Bare Wire, Banana or Spade connections. Can you hear a difference?

[Bruce B]

What amps are you using? I can''t tell from your profile. Anyone with an SET should hear the same thing- I don't think its limited to us.

At the time, I tried it with a Classe' and an Audio Research.

 

[esldude]

Hi esldude could you please let me know the model of your Soundlabs ????? Thank You

I have some Auras. The panels are pretty much what is in an M3. The Auras had a steel frame with some better looking cosmetics.

 

[Atmasphere]

We did a show with Auras many yeas ago. Nice speaker.

At the time, I tried it with a Classe' and an Audio Research.

If you used the same speakers, the Wilsons, I can see why your results were inconclusive. Wilsons are fairly easy to drive although not what I would call high impedance.

 

[MrAcoustat]

I have some Auras. The panels are pretty much what is in an M3. The Auras had a steel frame with some better looking cosmetics.

Thank's for the answer.

 

[esldude]

^^ So it sounds like we are on the same page then as I agree with Don's post as well? I don't like most bananas because they have poor connections, but the ones that allow you to tighten them seem to be just fine.



The Sound Lab's lowest impedance is actually between 1.5-3 ohms @ 20KHz depending on the position of the brilliance control. What is important to understand about the speaker is that its impedance curve is not related to its efficiency like a box speaker generally is. Its based on a capacitor. So the ability to double power as impedance is halved is not so beneficial with a speaker like this, and explains why zero feedback OTLs like we make can drive the speaker so well, despite their rather high output impedance. The MA-1 (which is the smallest amp in our lineup that I would recommend for Sound Labs) has an output impedance of about 2.3 ohms but does just fine on this speaker as long as the raw power requirements are sufficient.

BTW, and you can PM me on this if you like, are you aware that there is a new backpanel (introduced 2 years ago) that sounds better and makes the speaker easier to drive? Regardless of the amp you have the update is worthwhile! If you don't have the backpanel there are some simple mods that will get you about 90% of the way there. We have a lot of Sound Lab customers

http://www.stereophile.com/content/sound-lab-1-electrostatic-loudspeaker-measurements

I have measured mine, and they are more or less like the measurement at Stereophile of A1's. I have M3 sized panels though the interface is roughly the same. Mine have toroidal xfmrs so there is a bit of difference. Notice they say it is 1.3 ohms at 20 khz dropping above that frequency. If I am remembering correctly mine are right at 1 ohm there with maximum brilliance setting. It does go up if the brilliance setting is changed, and I typically run mine near halfway. It is a tough load anyway. Not quite fully capacitive though close in the treble.

Amp output impedance would reduce output. Just for instance in the region where the ac impedance of the panel is 2.3 ohms it would cause a frequency droop of about 3 db with your amp were the speaker fully capacitive which it isn't. But there would be droop just not as much as normal dynamic speakers would have. As the impedance drops at higher frequencies and gets closer to a pure capacitive load the speaker output would droop a bit more. So yes with ESL panels the voltage drop isn't as severe due to amp output impedance, and such panels respond to voltage more so than power. Yet it still causes a softening of the upper octave. Which some people no doubt like.

Thanks for mentioning the new back panel. I was aware of it. Also have looked into the DIY mods. A friend also has Soundlabs, and we probably will get together and work on those mods in time. Of course my friend wants to do the more radical thing and feed the transformers with two amps doing the frequency split at line level.

 

[esldude]

Thank's for the answer.

View attachment 18144

Nice picture.

 

[Orb]

http://www.stereophile.com/content/sound-lab-1-electrostatic-loudspeaker-measurements

I have measured mine, and they are more or less like the measurement at Stereophile of A1's. I have M3 sized panels though the interface is roughly the same. Mine have toroidal xfmrs so there is a bit of difference. Notice they say it is 1.3 ohms at 20 khz dropping above that frequency. If I am remembering correctly mine are right at 1 ohm there with maximum brilliance setting. It does go up if the brilliance setting is changed, and I typically run mine near halfway. It is a tough load anyway. Not quite fully capacitive though close in the treble......

Glad you shown that graph as it shows something I meant to raise earlier and that being phase angle; I would say that any discussion on this topic as a whole must also consider phase angle, and wow Sound Labs is a killer at just beyond 10khz.
Most modern info on this is that by Keith Howard and Equivalent Peak Dissipation Resistance (EPDR), which JA nicely touches upon: http://www.stereophile.com/content/heavy-load-how-loudspeakers-torture-amplifiers-page-2

How this may also be of influence with regards to connection/oxidation/design would be hard to deem, but is part of any consideration when discussing this subject and also recently ohm impedance related testing.

Cheers
Orb

 

[Atmasphere]

Thanks for mentioning the new back panel. I was aware of it. Also have looked into the DIY mods. A friend also has Soundlabs, and we probably will get together and work on those mods in time. Of course my friend wants to do the more radical thing and feed the transformers with two amps doing the frequency split at line level.

If you are interested, we have a number of customers that have done mods. PM me if interested; I've done one of the mods myself. Sounds like your speakers are stock from the day they were built.

 

[esldude]

If you are interested, we have a number of customers that have done mods. PM me if interested; I've done one of the mods myself. Sounds like your speakers are stock from the day they were built.

Okay will do. Yes, mine are stock, my friend's panels have been sent back and upgraded with the more recent (I believe thinner) mylar a couple years back.