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Stereo Reverb as in TUT2
Hi all!

I'd like to build the Stereo Reverb as in TUT2.
Has anyone done that?

Which Reverb Block would be best, the one in the LP Standard or the Standalone Reverb Kit?


(03-28-2021, 10:32 AM)Strelok Wrote: Hi all!

I'd like to build the Stereo Reverb as in TUT2.
Has anyone done that?

Which Reverb Block would be best, the one in the LP Standard or the Standalone Reverb Kit?



Some of how you'd choose to do it would be based on what type of signal you'd be handling.  By the "Standalone Reverb Kit"  do you mean the reverb unit shown in Tones or Tone (Fender style reverb driver)?  That one is setup for instrument levels of signal while the London Power style driver in the Standard is meant to be inside an amp but either style circuit could be adapted to a different purpose. What are you wanting to do with the reverb?
Greetings Strelok

We are brothers by the second syllable Smile

Is your question simply about the reverb driver stage? LP push-pull versus the everyday SE? I think Mr.O'Connor's description of the benefits of push-pull driver are all you need to know and then just look at the cost each way. Apparently one can acquire a "Fender" replacement reverb drive transformer for just a few bob and from a plethora of sources. There is a custom reverb drive transformer on the London Power site which is more expensive, although Mr. O'Connor kindly gives you alternatives in TUT2, referring to Hammond's 125A as a reasonable candidate.

One thing, too, is that the reverb path is what Kevin calls a "side-chain", which suggests that maybe the fidelity does not have to as high as in the main signal path? That may not be true for effects loops, but I think it is here? This may influence the transformer choice.

If you are building a stereo reverb for general use then maybe the reverb quality and noise are more important.

Hi Guys!

I wasn't all clear.
The reverb is for general use, like recording line levels mostly.

With the kit I meant REV, the standalone reverb on the site here.
It is Push-Pull, just like the on in the Standard.
It differs some from the circuit in the Standard, mainly that the Dwell pot seems to rest on a stand-off.
I don't know what it is called, but there's a voltage divider that connects to the second grid.
The first grid where the Dwell pot lands is tied to this divider through a 10M resistor.

At first I thought there was a big difference but I omited one resistor in my drawings, so there is not a big difference.

Also, there is a difference at the anode resistors.

I think I will go with the kit. I'll tap the signal from the Reverb pot.

I have some custom LP Reverb transformers so I can do the PushPull scenario.

Thank you very much for your feedback!
Hello Reactors,

I see I did not address all comments and questions.

I built the Fender StandAlone from Tonnes of Tone, there is a volume drop, I heard that's normal when you take the cathode-way out.
I built it to use in front of the Herzog, I don't want to break the chain of that amp, it sounds so good the way it is.

Yes Sherlok we are brothers by the second syllable indeed, you have the gift of noticing things!

I had a reverb Tx from an old Mesa Boogie, I built the Fender with that.
Thank you for mentioning the sourcing Smile

It will be a Push Pull yes.

I will read that part about the side chain, just for fun.


Hello fellow TubeHeads,

I am well on the way of building the schematic of the kit.
However I have a few questions.

The kit has a very high gain. I built it previously from a complete kit.
What would be the best way to lower the gain?
Use a higher Ck at the last stage?

Kevin, I am building this new one on an eyelet board.
I did not order the kit.
What is your view on this?
I mean, it kicks you out of income, I could have ordered at least the PCB.
Originally I ordered the kit so some money would come your way.

Kind regards,

Hi Strelok

By "kit" do you mean you are following the schematic shown in actual kit notes? Or are you speaking loosely referring to the TOT reverb project?

The REV kit has no more overall gain than the fender reverb block.

The Tonnes of Tone Reverb project has extra gain for the reverb driver because it must use a guitar-level input signal instead of a line-level signal as the references above have. Overall gain one hopes to be about unity BUT the dry path is tapped from a tube cathode and may actually be weaker than the raw guitar signal. Fortunately, most guitar amps including all classic fenders have excess gain to accommodate low-output pickups.

Have fun
Hi Kevin!

Thanks for the info!
I built the kit, and it was way over unity.
I popped in a 12UA7 and then it was unity again.
It must be in the last stage, is it advisable to have a higher Rk there?
Or a lower resistor for the anode?

I built the ToT a long time ago, it was unity if I recall correctly.

About the new unit the following.
The choice was between the kit notes and the reverb in the Standard as in the book.
I chose the kit because it is designed to be stand alone.
So yes, I am a PCB-pirate: I take the kit notes and build a new unit on an eyelet board.

Do you want compensation for this?

If you publish a book with projects you take into account that people will build them.
But if you sell kits with notes, maybe you don't.

Kind regards,

Hi Strelok

Building something for yourself from our books, or building a copy of one of our kits which you bought from us, again for your own use, is all fine.

As soon as you sell any of these things you should buy a Licence. We have this as a self-serve item on our site. The purchase of kits specifically for a unit that you will sell carry licencing for that build.

Note that the rights relating to the schematic remain property of London Power, so you cannot make those schematics available in any form.

As far as the reverb block overall gain goes, ideally it should be unity (gain = 1). Fender and similar do have a bit of gain but it is typically about 3x or so, not likely over 10x. This depends on what the resistance to ground is at the grid of the mixing tube. The 3M3 works against that resistance to attenuate the dry signal before the mix stage adds its gain = 100. Gain will be cut almost in half simply by removing Ck from the mix stage.
Hi Kevin!

Yes it is all for personal use.
No I would never make these designs public or share them.

I did not know that Ck had so much influence.
I thought about that "grid leak" too, it forms a pot with that 3m3 and the other incoming branch.
Funky attenuator Smile

Thank you so much!

Hi Guys

3m3 = 0.0033 ohms
3M3 = 3,300,000 ohms

Have fun

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