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Old 25th June 2010, 01:19 PM   #91
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Quote:
Originally Posted by wakibaki View Post
Hands down a chipamp is going to win. You're designing the transistors fer chrissake. You don't get that degree of freedom with a discrete amp. The transistors are matched. They're pretty much at the same temperature. These are advantages not to be sneezed at.
sure, but unfortunately there are drawbacks, too.

E.g. "thermal feedback" from the power out stage to the previous ones is surely not welcome, as are shared power supply (and/or ground) lines which may (will) introduce other unwanted interactions between stages.

IMVHO, the best would be to have an integrated "front-end" driving an integrated power out stage... but with the two parts built on separate chips!

P.S.: sorry for "rewinding" the thread with a late answer to an old post...
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Old 25th June 2010, 02:57 PM   #92
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I believe this is why the two "fancy" chip amps of the earlier post numbers in the 80s are both "composite" amps with separate front end ICs from the power stage IC. The early and highly copied BGW amp used IC front end with discrete output stage. ICs clearly have a lot of advantages BUT do not always have the best circuit design for a given application.

Walt Junge said much of the later audio IC work at Analog Devices was to assure thermal effects from the output stage of the ICs did not adversely affect the input and gain stages. He presented talks at AES meetings on this very subject with lots of graphs and explanations of newest designs- about year 2002.
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Old 28th June 2010, 02:45 AM   #93
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Default Is this a chip amp?

I'm not sure what is meant by chip amp.
This thread is interesting.
I have a link... 6moons.com - audio reviews: nOrh/IRD Le Amp

Is that a chip amp?
The referral to
nOrh should be ignored as this unit is actually the IRD MB-100 and is available. the nOrh no longer is.
If it is a chip amp, it compared favorably to the Bel Canto, which was mentioned in this thread as a good amp.
The IRD is MUCH less expensive and I have no reason to doubt that the reviewer's audition of MB-100 is less than reliable.
If it is not a chip amp, what type is it please?

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Old 28th June 2010, 02:56 AM   #94
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Quote:
Originally Posted by philmagnotta View Post
'm not sure what is meant by chip amp.
This thread is interesting.
I have a link... 6moons.com - audio reviews: nOrh/IRD Le Amp

Is that a chip amp?
For sure, and one which is being hyped in its output power. The review says its a '100W monoblock' but the single TDA7294 its employing can't push out that much power. Even the datasheet for it (shown on the page) states '100W music power'.
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Old 28th June 2010, 03:00 AM   #95
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Yes it is a chip amp.

IMHO the heat sink is scary small. It took 300 square inches of heat sink to keep two channels of mine cool running hard. I run two chips as balanced output as per earlier post which make 100 watts into 8 ohms and more into 4 ohms but I do not see my log book right this second so 4 ohm power is right this second a mystery. Sounds good in mono really!

Other than that the amp of the link looks just dandy.

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Last edited by sumaudioguy; 28th June 2010 at 03:03 AM.
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Old 28th June 2010, 04:01 AM   #96
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whatever the data sheet states, might it be possible within the design-as a whole- to be legitimate according to specs below.

I'll be auditioning this product very soon, so I'll see what is up with this unit, but I can not verify, technically, the stated specs below.
I've had several conversations with the designer who states that he has fully tested this unit and over a long period-at least 5 or 6 years in the market, almost zero failure rate.
His background in designing advanced medical equipment and their power supplies and other technical equipment allowed him excellent design skills.
However, I'm not qualified to test it technically.
I believe it should be possible to reach that design


IRD MB-100 MonoblockMB-100 Features

  • True high-end audio at a reasonable price
  • Heavy duty 400 watt oversized power supply
  • Easily drives most 8/4 ohm loudspeakers (handles impedance dips to 3 ohms)
  • Music program peaks of 125+ watts @8 and 250+ watts @4 ohm loads (observed on Oscilloscope)
  • Low THD+N performance
  • Powerful DMOS output stage - accurate bass, smooth midrange and extended highs - no irritating SS distortions
  • Superior build quality at this price point, designed to last a lifetime
  • Excellent thermal management, never gets hot even at full power for extended periods
  • Built-in SOA overload, short circuit protection, and thermal shutdown protection
MB-100 Specifications

Input Interface

Single ended mono input RCA Input Impedance 22.1k Ohms Input Sensitivity 1.25Vrms Main Specifications

Gain AC Signal = 26 dB (x20) ; DC = 0 dB (x1) Frequency Response 7 Hz-50k Hz 0.2 dB; 3 Hz-195kHz 3 dB Slew Rate > 10 V/us MOSFET output stage Class AB Output Power (IEC 60268-3) 100 Watts (RMS) minimum @ 8 Ohm Load SNR 93dB @ 12.5W
102dB @ 80W THD+N 0.011 % @ 75W Continuous into 8 Ohms
0.014 % @105W Continuous into 4 Ohms Built-in protection circuits SOA + Overload protection
+ Thermal shutdown protection Output Interface

Mono speaker output Machined metal binding post (9mm spade ID + >10awg hole) Peak Output Current > 10 A DC Offset Typically < 2 mV Recommended loudspeakers 8 /6 / 4 Ohm with impedance minimum >3 ohms Power—Physical

Mains AC Supply 110-120Vac (or) 220-240Vac @ 50/60 Hz IEC type removable power cord 2m (6'); 16awg / 3 wire; USA style plug Size 165mm (6.5") W
178mm (7.0") H
325mm (12.8")D Weight 11 Kgs (24 lb)

Last edited by philmagnotta; 28th June 2010 at 04:08 AM.
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Old 28th June 2010, 04:07 AM   #97
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Quote:
Originally Posted by philmagnotta View Post
whatever the data sheet states, might it be possible within the design-as a whole- to be legitimate according to specs below.
Is it a chip-based amp?

Oops. Nevermind.

se

Last edited by Steve Eddy; 28th June 2010 at 04:10 AM.
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Old 28th June 2010, 04:27 AM   #98
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Quote:
Originally Posted by philmagnotta View Post
whatever the data sheet states, might it be possible within the design-as a whole- to be legitimate according to specs below.
I'm not suggesting the design isn't legitimate, just that the specs are overly optimistic. But that's fairly common in the audio world.

Quote:
His background in designing advanced medical equipment and their power supplies and other technical equipment allowed him excellent design skills.
It certainly suggests it should be a reliable piece of equipment. But what does he know about achieving high quality sound from the design of medical power supplies I wonder?

Quote:
[*]Low THD+N performance
This is interesting. If my amps had low performance in THD+N I'd not be trumpeting the fact. Or is there something of the hair shirt mentality coming in here - low performance in THD means its optimised for something other than linearity?

Quote:
[*]Excellent thermal management, never gets hot even at full power for extended periods
Where full power is 100W into 8R? I can't help but see the irony here - the reason it never gets hot at full power is because it thermally limits and effectively shuts down.

Quote:
Slew Rate > 10 V/us
More hype here - the min specified slew rate is 7V/uS for the chip, 10 is the typical figure. Are we to believe that he hand picks the chips for better than typical slew rate?

Quote:
Output Power (IEC 60268-3) 100 Watts (RMS) minimum @ 8 Ohm Load
I don't have a copy of IEC 60268-3 so maybe it allows short term output power to be put on the spec sheet. Anyone else know about this?
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Old 28th June 2010, 04:38 AM   #99
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Of the 8-or-so reviews, a consistent remark was: running this amp hard for long periods barely gets past lukewarm. Performed favorably against Bel Canto and was practically indistinguishable against AYRE- another highly rated amp manufacturer. 100+ watts/8, 200+ watts/4 reliably and sonically.
Many units sold and still running for at least 6 years that I know of with very little failure or complaints.
Don't say It can't be done unless you can prove it regarding that unit.
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Old 28th June 2010, 04:53 AM   #100
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Quote:
Originally Posted by philmagnotta View Post
Don't say It can't be done unless you can prove it regarding that unit.
Running the amp hard with music would mean an average output power at least 14dB below clipping, even with the most compressed grunge imaginable. That's not really so difficult - I'm not taking issue with the performance when playing music just with its apparent claim of 100W RMS continuous. I do note though that the specs you showed do not give the distortion number at 100W, rather they show it at 75W. Interesting don't you think? I think a >100W continuous squarewave output is eminently do-able with that chip

I'm of the (perhaps biassed) view that if it was almost indistinguishable to the Ayre then those listeners need their ears syringing. The Ayre is a seriously engineered piece of kit, but I must admit I've never auditioned one myself.
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