Vox AC10 SRT? Schematic or any info?

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Gainzilla
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Vox AC10 SRT? Schematic or any info?

Post by Gainzilla »

This thing sounds great!

https://www.youtube.com/watch?v=alBO_yEn5o4

Cheers!
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Mr. dB
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Re: Vox AC10 SRT? Schematic or any info?

Post by Mr. dB »

Image
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Gainzilla
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Re: Vox AC10 SRT? Schematic or any info?

Post by Gainzilla »

Awesome, thanks!

-B
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Mr. dB
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Re: Vox AC10 SRT? Schematic or any info?

Post by Mr. dB »

The 710 is very similar, but with tone controls.
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Re: Vox AC10 SRT? Schematic or any info?

Post by Gainzilla »

Ok, so I really had to dig for the 710 schematic. Finally found it thanks to the wayback machine internet archive. Attached.

I haven't been able to really study the two, in part because old vox schematics give me a headache. :)

Assuming you have some experience with these, what are the main differences? Just the tone stack? The power amp plate voltage looks pretty similar.

Thanks for the tip!

- Bryce
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Mr. dB
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Re: Vox AC10 SRT? Schematic or any info?

Post by Mr. dB »

Gainzilla wrote: Tue Feb 28, 2017 5:13 pm Ok, so I really had to dig for the 710 schematic. Finally found it thanks to the wayback machine internet archive. Attached.

I haven't been able to really study the two, in part because old vox schematics give me a headache. :)
Agreed about the headache. Vox seemed to follow a sort of British tradition of drawing schematics that obfuscate more than illuminate.

There are AC10 and AC15 schematics from Thomas Organ that finally seem to cut the crap and show the circuits with clarity:

Image

Image

These are about the only Vox schematics out there that don't make me squirm.
Gainzilla wrote: Tue Feb 28, 2017 5:13 pm Assuming you have some experience with these, what are the main differences? Just the tone stack? The power amp plate voltage looks pretty similar.

No experience at all with either amp, apart from a brief look at the schematics.

But since the 710 schematic looks like an edited version of the AC10SRT schematic, I assume that's reflective of the design evolution as well?
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Re: Vox AC10 SRT? Schematic or any info?

Post by pompeiisneaks »

Man tell you what I was trying to figure out the Vox AC30/4 schematic online and its like someone used a blur tool on it. (As well as that really weird layout everyone's talking about) when I got it done, i found out that Sluckey had the AC15 you're showing here with the EF86 preamp, and its identical except for the 4 output tubes. I basically built that one in my recently posted video series. Came out great. I find it weird the AC10 uses 2xEL84, and the AC15 uses the same, but they seem to imply different wattage outputs? Why? Do they just run at different voltages? (seems from the two schematics it's only 5v different). The resistors and bias resistor/cap are all identical...? How is one an AC10 and the other an AC15?

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Mr. dB
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Re: Vox AC10 SRT? Schematic or any info?

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pompeiisneaks wrote: Tue Feb 28, 2017 9:28 pm I find it weird the AC10 uses 2xEL84, and the AC15 uses the same, but they seem to imply different wattage outputs? Why? Do they just run at different voltages? (seems from the two schematics it's only 5v different). The resistors and bias resistor/cap are all identical...? How is one an AC10 and the other an AC15?
I think mostly the difference is "advertising watts".

The part I find odd is the apparent mistake on the AC10 schematic, showing what should be the screen grid 100ohm resistors on the plates instead. Except that if you look at a real AC10, that's how they're built. Then there's those 220K resistors on the inputs, instead of the usual 68K. Like they deliberately hobbled the amp to punish you for not paying more and stepping up to the AC15.
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Re: Vox AC10 SRT? Schematic or any info?

Post by Gainzilla »

Huh. So same hardware configuration and voltage, but they've hobbled the amp in order to make more clearly defined price points. Lol

Hey Phil, fellow seattleite here!
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Re: RE: Re: Vox AC10 SRT? Schematic or any info?

Post by pompeiisneaks »

Gainzilla wrote:Huh. So same hardware configuration and voltage, but they've hobbled the amp in order to make more clearly defined price points. Lol

Hey Phil, fellow seattleite here!
[emoji477]️
Woot, I'm from Redmond actually, but must don't knows of it :). Do you build amps too?

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Re: Vox AC10 SRT? Schematic or any info?

Post by Gainzilla »

Ha! I used to live in Redmond but recently bought a house in Renton. Small world! I'll go out on a limb and assume you work in tech (thanks for saving us, btw!)? I used to design software at MS, but am now at a startup in pioneer square.

I do build amps! Mostly for fun, but partly because I clearly have issues. Lol
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Re: RE: Re: Vox AC10 SRT? Schematic or any info?

Post by pompeiisneaks »

Gainzilla wrote:Ha! I used to live in Redmond but recently bought a house in Renton. Small world! I'll go out on a limb and assume you work in tech (thanks for saving us, btw!)? I used to design software at MS, but am now at a startup in pioneer square.

I do build amps! Mostly for fun, but partly because I clearly have issues. Lol
Cool I do, I'm a systems engineer. Working downtown Seattle as well. Not far from pioneer square. I've been software engineer, sysadmin, etc. Many hats.

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Mr. dB
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Re: Vox AC10 SRT? Schematic or any info?

Post by Mr. dB »

Gainzilla wrote: Wed Mar 01, 2017 1:56 am Huh. So same hardware configuration and voltage, but they've hobbled the amp in order to make more clearly defined price points. Lol

They also simplified the preamp and the trem. Six tubes vs. eight.
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Re: Vox AC10 SRT? Schematic or any info?

Post by pullshocks »

I've been really interested in this amp too. I had to re-draw the schematic in a more conventional sequence before I could get my brain around it.

But I am still confused by V2B and C17. It is shown between the plate and plate resistor.

Mark (another Seattle guy).
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Re: Vox AC10 SRT? Schematic or any info?

Post by pompeiisneaks »

That's the oscillator, it just generates a sine wave for the tremolo. I just built a vox ac30/4 and it uses the same topology. Very cool stuff.

Phil
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