Which SE-ECL82 amp to build?

Tyimo · 15th October 2005, 07:04 AM

Hi!
I was looking for a nice and simple SE amp with one ECL82 per side and found two attractive circuits.
I would like ask the experts about these designs:
-are they operate in Class A?
-has any negative fead back in the circuits?
-which one is better? :-)

Thanks and greets:

Tyimo

Tyimo · 15th October 2005, 07:09 AM

Here is the another competitor!

Note. Power supply removed from schema -- to dangerous to contemplate

PRR · 15th October 2005, 07:41 AM

> -are they operate in Class A?

Yes, obviously.

> -has any negative fead back in the circuits?

No. (I won't count the cathode resistor in the first one.)

> -which one is better? :-)

They are essentially THE SAME. Draw them both in the same style: very minor differences.

One BIG difference: #1 does not show a power supply, #2 does, and the #2 power supply as drawn is a death trap!!! It shows one side of the wall-power line connected to chassis. There no indication which side is utility-ground. It is uncertain which wall-socket pin is grounded (60% of my kitchen outlets had black and white reversed). The chassis is exposed to the users at the input connector, which makes the whole hi-fi system "electrically HOT". It can kill you or your children. And as drawn, turning the power switch Off ensures that the chassis will be "hot". Do not build that power supply as shown!!!

Giaime · 15th October 2005, 08:44 AM

Please moderators, remove that awfully dangerous schematic, as PRR said.

Tyimo · 15th October 2005, 01:35 PM

And here is the first one's PSU:

Giaime · 15th October 2005, 05:04 PM

Quote:

Originally posted by Tyimo
Giaime: here is a corrected schem.

That is always no-good, the B+ runs directly from the mains. You should use an isolation trasformer between the diode and the mains, to mantain safety rules. And also a half wave rectifier is no good. Try to redesign the PSU using PSUDesigner.

kevinkr · 15th October 2005, 06:37 PM

I think I would just build the more recent of the two circuits, supply decoupling looks to be marginally better in the newer design.

If you do build the earlier one do get a power transformer with about a 180-200V secondary as well as a filament winding. You can use a bridge rectifier, bear in mind the original halfwave rectifier would have dropped significantly more voltage than a full wave bridge.

The old power supply design as previously stated is extremely hazardous to put it mildly.

Kevin

planet10 · 15th October 2005, 08:47 PM

How about Morse's Gnat?

Pics of my 6BM8 - The Gnat....

dave

Zen Mod · 15th October 2005, 10:18 PM

search for "Aleksandar Kitic" in this forum.
LH84 (if I remember OK ) looks promising

Tyimo · 16th October 2005, 05:52 AM

Hi!

Quote:

the B+ runs directly from the mains

Giaime! Yes, you are right! I looked only the main-audio circuit section and not the whole circuit with the PSU... That PSU design was realy a "deadly joke" Thanks for the moderators that removed it from the schematic!

Kevin: Thanks! Which one do you mean: the Noel82, with coloured schem ? I would anyway build a better PSU for this amp.

Greets:

Tyimo

15th October 2005, 08:47 PM	#8
planet10 frugal-phile(tm) diyAudio Moderator Join Date: Oct 2001 Location: Victoria, BC, NA, Sol III Blog Entries: 4	How about Morse's Gnat? Pics of my 6BM8 - The Gnat.... dave __________________ community sites t-linespeakers.org, frugal-horn.com ........ commercial site planet10-HiFi p10-hifi forum here at diyA

15th October 2005, 10:18 PM	#9
Zen Mod diyAudio Member Join Date: Jan 2003 Location: ancient Batsch , behind Iron Curtain	search for "Aleksandar Kitic" in this forum. LH84 (if I remember OK ) looks promising __________________ my Papa is smarter than your Nelson ! tnx to clean thread ; Cook Book ; PSM LS Cook Book ; Baby Diyaudio FORUM ; BAF Forum & Gallery;I'm dumb

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15th October 2005, 07:41 AM	#3
PRR diyAudio Member Join Date: Jun 2003 Location: USA	> -are they operate in Class A? Yes, obviously. > -has any negative fead back in the circuits? No. (I won't count the cathode resistor in the first one.) > -which one is better? :-) They are essentially THE SAME. Draw them both in the same style: very minor differences. One BIG difference: #1 does not show a power supply, #2 does, and the #2 power supply as drawn is a death trap!!! It shows one side of the wall-power line connected to chassis. There no indication which side is utility-ground. It is uncertain which wall-socket pin is grounded (60% of my kitchen outlets had black and white reversed). The chassis is exposed to the users at the input connector, which makes the whole hi-fi system "electrically HOT". It can kill you or your children. And as drawn, turning the power switch Off ensures that the chassis will be "hot". Do not build that power supply as shown!!!

15th October 2005, 08:44 AM	#4
Giaime diyAudio Member Join Date: Oct 2004	Please moderators, remove that awfully dangerous schematic, as PRR said.

15th October 2005, 06:37 PM	#7
kevinkr diyAudio Moderator Join Date: Sep 2004 Location: Boston, Massachusetts Blog Entries: 6	I think I would just build the more recent of the two circuits, supply decoupling looks to be marginally better in the newer design. If you do build the earlier one do get a power transformer with about a 180-200V secondary as well as a filament winding. You can use a bridge rectifier, bear in mind the original halfwave rectifier would have dropped significantly more voltage than a full wave bridge. The old power supply design as previously stated is extremely hazardous to put it mildly. Kevin

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