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Old 25th December 2011, 03:42 PM   #111
a.wayne is offline a.wayne  United States
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Quote:
Originally Posted by SY View Post
Yes, I know the Hafler box; it was designed to promote the XL280, if memory serves. There's far better ways of doing the same thing now- for example, the brilliant DiffMaker software. For ears-only listening comparisons, one can easily rig up a high quality switch box (see Linear Audio Volume 2 for a discussion of this).

There are a lot of amplifiers designed to be effects boxes, and there you get into a whole different set of questions. But the reasons that they're effects boxes and the nature of the effects are straightforward engineering.
Do tubes have more "effect's" than SS ..............?
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Old 25th December 2011, 03:58 PM   #112
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Hi,

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Originally Posted by wahab View Post
They both have higher THD in the audio band than the old dude...
Please show your measurements... I find they have substantially less under identical conditions with 1K loads...

Quote:
Originally Posted by wahab View Post
You are quite paradoxal since GBW product will inherently be a parameters of first importance for perfs once we apply NFB,
do we , to those circuits , in the aim to reduce....THD !!..
If a circuit has less THD than another (which the OPA627 has compared to the NE553X) then the implication is that it is more linear. If it is that while having less OLG than the other circuit, it simply means it is more linear.

Quote:
Originally Posted by wahab View Post
the NE553X wich has notoriously slow lateral PNP transistors, yet , it s still unsurpassed to these days for audio purposes, and when it is , it s only marginally..
It is not just marginally surpassed, but quite dramatically, once we get real circuits. But please continue to use if you like.

I use 553X in some specific applications (though not the direct signal path) where the relative decent specs and very low price make it an excellent choice. Heck, i have use for the TL081 at that in audio gear (but not to amplify audio)...

Ciao T
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Old 25th December 2011, 03:59 PM   #113
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Originally Posted by DBMandrake View Post
I find it very hard to accept that he never ever listened to his own designs.

I can accept that during a production run of amps that he would not listen to each one - simply verify that each met the expected set of measurements. No problem with that. Once the design is set in stone there is no point in individual listening tests of individual amps of the same design as long as they measure the same, in fact you're more likely to hear differences that aren't actually there in such testing.

I could even accept that during the design process he didn't listen to them, but was guided entirely by measurements and following specific design principles. This is a bit more of a stretch, but still believable.

But never listened to an amplifier he designed ? I don't believe that for a second. He never used one of his own designs on his own personal home system at any time ? Sounds a bit like actors who claim to have never watched one of their own movies...
Peter Walker was famous for saying that all amps sound the same unless they are broken ie 'wire with gain' (he may have even coined that phrase).

He didn't have any truck with fancy cables either.
However famously at one US audio exhibition one 'audiophile' came up to him and said that while he owned the exact same all-QUAD system as they demonstrated it never ever sounded as good. The only difference where the strikingly orange cables QUAD used at the show so he insisted on purchasing them.
Turns out that when the QUAD people packed the gear they completely forgot speaker cables but found some old Black&Decker mains cable in the skip which is what they used at the exhibition.
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Old 25th December 2011, 05:30 PM   #114
a.wayne is offline a.wayne  United States
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I heard my first Quad speaker in 74 and by then most of the "quad guys" had moved on from Quad amplifiers. Personally , I have never heard an Quad amplifier , to say good or bad, based on Past comments, by 74 they were surpassed by other offerings for driving the 57.
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Old 25th December 2011, 05:42 PM   #115
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Hi,

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Originally Posted by a.wayne View Post
Personally , I have never heard an Quad amplifier , to say good or bad
I serviced the whole SS Quad range while working at Music & Video Exchange (London) extensively, next to them Naim sounded "solid gold" and our cheap cheap Technics Class AA integrated "shop amp" walked so all over them, it was unfunny.

There was worse out there sonically, though, still these sounded such on our JBL Studio Monitors (the Shop Speakers) that I preferred running them into dummy loads for post repair testing, not speakers with msuic as we usually did.

I later worked on restoring a pair of Ex BBC Quad II's. These where not all that bad, quite nice little tube amp's, but they really did not offer anything special, power was not really better than a 300B SE Amp subjectively. Worked okay with Tannoy Reds.

Based on my experiences I find it hard to doubt that PW never listened to his company's amplifiers, neither would I...

Ciao T
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Old 25th December 2011, 05:55 PM   #116
wahab is offline wahab  Algeria
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Originally Posted by ThorstenL View Post

If a circuit has less THD than another (which the OPA627 has compared to the NE553X) then the implication is that it is more linear. If it is that while having less OLG than the other circuit, it simply means it is more linear.

It is not just marginally surpassed, but quite dramatically, once we get real circuits.
THD of both devices is about the same once we get on a real circuit...

As for linearity , well , the OPA627 use much more internal
local feedback than the 5532 , wich explain an apparently (only)
better linearity in open loop , but in fact it has worse intrinsical
linearity...
Attached Images
File Type: gif D SELF NE5532.gif (16.9 KB, 231 views)
File Type: gif D SELF OP627.gif (47.3 KB, 233 views)
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Old 25th December 2011, 06:10 PM   #117
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Build audio devices on opamps is like transport bread on tanks. Both are suboptimal for the task. But both can be used, especially when are mass produced, cheap and widely available.
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Old 25th December 2011, 06:14 PM   #118
a.wayne is offline a.wayne  United States
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I'm for discrete over op-amps myself, how good are these op-amps and where would you implement them if one were to use such.
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Old 25th December 2011, 06:23 PM   #119
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Quote:
Originally Posted by a.wayne View Post
Do tubes have more "effect's" than SS ..............?
Of course, no.
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Old 25th December 2011, 06:25 PM   #120
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Quote:
Originally Posted by a.wayne View Post
I'm for discrete over op-amps myself, how good are these op-amps and where would you implement them if one were to use such.
I.e. when you design bread-carrier, you prefer to build a tank from scratch, instead of building something more like a truck with appropriate shelves for bread?
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