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well, it sort of goes like this... [message #31059 is a reply to message #31058]

Tue, 19 April 2005 19:09

PakProtector
Messages: 935
Registered: May 2009

Illuminati (2nd Degree)

The 813 has a lot of unknown territory to cover I suspect. That and not-so-simple power supplies. So, it depends on where you want to draw the line at 'too complex' or too expensive' or 'too heavy' or...

The topology I laid out for Merlin is quite adaptable. Remarkably so I think. Where ever you feel like jumping in, there will be support and help, and you'll probably wind up learning something important that neither of us knows now at the begining.

There are many choices, and options in this world of DIY amps, I am not used to applying blinders or shades to the development or discussion. I'm also not quite comfortable saying that there is only one 'Best' for All. This leads to a muddle of options. gather some of them up and present them for discussion, and we can try to figure out what is the better path to experiiment on.
regards,
Douglas

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Re: well, it sort of goes like this... [message #31060 is a reply to message #31059]

Tue, 19 April 2005 21:47

Manualblock
Messages: 4973
Registered: May 2009

Illuminati (13th Degree)

sounds good. The thing is you have heard all the amps so therefor how about this; What would you choose that would be interesting for you to realise that provides minimum 20 watts; triode PP with tube rec and as far as power supply choke input with B+ as high as is required to obtain that big sound such as you describe with the 813's?
And whatever sounds personally intriqueing. I think you can get some dedicated experimenters here now that Guinevere turned out so well.
As little feedback; or even variable feedback as possible. Set a reasonable limit of say 800$ in parts.
Construct it in sections that can be individually tested before moving on to the next section. E-Linear with seperate DC filament supplies.
Start with the PS maybe; whatever seems best. Draw up a common top-plate template that can act as a reference for other projects but provide some uniformity between samples. Group buy whatever parts we can.
Just a thought, J.R.

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that's still wide open [message #31061 is a reply to message #31060]

Wed, 20 April 2005 07:15

PakProtector
Messages: 935
Registered: May 2009

Illuminati (2nd Degree)

this one:
minimum 20 watts; triode PP with tube rec and as far as power supply choke input with B+ as high as is required to obtain that big sound

I'll assume we're still full-on Class A. This 20W minimum still puts us in the moderate 845 B+ territory. Not exactly a bad thing.

I have been itching for a serious experimenter's power TX. Multiple taps on the primary like Varian requested from Paeco. Change the primary hook up to yeild 500-800V after an L-C filter Full-Wave with vacuum or Hg-vapour dioides. 300 mA deliverable at even the highest voltage. Probably ~$250 each. Slightly less if several are ordered.

On the 813 thing, I have not yet heard any, just an assumption I can get them to work well for me. The PP 845 is complex enough, and I am sure of that one. And I have OPTx's nearly tailor made for it. This is not a small thing to consider, availability of reasonably priced excellent OPTx.

As a swing for the fence( with a paid-off pitcher ), the PP845 amp is quite appetizing. 30W ought to be available fairly conservatively, and with no exotic parts. If it weren't for the 813's challenges, I'd build one next.
regards,
Douglas

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