Gainclone & Quad ESL 63

Tham · 3rd July 2008, 03:43 AM

Hi,

Newbie looking for some advice here....

I am currently driving my Quad ESL 63 pro with a 60w Class AB ss amp quite sufficiently in a 10" x 18" room.

Planning to build a LM3875 gainclone as my first amp project but would like to seek some advice here whether it can drive difficult load like my Quads.

Any help will be appreciated. TQ

Tham

Nuuk · 3rd July 2008, 08:02 AM

I would have said no once but there is somebody (I can't remember who now but I have seen him on one of these forums) who does exactly that. But you will need to find out exactly which version he uses.

jacco vermeulen · 3rd July 2008, 08:12 AM

It'll be the best protected power amp-LSP combo.

A single LM3785 will constantly shut down, an LM3886/BPA200 would be more up to the job imo.

Tham · 3rd July 2008, 08:52 AM

Hi Nuuk,

Thanks for the head up. Will do another search to locate the post you mentioned about.

Hi Jacco,

Many thanks. Will have to read up about LM3886/BPA200 combo.

Regards

Tham

ttan98 · 3rd July 2008, 09:56 AM

LM3875 will handle 8ohm very well, and will handle 4 ohms as clong as the supply voltage is below 25-27Vdc.

tobydog · 3rd July 2008, 03:07 PM

Tham,

Not quite as your asking, but may help :

ESL57 + LM3886 Brian GT boards
18-0-18 transformer Carlos snubbered

No problems.

Mick

tschrama · 3rd July 2008, 03:21 PM

I also have ELS-57s and these are actually not at all current hungry... Their impedance goes down to 2 Ohm at ?10KHZ? , but there is so little signal in that frequency range, that they don't demand that much current...

I don't know about the ESL67, but usualy it's the impedance dip in the low 20-400Hz range that can cause trouble with amps...

maybe an output inductor should be used to protect the amp from the capacitive load of the Esl67..

Tham · 4th July 2008, 12:12 AM

Hi,

Many thanks to all the help here so far. Looks like there is a better chance matching Quad ESL 63 with LM3886.

Regards

Tham

jacco vermeulen · 4th July 2008, 11:01 AM

The more rational choice, imo.

The ESL57 is a more difficult load than the 63 on a decent SS amp that copes with a capacitive load, on top of that the 57 doesn't have over-voltage protection.
The ESL57 dips below 2 Ohm in the high freq. range, while the 63 remains above 3.5-3.6

It's a different story on the other side of the impedance curve, the 57 remains at very comfortable levels but the ESL63 drops well below 4 Ohm again at 20Hz.
The 63 needs a bulkier output stage, the later models are much more driver seat friendly.
A chip amp is a nice bench mark for ESL's though, goes to show how much difference in sound power amps really make, also again demonstrates how mediocre Quad amps like the 303s really were.

erictoucan · 9th September 2010, 12:54 PM

why not use OPA549 or use OPA549 as current buffer output and high grade OP amp like OPA 445 or OPA 552 as voltage gain stage. You get a great deal of good current for low impedence ESLXX. The bandwidth will also much wider. The voltage gain stage should better be pulled down to -ve rail to create a single end class A stage. I trust this configuration will outperform more than 95% of commercial amp. Good luck

3rd July 2008, 03:43 AM	#1
Tham diyAudio Member Join Date: Jun 2006	Gainclone & Quad ESL 63 Hi, Newbie looking for some advice here.... I am currently driving my Quad ESL 63 pro with a 60w Class AB ss amp quite sufficiently in a 10" x 18" room. Planning to build a LM3875 gainclone as my first amp project but would like to seek some advice here whether it can drive difficult load like my Quads. Any help will be appreciated. TQ Tham

3rd July 2008, 08:02 AM	#2
Nuuk diyAudio Member Join Date: Feb 2003 Location: Somerset, SW England	I would have said no once but there is somebody (I can't remember who now but I have seen him on one of these forums) who does exactly that. But you will need to find out exactly which version he uses. __________________ The truth need not be veiled, for it veils itself from the eyes of the ignorant.

9th September 2010, 12:54 PM	#10
erictoucan diyAudio Member Join Date: Mar 2005 Location: Hong Kong	why not use OPA549 or use OPA549 as current buffer output and high grade OP amp like OPA 445 or OPA 552 as voltage gain stage. You get a great deal of good current for low impedence ESLXX. The bandwidth will also much wider. The voltage gain stage should better be pulled down to -ve rail to create a single end class A stage. I trust this configuration will outperform more than 95% of commercial amp. Good luck __________________ chung

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3rd July 2008, 08:12 AM	#3
jacco vermeulen diyAudio Member Join Date: Oct 2004 Location: At the sea front, just under Rotterdam	It'll be the best protected power amp-LSP combo. A single LM3785 will constantly shut down, an LM3886/BPA200 would be more up to the job imo.

3rd July 2008, 08:52 AM	#4
Tham diyAudio Member Join Date: Jun 2006	Hi Nuuk, Thanks for the head up. Will do another search to locate the post you mentioned about. Hi Jacco, Many thanks. Will have to read up about LM3886/BPA200 combo. Regards Tham

3rd July 2008, 09:56 AM	#5
ttan98 diyAudio Member Join Date: Apr 2006 Location: Melb	LM3875 will handle 8ohm very well, and will handle 4 ohms as clong as the supply voltage is below 25-27Vdc.

3rd July 2008, 03:07 PM	#6
tobydog diyAudio Member Join Date: Mar 2004 Location: Near Saarfend, Essex	Tham, Not quite as your asking, but may help : ESL57 + LM3886 Brian GT boards 18-0-18 transformer Carlos snubbered No problems. Mick

3rd July 2008, 03:21 PM	#7
tschrama diyAudio Member Join Date: Jul 2001 Location: The Netherlands	I also have ELS-57s and these are actually not at all current hungry... Their impedance goes down to 2 Ohm at ?10KHZ? , but there is so little signal in that frequency range, that they don't demand that much current... I don't know about the ESL67, but usualy it's the impedance dip in the low 20-400Hz range that can cause trouble with amps... maybe an output inductor should be used to protect the amp from the capacitive load of the Esl67..

4th July 2008, 12:12 AM	#8
Tham diyAudio Member Join Date: Jun 2006	Hi, Many thanks to all the help here so far. Looks like there is a better chance matching Quad ESL 63 with LM3886. Regards Tham

4th July 2008, 11:01 AM	#9
jacco vermeulen diyAudio Member Join Date: Oct 2004 Location: At the sea front, just under Rotterdam	The more rational choice, imo. The ESL57 is a more difficult load than the 63 on a decent SS amp that copes with a capacitive load, on top of that the 57 doesn't have over-voltage protection. The ESL57 dips below 2 Ohm in the high freq. range, while the 63 remains above 3.5-3.6 It's a different story on the other side of the impedance curve, the 57 remains at very comfortable levels but the ESL63 drops well below 4 Ohm again at 20Hz. The 63 needs a bulkier output stage, the later models are much more driver seat friendly. A chip amp is a nice bench mark for ESL's though, goes to show how much difference in sound power amps really make, also again demonstrates how mediocre Quad amps like the 303s really were.

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