Guyatone - TD-1 Tube Distortion  [schematic]

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Guyatone - TD-1 Tube Distortion  [schematic]

Postby Manfred » 01 Jan 2015, 03:26

I traced the TD-1 a couple of years ago.
Now I found the images on my Database.

http://postimg.org/gallery/1ta9mcadg/

For this message the author Manfred has received thanks: 7
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Re: Guyatone - TD-1 Tube Distortion

Postby fretzburner » 05 Sep 2015, 06:41

I removed the feedback diodes and 470pf cap to make it as clean preamp. My question is it possible to add full tonestack considering it has only one tube?
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Re: Guyatone - TD-1 Tube Distortion

Postby Manfred » 05 Sep 2015, 07:34

fretzburner wrote:I removed the feedback diodes and 470pf cap to make it as clean preamp. My question is it possible to add full tonestack considering it has only one tube?


In my opinion that will work, because it is a standard triode stage applied on many amps.
Maybe a level recovery stage after the tone stack is needed, it could be a BJT or FET stage for low voltage supply,
or have a look at LND150 applications for high voltage supply.
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Re: Guyatone - TD-1 Tube Distortion

Postby fretzburner » 06 Sep 2015, 01:32

Thanks Manfred , without additional recovery stage can it be used as clean preamp direct to mixer purposes? with analog pedalboard in front of it.Actually it's my main purpose for direct to mixer only, not for power amp.
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Re: Guyatone - TD-1 Tube Distortion

Postby okgb » 06 Sep 2015, 20:07

What is the plate voltage ?
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Re: Guyatone - TD-1 Tube Distortion

Postby Manfred » 06 Sep 2015, 22:04

fretzburner wrote:Thanks Manfred , without additional recovery stage can it be used as clean preamp direct to mixer purposes? with analog pedalboard in front of it.Actually it's my main purpose for direct to mixer only, not for power amp.


Yes, it could works without a recovery stage too, because the level can recovered due to the mixer gain control.
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Re: Guyatone - TD-1 Tube Distortion

Postby fretzburner » 06 Sep 2015, 23:53

okgb wrote:What is the plate voltage ?

I did not measure the actual circuit voltage yet but based on schematic more than 200v dc.


Manfred wrote:
fretzburner wrote:Thanks Manfred , without additional recovery stage can it be used as clean preamp direct to mixer purposes? with analog pedalboard in front of it.Actually it's my main purpose for direct to mixer only, not for power amp.


Yes, it could works without a recovery stage too, because the level can recovered due to the mixer gain control.

So it's applicable. thanks
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Re: Guyatone - TD-1 Tube Distortion

Postby Manfred » 07 Sep 2015, 08:08

okgb wrote:What is the plate voltage ?


As far as I can remember, the voltage was about 250 Volts.
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Re: Guyatone - TD-1 Tube Distortion

Postby phatt » 07 Sep 2015, 13:29

That's a scary box I doubt it would pass safety standards today.
With no Earth and bare mains inter weaved with signal it's a death trap waiting for a sucker. [smilie=pope.gif]

I certainty would not use it. [smilie=thumbdown2.gif]

Circuit wise,, the second grid has no ground reference which might cause issues, or maybe it's drawn wrong. [smilie=a_whyme.gif]
Better minds might know more?
Phil.
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Re: Guyatone - TD-1 Tube Distortion

Postby nickthemen » 07 Sep 2015, 17:51

I had one some time ago, sound was nice! But hum made it unuseable.
Output cap is 0.022
Volume pot is wired to the ground.
Diodes where wired to the second halve of the tube kathode.
gr
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Re: Guyatone - TD-1 Tube Distortion

Postby fretzburner » 07 Sep 2015, 23:59

Schematic same as westbury W-20(i checked it based on my stock TD-1)
Image
upload imagem
What i did is change coupling caps to 0.022uF, removed 470pF cap and IN914 diodes, added Tweed tone control(1M pot/4.7nF/500pF) at the volume.Still not sounding good as clean preamp direct to mixer.
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Re: Guyatone - TD-1 Tube Distortion

Postby fretzburner » 08 Sep 2015, 00:09

How to remove image? Just noticed the copyright note .Sorry Mr.R.G. Keen
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Re: Guyatone - TD-1 Tube Distortion

Postby ppluis0 » 08 Sep 2015, 02:01

fretzburner wrote:What i did is change coupling caps to 0.022uF, removed 470pF cap and IN914 diodes, added Tweed tone control(1M pot/4.7nF/500pF) at the volume.Still not sounding good as clean preamp direct to mixer.


Hi fretzburner,

Try to place a resistor in the position previously occuped by the 470 pF cap. You can try values from 100K to 470K (or even place a 500K preset and reduce their resistance judging by ear).

The reason is that there is a lot of gain in the first triode section to drive the second one into saturation, so attenuate the signal at the second triode grid can help you. 8)

Good luck,
Jose
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Re: Guyatone - TD-1 Tube Distortion

Postby fretzburner » 08 Sep 2015, 02:28

ppluis0 wrote:
fretzburner wrote:What i did is change coupling caps to 0.022uF, removed 470pF cap and IN914 diodes, added Tweed tone control(1M pot/4.7nF/500pF) at the volume.Still not sounding good as clean preamp direct to mixer.


Hi fretzburner,

Try to place a resistor in the position previously occuped by the 470 pF cap. You can try values from 100K to 470K (or even place a 500K preset and reduce their resistance judging by ear).

The reason is that there is a lot of gain in the first triode section to drive the second one into saturation, so attenuate the signal at the second triode grid can help you. 8)

Good luck,
Jose

Thanks Jose, is this something like to achieve much cleaner sound? I can get a clean sound by lowering the gain control.
My big concern is some sort of good clean sound in terms of tone, more on tone shaping that's why i'm asking the possibility of a full tonestack.But i will add your suggestion to make my clean gain setting around 3-4(on 1-10 dial).
This setup: Usual pedalboard-TD1(modified)-Cabsim-Mixer
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Re: Guyatone - TD-1 Tube Distortion

Postby ppluis0 » 09 Sep 2015, 02:53

Hi fretzburner,

Take a look at the schematic in the first post of this link:

viewtopic.php?f=1&t=17978&p=193998&hilit=+reussenzehn&#p193998

I think you have many similarities using your Guyatone and add the tone stack as the unit mentioned there.

Cheers,
Jose
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Re: Guyatone - TD-1 Tube Distortion

Postby phatt » 09 Sep 2015, 08:01

nickthemen wrote:I had one some time ago, sound was nice! But hum made it unuseable.
Output cap is 0.022
Volume pot is wired to the ground.
Diodes where wired to the second halve of the tube kathode.
gr


Why does that not surprise me? lol.
Yes with the mains transformer next to sensitive signal path it's a nightmare layout. :slap:

Yes your explanation makes more sense than the first drawing :thumbsup
Phil.
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Re: Guyatone - TD-1 Tube Distortion

Postby fretzburner » 09 Sep 2015, 23:35

ppluis0 wrote:Hi fretzburner,

Take a look at the schematic in the first post of this link:

viewtopic.php?f=1&t=17978&p=193998&hilit=+reussenzehn&#p193998

I think you have many similarities using your Guyatone and add the tone stack as the unit mentioned there.

Cheers,
Jose

Thanks Jose, it really is same with what i have in mind.It's working time :D
Maybe rehousing it too and improve the layout as mr. phatt suggested.

Thanks guys,
Barry
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Re: Guyatone - TD-1 Tube Distortion

Postby phatt » 10 Sep 2015, 02:23

fretzburner wrote:
ppluis0 wrote:Hi fretzburner,

Take a look at the schematic in the first post of this link:

viewtopic.php?f=1&t=17978&p=193998&hilit=+reussenzehn&#p193998

I think you have many similarities using your Guyatone and add the tone stack as the unit mentioned there.

Cheers,
Jose

Thanks Jose, it really is same with what i have in mind.It's working time :D
Maybe rehousing it too and improve the layout as mr. phatt suggested.

Thanks guys,
Barry


Hey Fretzburner,

Just don't build it with an UnEarthed mains supply inside the box as it's a death trap. (that stuff should be outlawed) :twisted:
Use the supply shown in Dirk Hendrik drawing (Reussenzehn blackface) as it uses an *Isolated supply* ,, a much better idea.

Bare in mind those tone stacks suffer from insertion loss and hence you don't get much clipping.

If clean is all you want then it's the ideal circuit but if you want to keep the gain then as has been mentioned already you can keep the gain stage and insert a tone stage after that.
You will then need a buffer which could be as simple SS device which can be run from the low voltage side of the supply.
I've build a few oddball hybrid preamps built around that idea.

I got my inspiration from the Mesa V Twin circuit. :thumbsup
Phil.
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Re: Guyatone - TD-1 Tube Distortion

Postby fretzburner » 12 Sep 2015, 00:46

[/quote]

Hey Fretzburner,

Just don't build it with an UnEarthed mains supply inside the box as it's a death trap. (that stuff should be outlawed) :twisted:
Use the supply shown in Dirk Hendrik drawing (Reussenzehn blackface) as it uses an *Isolated supply* ,, a much better idea.

Bare in mind those tone stacks suffer from insertion loss and hence you don't get much clipping.

If clean is all you want then it's the ideal circuit but if you want to keep the gain then as has been mentioned already you can keep the gain stage and insert a tone stage after that.
You will then need a buffer which could be as simple SS device which can be run from the low voltage side of the supply.
I've build a few oddball hybrid preamps built around that idea.

I got my inspiration from the Mesa V Twin circuit. :thumbsup
Phil.[/quote]
THanks Phil, that power supply safety issues was never my concern until you pointed it out clearly to me. I'm very careless which could have put me in danger.I thought it was okay because it's unmodified from factory :D
I will try first without a recovery.
Thanks again,
Barry
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Re: Guyatone - TD-1 Tube Distortion

Postby phatt » 12 Sep 2015, 12:19

hi Fretz,,
Electric guitar is one of the rare situations where the Ground of the guitar is directly coupled to the chassis of an amplifier (in this situation the case of the pedal unit). With no Earth to the conductive case means almost any wire inside could short to mains side of supply and you are then in direct contact with Mains voltage and deadly voltage will flow from the strings of the guitar down through your heart and you will most likely be dead.

Grounding the case makes it safer but introduces a ground loop, the classic circuit hummmmmmmm. :evil:
There are ways around that,,one here;
http://sound.westhost.com/project27b.htm
Fig 3, halfway down under Power Supply.

Of course if the pedal is powered from a low voltage wallwart then earth is no longer an issue. :thumbsup
Tiss good to know You are now aware of the danger.
Yes Never assume the factory knows what they are doing. I've worked around engineers who are way more qualified than myself but I've demonstrated on some occasions that their crazy ideas are flawed, And fail in the real world.

Now that safety is understood re the circuit. :hug:
I Strongly urge you to setup a breadboard as layout can be quite tricky.
This will allow you to suss out any problems before committing to a build project.
There is nothing more defeating than building something on the claim of another only to find it has to be rebuilt and often completely.
Take the time and you will learn a lot more rather than just building and pray it works. :slap:
Phil.
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