Soulution 701 monoblocks and 711 stereo amplifier

[FrantzM]

i have not heard these amps but can think of no reason why a switcher can not be used in a well thought out audio design.

Hi

agreed and that was my point too. There is no reason why it can't sound good . Also I am not sure about the point about the 1 Farad being slow to charge and sow to release the energy ... I don't think that is correct .. The real question remain how good it sounds compared to amp costing much less Pass, Bryston monos , and especially Spectral .. .

Heard the more expensive Soulution (700?)and though them very good .. Whether they could justify their prices to my ears was a different question as I have heard amps competing and a less loftier price point among them Spectral and Bryston which don't sound similar but are fully competitive with anything out there regardless of price ...High End Audio has turned completely in a game of luxury-typepricing. Prices go up seemingly without reason although we do provide rationale, we the ever compliant audiophiles

 

[microstrip]

Just to refer that Devialet has been using switching power supplies for some time, apparently with great success. It seems the question is not a philosophical to be SMPS or not SMPS, but how to implement an amplifier using a SMPS that sounds great.

 

[ack]

Also I am not sure about the point about the 1 Farad being slow to charge and sow to release the energy ... I don't think that is correct ..

In layman's terms, see http://en.wikipedia.org/wiki/Capacitor

The more a capacitor is charged, the larger its voltage drop; i.e., the more it "pushes back" against the charging current. This is analogous to the fact that the more a membrane is stretched, the more it pushes back on the water.

For a more technical discussion, see this graph from http://hyperphysics.phy-astr.gsu.edu/hbase/electric/capchg.html or similar

The time it takes to charge a capacitor to _one_ time constant (RC in the graph above) is t=R*C (hence the points on the X axis are marked xRC). For the total time it takes to charge a capacitor see Formula 1 in http://www.us.tdk-lambda.com/hp/pdfs/application notes/93008500rD.pdf or similar (and also refer to Which Is The Best Equation To Use section). More importantly, you will notice that the time needed to charge a capacitor is proportional to its capacitance. Related to this, you can also see how much energy is required to reduce the total charge time of such a large capacitor bank.

Anyone feel free to correct me.

 

[FrantzM]

In layman's terms, see http://en.wikipedia.org/wiki/Capacitor



For a more technical discussion, see this graph from http://hyperphysics.phy-astr.gsu.edu/hbase/electric/capchg.html or similar

The time it takes to charge a capacitor to _one_ time constant (RC in the graph above) is t=R*C (hence the points on the X axis are marked xRC). For the total time it takes to charge a capacitor see Formula 1 in http://www.us.tdk-lambda.com/hp/pdfs/application notes/93008500rD.pdf or similar (and also refer to Which Is The Best Equation To Use section). More importantly, you will notice that the time needed to charge a capacitor is proportional to its capacitance. Related to this, you can also see how much energy is required to reduce the total charge time of such a large capacitor bank.

Anyone feel free to correct me.

There are better qualified people than I to move the discussion forward. I was fully aware of the RC time constant. I would however note that the time constant is also proportional to "R" thus a low R would reduce the time needed to charge the capacitor ... For a farad and with an R of, say, 100 ohms (rather large for a SMPS power supply I would think) it would take less than 2 minutes to charge such a bank .. Not a huge problem if you ask me .. You turn the darn thing on and wait a few minutes (more than 2 ) until the capacitor bank is fully charged. As for the speed of discharge, it is again a function of the load and its draw all can be optimized with appropriate design choices...

Still that says nothing abotu how the gear sound and to repeat microstrip the Devialet which also uses a SMPS sound very good according to several ears ...

 

[microstrip]

In layman's terms, see http://en.wikipedia.org/wiki/Capacitor



For a more technical discussion, see this graph from http://hyperphysics.phy-astr.gsu.edu/hbase/electric/capchg.html or similar

The time it takes to charge a capacitor to _one_ time constant (RC in the graph above) is t=R*C (hence the points on the X axis are marked xRC). For the total time it takes to charge a capacitor see Formula 1 in http://www.us.tdk-lambda.com/hp/pdfs/application notes/93008500rD.pdf or similar (and also refer to Which Is The Best Equation To Use section). More importantly, you will notice that the time needed to charge a capacitor is proportional to its capacitance. Related to this, you can also see how much energy is required to reduce the total charge time of such a large capacitor bank.

Anyone feel free to correct me.

All the physics is true - any one can pick capacitors, a small battery and a digital multimeter that should have 1 or 10 Mohms internal resistance and draw this nice curves.

Unfortunately the circuit of the power amplifier and the supply charging the capacitor are not just a resistor and any analogy or general conclusions about sound will made more harm than good - not better than assuming that a large capacitor should be heavier, and consequently the amplifier should be bass heavy. A power supply is much more complex than a capacitor - designers usually tune their power supplies for their sound quality desires. Unless the value of the capacitance was lower than optimum because of budget or size, changing its value will not improve the amplifier. Probably it will sound different, but possibly not better.
Designers have tricks to avoid bad sound signatures and have large capacitance - e.g. ARC uses small coils and selected capacitors to create banks of capacitors with large capacitance and fast transient response.

 

[ack]

There are better qualified people than I to move the discussion forward. I was fully aware of the RC time constant. I would however note that the time constant is also proportional to "R" thus a low R would reduce the time needed to charge the capacitor ... For a farad and with an R of, say, 100 ohms (rather large for a SMPS power supply I would think) it would take less than 2 minutes to charge such a bank .. Not a huge problem if you ask me .. You turn the darn thing on and wait a few minutes (more than 2 ) until the capacitor bank is fully charged. As for the speed of discharge, it is again a function of the load and its draw all can be optimized with appropriate design choices...

Still that says nothing abotu how the gear sound and to repeat microstrip the Devialet which also uses a SMPS sound very good according to several ears ...

I always advocate that it has to sound exactly the way it's engineered, although I can't possibly describe the sound based on just the design and measurements. But I am pretty confident on what to expect at a high level - e.g. the effect of the in-series DC-decoupling capacitor, that they claim they cannot hear. BTW, waiting two minutes to charge the bank is not the problem, it's the constant charging and discharging of said large bank during use that matters to me.

 

[ack]

All the physics is true - any one can pick capacitors, a small battery and a digital multimeter that should have 1 or 10 Mohms internal resistance and draw this nice curves.

Unfortunately the circuit of the power amplifier and the supply charging the capacitor are not just a resistor and any analogy or general conclusions about sound will made more harm than good - not better than assuming that a large capacitor should be heavier, and consequently the amplifier should be bass heavy. A power supply is much more complex than a capacitor - designers usually tune their power supplies for their sound quality desires. Unless the value of the capacitance was lower than optimum because of budget or size, changing its value will not improve the amplifier. Probably it will sound different, but possibly not better.
Designers have tricks to avoid bad sound signatures and have large capacitance - e.g. ARC uses small coils and selected capacitors to create banks of capacitors with large capacitance and fast transient response.

No offense, but I have to admit I have no idea what you are talking about. "R" is not the power supply's resistance, but the capacitor's (and Frantz correctly pointed it out indirectly as well in his calculations)... from then on, it went over me.

 

[microstrip]

No offense, but I have to admit I have no idea what you are talking about. "R" is not the power supply's resistance, but the capacitor's (and Frantz correctly pointed it out indirectly as well in his calculations)... from then on, it went over me.

ACK,
In the charge graphs you posted there is a resistor. This resistor should be there to emulate the behavior of the source of the charge - something equivalent to the internal resistance of the transformers and rectifying diodes. If this resistance was null the circuit would be fast even with large capacitance! Unhappily this model is too rough.
BTW , when we refer to resistance related to capacitors it is sometime with a very different meaning, associate to ESR - that means Equivalent Series Resistance. As far as I understand no one is debating ESR in this thread. I think you are misinterpreting Frank comment.

 

[Emre Üçöz]

Last 3 years I am using 710/720 combo and I am quite confident to say that they are absouletly stunning solid states. Couple of months ago I have spoken with Cyrill and he has mentioned about this upgrade and this will be retrofitted to the current owners products.

 

[ack]

ACK,
In the charge graphs you posted there is a resistor. This resistor should be there to emulate the behavior of the source of the charge - something equivalent to the internal resistance of the transformers and rectifying diodes. If this resistance was null the circuit would be fast even with large capacitance! Unhappily this model is too rough.
BTW , when we refer to resistance related to capacitors it is sometime with a very different meaning, associate to ESR - that means Equivalent Series Resistance. As far as I understand no one is debating ESR in this thread. I think you are misinterpreting Frank comment.

It doesn't matter how complex or simple this R is; the point is still that the time to charge the capacitor is proportional to its capacitance, as shown, no matter how small R is; it's a very simple formula

 

[KeithR]

It is interesting that Soulution clearly uses a lot of negative feedback in their designs. That isn't the trend these days. I can't say I've ever heard them sound good in a system, but have never had them at home.

 

[dallasjustice]

I had the 710 for about 6 months. I recently traded it in. I've had a lot of amps and can say the 710 is an excellent amp, notwithstanding the heavy use of feedback. They have obviously figured out how to use feedback in a way most others don't. Having said that, I think it's possible to find better gear at the same retail price; at least that's what I've found in my system.

 

[opus111]

BTW, waiting two minutes to charge the bank is not the problem, it's the constant charging and discharging of said large bank during use that matters to me.

It therefore follows as you state that as a concern, that you should only choose the amps with the biggest capacitor banks. Smaller capacitor banks will discharge quicker under load than bigger - as the music ebbs and flows there's more charging and discharging going on.

I cannot for the life of me figure out why you'd be concerned about this process - care to explain why that's an issue for you?

 

[microstrip]

It doesn't matter how complex or simple this R is; the point is still that the time to charge the capacitor is proportional to its capacitance, as shown, no matter how small R is; it's a very simple formula

And what do you use this nice basic formula for? Sorry I can not follow you. If you are just wanting to tell us that a large deposit takes longer to fill, OK.

 

[ack]

And what do you use this nice basic formula for? Sorry I can not follow you. If you are just wanting to tell us that a large deposit takes longer to fill, OK.

Yes, thank you micro; that's what I said upthread. I can't hide it, I was underwhelmed with the 500 series for its price.

 

[microstrip]

Yes, thank you micro; that's what I said upthread. I can't hide it, I was underwhelmed with the 500 series for its price.

Yes, but we were commenting FrantzM statement " Also I am not sure about the point about the 1 Farad being slow to charge and sow to release the energy ... I don't think that is correct .." Just to make it clear I pointed that as the the diameter of the hose is also part of the problem of filling or emptying the deposit we can not consider that a 1Farad is slow to charge and slow to discharge and Frantz statement was very meaningful.

 

[dallasjustice]

I think Cyril should fix the binding posts while he is at it. They are not evenly spaced away from the massive handles flanking the rear. This means it's virtually impossible to get 2 sets of spades down under the wbt bp on the left channel; double runs were impossible in my case. The side firing iec doesn't make matters any easier. The 710 may be technically advanced but still not a high value product, IMO.

 

[defride]

Yes, thank you micro; that's what I said upthread. I can't hide it, I was underwhelmed with the 500 series for its price.

Was that in your own system?

 

[ack]

It therefore follows as you state that as a concern, that you should only choose the amps with the biggest capacitor banks. Smaller capacitor banks will discharge quicker under load than bigger - as the music ebbs and flows there's more charging and discharging going on.

On the underlined: Absolutely not, when it comes to me selecting amplifiers. I want a sensible - or large enough for the load - size for the capacitor bank, not small and certainly not this monster. Circuit speed is what I go after.

 

[ack]

I had the 710 for about 6 months. I recently traded it in. I've had a lot of amps and can say the 710 is an excellent amp, notwithstanding the heavy use of feedback. They have obviously figured out how to use feedback in a way most others don't. Having said that, I think it's possible to find better gear at the same retail price; at least that's what I've found in my system.

What did you end up with? Sorry, I haven't been following everyone's system changes. There was a very interesting sidebar in the TAS review a few years ago, explaining their unique negative-feedback approach in the 700 series. I certainly thought it was ground-breaking. I'll see if I can dig it up...