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Mark Levinson Replica Amp

TBone

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#41
Yes, I once owned some Classe DR3 VHC amps. Very nice. I also had some Classe 25 amps. A pair of 25's bridged will play Soundlabs very nicely as they should at 1 kwatt per channel. Yet my Wyred4Sound ST500 is better.
Hi Dennis ...

Two DR3's eat enough (too much) electricity, and supply enough heat (too much) for me. One VHC would do likewise, two, maybe unbearable ...

Another old amp, and perhaps my fav Classe amp for recommendation, at the time, was the DR9. That said, once Glen Grue took over Classe, and proceeded to "change" (I'm being nice) the line, I lost interest in their products - quickly.

1527691950659.png

Notice the blue tape on the right amp (the left has red tape) ... that bc when I take em apart (about once every two years or so ...) I need to keep the internals identifiable (and my mods & parts listing is coded red/blue) on assembly. What bothers me no-end ... is my silly insistence of using Red for left.ch and Blue for right.ch (when it really should be the other way around). Also notice the brass cone sitting on the heat sink - when visitors ask about 'em (which is the norm) - I suggest they pick em up - to use as hand warmers.
 
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TBone

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#42
Easy to understand as Classe DR3 is a beautifully designed amp for which I'm sure it plays extremely well. :)

Btw, my Rotel RMB 1075 is not bridged. At that time Rotel started to manufacture TXH certified amps for AV use but internally it has been built of 5 identical mono blocks - the same ones they were using inside stereo amps. Nominal power is rated at 5 * 120W, but when only 2 channels are driven the output raises to 140W thanks to it's power supply consisting of 1.5 kVA toroidal transformer and 8*10.000 µF slit-foil capacitors. MSRP was $1200, which I found reasonable for such amp. I was so impressed with it's ability to play consistently whatever you throw at it that I decided to keep it. It's been with me now for 15 years. :)
I luv my DR3's, although they are ugly (I prefer the term "industrial") but certainly, they are not for everyone.

The bridged Rotels didn't work all that well in my system (my speakers are relatively hard to drive/grip). In stereo mode, they performed better, but seemed to lack headroom. Unlike the Rotel, the mono DR3s grip nicely. They maybe rated at only 100w (the least powerful amps I've had in my system, on paper) but, except perhaps the SIM, they appear to sound much more powerful . That said, I kinda wish I kept the little tank (ATI), it may run warm, but it would have been a much better choice during the summer heat waves.
 

Sir Sanders Zingmore

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#43
Yes the ST500 handles the difficult load of the Soundlabs better.
Makes sense. I think the way an amp interacts with various speaker loads will affect its sound.
Two amps that can drive the same speakers without clipping and with sufficient linearity should sound almost indistinguishable.

But that doesn’t necessarily mean those two amps will sound the same on a different set of speakers
 

Krunok

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#44
In stereo mode, they performed better, but seemed to lack headroom.
What exactly do you mean when you say "headroom"?

Unlike the Rotel, the mono DR3s grip nicely. They maybe rated at only 100w (the least powerful amps I've had in my system, on paper) but, except perhaps the SIM, they appear to sound much more powerful .
I don't really believe in subjective impressions that are not backed up with specs/measurements. I strongly believe my Rotel which has 1.5kVA power supply, 140W in stereo mode, 0.03% THD when driven from 1W to 140W can eat my class A tube amp for breakfast in all scenarios except when you give them to drive speakers with very low impedance. In that case Rotel may experience some problems as any other solid state amp would, while my tube amp wouldn't even notice that as it's outputs can literally be shorted and it will continue to work. Luckilly, modern speakers don't really have such low impedance issues as before.
 
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Krunok

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#45
Makes sense. I think the way an amp interacts with various speaker loads will affect its sound.
Two amps that can drive the same speakers without clipping and with sufficient linearity should sound almost indistinguishable.

But that doesn’t necessarily mean those two amps will sound the same on a different set of speakers
I believe it's the low speaker's impedance that causes most of the problems for amps. If impedance is ok than vast majority of amps operate well and within their specs. But even with "problematic" (from impedance point of view) speakers like electrostatics, whose impedance falls below 2 ohms, this happens after 10khz where signals are not that high so chances are most amps will actually manage to get it unless played very loud or the music material is so specific that it has strong signals there.
 
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Sir Sanders Zingmore

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#46
I believe it's the low speaker's impedance that causes most of the problems for amps. If impedance is ok than vast majority of amps operate well and within their specs. But even with "problematic" (from impedance point of view) speakers like electrostatics, whose impedance falls below 2 ohms, this happens after 10khz where signals are not that high so chances are most amps will actually manage to get it unless played very loud or the music material is so specific that it has strong signals there.
I tend to agree with Roger Sanders (note the “Sanders” in my moniker). To paraphrase, his view is that most amps are underpowered into most “normal” speakers. Even at relatively low volumes they don’t have enough headroom to reproduce transients without clipping.

This clipping is very short lived and often isn’t identified as clipping by the listener. However, because different amps behave differently when they clip, it is identified as amps sounding different
 

TBone

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#47
I don't really believe in subjective impressions that are not backed up with specs/measurements ...
Whatever floats your sonic boat ... since I've not measured 'em with my speakers, and have no plans to do so, I'll refrain from discussing 'em any further.

The following review includes a very detailed circuit description, DBT test (vs Onkyo M510), and a subjective review.
http://www.hifi-equipment.com/5-classe-audio-dr-3.html
 

Krunok

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#48
I tend to agree with Roger Sanders (note the “Sanders” in my moniker). To paraphrase, his view is that most amps are underpowered into most “normal” speakers. Even at relatively low volumes they don’t have enough headroom to reproduce transients without clipping.

This clipping is very short lived and often isn’t identified as clipping by the listener. However, because different amps behave differently when they clip, it is identified as amps sounding different
It would be easy to measure if such clipping occurs during playout so no need for guesswork there. It would be even easier to measure if some non-orchestral "typical" music frequently have such dynamics that would require power of say 200W to handle transient peak when playing on medium power of 10W. Somehow I suspect any of this happens, but if it does there should be a lot of proof on the Net because it's really not hard to measure such situations.
 

Sir Sanders Zingmore

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#49
It would be easy to measure if such clipping occurs during playout so no need for guesswork there. It would be even easier to measure if some non-orchestral "typical" music frequently have such dynamics that would require power of say 200W to handle transient peak when playing on medium power of 10W. Somehow I suspect any of this happens, but if it does there should be a lot of proof on the Net because it's really not hard to measure such situations.
One of my earlier speakers were Zingali horns, quoted at 96dB efficient. Using a CRO, I saw my 50w amp clipping at only slightly louder than my normal listening levels.
The waveform clearly hit a brick wall. It was “blink and you’d miss it” short lived but it was clearly happening.

So, I agree with you that it’s not hard to measure (if I could do it, anyone could :) )
 

Krunok

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#50
One of my earlier speakers were Zingali horns, quoted at 96dB efficient. Using a CRO, I saw my 50w amp clipping at only slightly louder than my normal listening levels.
The waveform clearly hit a brick wall. It was “blink and you’d miss it” short lived but it was clearly happening.

So, I agree with you that it’s not hard to measure (if I could do it, anyone could :) )
Sure. But such clipping occurs pretty much only with low frequency slams. Although it results in increased distortion our ears are much more tolerant in that part of the spectrum than if the same thing would happen in higher end of the spectrum.

The other part of the story is that SS amps clip in a very "ugly" way as they work on relatively low voltage while tube amps clip in a much more "softer" way as the clipping doesn't occur when hitting the voltage ceiling.
 

Sir Sanders Zingmore

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#51
Sure. But such clipping occurs pretty much only with low frequency slams. Although it results in increased distortion our ears are much more tolerant in that part of the spectrum than if the same thing would happen in higher end of the spectrum.

The other part of the story is that SS amps clip in a very "ugly" way as they work on relatively low voltage while tube amps clip in a much more "softer" way as the clipping doesn't occur when hitting the voltage ceiling.
I think Sander’s point is that why would you want your amp to clip at all?
Also, different amps react differently when they clip and that is the primary reason that amps sound different.

So that takes us back to my original comment which was, if I can summarise myself:
- amps that are linear and are sufficiently powerful not to clip will be pretty much indistinguishable
- most amps are not sufficiently powerful. Therefore amps sound different.
 

Wombat

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#52
I think Sander’s point is that why would you want your amp to clip at all?
Also, different amps react differently when they clip and that is the primary reason that amps sound different.

So that takes us back to my original comment which was, if I can summarise myself:
- amps that are linear and are sufficiently powerful not to clip will be pretty much indistinguishable
- most amps are not sufficiently powerful. Therefore amps sound different.
Most audiophile systems combine lower sensitivity loudspeakers with amplifiers below 75W RMS. Not a good match for performance.
 

Krunok

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#53
I think Sander’s point is that why would you want your amp to clip at all?
Also, different amps react differently when they clip and that is the primary reason that amps sound different.

So that takes us back to my original comment which was, if I can summarise myself:
- amps that are linear and are sufficiently powerful not to clip will be pretty much indistinguishable
- most amps are not sufficiently powerful. Therefore amps sound different.
You certainly would not want them to clip at your normal listening levels. My speakers are of medium sensitivity (87db) and I haven't noticed any clipping with my 140W Rotel, but neither with 50W tube amp. Although, as I said, I'm not really sure one would easily notice clipping of a transient low frequency peak , especially with a tube amp.
 

watchnerd

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#57
Digital volume control and Class D amplification are two persistent audiophile bugbears.

Digital volume control, if implemented well, is completely transparent. It's likely possible but more difficult and expensive to achieve the same transparency with analog volume control. The IC solution for digital volume control in the JOB INT is probably fine. That said, because of the unusually high gain of Goldmund's JOB amplifier circuit, the JOB products are not a slam dunk; the gain seems to make them prone to hiss and grounding noise with most equipment.

Class D amplification can be fine, too. The three best speakers that I have heard--the Kii Threes, Dutch & Dutch 8Cs, and B&O BeoLab 90s--all use Class D amplification, and two of the three best systems that I have heard used Class D amplifiers (NCore amplifiers in one case, Pascal amplifiers in the other).

With these technologies, all depends on the implementation. The Nord amplifiers seem promising, but it's impossible to know without measurements.
My Devialet Expert 400 uses both Class D (actually it's their hybrid A/D ADH circuit) + digital volume control.

The digital volume control uses 40 bits floating point, which is 32 bits of mantissa and 8 bits of exponent, which means no loss of a single bit of precision on 24 bit content.

It's adjustable in +0.5 dB steps and, to my ears, is the theoretical a straight wire with gain, totally transparent.

FWIW, for most listening I have the gain set to between -20 dB and -10dB.
 

Dialectic

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#58
My Devialet Expert 400 uses both Class D (actually it's their hybrid A/D ADH circuit) + digital volume control.

The digital volume control uses 40 bits floating point, which is 32 bits of mantissa and 8 bits of exponent, which means no loss of a single bit of precision on 24 bit content.

It's adjustable in +0.5 dB steps and, to my ears, is the theoretical a straight wire with gain, totally transparent.

FWIW, for most listening I have the gain set to between -20 dB and -10dB.
I have a Devialet 120 in my second system.
 

Krunok

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