Well, the mix controls the ratio of "wet" to "dry' signal. Since you replaced the 12AX7 already, make sure that the wire connections to the actual spring pan are well-seated. And that the retaining mechanism is off!

It is not sounding fine at 2-3, by the way; that is blasphemy!

SSIV

Based on the diagram, it would make sense that the signal might drop with the dwell low and the mixer high (since dwell is driving the tank). But I'm not sure.

First basic Q I have is whether there is anything wrong with my unit. If this is how they behave normally, that's OK. But I've seen some other posts on the internet suggesting this is not normal.

cesjr
...would make sense that the signal might drop with the dwell low...But I'm not sure

On my reissue reverb if the Mix and Tone on 10 and the Dwell is on 1 it sounds flat, no reverb, but by the time the Dwell up to 4 it sounds like you are in a cave.
I wasn't sure when I first got my tank either. The positioning springs that hold the transducers in place inside the tank itself had become detached during shipping. I'll also discovered that some NOS tubes sound better than others.
I learned a lot from searching these Forums.

i have this same problem, i always assumed it was normal. thank god for a thumper of an amp to make up the difference

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cesjr wrote:

Yes, I'm new to the reverb unit world.

It sounds like I should open up the tank and check to
see if the transducers are properly attached. I also
read somewhere (maybe here) about using epoxy in a few
places inside the tank to improve the signal
flow/connections.

I doubt if there's anything wrong with your unit. 'Lower volume' from the wet signal is normal with just about any type of reverb. This is because the signal from the pan's output transducer is really weak in any event, so you are starting with a weak signal, which you are then trying to amplify through the following recovery (gain) stage. In a SAR, this wet signal has to compete with the dry signal coming from the geetar via the CF bypass. The level of wet/vs dry is not too bad considering. In other types of amps, like BF reverb amps for example, there is a relatively high amount of attenuation of the dry signal where the wet signal is injected back into the signal path for this very reason.

He who dies with the most tubes... wins

Surf Daddies

This is pretty normal.

Irronically, the Boss FRV1 pedal does the same thing.

METEOR IV on reverbnation

sonni wrote:

so if it's problematic to boost the wet signal at the
Reverb Recovery section, maybe it would be easy
possible to lower the dry signal at the Buffer a
little?

One way of doing this in the 6G15 circuit would be a voltage divider between the bypass stage's output coupling cap and the mixing control. If you were seriously considering that, you should use a 500k-1M (audio taper) pot so you can experiment with the amount of dry signal reduction. You also may want to put a bright cap across the input-wiper lug of any such pot (if you did this) so you keep the highs when the pot is in 'cut' mode. It would be more of a PITA to implement because you need a space to mount the pot etc.

Another way would be to reconfigure the CF (bypass) stage to have a lower output. In the 6G15 circuit the CF stage is fixed bias, so if you decreased the cathode resistor (to say something like 56k - I wouldn't go any lower with a 12AX7 stage because it will run too hot otherwise), you would also want to change both of the (2M2) bias resistors, so that the grid was biased properly w.r.t. the cathode voltage. (Another way of dealing with the biasing would be to convert the CF stage to cathode-bias, by removing the both the 2M2 resistors and putting a 1k bias resistor between the cathode and the (new - lower value) cathode resistor, and putting in a 470k-1M grid load resistor from the grid to the junction of the new bias resistor and cathode resistor. This would make the biasing of the CF stage automatic, and you could experiment a bit more with cathode resistor values. But I would keep an eye on the h-k voltage and the tube current - to keep within 12AX7 'spec').

In any event, you may or may not like the result. Most peeps just live with the (dry/wet) difference anyhow.

He who dies with the most tubes... wins

Surf Daddies

Last edited: Jan 31, 2012 11:59:20

derekirving wrote:

I had a '64 reissue and experienced the same thing
(drastic volume drop off, mix at 10 and it sounded like
3) before the reverb transformer crapped out.

Sounds like the driver tube was bad and then it took out your RT. Bad tubes can cause loss of volume too.

He who dies with the most tubes... wins

Surf Daddies