Shindo Montrachet EL34 amp -- can it handle impedance of Snell Type A?


I have a Shindo Montrachet EL34 amp and Vandersteen 2wq subs that cross at 100hz with passive first order MP-5 crossovers. I either need to sell the amp or sell my Quad ESL-63 speakers, which I also love, because the authorized Shindo dealer tells me the Quads could damage the Shindo (it is really designed for higher efficiency 16 ohm Shindo speaker loads). I believe the Quads drop to 3.5 ohms or so in the bass and rise quite high in the treble.

I have an opportunity to acquire an old friend -- Snell Type A speakers. I am not worried right now about the Shindo's ability to "drive" the Snells in terms of power/dynamics. But I am concerned that the Snells could also present difficulty/danger for the Shindo due to impedance. The Snells have a minimum impedance of 4 ohms, but I do not know the exact maximum or the full impedance curve. I'm trying to find out, if anyone knows the impedance curve.

Does anyone know if the Snells would be safer with the Shindo than the Quads are? Does the fact that the Snells are a dynamic speaker and not an electrostatic inherently make it easier for the amplifier to stomach?

Thanks for any thoughts. Again, not looking for sound quality advice or speculation. I will be able to listen to the Snells before buying. But I don't want to endanger the Shindo amp.
montaldo
I believe the Quads drop to 3.5 ohms or so in the bass and rise quite high in the treble.
Actually, as with most electrostatics it is the opposite of that.  The impedance of a capacitor decreases as frequency increases, and from an electrical standpoint an electrostatic panel is essentially a giant capacitor.

Here are impedance curves and other measurements for the ESL-63 and for one of the versions of the Snell Type A:

http://www.stereophile.com/content/quad-esl-63-loudspeaker-measurements

http://www.stereophile.com/content/snell-acoustics-type-reference-loudspeaker-measurements

It appears that the Montrachet only provides a single output tap, and I wasn't able to find a spec on what nominal load impedance it is designed for.  But if the answer is 16 ohms, as you mentioned, the fact that both speakers have impedances that are well under 4 ohms at certain frequencies in the treble region does not bode well with respect to sonics.  Nor does the relatively low 86 db/2.83 volts/1 meter measured sensitivity of that version of the Snell Type A.

With the Snell, though, I don't see these measurements as being suggestive of any danger to the amp.  The one possible danger to the amp that I can see in any of these measurements relates to the 2 ohm impedance of the Quad at 30 kHz.  Even though that frequency is well above audibility and above any substantial frequency content the music may have, a low and highly capacitive impedance at high frequencies can cause some amplifiers to oscillate.  Perhaps that was the possibility the dealer had in mind.  Although in general I would expect that to be more likely to be an issue with a solid state amp than with a tube amp.

Good luck.  Regards,
-- Al 
 
@almarg 

Al,
I have no information as to why, but my Ars Sonus Filarmonia SJ Integrated (EL34 PP) has 8 Ohm output taps (only) and there are cautionary notes in the owners manual warning that damage could occur to the amp if operated with speakers that drop below 4.3 ohms impedance.
I use the amp with Merlin TSM Black Magic speakers and a REL R305 (powered).


Brad
Thanks Al! The Snell A impedance data you sent is for the Type A Reference which is several generations from the original Type A. I think this is an entirely different speaker separated by 20 years and entirely different design. It is challenging to find data on the original.

I suppose what I am hoping to hear is what you hinted at ... That the 1970's snell is inherently less threatening to the shindo than is the Quad esl-63.

I found the following link, which indicates a nominal impedance of 4 ohms and sensitivity of 86db, similar to that for the more recent version of the speaker:  http://www.snell.no/the_archives_type_A.htm.

The old Stereophile reviews don't have Atkinson's measurements, sadly.  The reviewers did use very powerful amps in their reviews, mainly to take advantage of the Type A's bass capabilities.  In Googling the speaker I found some forums where people seemed to be endorsing using lower-powered tube amps with them, but unfortunately no specs.

Yes I know those archives. I must have read elsewhere that the four ohm figure was the minimum impedance, not nominal. But now all I see is 4 ohm everywhere I read. You must be right. If this is the case I think it may be  o good for the shindig. I have posts in a shindo forum and an email to the Snell servicing company and will see if I hear anything different.