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In Reply to: RE: Then, what if the measures you take in attempting to reduce distortion just "sound bad" posted by rick_m on June 27, 2014 at 12:37:32
And that the best sound is from amplifiers with only single pairs per channel of output transistors.
The link is to the NHB-108 amp owner's manual. The technical talk starts on page 9, FWIW & YMMV.
JM
Follow Ups:
Nelson Pass SIT amps use a single transistor for the entire amp.
If your speakers work in that environment, good deal
As for me, I favor the coherency and uniform directivity of my stats- which requires a more heroic amp that a single transistor can muster today. In the grand scheme of things, I find that speakers influence a greater aspect of the end result than does the amplification - don't get me wrong, I'm all about amps with simple architecture and minimal corrective feedback.
When a single SIT device can muster 200 watts, I'm all aboard. :)
critical component. Speakers are the vocal chords of a system.
Single pair of transistors per side, if this is true why does the latest Sony amplifier TA-1ES sound at least to my ears and to a loudspeaker designer that I know, so bad yet gets rave reviews in HFN & RR & Words & Music. I find the Sony amplifier to sound artificial with a poor bass, (probably due to the FET input) I have yet to see a US review of this amplifier which fortunately can be tried out for 30 Days with a full refund including carriage (in the UK) direct from Sony.
Edits: 06/28/14 06/28/14
Perhaps there are other things that account for the Sony unit's sound.
I think that it has often been noted that well-known critics believe that the lowest-powered amps from Plinius and Krell were the best-sounding, in both cases 50Wpc stereo amps with single pairs of output transistors.
JM
Thanks for the link.
I especially liked the bit about matched transmission lines not having losses... Would that it were true! And I'm not sangiune about lumping jitter with TIM into one puddle as "TD" just because "time" has something to do with both. Guess that's marketing for you.
Regards, Rick
I have the luxury of being able to shrug and say (as I often do) "We don't know whether this item sounds good BECAUSE of a certain design feature or IN SPITE OF that design feature."
And I have to assume that darTZeel departed from its own professed orthodoxy when it made its monster monoblock amps--those cannot have just two output transistors per channel... .
JM
I owned the darTZeel NHB-108's for 6 years, and now own the NHB-458 monoblocks.
some info I have from darZTeel on the monoblocks;
> > > > > > --no contact, nor switch, relay whatsoever in the signal path.
--no negative feedback in the input stage.
--no negative feedback in the output stage.
--there are "only three (3) discrete junctions (transistors) in the signal path per polarity, whereas in the 108 there are 6.......in terms of measured distortion, figures are similar as for the NHB-108. THD is kept below 1% audible threshold, while the most critical temporal distortion is completely absent from the equation".
--the main AC fuse has been replaced by a thermal breaker. < < < < <
this is from Fremer's review of the NHB-458 monoblocks;
> > > > > > > "Total harmonic distortion is specified at less than 1% from 7Hz to 77kHz. That's fairly high in today's solid-state world (though across that bandwidth it's pretty impressive), but Hervé Delétraz claims that THD "has nothing to do with musical performance." Like the darTZeel's original NHB-108 integrated amplifier, the NHB-458 has a zero-feedback, true open-loop output stage, so there's no output-impedance compensation (ie, Zobel Network). The specified output impedance is less than 0.28 ohm, 20Hz–20kHz.
Delétraz cautions that the NHB-458 is not suited for speakers with a nominal impedance of 1 ohm because of its low parts count: despite the high power, there are only four transistor pairs in the output stage." < < < < < < < <
these amps are quite amazing in terms of ridiculously low noise floor and lack of distortion. yet they don't sound like solid state or tubes, they sound like music.
mikel
jm
Hugh Dean - AKSA amps.
But the max power he can get out of 1 device is 80wpc (into 8 ohms). Although he does produce a 100wpc amp which has a pair of output devices in each channel.
Something about it being impossible to get multiple devices working precisely in synch - and the more you have, the harder it is. :-))
Regards,
Andy
Hi i am not an expert ... but i read a lot
I like hugely the single output pair philosophy
But, as you say, is difficult to get high power
Another thing that i like is quasi complementary designs, where the output pair is formed by two identical NPN, more robust transistors i understand
At Sanken they have in their catalog NPNs up to 200 W
You should get around 100W as max power out of a pair of them, more or less
My perfect amp has a pair of these NPNs at the output
I do not think it already exists anyway
If i would like more SPLs i would act on the speakers side, not on the amp side
Because i have read that paralleling output pairs usually ends up with a less refined sound, altough more powerful, of course
Another case where power corrupts
Kind regards,
bg
Edits: 06/29/14 06/29/14
My NAT Symbiosis gets 100 watts, Single ended, from a single MOSFET per channel...not a push pull pair but a single MOSFET.
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