Marcus0000 said:I don't have the original one so I'm not sure what model was used. Will this work?
Yep! There are two common sizes. Fender used the long ones and Marshall and Ampeg used the shorter ones, although there are enough exceptions to make one check it out and not make an assumption.traynor_garnet said:Don't mean to hi-jack the thread but does anyone know if different reverb tanks sound different? The reverb in my Traynor YGM-1 sounds metallic and "ploinky" and I am wondering if changing the reverb tank would help?
I often hear comments about a "long" tank and "short" tank. Is this referring to the physical size or something else?
Wild Bill said:Yep! There are two common sizes. Fender used the long ones and Marshall and Ampeg used the shorter ones, although there are enough exceptions to make one check it out and not make an assumption.
Long tanks have a longer "echo" delay than shorter ones, as only makes sense. "Surfers" like the long tanks.
Traynor reverb sounds different because of the circuit and not the length. Unlike Fender, where the reverb driver is like the output tube of a Champ with an output transformer that steps it down to 8 ohms and into the tank, Traynor eliminated the output transformer in that stage and just directly coupled the reverb drive from the tube plate with a big ass capacitor. It saved a dollar or two - the cap was much cheaper.
This accounts for a different reverb sound. Some like it more, some less. As usual, it's all taste.
If you don't like it a good tech could pull the cap in favour of a small output transformer but you'll need to buy another reverb tank. Tanks are different not just in length but in input and output impedances. The Traynor tank with cap input has an input impedance of a couple of thousand ohms. If you use a trannie then you'll need a Fender style tank with an 8 ohm input.
Hmmm...if the plate resistor for V1 is 100k then the circuit is designed for a 12AX7. A 12AU7 plate resistor would have been much lower in value, like anywhere from 47k to as low as 10k! Pete Traynor was more than smart enough to know this. People stuff 12AU7's into 12AX7 sockets all the time I know and it may seem to work but the distortion as you crank it will be excessive. 12AU7's need a different plate resistor to run properly.traynor_garnet said:Thanks for the info Wild Bill!
I've already had the amp's tone circuit modded to Fender values (got rid of that crazy stock mid cap value). The only other real "mod" is that I run a 12ax7 in V1 rather than a 12au7. The tube chart originally read 12ax7 but is crossed out and has 12au7 written in pen; since the schematic calls for a 12ax7, I think my amp must be a very early one.
It sounds much better with the 12ax7 in V1 but the extra gain drives the reverb harder. There is so much reverb that anything above 1 is wash city. In fact, I put the reverb knob on about .5 on the dial. The reverb was way to strong even with the 12au7 in V1 so I think I need a minor mod in the circuit (send less signal to the tank perhaps?). Either way, the reverb still sounds metallic and "ploinky" regardless of what tube is in V1.
Wild Bill said:You're quite right that the problem may be the tank being overdriven. It does make the sound more harsh and clanky.
So what's the solution? Well, you could try going to that 12AX7 that drives the reverb transformer to the tank and play with that 1 meg resistor. If you look at the schematic you'll quickly see how the two triodes are strapped in parallel, with a 1meg resistor to ground. Change it to a 220k, or even less. Or maybe use a 1M pot to find the reverb "sweet spot", wired like a volume control with the wiper then feeding the grid. You could either mount the pot on the back to give you a dwell control or you could just meter the pot to get the resistance reading when things sound ok and stuff in a close fixed value resistor.
You'd probably really like having a dwell control. As you already figured out, cranking the volume means cranking the tank input and thus changing the reverb tone at different levels.
Come to think of it, Pete used a linear taper for the reverb level control. That might explain part or all of the lack of any range. Try an audio taper for that one too!
Despite these little quirks you still have a nice sounding amp!
You might drill a new hole on the back for a "dwell". If you've got that redundant ground switch you could use it to break the negative feedback loop. Look for a resistor tapped onto the speaker line that feeds back to the phase inverter 12AX7 that drives the output EL84/6BQ5's. It's probably on the board, with a wire running to the speaker jack. Cut that wire and run it through the switch.traynor_garnet said:Thanks again Bill, awesome information!
I could probably put a dwell control on the back of my amp where the ground switch is (since having it converted to a grounded plug I no longer need the switch). I'll have to see what my local tech would charge for this but I think a dwell control and changing the resistor value would REALLY help. As it is, it is just way too much reverb. I did try running a 12au7 in the reverb driver but the tube started overheating and glowing so I had to go back to a 12ax7.
Do you think the "sound" of the reverb will improve with with these changes or should I change the tank out too? As I stated before, the reverb is very metallic and ploinky but maybe this is just because it is being hit hard (although at any volume the reverb is still overbearing). I wondering if I have a two spring short tank in here or something . . .
Again, thanks so much for your help. I'll buy you a beer if you ever find yourself in Edmonton!
here:Hamm Guitars said:Sorry, this is a little off topic, but the thread brough back a deep seeded memory.
Who uses the reveb tanks that say "Made by beatiful women...."?
I'm sure I've seen this at least once or twice before, but its been a while.