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Old 27th May 2003, 11:56 PM   #21
dhaen is offline dhaen  Europe
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Quote:
Originally posted by fdegrove
Hi,



Why? Does anyone want more distortion and less power?

The SET guys might...

No, Tim, the idea is to be able to use a PP OPT iso the more expensive SE OPTs.

Cheers,
AND, get good power supply ripple and (some) noise rejection..

Cheers,
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Old 28th May 2003, 12:06 AM   #22
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Hi,

O.K....

Quote:
AND, get good power supply ripple and (some) noise rejection..
AND no reason I can think of why you can't do that with a SET as well.

What I critisise the SET brigade for is the way they go to ridiculous extremes and claim it sounds good.

From what I've seen from your work that's certainly not the case but some guys present 10 uF supplies and microwatt power and still make claims as if they'd invented hot water...
Sorry, but audio is still physics last time I checked.
Add a good dose of voodoo and you're in audio Nirvana...

Mister PS,
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Old 28th May 2003, 12:14 AM   #23
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Frank said:
Quote:
AND no reason I can think of why you can't do that with a SET as well.
No, of course not. It's just more difficult. That's what makes James's presentation elegant.

and:
Quote:
Sorry, but audio is still physics last time I checked.
Hmm, not when the discussion topic is silver wire and suchlike.

Cheers,
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Old 28th May 2003, 12:18 AM   #24
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Hi,

Quote:
Hmm, not when the discussion topic is silver wire and suchlike.
As far as silver goes it sure has alot of advantages, even beyond the purely electrical ones.

It would be best to discuss that in the appopriate thread though.

We have plenty of those to choose from lately it seems...
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Old 28th May 2003, 12:27 AM   #25
dhaen is offline dhaen  Europe
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Default What distortion?

Actually, none of the replies has properly addressed Tim's question:
Quote:
Well why the heck would you have it in then? More power and less distortion.
So perhaps we'd better wait for James's reply.

Cheers,
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Old 28th May 2003, 02:31 AM   #26
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The other thing I don't understand is how that power amp schematic got into a preamp thread.

Tim
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Old 28th May 2003, 03:04 AM   #27
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Default UH OH...

Hi,

Quote:
The other thing I don't understand is how that power amp schematic got into a preamp thread
And it really oozes power, right?

Shuttup, Tim.
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Old 28th May 2003, 04:24 AM   #28
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Hrm...guess I should actually see what the heck a 6N6P is... I assumed it was a beefy triode, after all you don't want to be riding on transconductance, what with a 3 or 4k plate load...

Hey...ya know what? The other triode's plate will load down the 'free' end of the OPT...
Also, the CCS isn't a very good one seeing as IT'S SHUNTED BY CAPACITANCE! LOL can't believe that just occured to me..

Tim
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Old 28th May 2003, 07:33 AM   #29
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Default ...what a nice start to the day...

Tim,

Many thanks for the amusement - I greatly enjoyed reading through your comments. I don't usually laugh out loud before my first coffee

Where to start...

As I stated earlier, to try to hit the cost boundary but use an OPT I needed to use a PP OPT. My first thought was to use a 3B7 a siamese double DHT as they are very cheap and have a reasonable mu (20) and Gm (2-2.5 mA/V) but I couldn't solve the signal and heater conflict cheaply enough (two channels one supply). It also needed a -ve supply for the long tail...

So back to IHTs. I like the 6N6P and it is happy with -6V bias so I could squeeze a ss constant current source under it! We're in business

Now psu... got a nice cheap Xfmr but any choice of chokes breaks the bank Oh well use RC filtering. It's PP so I don't need to work so hard on the PSU. I've got these nice cheap 3 section elec. so that's easy... Unfortunately 3 section RC psu with relatively large electrolytics sound crap - really crap - so how to release the sound of the 6N6Ps...

I know use ultrapath philosophy and get the psu out of the signal path! Disadvantage is that it's not pp for signal but it is pp for d.c. Cheap OPT and better PSRR A win-win!

Tim,

Have another look at the OPT configuration - 12.5k:8R.

Look at the winding ratio... now consider the typical load driving a power amp...

What reflected impedance does that give the 6N6P as anode load for audio?

Not 3-4K is it...

Colt 45, if you have 6N6p for 4 euro - I'll have 50.

ciao

James
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Old 28th May 2003, 07:55 AM   #30
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Default An Englishman abroad....

James,

Quote:
I know use ultrapath philosophy and get the psu out of the signal path!
Of course! that's the key I was missing at 2AM this morning By brain

Quote:
What reflected impedance does that give the 6N6P as anode load for audio?
(Rhetorical)

Indeed. But what about the inductance, it being a small TX?

Cheers,
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