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Stax Tube Amplifier Distortion vs Solid State

F1308

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#61
BTW frequency response was identical using both amps so any perceived tonality difference is imagined.
Ohhhh.....
Please, mind the hour it is.
Santa came a few days ago and the Three Wise Men are approaching, again with new gear...

You surely meant your very-expensive-SOTA-testing equipment was still not yet capable of detecting the sweetness tubes provide music with...
Isn't it ?
 

Francis Vaughan

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#62
which amp did you use? and what exactly improved when you used srm1
To be honest, it was such a long time ago I would hesitate to say what gear I was using. Even percptions are vague now. Less harsh I think. Seriously, this was back in about 1985.
 

the_brunx

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#63
To be honest, it was such a long time ago I would hesitate to say what gear I was using. Even percptions are vague now. Less harsh I think. Seriously, this was back in about 1985.
In my experience the biggest factor affecting the srd7 is the amp you use it with. Generally, With a good measuring amp you shouldn’t hear any background noise or distortion (at listening level). And you will get more power before clipping than any stax amp. But I will let measurements have the final word. Hopefully soon.
 
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Degru

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#66
[QUOTE="


The SRD-7 was in my experience a pretty second rate answer. But indeed, it would be a pretty interesting experiment.

which amp did you use? and what exactly improved when you used srm1?
In my experience SRD7 with a $200 (used) class AB amp (Adcom GFA545ii) drastically outperforms an SRM-3 (somewhat improved SRM1). The entire sound is much more dynamic, cleaner, and better separated. Bass has way more heft to it and the mids are much less shouty. This is even more obvious with more difficult Stax like the Lambda Signature, which I absolutely loved from speaker amp but thought sounded terrible from the SRM.

By comparison the SRM had this weird layer of congestion over everything; you could pick out individual detail just fine but trying to take in the entire track at once sounded weird and wrong, and it never felt like it hit quite hard enough.


However SRD is only as good as the amp in front of it, and it is quite amp picky.
 
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Degru

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#67
I use an srd7-sb mk2 with bridged nuerochrome power amps and sr lambda pro headphones. I'd be happy to ship the amp unit over if Amir wished to measure it.
SB variants are weird and considerably worse than the normal ones. They are purely for convenience and derive bias voltage from the speaker signal as opposed to having its own power supply. This basically leaches power out of the signal chain and introduces all kinds of nonlinearities as well as inconsistent bias voltage. I wouldn't use one as any kind of reference for measurements.
 

brimble

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#68
SB variants are weird and considerably worse than the normal ones. They are purely for convenience and derive bias voltage from the speaker signal as opposed to having its own power supply. This basically leaches power out of the signal chain and introduces all kinds of nonlinearities. I wouldn't use one as any kind of reference for this kind of system.
Isn't the power that goes to maintain the bias almost exactly zero after the initial charge?
 

Degru

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#69
Isn't the power that goes to maintain the bias almost exactly zero after the initial charge?
Yes, but there's still all the circuitry for this that the signal has to pass through, which is where the issues come from. Plus the bias charge itself will end up varying depending on what you play through it, which is not ideal.
 

Degru

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#71
I own a pair of the original Lambdas. (They are on long term loan to a colleague, otherwise I would get them out and do a bit of testing. I really need to get them back.) When I first bought them I got the transformer energiser. I then bought the SRM-1 mk-2. It was a huge improvement.
The SRM-1 has more than a fleeting resemblance to the 007t. They both share basically the same input stage, and the 007t's tubes replace the output transistors in what is otherwise a nearly identical topology. It isn't a particularly advanced design. Back in the early 80's they were doing the best they could.
Transformers have all manner of difficult problems to manage. To make at a sane price and get the quality isn't trivial. Doable, but not trivial.
If you look at Kevin Gilmore's high end designs you get near perfect amplification, but the level of complexity is jaw dropping. He seems to have thrown the kitchen sink at the designs. Commercial realisations are not cheap. Then again the current Stax amplifiers are not either.
I think it's not really possible to make generalizations about the overall sound of SRD setup because it depends so much on the amp pairing. I had the opposite experience from you with 404LE, Adcom GFA545ii vs an SRM3 (improved SRM1 design). The Adcom with SRD drastically outperforms the SRM to my ear. But I've also heard the SRD from speaker amps that made it sound like hot garbage that I would take even an SRM-212 over any day of the week.
 

Francis Vaughan

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#72
probably the sb variant is what gives srd7 a bad name. i know many people online say don't buy the sb version.
Ah yes. Now I think about it, I had the self biasing version. It isn't a great idea. I don't really think it adds any discernible load to the amplifier, but the vagaries of how good a bias voltage it can maintain is an issue.
An amplifier will be delivering next to no power to an SRD, but it does need to swing the volts.
 

bobbooo

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#73
Do these results suggest the Koss E/90X energizer's frequency response abnormalities from the original measurements were also not really there?
 

Cortes

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#74
How loud is +112 dBSPL?
Enough to go deaf very quickly.

My calibrated GLM kit says that ~60db (put a bit more/less depending on the ambient noise) playing music during hours is the lower limit I begin to worry about hearing loss.

I have to understand those ridiculous high levels of SPL. Probably they are needed for some frequencies during quick transients, but no more than that. Whenever I read Amir's reviews I get worried about his hearing health.
 

the_brunx

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#75
it seems like most modern music is made to slightly damage the ears to be part of the full intended experience by the artists. in fact they tried to hack your volume control by sacrificing dynamics and sound quality to play everything a little more louder. the artists seem to prioritise loudness over sound quality, unlike all of us here. :p
 

JohnnyHonda

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#80
There is no question that the tube energizer has lower power capability before its distortion rises. To the extent you listen softly then you won't notice it. In my use I do and have been frustrated for a lot time about the tube amp becoming distorted before I run out of satisfaction with the volume. :)

And oh, this is evidence that electronic distortion can be worse than our transducers (speakers and headphones). Always get electronics that are far better than your transducers to avoid this. Definitely don't skimp on power capability.

Thank you Amirm for testing and posting the Stax amp and headphone results. Much appreciated. JohnnyHonda
 

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