Fender 6g15 Compared to Amp Reverb?

Tube or solid-state, this section goes to eleven!
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LooseCannon
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Post by LooseCannon »

Hey guys,

So I was looking at the schematics of the 6g15 reverb unit and a twin reverb and I am trying to understand the differences.

I'm no schematics reading expert so maybe you guys could enlighten me on a couple of things.

The 6g15 seems to have a lot more decay, even with the dwell at minimum, why is that? And how does the dwell control compare to the twin? It's located between the two halves of the first tube, and in the twin there's just a resistor and capacitor in parallel to ground.

How does the mixer circuit differ between the two? In the 6g15 its value is 250k and it seems to drop the volume a lot, and in the twin it's 100k.

Thanks in advance!

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phatt
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Post by phatt »

Don't have a schemo in front of me but from memory; :hmmm:
The twin has triode drive the other is pentode drive = stronger drive end = longer times.
If I recall the Rev unit has 3 knobs, tone mix/blend and dwell controls whereas most combo reverb setups only have a mix or Rev level pot so they are limited.
The value of the mix pot is of little use as reference for level as it depends on how the whole mix of wet/dry is setup.
Quite a lot of Spring reverb circuits do suffer if the driver part is not strong enough, A lot of SS rev drive circuits suffer even moreso.
HTH, Phil.

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B3ar
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Post by B3ar »

The Dwell control is a pre-spring pan level control. Surf guys are gonna leave it pretty high for ugly artifacts and sproing--they usually hate when spring reverbs sound too clean. When I had a silverface reverb amp, I could have really used an additional Dwell control to minimize sproing, or I could have, if I had been savvy back then, just lowered the level to the pan on a fixed basis.

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LooseCannon
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Post by LooseCannon »

Thanks guys.

I know the purpose of the dwell knob, my question is how does the circuit around it work in comparison to the twin.

Regarding the mixer- it seems that the 6G15 changes the wet\dry ratio while the twin mix knob sends the wet signal to ground. Did I get it right?

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Post by phatt »

Yes you are right, the 6g15 has a mixer which can be dialed in at any place from all Wet to all dry while the twin has the dry level at fixed preset mix, the Dwell is also fixed. As *B3ar* has noted you can easy alter the Drive/Dwell for control of spring slap in the twin.
Most of the fender combo range use a dual triode to drive the tank but adding the 6K6 pentode will have more drive power. It may not be obvious at a glace but the 6G15 will have a different frequency response, more bass is delivered to the tank which may or may not be noticed at lower reverb levels but side side they will sound quite different, allowing more bass and the extra boost from pentode the 6G15 will deliver more tank slap while the combos have more sparkle due to less bass passing through the reverb.
Phil.

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