Questions on HiWatt

Vox and Hiwatt Discussion

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SilverFox
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Joined: Fri Feb 10, 2012 6:03 pm

Questions on HiWatt

Post by SilverFox »

What is it about the preamp section that makes this amp unique? How much does the poweramp section add to the the classic tone?

The Reeves Super 78 sounds fantastic! Is there some sort of Marshall style preamp circuit in the '78' that gets that sound? Clean to Mean.

https://www.youtube.com/watch?v=dKpuanR5ZjQ

My understanding is HiWatt is basically a clean sounding amp although I've heard several on youtube that have some gain distortion.

Thanks for any information as I'm looking into a build of a slightly altered HiWatt, perhaps the 501,

silverfox.
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M Fowler
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Re: Questions on HiWatt

Post by M Fowler »

The Hiwatt has a voltage stabilizer and a fixed bias phase splitter. Half of the 3rd 12AX7 is used as a voltage regulator to provide a fixed bias to the 12AX7 phase splitter stage to keep the signal optimally balanced at about 68 volts to minimize signal clipping (distortion) resulting in unusually clean sound.

Per page 79 Building Vacuum tube guitar and bass amplifiers Volume 3 Tino Zottola. Hiwat DR103 build.

Mark
SilverFox
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About those books?

Post by SilverFox »

I wonder if I should buy the 3 vol. set? Is there anything beyond layout information and construction techniques- Yes I realize you quoted the voltage regulation theory. Sometimes a book can be rather anti-climactic.

I'm curious to know also what the impact of the regulation would be on any high gain distortion introduced into the signal chain? Presumably it could only help. So many of the amps I hear that are high gain have a fizz to the treble portion. A sort of a white noise in the signal.

regards,

silverfox.
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jaysg
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Re: Questions on HiWatt

Post by jaysg »

hmm...just listened to that youtube and looked at the Reeve's site. Since no one famous named Eddie played Hiwatt, and from looking at the literature, that is not a standard Hiwatt amp...may be what you want, but who knows what's going on in it until someone documents it.

The Jimmy Page model is based on a real amp...but not a production model. The originals ran too hot, but sounded glorious as their tubes died.
JD0x0
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Re: Questions on HiWatt

Post by JD0x0 »

Based on that clip, and the 78' name, I'd suspect that amp is actually one of the early 'LEAD' amps, or some variation on that circuit, otherwise known as DR504OL, if I'm not mistaken. They seem to have a lot more gain on tap than the older designs.

I've got an early 80's Lead 50, without the second 'overdrive/gain' knob, on the front panel, and it sounds a lot like the gain sounds he was getting.

Here's a modded schematic of my amp currently if you're looking for some ideas, or a potential layout. There's probably some improvements that can be made on the original design, that I haven't changed.

Ceriatone also has layouts for the OL Hiwatts.
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SilverFox
Posts: 222
Joined: Fri Feb 10, 2012 6:03 pm

SuperHiWatt

Post by SilverFox »

Thanks JD. I just checked back into this thread. I've been working on getting a power amp debugged and I've gotten that done now. Kinda off in a bit of a tangent but still collecting information on the Super 78.

silverfox.
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