Help me fine tune a Dumble copy (Two Rock TS-1)

[Dugmore]

Hi guys, I have this Two Rock TS-1 amp I could use some help with.

The amp sounds pretty good, but there are a couple of issues that bother me. First, there seems to be a big imbalance in tone when switching channels. If I adjust the bass control so that it sounds nice and full on the clean channel, the overdrive channel sounds way to bass heavy and just turns to mud. If I dial in a nice overdrive tone by backing the bass way off, the clean channel sounds thin.

Second, the overdrive sounds a lot more fizzy and almost fuzz like than I prefer.

Any hints from you experts on what I could do to tweak this amp? I'm pretty handy with a soldering iron, but no expert on Dumble circuits.

Here's a pic, maybe it helps to identify the basic topology of this amp.


Thanks!


[IMG:760:570]http://pic100.picturetrail.com/VOL921/4 ... 200606.jpg[/img]

[Structo]

Welcome to the forum and to the world of non HRM amps.
You are describing what many of us spend a long time to resolve.

I'm afraid there is no simple answer.

Did you buy this amp new? If so maybe Two Rock would be willing to tweak it for you?

Do you have experience in working inside a tube amp?

First make sure the filter caps are discharged.
If you don't know how to do that then you should take your amp to a qualified tech.

The Overdrive can be fine tuned with the trimmer resistor that sits in front of the relays.

Set your meter to read resistance and clip the black lead to chassis ground.
Now touch the red probe to the middle leg of the trimmer (wiper)
Set the trimmer to read between 20K and 30K.
Let your ears be your guide on that one.
Be sure the amp is discharged before setting it.

As far as the channel imbalance, it depends where you set the Master.
You should be able to set the Ratio (OD Master) to where it matches the clean sound.

What really helps these amps is the addition of a Dumbleator buffered effects loop.
I know that Two Rock charges an arm and leg for one but you can find them cheaper from other D clone companies.
You can put your time based effects in the loop such as reverb and delay.
But the neat thing is you can use the output pot on the loop as your overall master.
On my amp I set the pre-gain at around 1:00 and the master at 2:00.
Then I use the output on the loop to control the overall loudness.

Anyway, I hope this helps somewhat.
I'm sure others will chime in to help as well.

[tubedogsmith]

where are you running the masters? Although their are lots of opinions on this I think the amps really open up and sound better with them up over halfway. Use a loop box for your master.

[dmagalhaes]

Anybody know what brand of signal caps those are? Look like Sprague but never seen blue Orange Drops before.

[exocet]

Anybody know what brand of signal caps those are? Look like Sprague but never seen blue Orange Drops before.

They are most likely Sprague 6PS

If you order enough from manufacturer, you can have them in a variety of colours.

[markusw]

If you feel confident that you won't kill yourself (please, not offense intended ) you could add a "pre-OD cap". This way you can lower the bass content hitting the OD section and adjust it to match the clean settings you like.

Regards,

Markus

[boldaslove6789]

where are you running the masters? Although their are lots of opinions on this I think the amps really open up and sound better with them up over halfway. Use a loop box for your master.

Indeed I agree. Structo and Tubedog are right, The addition of a Dumbleator will give the amp so much more balance and character. Getting that master and Ratio knob up (set the Ratio @ like 1 O'clock, and the Master Vol @ about 11 o'clock) is definitely crucial to getting the amp to sound great, as well as setting the OD trimmer.

Using a Dumbleator will also change the OD sound for the better, add a slight compression, and tame that fizziness and increase harmonic bloom.

[Structo]

Hopefully Dugmore will come back.

If you do, PM me and I might have an alternative for you concerning the Dumbleator.

As markusw mentioned, if your OD tone is too dark or bass heavy, there is a mod you can do that will fix that.

But be aware that in a non HRM amp, it is a juggling act with trade offs because anything you do on the clean side will affect the OD side.

Let me ask this, do you feel the amp has too much bass on both channels?

[Mac Daddy]

I owned one of the first TS1's
I had Bill mod mine , Which went on to be called the "Eastcoast Mod" or as I would say the " The Mac Smoothie mod "

Take the bright caps out...Now

http://youtu.be/_TC9qPCvra8

[Dugmore]

Thanks for your replies, everybody.

I'm in Europe, so sending the amp to Two Rock for modding is out of the question.

I was hoping you guys would have some ideas of what I could try, but maybe it really just is what it is.

Mac Daddy, why do you suggest removing the bright cap? How would that be different from simply turning the bright switch off? I never use it anyway, as it makes the OD even fizzier.

What exactly is the "East Coast Mod", and what does it do?

As markusw mentioned, if your OD tone is too dark or bass heavy, there is a mod you can do that will fix that.


Let me ask this, do you feel the amp has too much bass on both channels?

Can you tell me what that mod is? The OD is not too dark, and the bass heaviness can be dialed out. The problem is that the same bass control setting does not work for both channels.

[markusw]

Can you tell me what that mod is? The OD is not too dark, and the bass heaviness can be dialed out. The problem is that the same bass control setting does not work for both channels.

Basically, an additional cap (4n7 or larger per taste) paralleled by a 4M7 resistor is added in front of the OD entrance. This cap - since it is in series with the output cap (e.g. 50n) of the clean channel reduces the bass content hitting the OD.

There are several threads about this mod (often referred to as "Gil's mod")
e.g.

In the first thread there's also an image showing a slight variant of the mod, a 50n cap preceded by a 10M resistor to gnd.
This variant probably would be easier to implement.

https://tubeamparchive.com/viewtopic.ph ... sc&start=0

https://tubeamparchive.com/viewtopic.ph ... highlight=

https://tubeamparchive.com/viewtopic.ph ... highlight=

In the image you posted you needed to add the cap//resistor between the resistor feeding the right hand trim pot and the wire connected to the resistor.

Hope this helps.

Peace,

Markus

[Structo]

Dugmore,

The bright cap is on the master volume pot.
You will see a small silver mica or ceramic cap on the right two terminals (when looking at the amp from the rear).

This cap will add brightness until the knob is up half way and above.
After that it has little effect.

If you don't use a Dumbleator, this cap can make things sound a bit crispy on the top end.
Sizzle or fizzy.

If you are handy with a soldering iron, you could remove it to see how you like it without the bright cap.

Not all amps have them and your picture does not show the master volume.

[Dugmore]

markusw, that was very helpful, thank you.

Structo, there doesn't appear to be a bright cap on the Master Volume:

[IMG:760:570]http://pic100.picturetrail.com/VOL921/4 ... 226284.jpg[/img]

[Structo]

Yes then the OD entrance mod as markusw described is probably your best choice.