got another one... replacement reverb tank for '69 super reverb

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?

Thanks

TG

Click to expand...

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.

Just FYI.
:food-smiley-004: :rockon:

Thanks for the info Wild Bill!

My Traynor actually does use a reverb transformer; it is a very early YGM-1 and a bit of a rarity from what I can tell.
I'm not sure what tank my amp uses. It is covered in foam but I may open it up and take a look.Here is the schematic for my amp:

http://www.lynx.bc.ca/~jc/670214_Ygm1.gif

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.

TG



TG

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.

Just FYI.
:food-smiley-004: :rockon:

Click to expand...

"Man, I make a lot of money on Boogie problems!"

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.

TG
TG

Click to expand...

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.

My money says that someone tried a 12AU7 and made a note on the schematic. Pete would have been horrified.

If you were running one of the 60's stand-alone reverb units or one of the blond Bassman models you'd have a "dwell" control. This controls the drive into the tank. 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. A dwell would let you set it for whatever volume level you're playing at! I've built several stand-alone units with dwell and they all got snapped up quickly, usually for jazz guys. They like to set a lower dwell to drive the tank more softly and put the reverb mix control on only 2-3, not enough to be obvious but just enough to brighten it up.

Surf guys just dime both controls!evilGuitar:

Fenderizing the tone stack/volume control was a good idea. Getting rid of that linear taper 1 meg vol pot in favour of an audio taper unit will give you much better range on the control. 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!

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!

TG

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!

Click to expand...

"I don't get out much..." - The Birdman of Alcatraz

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!

TG

Click to expand...

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.

If you're not familiar with how negative feedback loops work don't worry about it. Think Vox or VibroKing!

Easiest mod in the world. One side of the switch is a new sound great for rockin' blues and the other is strictly stock.

You'll love it!

As far as the tank goes, the harsh "ploinks" are most likely because of excessive drive so the dwell will fix that up. The lack of range on the reverb control is almost certainly because of Pete using a linear taper 1m control. Changing to an audio taper will improve the low end range a bunch.

It would still be a good idea to open up the tank and take a look. It's partly a mechanical device and may have gotten screwed up over the years. You've got the springs running down the tank between the transducers. Sometimes one spring breaks. The tank still works but you get some extra harsh noises. Also, the springs and transducers are usually mounted on some kind of a tray and the entire tray is floated with springs at the corners. These springs can get broken or simply "tired". If the tray is lying low from stretched springs it may tap against the shell.

The poor thing is like 40 years old! Can't hurt to take a look!

Thanks for the beer offer! Never know if I'll get out west. I'm not dead yet!:tongue: I still remember the taste of "barley sandwiches" (Calgary Export). Great taste in a giant bottle! Hard for a puny Eastern boy to handle but I tried hard and sank a whole bunch...:food-smiley-004: