Dumble Light Tone Stack Questions

[Dagan8]

First of all I would like to say hello as this is my first post. From what I have seen so far there is a lot of good information on this forum.

Now for a few questions to get me pointed in the right direction.

I want to add a single channel, no OD, Dumble inspired tone stack to a project I am working on. The amp that I am using for inspiration is the TR Studio Pro 35. I have posted 2 clips showcasing the tone I am after. I'm hoping that someone who has heard some of the different D style tone stacks can help answer.

http://www.youtube.com/watch?feature=en ... KyzeI&NR=1
http://www.youtube.com/watch?v=b40v88aQ4G8

Q1) I want to have only the 3 following switches: Bright, Mid Boost, and Deep. Do I hard wire for Rock mode or should I hard wire for Jazz mode?

Q2) Which Tone stack(from Sticky's) should I be looking at to lift the Bright, Mid, Deep controls from.

Thank you in advance everyone. I am really excited for this project. Just looking for some primary direction. I Don't expect to someone else to totally design it for me.

Cheers

[odourboy]

Hi Dagan. Nobody else seems to be online tonight so let me be the welcoming committee!

Okay - so you want a clean amp with lots of control over tone shaping...

I would recommend a Skyliner stack, IMHO the best for clean tone shaping. Hardwire it for 'Rock'. You can do some cool stuff with Jazz, but for clean, Rock is where it's at.

You can scoop the stack design from here, with the bright and mid boost:
https://tubeamparchive.com/files/dumble ... ic_172.pdf (though I prefer a more subtle 'bright' cap value, say 120 pF).

Here's as good a 'Deep' circuit as any: https://tubeamparchive.com/download/file.php?id=21252

let us know how it turns out!

[10thTx]

This is a DRAFT idea that I have not built. Please compare this to the values in the schematic that Odourboy posted.

With respect, 10thtx

[Dagan8]

Wow. Thanks for the warm welcome and all of the good info. I am sketching something out on graph paper now.

10thTx - I noticed something on your design that may differ from the 2 circuits posted by odourboy. On the #124 circuit the middle and "top" tap of the BASS pot get connected together when the PAB is off and in ROCK mode. This doesn't happen in your circuit. Done intentionally?

When I am done my rough sketch I will post it and hopefully I can get some extra eyes looking at it.

Cheers

[10thTx]

I copied that from yet another schematic.

Note that when the DPDT is sent to the non connected poles that it breaks the connection between the treble and bass. Reportedly, there are different schematics showing different ways of doing this.

With respect, 10thtx

[Structo]

Yeah, that bass pot jumper is important.

When in normal mode the bass pot with the jumper is a variable resistor.
When PAB is switched on that jumper is broken and it takes the bass pot out of circuit as well as the treble pot.
I believe it drops a few db's of bass this way.

As a FIY, the Brown Note D'lite doesn't have the Rock/ Jazz switch, it is hard wired for Rock.
When the PAB is switched on it breaks the link between the bass and treble pots, removing them from the circuit.
Since passive tone stacks are lossy, you gain back that volume when in PAB making it louder.

I'm probably wrong but that is my take on it.

[10thTx]

Dagan8,

You did not have PAB on your list of switches in the original post, having said that ..................

There is a whole thread on PAB comparisons here:

https://tubeamparchive.com/viewtopic.ph ... omparisons

You might find that worth looking over.

With respect, 10thtx

[Dagan8]

You did not have PAB on your list of switches in the original post, having said that ..................

Yes. It's when I was doing up my draft with the PAB taken out that I noticed the difference in yours(missing connection). I didn't realize that there was different ways of wiring this nor did I really look. For now I will stick to the #124 as a template.

[Dagan8]

OK. Here is my draft of the #124 pre with the DEEP added and the PAB removed.

I would appreciate if anyone can give it a look over for obvious mistakes.

[10thTx]

Your schematic looks correct to me. You can do the mid switch the way you have drawn it or as in this schematic. Either should work fine.

With respect, 10thtx

[Dagan8]

Thank you so much. I can't wait to get started. The pre amp is going into the second channel of a 90's fender twin type amp. The other channel will remain as Fender Blackface.

[odourboy]

Gentlemen,

I believe there's a mistake in your deep circuits that I failed to notice first time around... the 1M resistor and .01uF cap should be tied together at the switch side as well - i.e. join the two terminals where these components connect to the switch.

Have a look at this schematic which shows it more clearly:

https://tubeamparchive.com/files/124_sc ... 84_208.pdf

[Dagan8]

Hi odorboy. Thanks for pointing this out. I was confused because I see this mistake in many of the schematics posted. Actually the deep circuit you posted in your first post of this thread has the error as well. I will add the jumper and repost the circuit. Thanks for looking it over odorboy.

[odourboy]

Actually the deep circuit you posted in your first post of this thread has the error as well.

Yes - that schematic was done by 10thTx, also posting on this thread so I thought I'd kill two birds with one stone - so to speak. I failed to notice the omission on his as well.

[Dagan8]

Thanks again for your help odorboy.