Ron’s New System

[Ron Resnick]

One can have an amp connect to a speaker and everything is just dandy.
Then they can change only the speaker cable, and that same amp and speaker now goes into oscillation.

I am skeptical about this for any normal loudspeaker cable.

Can you please give us one or two specific amplifier/loudspeaker/speaker cable examples in which this happened?

 

[DasguteOhr]

Post #18 impedance curve mesurements

Clarisys Audio USA

High End Audio Speakers - Clarisys Audio USA Sent from my iPhone using Tapatalk Pro

www.audioshark.org

The only thing that's a bit of a stretch is the efficiency, measured at 2.83 volts/1 watt at 8 ohms, when everyone knows that 4 ohm speakers are measured at 2.0 volts/1 watt. So, more like 85.5 dB instead of 88 dB.

 

[John T]

I think I mentioned before that Don and Ralph are amongst other “Subject Matter Experts” (SMEs) in this stuff.
I am not going to pretend, but I am at least a bit aware.

Something about capacitance, or maybe inductance of the system in the MHz or kHz range causing poles to move outside of the unity circle if you speak “Bode plots”.
(I think it is when one gets a high capacitance?)
I can identify a Bode plot, but I am just not a EE.

The fact that this can happen with just changing speaker cables - and the fact that one can see it clearly on an o-scope well outside of our hearing range, is why one may want to consider using an o-scope.
And the oscillation can burn an amp up in a hurry.
If the system is not buzzing away in the RF range then switch to subjective. If it is buzzing away, then objectively one knows that all hell is going to be breaking loose soon, and it is best to stop before the magic smoke leaves the scene. (IMHO)

But there is a crossover… and we do, or at least I, not know what the impedance of that ribbon is.

I am also not sure how the XO is used to combine the speakers with the subwoofers.
There are hundreds of pages I probably missed a lot, like a block diagram.

Some amps also do not like capacitively coupled loads, and want some resistance at DC.
That could be a potential causal mechanism… at least for people like me that understand Ishkawa charts better than Bode plots.

I'll provide an example Ron @Ron Resnick; Gryphon Mephisto with Cardas Clear Beyond. The Capacitance of the Clear Beyond is much higher than Cardas Clear. CC off the top of my head has a capacitance of 278 picofarad pF (per foot) the Clear Beyond is much higher (I think double) The Cardas Clear can be used as I did for sometime. When Cardas sent me the Clear Beyond to demo, the amp started oscillating. I talked with Nils from Gryphon in Denmark and he wasn't surprised due to the capacitance and the high bandwidth of the Mephisto...I now use Furutech DSS 4.1...BTW my speakers remain Joseph Audio Pearl 20/20's. They had no bearing in the example I provided...EDIT; BTW the Furutech have a capacitance of 51.69 pF per meter...

 

[AudioHR]

I haven’t seen the graphs of the impedance of the speaker.
Feel free to post it.

But I have also not seen many graphs that go up into the hundreds or kHz.

But let’s just ignore the ribbon for the moment.
One can have an amp connect to a speaker and everything is just dandy.
Then they can change only the speaker cable, and that same amp and speaker now goes into oscillation.
So there is more to what is happening than solely the presence of a ribbon.

No expert on this but haven't heard about this happening since the mid 70' Polk /Cobra speaker cables.

They were high capacitance and could cause some instability in some solid state amps. I used them with a Crown DC 300a with no problem but I was aware there could be issues. Despite the possible issues they were above average in sound, apparently best configured in parallel and used in shorter lengths although I just used a shorter single round cable. I think I was using Double Advents at the time.

Perhaps a few new manufacturers have picked up on the possibilities of its design and the issues remain?

 

[Ron Resnick]

I'll provide an example Ron @Ron Resnick; Gryphon Mephisto with Cardas Clear Beyond. The Capacitance of the Clear Beyond is much higher than Cardas Clear. CC off the top of my head has a capacitance of 278 picofarad pF (per foot) the Clear Beyond is much higher (I think double) The Cardas Clear can be used as I did for sometime. When Cardas sent me the Clear Beyond to demo, the amp started oscillating. I talked with Nils from Gryphon in Denmark and he wasn't surprised due to the capacitance and the high bandwidth of the Mephisto...I now use Furutech DSS 4.1...BTW my speakers remain Joseph Audio Pearl 20/20's. They had no bearing in the example I provided...EDIT; BTW the Furutech have a capacitance of 51.69 pF per meter...

Thank you for this example, John. How long was the interconnect run in this situation?

 

[AudioHR]

Thank you for this example, John. How long was the interconnect run in this situation?

Good question! Perhaps resistance was an issue.

 

[Holmz]

No expert on this but haven't heard about this happening since the mid 70' Polk /Cobra speaker cables.

They were high capacitance and could cause some instability in some solid state amps. I used them with a Crown DC 300a with no problem but I was aware there could be issues. Despite the possible issues they were above average in sound, apparently best configured in parallel and used in shorter lengths although I just used a shorter single round cable. I think I was using Double Advents at the time.

Perhaps a few new manufacturers have picked up on the possibilities of its design and the issues remain?

Generally the best amps have huge bandwidths and therefore can amplify RF is they are asked to do so.
So those amps with high capacitance cables are where the evilness happens.

Thank you for this example, John. How long was the interconnect run in this situation?

You keep em as short as possible as C-total = C-foot * feet
And also why monoblocks are great, as the cable length get short and all those numbers go toward zero.

Good question! Perhaps resistance was an issue.

No - it is all the complex part, unless the amp also needs to see DC resistance.
However - it is sort of an “yes” ans increasing cable resistance does tend to pull the Bode plot pole towards the centre (I think).

 

[John T]

Thank you for this example, John. How long was the interconnect run in this situation?

Your Welcome Ron, 3 meters...

 

[morricab]

Generally the best amps have huge bandwidths and therefore can amplify RF is they are asked to do so.
So those amps with high capacitance cables are where the evilness happens.


You keep em as short as possible as C-total = C-foot * feet
And also why monoblocks are great, as the cable length get short and all those numbers go toward zero.


No - it is all the complex part, unless the amp also needs to see DC resistance.
However - it is sort of an “yes” ans increasing cable resistance does tend to pull the Bode plot pole towards the centre (I think).

You realize that the amp in question is zero feedback SET? It has a bandwidth of maybe 50kHz, so no RF. It has no feedback loop to have a pathway back into the amp circuit. Ribbons are the closest to a pure resistor of any driver. You need significant reactance from the speaker/crossover to setup an oscillation situation in a marginally stable amp.

So, can you please stick to a realistic scenario for Ron’s system?

 

[Ron Resnick]

Good question! Perhaps resistance was an issue.

I think we have too many peanut gallery, wanna-be electrical engineers here, practicing without a license.

I think we should leave these technical electrical topics to members like Don and Ralph.

 

[Ron Resnick]

Your Welcome Ron, 3 meters...

Thank you.

A Gryphon Mephisto wouldn't work with 3 meters of Cardas Clear Beyond?

I don't believe it. Something else must have been the issue.

 

[John T]

Thank you.

A Gryphon Mephisto wouldn't work with 3 meters of Cardas Clear Beyond?

I don't believe it. Something else must have been the issue.

Call Brian at Cardas and ask him, please let me know what he says. I can assure you I didn't imagine this. It even blew a fuse in which never occurred. I went to a lower capacitance and I like the results. If your really in doubt send a message to Nils at Gryphon and he will provide a better explanation...

 

[Holmz]

You realize that the amp in question is zero feedback SET? It has a bandwidth of maybe 50kHz, so no RF. It has no feedback loop to have a pathway back into the amp circuit. Ribbons are the closest to a pure resistor of any driver. You need significant reactance from the speaker/crossover to setup an oscillation situation in a marginally stable amp.

@morricab I cannot really keep up, as page 1 started out crate that looked like David and the 6 fingered Marfan’s sufferer Goliath could be buried in them. And every thing changes/changed.

All I am trying to bring is a little rigour to the fault analysis.
Ralphs talk about Zobel networks is a possible causal mechanism… but in the ideal we have all the causal mechanisms listed, and then either check them off as tested to be “Not the cause” or kept on the list.
Gthere is most likely going to be something that comports with measurable electronics, to give the subject dislike.

So, can you please stick to a realistic scenario for Ron’s system?

It’s doubtful…

Mostly I like the occasional diversions from the Mother’s Day cooking of soup and watching of “Top Gun: Maverick” … Plus I like Ishikawa analysis a lot. And others will have similar amps going into oscillation, so it is a PSA of sorts.

In terms of deviating off on a tangent…
We listened to an audiobook by Brice Courtney called, “Fishing for Stars”, which in parts tools place in Japan, and so Ishkawa was on my mind.

 

[Holmz]

Call Brian at Cardas and ask him, please let me know what he says. I can assure you I didn't imagine this. It even blew a fuse in which never occurred. I went to a lower capacitance and I like the results. If your really in doubt send a message to Nils at Gryphon and he will provide a better explanation...

Like Fox Moulder, or maybe MLK… “I believe.”

 

[microstrip]

I think we have too many peanut gallery, wanna-be electrical engineers here, practicing without a license.

I think we should leave these technical electrical topics to members like Don and Ralph.

Ridiculous. We have many people able to deal with the simple questions you are addressing - it is not rocket science. But we need proper data on the gear and cables, not speculation, and some logic thought - we are now mixing speaker cables with ICs.

I am skeptical about this for any normal loudspeaker cable.

Can you please give us one or two specific amplifier/loudspeaker/speaker cable examples in which this happened?

Known since long and discussed many times. For example, old Naim amplifiers could not be used with high capacitance speakers cables - even ChatGPT knows about it ... Possible consequences - oscillation (sometimes inaudible), harsh or edgy sound and overheating / amplifier damage.

 

[Ron Resnick]

This is not relevant to my 2.0 meter Purist Audio Design Musaeus or my 2.0 meter Cardas Clear Reflection, neither of which is very high in capacitance, and both of which pass the exact same edginess/brightness to the speakers.

 

[AudioHR]

I think we have too many peanut gallery, wanna-be electrical engineers here, practicing without a license.

I think we should leave these technical electrical topics to members like Don and Ralph.

Fair enough! I am certainly not an electrical engineer.

Really just commenting on the reality that cables can cause amplifier issues. No particular expertise necessary for that, I assumed as this is a forum my comment might stimulate further response. Possibly from an expert, lol!

 

[morricab]

Ridiculous. We have many people able to deal with the simple questions you are addressing - it is not rocket science. But we need proper data on the gear and cables, not speculation, and some logic thought - we are now mixing speaker cables with ICs.



Known since long and discussed many times. For example, old Naim amplifiers could not be used with high capacitance speakers cables - even ChatGPT knows about it ... Possible consequences - oscillation (sometimes inaudible), harsh or edgy sound and overheating / amplifier damage.

What’s ridiculous is you persist even though you know very well that the amp in question is not all like the examples given of marginally stable, push pull Class AB, high negative feedback, solid state amplifiers.

If I understand Ralph’s argument on why to use a zobel, it is to flatten impedance to prevent frequency response change, not to prevent oscillation, which the MastersounD is in no danger of doing. A man with your knowledge and experience knows this but keeps the bizarre line of inquiry alive…why?

 

[DasguteOhr]

No expert on this but haven't heard about this happening since the mid 70' Polk /Cobra speaker cables.

They were high capacitance and could cause some instability in some solid state amps. I used them with a Crown DC 300a with no problem but I was aware there could be issues. Despite the possible issues they were above average in sound, apparently best configured in parallel and used in shorter lengths although I just used a shorter single round cable. I think I was using Double Advents at the time.

Perhaps a few new manufacturers have picked up on the possibilities of its design and the issues remain?

All highly capacitive cables, such as speaker foil cables, can cause problems for amplifiers that tend to oscillate (load + high phase angle). A counterexample is Bryston, which is almost immune to oscillation.
P.S
Test report from a German hi-fi magazine. It's nice that something like this still exists. And not just flowery descriptions of the sound.

 

[Ron Resnick]

All highly capacitive cables, such as speaker foil cables, can cause problems for amplifiers that tend to oscillate (load + high phase angle). A counterexample is Bryston, which is almost immune to oscillation.
P.S
Test report from a German hi-fi magazine. It's nice that something like this still exists. And not just flowery descriptions of the sound.View attachment 150070
View attachment 150071

What is the point of going into this inapposite discussion?

Foil cables are not in issue here as I have been clear to point out the brands and models of the two speaker cables I have.

There are loads of random technical topics that could be dropped from the peanut gallery that none of my components or reports has anything to do with.