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Old 18th January 2012, 10:43 PM   #1071
a.wayne is offline a.wayne  United States
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Quote:
Originally Posted by vacuphile View Post
No, third is fine. Many like it. For the rest, random noise doesn't intermodulate, so yes.
OK, 1st is Soulution , last is VTL ....


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Originally Posted by scott wurcer View Post
I suspect they have the usual creative definition of "zero" feedback. A couple of obvious thought questions. What bi-polar output stage at any bias level has a ppm level open-loop transfer function? How do you make an arrangement of bi-polar devices have a usable well defined temperature stable gain with NO feedback (which includes degeneration)?

Love the build quality.
Who doesn't ....

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Originally Posted by Pano View Post
Have you ever measured the Denon?
He's scared ..... Now could Wave tell the difference between Triode and Denon , blindly that is .
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Old 18th January 2012, 11:01 PM   #1072
tvrgeek is offline tvrgeek  United States
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Driver frames in gun metal blue? Baffle has to be hand checkered to help diffraction. You have top get with the times though and have a special version in pink camo grill cloths.

My old Denon DRA 35 was a bottom end stereo receiver. It has put many a big buck amp to shame for simple listenability in it's time. Yea, it fails my wife's test.
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Old 18th January 2012, 11:40 PM   #1073
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Quote:
Originally Posted by Pano View Post
Have you ever measured the Denon?
What for?

I hear it sounds darn good. And when I looked at schematic recently I understood why: it has simple and optimal like Kalashnikov machinegun output stages. Well balanced. No odd things to improve DF and THD for marketing-related measurements.
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Old 18th January 2012, 11:47 PM   #1074
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Originally Posted by a.wayne View Post

He's scared ..... Now could Wave tell the difference between Triode and Denon , blindly that is .
Actually, I can. Denon still sounds like a darn good amp; triode itself does not sound at all, but well prepared it sometimes sounds as if it does not exist. I myself was fooled several times by my own prototypes, and other people were. I once jumped and turned around, before realized that there can't be a waterfall in my living room.
However, that time it was not a triode, it was a single ended MOSFET output, bootstrapped by one more MOSFET follower, and loaded on a current mirror. Driver was a pair of vacuum tube triodes, active loaded on gyrators, with deep feedback around them. It really scared me before I realized that is a reproduction from an ordinary CD.


Such tests I value much more than that ober-organized double blind sessions... If subjective mind had been fooled, that's it!
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Old 18th January 2012, 11:51 PM   #1075
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Just curious. If you have found a mainstream, reasonably priced amp that sounds great subjectively - maybe something in the measurements would indicate why.
Harmonic structure
TIM
IMD
Noise
Output impedance vs frequency
Stability into difficult loads

Stuff like that. But maybe that's just me. I like to measure stuff.
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Old 19th January 2012, 12:27 AM   #1076
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Pano
Amazing how a thread can come right back on topic after 1075 posts!

You are in good company with we who like real repeatable objective measurements. When I have subjective evidence I can't explain, I want numbers.

Here is an amp to test. Rotel 840 integrated. Ignore the preamp as it is passive save the RIAA, from the early 90's. Along with the RB 941's I have, the only amps that normal people (socio-economic, no pretense to mental "normalcy") can buy that pass my wife's critical horn test. Nothing special I can see about its schematic, but I am just learning. You can get one off e-bay for just under what they cost new. ($300) I have seen them go for close to that. Not much used stereo goes for retail. I have an early Creek that sounds very good to my ear, but it has not be in front of The Judge.

What failed her "horns grate her teeth, give her a headache test"? BTW live does not and these fail at very reasonable levels.
Hafler,B&K, Addcom, HK, Meng, Yamaha, Onkyo, PS, CM Labs, Sanyo Plus, Brown, Bedini, Parasound (pre John C.), Denon, Sony. She did like the Cary triode. I did not bring the Aragon home as it was too expensive but I loved it. Of this failing set, only the B&K and Hafler could pass my "steel string" distortion where Julian Bream's bass strings sound metal, not nylon. I can conclude with available subjective information, the issues are likely related. Now, let's look for a objective measure.

The Rotel is clean, but not great. DF about 40 at 1K. I need to measure higher. Bi-polar. Classic simple LTP input, VAS and twin outputs. Reasonable bandwidth. Nothing special in the specs I could point to. Amp 2, Hafler 120. Again nothing too special. Cleaner numbers, higher DF, wider BW. Schematic I don't quite understand yet but basic topology pretty conventional. MOSFET outputs. Twice the power of the Rotel.

I was comparing it's acoustic output to my DH 120. Injecting an artificially contrived zero starting pulse, the Rotel first rise time was not as delayed as the Hafler, and it became in sync with the electrical output quicker. Does this mean anything? I don't know. It is a difference I could measure. As soon as I get the 120 rebuilt I will test again. ( I was testing the limits of some power supply mods... I found them). I am trying to build a current probe that can see down to 4K where I was testing. My attempt is stalled at about 10 K. I may have to put an amp on it. I want to compare the voltage to the phase at the amp terminals in this test and see if there is a difference I can measure. Then see if it is still there with a resistive load. Ideas most welcom.
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Old 19th January 2012, 12:35 AM   #1077
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If you listen and measure some amps built by the manufacturer for less than $500, you will have compromises that should be audible, including my own designs.
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Old 19th January 2012, 01:06 AM   #1078
a.wayne is offline a.wayne  United States
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John,

Thoughts on the soulution measurements ...?
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Old 19th January 2012, 01:08 AM   #1079
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7th and 9th harmonic distortion with a 5KHz test tone at levels between 0.1W and 25W. There will be a worst case level at the transition between Class B and Class AB.
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Old 19th January 2012, 01:31 AM   #1080
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Quote:
Originally Posted by a.wayne View Post
6moons industry features: A visit to Soulution
...its slew rate is faster than 0.4 microseconds
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