ROG Tonemender  [schematic]

Stompboxes circuits published in magazines, books or on DIY electronics websites.

ROG Tonemender  [schematic]

Postby ct88 » 14 Sep 2010, 14:29

Hello everyone,

just finished the VERO Layout for Tonemender project (http://www.runoffgroove.com/tonemender.html) and wanted to share :)

Tonemender.gif


still unverified, i'm a little n00b on creating Vero Layouts, but hope i did it correctly.
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Re: ROG Tonemender

Postby phatt » 15 Sep 2010, 10:01

Be very aware that this circuit will be very noise prone.
IME there are much smarter ways to do the same thing with far less noise.
If interested I'll post some ideas for you to play with.

Phil
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Re: ROG Tonemender

Postby ct88 » 15 Sep 2010, 15:20

yes please :) it will be very pleasant
thanks in advance :)

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Re: ROG Tonemender

Postby B Tremblay » 15 Sep 2010, 15:57

phatt wrote:Be very aware that this circuit will be very noise prone.
IME there are much smarter ways to do the same thing with far less noise.
If interested I'll post some ideas for you to play with.

Phil


I'm quite interested as well.
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Re: ROG Tonemender

Postby phatt » 16 Sep 2010, 07:08

Hi folks,
After wearing out 3 bread boards,, here's what I v'e found.

Consider the impedance through Tonemender circuit? Opamp 1 is wired as a buffer (high input imp, Low output imp).
Simple enough but hang on? The output end of the tone stack has just converted your Simple buffer trick right back up to high output imp so the second opamp also sees a high imp, In effect the first buffer is rendered useless.

What is not obvious to the novice is this: High imp input and High gain on the same chip equals *NOISE*

In Tonemender the second opamp also has a high imp input (has to be higher than the tone circuit other wise it suffers massive loss). But it also has a 500k pot for gain!! ouch!! :shock: Even if you use metal film R's and the lowest noise opamps it will make little difference to the noise from such a circuit. :slap:


How to fix it, See Schematic.
By utilizing the buffer *After tone controls* you turn the high imp into low.
(The 2 x 10k r's (R5,R6) after the buffer force low imp on the second opamp.
*NOW you CAN introduce substatial gain but without the dreaded noise problem*. :thumbsup

Even then this circuit will be quite hissy if you try to grab to much gain as in all audio setups you are better off to spread your gain over several stages. I use my PhAbbTone circuit as a front end into simple OD pedal type circuits, they do the gain tricks. A high impedance tone stage is not the place to do massive gain.

My PhAbbTone circuit is wired true by pass and I use a 50k pot to trim gain. Only really there to maintain volume balance between the bypass signal. (you can try 100k pot but watch out for the dreaded hiss.)
Mess with the 10k x 10k Voltage divider after opamp 1 at your own peril,, the noise will likely come back.
Note;
Contrary to common practise the buffer in front of a high imp tone stack like this does little. You will only get a tiny bit more bandwidth (most of which is useless for Hi Gain guitar anyway).

You CAN (believe it or not) plug your axe directly into the *Passive front end* of most of the famous tone circuits.
The only time you will encounter a problem is if you use an acoustic with passive peizo PU.
They tend to need a buffer no matter what you plug into anyway so unlikely you will ever have issue.
If the idea erks you then add a buffer,, hey opamps are cheap. :mrgreen:


I use my tricked up HiWatt tone stack (shown in schematic) because it has the best tone shaping effect.
Bass and treble response is much like fender circuits but the mid cut ability of the HiWatt is just stunning. (See pic below)
I've built most of the famous tone stacks (both in Valve and SS designs)

IME, Switching tricks like Tonemender and Dumble circuits are just a patchup for a lacking midrange circuit.

Hi watt mid cut delivers a very steep mid notch at around 400hZ.
I've found the common tone circuits just deliver a shallow scoop and by the time you cut enough mid you have also pulled down most of the energy and the sound is very unconvincing.

One note about deriving a bias voltage.
The Tonemender bias is a bit silly as it uses 2x 100k resistors for division. I find the old 1k per volt rule of thumb is good to remember here. i.e. When working with 10 volts supply use a 10k resistor, 100k is miles to big and will likely do nothing except add more noise.

It should be obvious that you can of course use most of the famous tone circuits in place of mine.
As long as you use the setup shown you will have much better success than Tonemender.
No disrespect to *ROG*, They have some good circuits but sadly this one is not one of their better ideas. :roll:
Have fun with it all, Phil.
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Re: ROG Tonemender

Postby ct88 » 16 Sep 2010, 19:28

thanks a lot for ideas, will work on that :D

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Re: ROG Tonemender

Postby Zombie_Crush » 07 Apr 2012, 10:55

Hi ct88

is your build now verified

download/file.php?id=9084&mode=view


also the wires that link - example - Treble 1 & Bass 2&3
do these wires link in chain from pot to pot? or two wires from the board independently linked to the pots?


Cheers :wink:
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Re: ROG Tonemender

Postby Zombie_Crush » 07 Apr 2012, 14:48

Tried wiring my pots both ways

appears the Vero layout above for the Tonemender does not appear to work sadly :?
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Re: ROG Tonemender

Postby phatt » 11 Apr 2012, 09:19

Zombie_Crush wrote:Tried wiring my pots both ways

appears the Vero layout above for the Tonemender does not appear to work sadly :?


The *Tonemender Circuit* works (I should know as I've tested it for real) so I'd say check your circuit layout. :blackeye
I tried to go through it but I got lost :oops:
With no actual connections to pots and like components it's hard to tell where any mistakes may be?

BTW (As I've already tried to point out) it 's a noise prone circuit so beware.
Phil.
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Re: ROG Tonemender

Postby Duckman » 11 Apr 2012, 10:44

Nice tips!
phatt wrote:The only time you will encounter a problem is if you use an acoustic with passive peizo PU.
They tend to need a buffer no matter what you plug into anyway so unlikely you will ever have issue.
If the idea erks you then add a buffer,, hey opamps are cheap. :mrgreen:

How to do that without becoming noisy again? :scratch:
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Re: ROG Tonemender

Postby phatt » 11 Apr 2012, 15:16

Hi Duckman,

Yeah mate not easy to do but through many wornout bread boards and lots of land fill circuits I finally worked out some of the hidden gotchya's in making these circuits less noise prone. There is much debate about HOW and I'm not q'd enough to argue with slick maths geeks but My *PhAbbTone* schematic will get you damn close.
The *Buffer* is the key to success,, the gain is on the second chip which has much lower Z input.
Big Gain opamps (no matter how good the specs) after a Hi Z Tone is a sure fire way to amplify NOISE,, winky.

The front end of the TS9 has a simple BJT buffer which some hot rod geeks REMOVE thinking they gain some mojo but it just creates noise issues.
A BJT is not up to the task of really Hi Z for tone circuits so the opamp makes it a breeze.

It should become obvious that most of these tone circuits work in similar fashion,,, so just insert your tone weapon of choice.

If you just can't find the courage to make the input passive you will need a buffer in front. That's up to you but there won't be very much difference in performance. Just means another chip and I wanted something really simple and uncomplicated. :thumbsup

Used directly after a passive Magnetic PU guitar will have an effect on top end but the loss I find is a positive asset as it forces a natural top cut in front of often harsh distortion boxes this can really tame those down. Used after,, well try it both ways and make up your own mind. [smilie=a_whyme.gif]

Note;
When I say Hi freq Loss I don't mean it turns to mud,, far from it!
My guess is it's removing that hi freq hash which a lot of dirt pedals tend to deliver in bucket loads when cranked up hard this softens that out without loosing the sparkle.
Phil.
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Re: ROG Tonemender

Postby Zombie_Crush » 13 Apr 2012, 18:48

hmmmm

cheers phatt - will do :wink:
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Need ROG Tonemender..

Postby Robertodue » 23 Jun 2017, 20:44

Anyone have one they are willing to part with? The circuit is pretty easy... perhaps make one for me? I would prefer it WTHOUT the enclosure. Thanks!
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Re: Need ROG Tonemender..

Postby toneman » 26 Jun 2017, 23:50

I made an offer and revised the ROG Tonemender schematic.

I think the opamp with adjustable gain should go in FRONT of the EQ section.

Here's a link to the modified schematic:

http://s1305.photobucket.com/user/toneman22/media/Tonemender-ROG/tonemender2005rogEDIT4_zpsasfepoud.jpg.html?o=1

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