schematic. It is very nice pedal, but use 4 pots. You only need 2. You simply set the set the volume to unity using a resistor. What I do is simply setup the whole circuit and tweak it to the amount of Distortion I want. Makes a third channel. You could make it adjustable with a 1meg pot on the drive, but this is way too much if already running overdriven.
The Timmy pedal circuit schematics are easy to google. In reality, you can use anything you want, but that is all "new heavily saturated designs" are using. Heck, even Bogner added a Tube Screamer channel in one of his amps from the late 80's.
The biggest benefit is your first amplification comes from a clean signal hitting a tube and will avoid some of the sterile tones pedals can give. That is if you are not running 3 fuzz pedals, and overdrive and 2 distortions with a 24bd boost.