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Mark Levinson Replica Amp

TheInquiring

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Thank you very kindly!
I'll try to have a listen. Sure, this Denon looks very nice indeed.
Any alternatives I should also consider, please?
 
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watchnerd

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It's really quiet, and I love SAM. I'm not crazy about the finish.

On balance, I don't think there's a better way to drive passive speakers in stereo than with a Devialet amp.

Ditto on the finish. My cat loves to lie on top of it because it's warm so the top is nothing but a series of paw prints. I've given up trying to keep it smudge-less.

There is a SAM profile for my speakers (3 actually), and I have it enabled, but turned down to 0% (speakers were new). It might be time to turn it back on.

My big wish: a web interface for config changes.

But overall, yes, great way to drive 2 channel passives.
 
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watchnerd

watchnerd

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Yeah, I really do not like the configurator. I have to worry about Devialet going out of business. I frequently walk by their ridiculous all-glass shop in Grand Central station, and I have not once seen a customer inside.

TBH, having them go out of business....and having someone else acquire the assets, IP and run the company better....might not be entirely bad.
 

RayDunzl

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I always like to see when power doubles when going from 8 ohms to 4 ohms.

I'm somewhat suspicious that capability is accomplished by under-rating the 8 ohm output.

I have a 250/350 amp in one room.

They could have rated it 175/350 and it would be one of the magical devices that double-down.

A published example was the Krell FPB 600.

As I remember it was 600/1200/2400 in 8/4/2 ohms, but tested at 945 at 8 ohms, leaving a nice margin for internal losses as the load impedance was reduced.
 

Krunok

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They could have rated it 175/350 and it would be one of the magical devices that double-down.

Sure they could, and it would still be the same amp. :)
Different manufacturers rate their products in the different way. In the real world those amps aren't anyhow driving 8 or 4 ohms resistors but real world speakers whose impedance varies with frequency, in some cases in quite a wild fashion.
 

Wombat

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Hmm, I know that some of our fellow members here have criticized the QC and reliability of the NAD amplifiers, but in my experience, they offer good value. I had an NAD C370 for 13 years, and it could power every speaker I threw at it, including some very difficult ribbon loads. A relative of mine took it, and I am told that it is still running nicely after almost 20 years of heavy use.

Service manuals for NAD amps are all over the internet now, and finding replacement parts for any reasonably recent NAD amp is unlikely ever to pose an issue.

My anecdote isn't much of a sample, though, I admit.


I agree. My experience with NAD is positive. They are still one of the most popular brands. Nad started in 1972(45 years ago) and are still going strong.
The few internet negatives compared to the numbers sold are inconsequential.
 

Krunok

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Magical is the word. No amp doubles down, it’s physically impossible.

Why?

P.S. I am speaking of laboratory condition in which amp is driving a variable resistor and you measure voltage on the resistor and current through it to calculate power.
 

Krunok

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Because it would need to be 100% efficient

Sure, but many amps will come very close to double the power when impedance drop from 8 to 4 ohms. As long as their output stage can channel enough current without voltage drop from the power supply I see no reason why they wouldn't. Of course the losses will increase with the power, but they will still come reasonably close to double the power.
 
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TBone

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I agree. My experience with NAD is positive. They are still one of the most popular brands. Nad started in 1972(45 years ago) and are still going strong.
The few internet negatives compared to the numbers sold are inconsequential.

Earliest NAD models had female rca's soldered directly to the mother-board; at the back of the unit. The user would plug the male interconnects directly down into the rca socket. That act itself, plus the constant pull of the interconnect over time, would often weaken the rca connection to the motherboard, causing many connectivity problems.

Past those initial days, IMO, it's been mostly positive.
 

RayDunzl

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Sure, but many amps will come very close to double the power when impedance drop from 8 to 4 ohms.

I agree. They should all "double down" within some range of operation. Feedback compares the output voltage to the input, and maintains the gain, so double the current flows into the reduced impedance of the load.

1W into 8 ohms becomes 2W into 4.

5 becomes 10 and so on.

The problem with doubling comes at the limits of the device.

Random example:

https://www.stereophile.com/content/luxman-l-509x-integrated-amplifier-measurements

"With clipping defined as when the THD+noise in the output reaches 1%, I measured clipping powers of 154Wpc into 8 ohms (21.9dBW, fig.5) and 250Wpc into 4 ohms (21dBW, fig.6)."

The manufacturer rated it at 120/2200, almost a double.

They could have underrated it at 110/220, and claimed the double.
 
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Krunok

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The problem with doubling comes at the limits of the device.

Random example:

https://www.stereophile.com/content/luxman-l-509x-integrated-amplifier-measurements

"With clipping defined as when the THD+noise in the output reaches 1%, I measured clipping powers of 154Wpc into 8 ohms (21.9dBW, fig.5) and 250Wpc into 4 ohms (21dBW, fig.6)."

That's true. But let me show you a Rotel amp which has slightly stronger output stage than mine also measured by Stereophile guys:

"Using the conventional 1% THD definition of clipping, the Rotel puts out 291W into 8 ohms with one channel driven (24.6dBW), 558W into 4 ohms (24dBW), and even 800W into 2 ohms (23dBW)!"

I hope we'll agree that 558W is not really far from 291 being doubled. :D

https://www.stereophile.com/content/rotel-rb-1080-power-amplifier-measurements

That amp has been rated as 200W by Rotel. Mine is rated at 140W and it really doesn't make any sense to push it to the max as speakers will not sound very well there and my neighbours will not talk to me for a while. :D
 
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Ellisr63

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Well I couldn't resist getting a clone amp case for my B&O 3 channel biamped setup. I just ordered a clone KSA 50S amp case on eBay. I did not care if it said Krell or not (30 years ago I could have bought a Krell, but I chose going with Classe DR10 amps bridged instead...long since gone now). I just have always liked the look of the Krell amps with their massive handles and heatsinks. I looked at other options, but the plain Jane amp cases that were big enough just were blah looking. If I like this one I will see if I can find a smaller one for my biamped rear channels when I get that far on our Home Theater.
 
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watchnerd

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Well I couldn't resist getting a clone amp case for my B&O 3 channel biamped setup. I just ordered a clone KSA 50S amp case on eBay. I did not care if it said Krell or not (30 years ago I could have bought a Krell, but I chose going with Classe DR10 amps bridged instead...long since gone now). I just have always liked the look of the Krell amps with their massive handles and heatsinks. I looked at other options, but the plain Jane amp cases that were big enough just were blah looking. If I like this one I will see if I can find a smaller one for my biamped rear channels when I get that far on our Home Theater.

Am I reading correctly that you put a whole amp inside the case?

Or just boards, power supply, etc?
 

Ellisr63

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I only purchased a clone case. I will be making it into a 3 channel amp (biamped). I will be installing 3 B&O 50asx amp modules, and 3 125asx amp modules (balanced/bridged). I will be punching or drilling the extra inputs, and outputs needed to complete the amp.
A couple of years ago a friend of mine assembled my B&O amp modules into a 14 channel amp, and when we moved to our current location I decided i wanted my new setup to be a balanced one (we were going to have the front speakers 75` from our preamp, so I started buying the balanced version of the 50 watt B&O modules... the 125w modules you can change to bridged/balanced). So a few months ago I started to disassemble the 14 channel amp, and also started to look for a better amp case since we had originally gutted a defective amp.
 
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DKT88

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That low end roll-off is obscene.

What coupling are you using and what capture device/software? Is it a soundcard front end? Mic input/Line?

What about this front panel markings- they cannot be serious! :)

View attachment 12511

Left Eye, Right eye and Power Nose!
and what body part euphemism do they use for the output? I won't venture a guess in this public forum.
 

Ellisr63

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and what body part euphemism do they use for the output? I won't venture a guess in this public forum.
Speaker jacks must be an orifice. ROFL
 

restorer-john

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I agree. They should all "double down" within some range of operation. Feedback compares the output voltage to the input, and maintains the gain, so double the current flows into the reduced impedance of the load.

Doubling the current is one thing, but the voltage swing cannot be maintained due to the increased voltage drops across the emitter resistors and Tr junctions. As power is a function of voltage and current, 'doubling down' never can truly happen.

The usual trick is to derate the high impedance specification to give the illusion to audiophiles who buy on numbers. When the amplifier gets reviewed, they think they are getting an even better deal because it tests way above spec or 'punches above its weight' etc.
 

restorer-john

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"Using the conventional 1% THD definition of clipping, the Rotel puts out 291W into 8 ohms with one channel driven (24.6dBW), 558W into 4 ohms (24dBW), and even 800W into 2 ohms (23dBW)!"

I hope we'll agree that 558W is not really far from 291 being doubled. :D

That Rotel also blew up when being tested into low impedances. Clearly took out a channel and they only had a single channel left to run tests on. An amplifier that almost doubles down, blows its fuses and then ceases to function is a fail as far as I am concerned.

That said, I love Rotel gear. Generally, it is built beautifully and pretty much always performs better than spec.

I ran some tests only yesterday on a little vintage integrated Rotel (RA-930AX) I'll post in the reactive load thread today if you're interested.
 
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