Isn't true balanced design difficult to execute, thinking that it's hard to exactly match the components of the two opposite-phase circuits? Isn't it even harder to match tubes within said circuits? How tight would tolerances have to be to call a true balanced circuit successful and superior to single-ended?
Tolerances would have to be extremely close. You're essentially building two of everything, and let's not even think about the cost of all those matched sets of tubes. The cost of matched tubes seems to go up exponentially from pairs to quads to sextets, octets to "moretets." I shudder to think what matched sets of power tubes on the big 750 watt ARC amps would cost. -- Definitely not in my budget!
you're correct. As I stated Vlad never IIRC use an XLR input but does use them in the output but as mentioned they are pseudobalanced connections with one of the pins shorted.
Pseudobalanced??? Maybe they like the XLR connector because the connection pins are bigger and the plugs are much more sturdy than RCA plugs, but shorting one of the pins gives you an plain single ended connection. I'm not saying that's bad, but that is what it is. The XLR cable is differential/balanced only when all the three conductors/pins are connected.
Quasi-balanced circuits typically are single-ended internally with a single inverter at the output to generate the out-of-phase (complementary) signal. True differential designs do not have separate "+" and "-" paths, it is a single differential circuit. However, that does indeed require ~2x the devices. I think ARC amplifier designs are already differential internally, with an inverter in the input stage (at least that's how I recall my D79 signal path). Their preamps, at least those I have sen schematics for (SP1 or 2 up to 10 or 11), are single-ended.
Pseudobalanced??? Maybe they like the XLR connector because the connection pins are bigger and the plugs are much more sturdy than RCA plugs, but shorting one of the pins gives you an plain single ended connection. I'm not saying that's bad, but that is what it is. The XLR cable is differential/balanced only when all the three conductors/pins are connected.
I don't think, by definition, that the Lamm amps, which are SETs, can be 'balanced.' I'm pretty ambivalent to the whole issue- i like the firm grip of the xlr connectors and use them, from phono stage to line stage, and from line stage to amps.
I personally believe that you need to live with and listen to components for awhile in order to make meaningful judgements with regards to which one is *best.* Unless of course that one device is so far superior to the other that it's laughable. I for one would not want to spend my money on buying a component strictly based on a six gun double blind shoot out. I truly think you need to live with a component for a period of time before you can make meaningful judgements of where it stands in your pecking order.
you're correct. As I stated Vlad never IIRC use an XLR input but does use them in the output but as mentioned they are pseudobalanced connections with one of the pins shorted.
There really isn't any such thing as pseudobalanced. Its either balanced, or its single-ended. There is no in-between. In that regard its like being pregnant.
Tolerances would have to be extremely close. You're essentially building two of everything, and let's not even think about the cost of all those matched sets of tubes. The cost of matched tubes seems to go up exponentially from pairs to quads to sextets, octets to "moretets." I shudder to think what matched sets of power tubes on the big 750 watt ARC amps would cost. -- Definitely not in my budget!
This is one of the more common myths about balanced circuits- the part about 'building two of everything'. Differential amplifiers are balanced, and they don't require double the parts. You also don't have to match the tubes. If the gain of the circuit is high and if there is a good Constant Current Source, mis-matched tubes will still do a fine job with CMRR numbers in the upper 90 db to lower 100db region. Now if differentail circuits are avoided, then all of the above comment is correct. I'd be very much surprised if anyone in high end audio is actually building such a thing!
I don't think, by definition, that the Lamm amps, which are SETs, can be 'balanced.' I'm pretty ambivalent to the whole issue- i like the firm grip of the xlr connectors and use them, from phono stage to line stage, and from line stage to amps.
Actually it is possible for any SET to recieve a balanced signal in the differential domain, but must designers have no idea this is possible. IOW I am saying that an SET can process both the non-inverted and inverted signals without modification of the SET circuit.
(...) I think ARC amplifier designs are already differential internally, with an inverter in the input stage (at least that's how I recall my D79 signal path). Their preamps, at least those I have sen schematics for (SP1 or 2 up to 10 or 11), are single-ended.
Yes, their power amps have been truly balanced from start - their output transformers were also balanced, grounding the 4ohm tap and applying feedback in a symmetrical way. It is why they always had a 16 ohm tap. Although older ones included an inverter most designs did not have it and could only be used with truly balanced preamplifiers.
The ARC LS5 mk1 and mk2 preamplfiers were also fully balanced from input to output - four exactly equal channels with four linked attenuators. They could not accept SE signals - ARC had a special unit just to create the balanced signals. I loved the sound of the LS5 mk2 when used with their VT150 monoblocks and a pair of Quad ESL63. Perhaps I could have stopped at that point!
Modern ones have balanced inputs, a SE atenuator and balanced output stages.
. . . . I personally believe that you need to live with and listen to components for awhile in order to make meaningful judgements with regards to which one is *best.* Unless of course that one device is so far superior to the other that it's laughable. I for one would not want to spend my money on buying a component strictly based on a six gun double blind shoot out. I truly think you need to live with a component for a period of time before you can make meaningful judgements of where it stands in your pecking order.
I agree that it would be very nice to have a component for months to make meaningful judgements. How long do you think a dealer will let you keep a component in your house to do that or allow you to sit alone in his sound room before he sends in the next customer? With regard to professional reviewers on the same question, no one is rushing them to write their reviews. A credible reviewer who has the ability to make or break a product and to sway and create opinions for others, has the responsibility to do a blind test.
I don't know what you mean by a "six gun double blind shoot-out," but a double blind, or blind test clearly has more controls than a gratuitous "six gun shoot-out."
When a reviewer is listening to a $250k Goldmund or $140k Soulution power amp or a $150k Audio Note or $120k FM Acoustics preamp, or a $125k Vivaldi stack, he has the lore of its retail price to deal with when reviewing it and I find it almost impossible to believe a reviewer would ever admit that they could not reliably identify the expensive piece being reviewed over a "lesser model" costing one tenth as much, still very expensive for most folks--which should be part of any review. A reviewer saying, "this amplifier [or whatever component] is a game changer" or "is leaps and bounds above the rest," loses its credibility if it cannot be correctly repeatedly identified in a blind test. I mean if you can't correctly identify a $10k amp vs a $250k amp, what does that say about the equipment and/or the reviewers?
I realize some components have exceptional build characteristics and finish, but the polished exotic wood rails and half inch thick milled aluminum chassis on some very expensive power amps don't do anything for the sound. I don't object paying for art, but these attributes should be regarded as such, and should not be cause for a reviewer to make claims of exemplary sound because the components look beautiful.
Listen with your ears, not with your eyes.
I'm just looking for what they call "transparency" in the political arena.
Gary-I have kicked an $8500 Jadis Defy 7 MKII to the curb because it couldn't do what my Phase Linear 400 Series 2 could do with my speakers. So bling doesn't mean a thing to me with regards to what sounds best in my system. If I had to choose between two components which sounded so close that I couldn't really distinguish between them, then I would base my decision on which one I liked the looks of better. I happen to think the Jadis Defy 7 is a gorgeous looking amp, but the looks didn't matter to me over performance.
And what I mean by a "double blind six gun shootout" is that you never had the opportunity to listen to both pieces for any length of time in your system and you were basing your purchasing decision on hearing snippets of music played on both pieces over a short period of time and basing your purchasing decision on that shoot out.
I think it's very risky to sell off a piece of gear that you are hoping to replace with a *better* sounding piece of gear before you get to live with the replacement for awhile and are confident that you are making the correct decision.
I wasn't saying to do a test based on short little snippets of music. You should listen for a while. Take your time. I think three to five 30 minute sessions with a given piece should be enough to tell if that's the one you like better. If you can't decide over one weekend, take another. Who is rushing you?
IMHO you want to replace a system that can be guilty of some bias with an inefficient almost random system, that can easily become strongly biased for non experts.
I acknowledge your contributions to spot the existing reviewing and selection problems, but you seem more interested in dissecting them than in telling us solutions that can be implemented. All your practical suggestions for blind testing seem impossible to realize in good practice - they are just nice for the political arena, where implementation is not an issue.
I thought I did say how to implement blind testing, but here it is again. You need a listener [or how ever many you want] and a person to do the blind switching. Two people is all you need.
I can't describe it any better, so I guess I have said all I have to say
