Output mod

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Thewilltopowerrock
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Re: Output mod

Post by Thewilltopowerrock »

Didn’t realise there were so many politicians here - 2 pages of replies and basically no answer to the question! 😂

Mike, could you go into slightly more detail about what work would be required? What would actually be changed/added? Keep it layman level please haha.

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Re: Output mod

Post by Kris »

MattAnt wrote: Tue Oct 19, 2021 9:11 am
Kris wrote: Mon Oct 18, 2021 8:45 pm I don't understand anyone who says under 50w tube is enough for a jam situation with acoustic drums. Unless I just happen to have struck a homicidal maniac percussionist every band I've been in.
Which is actually likey....pitfalls of the genre I guess
Your drummer must be insane, or more likely, your low wattage amps on the quiet side.

I have 15w - 30w amps that I can barely turn on they are so loud, at full boar the are window shaking. Then I have 15w amps that are much more modest in volume and wouldn't keep up with a loud drummer.
the biggest prob ive found are el84's,which is in the majority of small wattage and lunchbox style heads.I had a krank that had uhhhhh.....2 5881's (6l6gc) and that was much louder,but still not enough.tuned to E standard and not having to lift above a band maybe....but not in my usual application.
Drummer from that band was insane,but not the hardest hitter ive encountered :)

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Re: Output mod

Post by Kris »

Thewilltopowerrock wrote: Tue Oct 19, 2021 11:20 am Didn’t realise there were so many politicians here - 2 pages of replies and basically no answer to the question! 😂

welcome to the forum,you must be new here ;)

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Re: Output mod

Post by RectifiedAmps »

Thewilltopowerrock wrote: Tue Oct 19, 2021 11:20 am Didn’t realise there were so many politicians here - 2 pages of replies and basically no answer to the question! 😂

Mike, could you go into slightly more detail about what work would be required? What would actually be changed/added? Keep it layman level please haha.
Sorry, I thought I had answered it but I think I was focused on the ‘why’ more than the ‘how’. It can be done quite easily on any cathode-biased amp. You’d just need a switch that bypasses/shorts a biasing resistor when it’s on. Switch off= cold bias, switch on= hot bias. Cheap parts, fairly cheap/easy/fast to install.

If you refer to the schematic I posted, you’ll simply have to add R200 (cold biasing resistor) and switch SW4B (to bypass R200 when on). Depending on the amp, you might have to fiddle with the biasing resistors to get the right balance between hi and low options.

Whether you’ll like the sound of the result and whether it’ll be useful is what I was originally getting at.

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Re: Output mod

Post by Thewilltopowerrock »

RectifiedAmps wrote: Tue Oct 19, 2021 11:50 am
Thewilltopowerrock wrote: Tue Oct 19, 2021 11:20 am Didn’t realise there were so many politicians here - 2 pages of replies and basically no answer to the question! 😂

Mike, could you go into slightly more detail about what work would be required? What would actually be changed/added? Keep it layman level please haha.
Sorry, I thought I had answered it but I think I was focused on the ‘why’ more than the ‘how’. It can be done quite easily on any cathode-biased amp. You’d just need a switch that bypasses/shorts a biasing resistor when it’s on. Switch off= cold bias, switch on= hot bias. Cheap parts, fairly cheap/easy/fast to install.

If you refer to the schematic I posted, you’ll simply have to add R200 (cold biasing resistor) and switch SW4B (to bypass R200 when on). Depending on the amp, you might have to fiddle with the biasing resistors to get the right balance between hi and low options.

Whether you’ll like the sound of the result and whether it’ll be useful is what I was originally getting at.
I was slightly unfair in my previous post because you had responded appropriately haha.

Thanks for the additional info, good to know. Fair point about the end result, I guess that would be the gamble but worst case you never use the switching! 😅

Depending on how my amp search goes I might PM you. As I said previously if it’s doable it’s potentially an attractive alternative to having the extra bit of kit such as the Fryette.

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Re: Output mod

Post by codedog »

MikeC wrote: Tue Oct 19, 2021 11:03 am Anything can be done (pretty much) with an unlimited budget.
Including buying a new one!

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Re: Output mod

Post by MikeC »

Thewilltopowerrock wrote: Tue Oct 19, 2021 11:20 am Didn’t realise there were so many politicians here - 2 pages of replies and basically no answer to the question! 😂

Mike, could you go into slightly more detail about what work would be required? What would actually be changed/added? Keep it layman level please haha.
Without knowing which specific amp and what you're trying to achieve, I can't :geek:

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Re: Output mod

Post by NippleWrestler »

RectifiedAmps wrote: Tue Oct 19, 2021 11:50 am
Thewilltopowerrock wrote: Tue Oct 19, 2021 11:20 am Didn’t realise there were so many politicians here - 2 pages of replies and basically no answer to the question! 😂

Mike, could you go into slightly more detail about what work would be required? What would actually be changed/added? Keep it layman level please haha.
Sorry, I thought I had answered it but I think I was focused on the ‘why’ more than the ‘how’. It can be done quite easily on any cathode-biased amp. You’d just need a switch that bypasses/shorts a biasing resistor when it’s on. Switch off= cold bias, switch on= hot bias. Cheap parts, fairly cheap/easy/fast to install.

If you refer to the schematic I posted, you’ll simply have to add R200 (cold biasing resistor) and switch SW4B (to bypass R200 when on). Depending on the amp, you might have to fiddle with the biasing resistors to get the right balance between hi and low options.

Whether you’ll like the sound of the result and whether it’ll be useful is what I was originally getting at.
In the interests of safety would it be more prudent to have 1 resistor permanently in circuit and then switch in another in parallel to drop the value? Switching between 1 or the other is going to allow a momentary lapse where nothing is in circuit (unless it's a make before break switch which they usually aren't) then bringing it all back once the switch is connected.

I don't know how amps would react to that. Maybe nothing, maybe something, but a parallel resistor switch mitigates any threat... I think.

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Re: Output mod

Post by jeremyb »

Thewilltopowerrock wrote: Tue Oct 19, 2021 11:20 am Didn’t realise there were so many politicians here - 2 pages of replies and basically no answer to the question! 😂

Mike, could you go into slightly more detail about what work would be required? What would actually be changed/added? Keep it layman level please haha.
See my answer, easy mod to any amp to make it quieter but preserve the power amp toan :-)
Birds aren’t real.

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Re: Output mod

Post by MikeC »

jeremyb wrote: Tue Oct 19, 2021 1:43 pm
Thewilltopowerrock wrote: Tue Oct 19, 2021 11:20 am Didn’t realise there were so many politicians here - 2 pages of replies and basically no answer to the question! 😂

Mike, could you go into slightly more detail about what work would be required? What would actually be changed/added? Keep it layman level please haha.
See my answer, easy mod to any amp to make it quieter but preserve the power amp toan :-)
Not so easy (or possible even) to use global VVR if the amp's power stage is grid biased (which the big ones typically are).

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Re: Output mod

Post by jimi »

The power scaling in the Marshall AFD100 / YJM100 is pretty amazing - 0.1w - 100w.

Totally usable at home, and for gigging at any scale (assuming a Marshall set up to sound like Slash is the tone you want). I found around 15-20w to be right for the gigs I play (5 piece, acoustic drums, vocals only in the PA).

Of course with a 2x12 cab its not the most portable for a bedroom amp - totally usurped by a Katana Mini for at home convenience.

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Re: Output mod

Post by RectifiedAmps »

NippleWrestler wrote: Tue Oct 19, 2021 1:38 pm In the interests of safety would it be more prudent to have 1 resistor permanently in circuit and then switch in another in parallel to drop the value? Switching between 1 or the other is going to allow a momentary lapse where nothing is in circuit (unless it's a make before break switch which they usually aren't) then bringing it all back once the switch is connected.

I don't know how amps would react to that. Maybe nothing, maybe something, but a parallel resistor switch mitigates any threat... I think.
The Vox AC15HW switch isn’t breaking the cathode to ground connection. It’s just shorting (or not) a resistor that is stacked ontop of the usual cathode resistor+ bypass cap, so it’s basically doing what you suggest.

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Re: Output mod

Post by RectifiedAmps »

MikeC wrote: Tue Oct 19, 2021 1:47 pm
jeremyb wrote: Tue Oct 19, 2021 1:43 pm
Thewilltopowerrock wrote: Tue Oct 19, 2021 11:20 am Didn’t realise there were so many politicians here - 2 pages of replies and basically no answer to the question! 😂

Mike, could you go into slightly more detail about what work would be required? What would actually be changed/added? Keep it layman level please haha.
See my answer, easy mod to any amp to make it quieter but preserve the power amp toan :-)
Not so easy (or possible even) to use global VVR if the amp's power stage is grid biased (which the big ones typically are).
Merlin Blencowe (the Valve Wizard) has a great VVR circuit for fixed bias amps that scales the bias in parallel to the B+. I installed it in a customer’s Bluesbreaker a while back and it worked well, although it was a bit fiddly to set up.

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Re: Output mod

Post by jeremyb »

I found even with the MK2 Katana head at 0.5W thru a 2x12 it was too loud for my bedroom use, the AC10 can get fairly quiet but its still marginal, so the Spark is my go to when theres anyone else in the house :-)
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Re: Output mod

Post by MikeC »

RectifiedAmps wrote: Tue Oct 19, 2021 2:30 pm
MikeC wrote: Tue Oct 19, 2021 1:47 pm
jeremyb wrote: Tue Oct 19, 2021 1:43 pm

See my answer, easy mod to any amp to make it quieter but preserve the power amp toan :-)
Not so easy (or possible even) to use global VVR if the amp's power stage is grid biased (which the big ones typically are).
Merlin Blencowe (the Valve Wizard) has a great VVR circuit for fixed bias amps that scales the bias in parallel to the B+. I installed it in a customer’s Bluesbreaker a while back and it worked well, although it was a bit fiddly to set up.
That sounds interesting - don't suppose you can give me a link to save me an internet hunt? Thanks.

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