Gretsch 6152 Reverb doesn't work

[OracleGreen]

I bought a model 6152 Gretsch amp a couple weeks ago and the reverb was dead when I got it. The reverb tank is housed in a cardboard box but the tank itself is much like any other except smaller than any Ive seen. Someone must of tried to mess with it because one of the long springs is busted at the terminal and two of the side springs were mangled. I don't know how this could of happened except its a repair gone wrong I guess. Anyway, I did some research and read somewhere that a compatable tank replacement would be a 8AB2A1B tank. I found one at amazon:

http://www.amazon.com/gp/product/B003OF ... ss_product

So I bought one and replaced the stock tank with it. This tank works but on about 2 it sounds like Carlsbad Caverns. When I turn it up I get a high pitch feedback sort of sound. I took another look at the old tank but it doesn't look fixable to me so I have to find a replacement or make the one I have work. Could I need a different reverb transformer to power the new tank? Or does anyone have any idea what a better replacement tank would be?

[OracleGreen]

If it helps the Gretsch 6152 was sort of a big brother to the 6150 and 6151. It was also sold as the Supro model S6422TR (and S6522TR), National model N6422TR, and Airline model 62-9025A. I believe it is the smallest single end amp that has both reverb and tremolo on board. I had heard the stock reverb was kind of weenie so I figured I would have to upgrade to something better anyway.

[Alexo]

Sounds like you just need to attenuate the reverb return to a usable level with a voltage divider, or an R in series with the 'verb pot (hard to say without a scheme). The whine/feedback is just that, considering the tank acts like a mic set right next to the speaker that's reproducing it - it can be cured sometimes by a heavy reverb bag, or stuffing an old sweatshirt around the tank, or attenuating the return signal.

Good luck!

[KT66]

That cardboard tank on those amps was weak so when you put a more efficient one in you get the Carsbad Caverns effect . I built a clone of this amp for someone and anticipated this problem, so I added a Dwell control which allows you to control the amount of signal that gets fed into the tank. All you need is a 100KA pot in place of the 100K grid load on V1 - see the schematic here : http://www.classictubeamps.com/schemati ... ematic.pdf The pot is labled "P1".

I think that will fix your problem. If you don't want to put a hole in the chassis to mount the pot ( I would see if there is space on the bottom of the chassis) then you could use an internal trim pot and just set it permanently at a value that you like.

As a side note, the other grid load on V1 I have labeled as 470K ( R30) but it was a guess based on other Valco amps because the schematic floating around the web has this value omitted. If it's possible at some point look at the one in your amp and let me know what it really is I would appreciate it.

[OracleGreen]

I would love to have a dwell on my reverb. I got to try out a Kendrick reverb with dwell and it was sweet. The repair sounds a little over my head but I want to try so I will research all that you've said and see if I can tackle the job. I saw your website and it rocks! I will learn a lot from it Im sure. Awesome custom build of the 6152 Gretsch you did for a customer too. I will get that info you requested along the way too and post it here. First Im going to try a heavy bag as suggested by Alexo to see what that does and then take it from there. Thanks!

[Bill Moore]

I am really impressed with the original Hammond tank that came with my little Airline. It's too bad you can't salvage yours. Like the previous posts, I think the Hammond tank is less efficient than current models. Just look how they drive it. The reverb transformer is the same as the output in mine! 62-9035A, It uses a single 12" 8 ohm speaker.

[jon]

I would love to have a dwell on my reverb. I got to try out a Kendrick reverb with dwell and it was sweet. The repair sounds a little over my head but I want to try so I will research all that you've said and see if I can tackle the job. I saw your website and it rocks! I will learn a lot from it Im sure. Awesome custom build of the 6152 Gretsch you did for a customer too. I will get that info you requested along the way too and post it here. First Im going to try a heavy bag as suggested by Alexo to see what that does and then take it from there. Thanks!

Any update on your reverb issue? I am thinking about building one of these amps.

[cbass]

Hey guys I feel kinda wierd making my first post in an old thread.Hopeits ok I think I can add something.

I have the CustomKraft Brand version of this amp .It is a later version with Teble Bass and Temolo Intensity.

To answer KT66's question.About the gridload resistor on the input.
Mine is a 470k.Just like you suspected.

As far as the OP's problem with the reverb .First I put a 12at7 in v2.Then I belive in my amp(its been a while since I've had It open) I put a 220k resistor across the 100k grid load resistor on valve 1b to tame the reverb I think I may have also done the same thing to GLR on V2.The reverb went from being unusable to being pretty good.

I also added bypass caps across cahode resistors on the 6v6 and V3 and removed the 470k resistor to ground in front of the volume pot.This gave the amp some balls.It sounds very very good now.