Reverb Level too sensitive Fender Twin Reverb, Deluxe Reverb, etc

[nevetslab]

As I too know well regarding what you see CAN be made available from a given mfgr if you're buying production quantities. I come from Manufacturing, and one thing that did offer was samples of something that you normally wouldn't be able to purchase from distribution. It may take 3 months to get any 'specials', but if not in a rush, who cares.

After I had made mention on the pot solution Fender used on the Hot Rod series to get a more reasonable taper from their 25k Lin Reverb Pot, I forgot that it's being sourced from a TL070-series Op Amp. Can't do that with a 100k Linear pot sourced from a 12AX7 stage and then slug it with a 6.2k between the top of the pot and the wiper. You'd be distorting the signal from the load until you got well above that low resistance range.

That Bourns page was mostly for showing graphically what the various tapers are.

So, I'll have to rely on either a 250k-10A or a 250k 30A pot. Haven't been over to the Guitar Dept a few blocks away to dig thru their Fender spare parts box.

[Helmholtz]

After I had made mention on the pot solution Fender used on the Hot Rod series to get a more reasonable taper from their 25k Lin Reverb Pot, I forgot that it's being sourced from a TL070-series Op Amp. Can't do that with a 100k Linear pot sourced from a 12AX7 stage and then slug it with a 6.2k between the top of the pot and the wiper. You'd be distorting the signal from the load until you got well above that low resistance range.

Even without the loading effect any bypass between pot input and output would increase the problem.
I think the main difference is that the opamp rev. drive is significantly weaker than the tube drive.

[Leo_Gnardo]

I have found some relief by installing a 100K audio taper reverb pot. Generic, Alpha most often. With this the player may be able to turn up . . . but still leaves the control zone a point or so at the low end of the reverb pot. Additionally I often alter the drive end. Fender's classic design smacks that tank pretty hard. Not everybody wants to surpass ol' Dick Dale in surfiness, in fact I've never had a customer who felt the need to go there. The order is always LESS! So, part 2 consists of simply removing the cathode bypass cap on the reverb drive tube. That cuts drive noticeably but it's still plenty strong. Sweet spot moves up to maybe 4 or 5 or 6 now, with absolutely plenty of room to dime it and challenge the King of Surf Guitar.

Should more extreme measures be required, a simple resistor pad to the reverb pot customizes control zone to taste for tasty guitarists who never want to hang ten or sound like they do. Got too dull? Bypass that pad with a little cap to add shimmer.

[Chuck H]

I have found some relief by installing a 100K audio taper reverb pot. Generic, Alpha most often.

Yep. That was my suggestion in post 9. Plain Alpha 100k A.

I personally do like the more sproingy sound of the stock tank drive that Fender used. Or maybe it's just what I'm familiar with. I built a "reverb only" amp for a customer once that drives the tank off the host amp. It has a meter and adjustable tank drive so it can be used with amps of any wattage. Protection diodes prevent failure in case it's adjusted wrong. But having the adjustable drive option allowed me to experiment with different tank drive levels and you really can hear a difference.

[g1]

Am I correct that 'Dwell' is the control over the amount of tank drive with the Fender stand-alone reverb units?

[Chuck H]

Yes. That's what gave me the idea to listen to different drive levels with the unit I built. I knew the Fender stand alone did that. The term "dwell" didn't make much sense to me because I didn't notice much difference in decay time until the level was set really low. At which point the effect didn't sound as good. But I guess they had to call it something.

[Leo_Gnardo]

Am I correct that 'Dwell' is the control over the amount of tank drive with the Fender stand-alone reverb units?

Correct. I tell folks it's a volume control on the amp that drives the tank. Full up for maximum tank spank and dial down for subtler effect.