Vox AC50 build

Vox and Hiwatt Discussion

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JoeCon
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Vox AC50 build

Post by JoeCon »

Guys

I'm starting an AC50 build using the MkIII preamp with a 12AU7 and separate vol, treble and bass for the normal and brilliant channels and the Mk I PI and power tube circuit. So SS recto and LTP driver.

I had some parts around and decided to try them together. An express chassis which I punched out for the extra tube and an Edcor PT 570V and 250mA. A Classictone 40-1801 4.2K OT with a Hammond choke 6h 200mA.

Some early pics...
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Colossal
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Re: Vox AC50 build

Post by Colossal »

Off to a great start! Looks solid.
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JoeCon
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Re: Vox AC50 build

Post by JoeCon »

Thanks Dave! If it comes out as good as the 6V6 Plexi you helped me with it
will be awesome.

Going for single input with this one too. But each channel will have it's own tone stack unlike the Plexi. But with separate volumes I should be able to mix them nicely.

Also with 12AU7 first stage should have a lot more clean headroom. Hope it will be a good "pedal" amp.
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M Fowler
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Re: Vox AC50 build

Post by M Fowler »

Should be great.

I always considered our Trainwreck Rocket with Octal power tubes an AC50 so should sound about the same, yes/no?
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Re: Vox AC50 build

Post by Stevem »

Not really if you listen close!
A 6v6 is a beam tetrode, EL84s and 34s are not.
Dependant on how hard you drive the tube from the PI and if the amp uses feedback or not, then dynamics wise in the output stage at least 84s and 34s will go smother in and out of clipping!
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rp
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Re: Vox AC50 build

Post by rp »

If you don't need both the normal brilliant inputs hunt down a 12DW7, that way you can do one channel as a 12XA7 other as a 12AU7, set the V1 caps and resistors involved to your liking.
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JoeCon
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Re: Vox AC50 build

Post by JoeCon »

Mark

Sort of. I read they, Vox, tried an AC30 with El34's as a starting point.

The Rockster is setup a liitle different. In fact mine has KT66 tubes so mine is a top boost with a bluesbreaker kinda sound.

rp, want both channels to mix and match as needed.
Last edited by JoeCon on Tue Oct 20, 2015 1:24 pm, edited 1 time in total.
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M Fowler
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Re: Vox AC50 build

Post by M Fowler »

Yeah I've used about everything behind the Rocket preamp KT66, KT77, EL34, 6L6GC, 6550, KT88 and KT120.

I like the 6550 and KT120 the best smooth as pudding.

Instead of 12DW7 try ecc832 or ecc823 tubes.
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JoeCon
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Re: Vox AC50 build

Post by JoeCon »

Mark

I'm suspecting you used different transformers for whatever tube set you were driving. But how about the PI values did you adjust them as well?

Thanks...
In theory, theory is the same as practice. In practice it's different.
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M Fowler
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Re: Vox AC50 build

Post by M Fowler »

JoeCon wrote:Mark

I'm suspecting you used different transformers for whatever tube set you were driving. But how about the PI values did you adjust them as well?

Thanks...
Yes adjusted PI and many different transformer brands used Fender 4k, Marshall 3k4, Dynaclone A470-S 4k3, Edcor, etc.
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JoeCon
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Re: Vox AC50 build

Post by JoeCon »

OK a small update:

Got the holes all drilled and the iron mounted. Tube sockets next...
Also turrets in the boards, just waiting for some parts to start soldering.
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Jered
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Re: Vox AC50 build

Post by Jered »

Is this still in the works or finished? I'm curious how mixing those channels worked for you? Thanks
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Re: Vox AC50 build

Post by Jered »

Is this still in the works or finished? I'm curious how mixing those channels worked for you? Thanks
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M Fowler
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Re: Vox AC50 build

Post by M Fowler »

Looking nice :)
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JoeCon
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Re: Vox AC50 build

Post by JoeCon »

Sorry not much amp work due to "real" work and family visiting thru the holidays.

Hope to get back to it soon...
In theory, theory is the same as practice. In practice it's different.
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