Adding distortion: FET Input vs Diode Clipping

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M Fowler
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Re: Adding distortion: FET Input vs Diode Clipping

Post by M Fowler »

Lets see the schematics showing these mods since I don't have any. :)
Badside
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Re: Adding distortion: FET Input vs Diode Clipping

Post by Badside »

M Fowler wrote:Lets see the schematics showing these mods since I don't have any. :)
Unloading my mind to paper right now
When it's concise enough I'll commit it to the computer and share

I usually go straight from my mind to the turret layout, but for more complex projets like that, a schematic is a key step!

I do want to try a pair of Zener in my current 2204 first, to confirm if this is indeed the sound I'm looking for. Hopefully the surplus shop has what I need.
Amplifiers built:
Marshall 2204 head with some mods
Low-power 2204 (cathode biased 6V6s)
Single-knob dual-6K6GT amps using a Wattkins uPCB
AC30 clone with Plexified preamp section
AX84 Firefly
John_P_WI
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Location: Wisconsin

Re: Adding distortion: FET Input vs Diode Clipping

Post by John_P_WI »

M Fowler wrote:Lets see the schematics showing these mods since I don't have any. :)
Hmmm, Jose, Fortin, Cameron, Friedman, Niks Chupa - the LA 80's amps are back, bring out the long hair and real Charvels too :lol:
Badside wrote: I do want to try a pair of Zener in my current 2204 first, to confirm if this is indeed the sound I'm looking for.
Don't forget the resonance mod on the negative feedback too.

Badside, check this out:

Sound clips in the middle too.

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

https://tubeamparchive.com/viewtopic.ph ... highlight=
Last edited by John_P_WI on Thu Jan 24, 2013 5:41 pm, edited 2 times in total.
Badside
Posts: 90
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Location: Montreal, Canada

Re: Adding distortion: FET Input vs Diode Clipping

Post by Badside »

John_P_WI wrote:
M Fowler wrote:Lets see the schematics showing these mods since I don't have any. :)
Hmmm, Jose, Fortin, Cameron, Friedman, Niks Chupa - the LA 80's amps are back, bring out the long hair and real Charvels too :lol:
Hehe, that works out, I have a San Dimas inspired Warmoth, one of my favorite guitars even though it looks a bit obnoxious :)
It's natural oil-finished mahogany so could be worse!
Amplifiers built:
Marshall 2204 head with some mods
Low-power 2204 (cathode biased 6V6s)
Single-knob dual-6K6GT amps using a Wattkins uPCB
AC30 clone with Plexified preamp section
AX84 Firefly
Badside
Posts: 90
Joined: Wed Mar 24, 2010 12:40 pm
Location: Montreal, Canada

Re: Adding distortion: FET Input vs Diode Clipping

Post by Badside »

John_P_WI wrote: Don't forget the resonance mod on the negative feedback too.
The current amp already has that :twisted:
Amplifiers built:
Marshall 2204 head with some mods
Low-power 2204 (cathode biased 6V6s)
Single-knob dual-6K6GT amps using a Wattkins uPCB
AC30 clone with Plexified preamp section
AX84 Firefly
Roe
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Re: Adding distortion: FET Input vs Diode Clipping

Post by Roe »

to get more gain, I recommend the levi #34 mods: .1u bypass cap on the 10k cathode and .68 on the 820 (or .47 on 1k)
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kdmay
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Location: Melbourne, Australia

Re: Adding distortion: FET Input vs Diode Clipping

Post by kdmay »

Badside wrote:
John_P_WI wrote: Don't forget the resonance mod on the negative feedback too.
The current amp already has that :twisted:
I also subbed in a 250k pot for the NFB resistor (with a permanent 22k) for many NFB options. Very handy!
Last edited by kdmay on Thu Jan 24, 2013 8:30 pm, edited 1 time in total.
kdmay
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Re: Adding distortion: FET Input vs Diode Clipping

Post by kdmay »

M Fowler wrote:Lets see the schematics showing these mods since I don't have any. :)
[IMG:361:388]http://i641.photobucket.com/albums/uu13 ... daff4a.png[/img]
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Reeltarded
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Re: Adding distortion: FET Input vs Diode Clipping

Post by Reeltarded »

Put a 10-25k tail resistor on the Jose rig but no pot, or put a 25k pot as the tail instead of the volume. The 25k pot is now crush control. Congrats! Your amp doesn't sound like a Lab Series anymore. :)

My recent 4 stager has a 6-position rotary clip control with RED, 20v, 12v, Transistors, and 1n914s with a 25k crush control. I use it for tone shift more than a distortion generator. I can sound pretty much anywhere between Eat a Peach to Deathmetal with three stages. I have that unused triode wanting to drive an inverted Jose string.. ya know.. :)

I use it differently in every amp. Full on clipping isn't real but adjustable clipping isn't evident. Ya can't fool everyone all the time. Try.
Signatures have a 255 character limit that I could abuse, but I am not Cecil B. DeMille.
Badside
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Location: Montreal, Canada

Re: Adding distortion: FET Input vs Diode Clipping

Post by Badside »

Roe wrote:to get more gain, I recommend the levi #34 mods: .1u bypass cap on the 10k cathode and .68 on the 820 (or .47 on 1k)
The current 2204 build used to have a .68 on the 820 (I'm assuming we're talking about V2a, aka the stage that "drives" the cathode follower) and I removed it a long time ago. The amp was way too bright with it.

As for the 10k, it's currently 4k7 with a large electro cap for bypass.
Interesting facts: first stage has a 150k anode resistor (wanted more gain but found 220k to ruin the tone) and is coupled via a 0.01uF instead of 0.022uF (sounds a bit tighter this way).

A smaller bypass cap on the cold stage is food for thought though
Amplifiers built:
Marshall 2204 head with some mods
Low-power 2204 (cathode biased 6V6s)
Single-knob dual-6K6GT amps using a Wattkins uPCB
AC30 clone with Plexified preamp section
AX84 Firefly
Badside
Posts: 90
Joined: Wed Mar 24, 2010 12:40 pm
Location: Montreal, Canada

Re: Adding distortion: FET Input vs Diode Clipping

Post by Badside »

kdmay wrote:
Badside wrote:
John_P_WI wrote: Don't forget the resonance mod on the negative feedback too.
The current amp already has that :twisted:
I also subbed in a 250k pot for the NFB resistor (with a permanent 22k) for many NFB options. Very handy!
Oh I got that too (it's my experimenting amp I guess). Turns out I like a little less NFB that stock, but just a little less.
No NFB at all was fun for a while, but it just tries to take too much space in the spectrum that way
Amplifiers built:
Marshall 2204 head with some mods
Low-power 2204 (cathode biased 6V6s)
Single-knob dual-6K6GT amps using a Wattkins uPCB
AC30 clone with Plexified preamp section
AX84 Firefly
Badside
Posts: 90
Joined: Wed Mar 24, 2010 12:40 pm
Location: Montreal, Canada

Re: Adding distortion: FET Input vs Diode Clipping

Post by Badside »

Reeltarded wrote:Put a 10-25k tail resistor on the Jose rig but no pot, or put a 25k pot as the tail instead of the volume. The 25k pot is now crush control. Congrats! Your amp doesn't sound like a Lab Series anymore. :)

My recent 4 stager has a 6-position rotary clip control with RED, 20v, 12v, Transistors, and 1n914s with a 25k crush control. I use it for tone shift more than a distortion generator. I can sound pretty much anywhere between Eat a Peach to Deathmetal with three stages. I have that unused triode wanting to drive an inverted Jose string.. ya know.. :)

I use it differently in every amp. Full on clipping isn't real but adjustable clipping isn't evident. Ya can't fool everyone all the time. Try.
Actually I didn't want to put a 25k pot, but a 25k trimpot. Just to fine tune in the early stage then set and forget. Though I could just experiment on the current amp and hardwire my preferred setting on the new build.

That's a lot of options! Care to comment on the tone of each?
So far, 12V Zeners seemed to be what I'm rooting for.
Amplifiers built:
Marshall 2204 head with some mods
Low-power 2204 (cathode biased 6V6s)
Single-knob dual-6K6GT amps using a Wattkins uPCB
AC30 clone with Plexified preamp section
AX84 Firefly
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Reeltarded
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Location: GA USA

Re: Adding distortion: FET Input vs Diode Clipping

Post by Reeltarded »

You will like an external control, trust me. If you are putting it inside just find the number with a pot and stick a resistor on the tail.

I need the control.

I like the REDs at the onset with volume, and mostly the transistors and 914s after that.

I have a pair of 20v also shunting from the master volume wiper to ground. This isn't switchable and doesn't sound like it's there... ;)
Signatures have a 255 character limit that I could abuse, but I am not Cecil B. DeMille.
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chief mushroom cloud
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Re: Adding distortion: FET Input vs Diode Clipping

Post by chief mushroom cloud »

Don't overthink it. Just drink it.
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Reeltarded
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Re: Adding distortion: FET Input vs Diode Clipping

Post by Reeltarded »

Hey stop that!
Signatures have a 255 character limit that I could abuse, but I am not Cecil B. DeMille.
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