The Red Light District - another PP EL84 amp - Page 5

planet10 · 15th June 2006, 07:33 PM

Here is poobah's text as rendered by my default TextEdit font. (i just had to change the text encoding to see the text is Japanese -- i had to cut & past it into TextEdit to make it big.

Is it 98 or 86 LEDs?

I have my 98 laid out, but this is much more interesting (harder to wire no doubt)

dave

poobah · 15th June 2006, 07:44 PM

It just gets better and better. Don't we have work to do?

My symbol shows the forth leg of the second symbol as concave down.

Planet 10's symbol shows the forth leg as concave up.

Could P 10's symbol mean, "going to"; and my symbol mean, "just been"? Speaking of the district, that is.

mark_titano · 15th June 2006, 07:53 PM

Mhmm...the array works like a voltage source with low impedance from cathodes to gnd.

Good for recovery time indeed, but with this approach there is no way to set equal dc current in the OT primaries (which I suppose to be a good thing…).

Stuart, what do you think about the possibility of a mixed solution for the bias? I mean something like 6.8/8.5V from the array (four/five leds in series) and the remaining 5/3.5V with fixed bias, just to balance the dc currents…

Mark

SY · 15th June 2006, 07:57 PM

The beauty of not using fixed bias is that one of the principle mechanisms causing blocking is eliminated. And, though I hesitate to mention this, it's a cheaper solution. At surplus, I bought LEDs for less than 5 cents. The 98 that I use for two channels ends up costing less than a high quality electroltic capacitor.

pinkmouse · 15th June 2006, 07:58 PM

Quote:

Originally posted by planet10
...harder to wire no doubt...

I'm working on it.

Giaime · 15th June 2006, 08:02 PM

Mark raised an interesting question.

For you all, it's better to have zero DC flux on the output transformer or have those benefits in overload recovery?

And what could be the difference to bias the EL84 with a CCS?

poobah · 15th June 2006, 08:11 PM

Is it pure Class A operation?

pinkmouse · 15th June 2006, 09:49 PM

No copper yet...

anatech · 15th June 2006, 09:51 PM

Nice Al!

EC8010 · 15th June 2006, 09:55 PM

Perhaps a warning might be necessary to prevent plonkers from introducing their, well, bits, into hot/high voltage places?

15th June 2006, 07:57 PM	#44
SY diyAudio Moderator Join Date: Oct 2002 Location: Austin, TX Blog Entries: 1	The beauty of not using fixed bias is that one of the principle mechanisms causing blocking is eliminated. And, though I hesitate to mention this, it's a cheaper solution. At surplus, I bought LEDs for less than 5 cents. The 98 that I use for two channels ends up costing less than a high quality electroltic capacitor. __________________ “Listening to records is like ****ing a picture of Brigitte Bardot.” - Sergiu Celibidache

15th June 2006, 09:55 PM	#50
EC8010 diyAudio Moderator Join Date: Jan 2003 Location: Near London. UK	Very nice Perhaps a warning might be necessary to prevent plonkers from introducing their, well, bits, into hot/high voltage places? __________________ The loudspeaker: The only commercial Hi-Fi item where a disproportionate part of the budget isn't spent on the box. And the one where it would make a difference...

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15th June 2006, 07:44 PM	#42
poobah diyAudio Member Join Date: Nov 2005	It just gets better and better. Don't we have work to do? My symbol shows the forth leg of the second symbol as concave down. Planet 10's symbol shows the forth leg as concave up. Could P 10's symbol mean, "going to"; and my symbol mean, "just been"? Speaking of the district, that is.

15th June 2006, 07:53 PM	#43
mark_titano diyAudio Member Join Date: Oct 2004	Mhmm...the array works like a voltage source with low impedance from cathodes to gnd. Good for recovery time indeed, but with this approach there is no way to set equal dc current in the OT primaries (which I suppose to be a good thing…). Stuart, what do you think about the possibility of a mixed solution for the bias? I mean something like 6.8/8.5V from the array (four/five leds in series) and the remaining 5/3.5V with fixed bias, just to balance the dc currents… Mark

15th June 2006, 08:02 PM	#46
Giaime diyAudio Member Join Date: Oct 2004	Mark raised an interesting question. For you all, it's better to have zero DC flux on the output transformer or have those benefits in overload recovery? And what could be the difference to bias the EL84 with a CCS?

15th June 2006, 08:11 PM	#47
poobah diyAudio Member Join Date: Nov 2005	Is it pure Class A operation?

15th June 2006, 09:51 PM	#49
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Nice Al!

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