The Stax Thread III
Aug 22, 2015 at 1:41 AM Post #5,776 of 26,473
....  My budget will enable me to get the 009 but limit the amp to low end for about a year. So I am considering the 323s. How will the sound change compared to something like the Mal Valve now that I have a reference point?

And since I have the green light to make this big purchase, I might be able to slip in another small purchase in the same order from PJ. Would the 507 just collect dust if I add that to my purchase?

Every time I come back and read this thread, I start to inch closer and closer towards dropping the idea of a TOTL amp for my dynamic HPs and going for a STAX system. And like I said, since I have the green light to go ahead, I was thinking of the 009, 323s, 507 and now I thought about adding something like the SRD-7 so that I can also use the 009 or 507 at work or wherever there is a regular amp. Is there any difference in the sound when using one model from another (of those transformer adaptor boxes, i.e. SRD-7, or 4 or 6 or whatever model)? Any recommended with the system I am considering.
 
I will most likely be buying from Price Japan but I couldn't find the SRD-7 on their website. I find that their website is not very user friendly.
 
Thanks.
 
Aug 22, 2015 at 8:48 AM Post #5,778 of 26,473
Too bad, I used to have an almost NOS SRD-7/mk2 for sale some months ago : http://www.head-fi.org/t/766616/fs-stax-srd-7-mk2
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Ali
 
Aug 22, 2015 at 9:19 AM Post #5,779 of 26,473
  Too bad, I used to have an almost NOS SRD-7/mk2 for sale some months ago : http://www.head-fi.org/t/766616/fs-stax-srd-7-mk2
tongue.gif

 
Ali


And it would have worked here in Hong Kong without requiring a step down transformer. I guess it was just not meant to be.
 
BTW, I went to the local HP shop today to try out some TOTL amplifiers for my HD 800. That is the cross-roads I am at in terms of my next purchase: to upgrade my dynamic HP system or to try a new path with STAX. I have to say, I was mightily impressed with the Bryston BHA-1 with my HD 800. I also tried this other amp by Aurorasound called HEADA. It is exactly as Currawong described it in his review so I won't bother repeating it here. Also tried the Violectric V281. All of them were running from my MBA to Stello DA100 to the various amps.
 
BTW, he mentioned that a few of his customers have STAX and that they had to send them back to Japan after about six months to repair because of the humidity issue in Hong Kong. I do have an electronic dry box, the type that is used for camera equipment. I would have to constantly store them in there when they are not used, which would be inconvenient, but I WILL do it. But when I use them, and sometimes leave them around on occasion, will the humidity thing be an accumulating issue, or will putting them in the dry box return them back to the 'original' dry state? Have any of you had problems with humidity that they had to be returned for repair?
 
Aug 23, 2015 at 12:42 AM Post #5,781 of 26,473
  My stock KGST gets 100++ at the top of the case which is a generous 6" above the tubes (most KGST builds I see are 3U-4U variants). So I pull the cover, given the tall design of mine the back electronics is well hidden. Even then it's throwing off more heat than any Stax amp (except the T2 of course.). A regulated supply and twice the tubes will do that. Oh well the 727 probably is about the same since it has four tubes. 
 
Something to consider since the ratings on electrolytics plummet at around 100 degrees. 


I finally decided to check the temperature on my KGST. It's a 2U build, with the tubes just a few millimeters away from the fully-vented top panel. I never thought it ran particularly hot — I wouldn't keep my hand on it indefinitely, but it certainly doesn't burn. The temperature probe that comes with the Fluke 179 measured around 45degC tucked just inside a vent above one of the amp boards, between the two tubes, or around 20degC above ambient. FWIW, I run the PSU at 350V, and I used the largest Aavid heatsinks that fit in the available footprint where needed.
 
Aug 23, 2015 at 4:26 AM Post #5,782 of 26,473
This is obviously a very beginner Stax post.

But, I just watched this very informative video which flows effortlessly and informs completely imo just what the Stax 009 is.

Until now I didn't realize exactly why the 009 is so highly regarded, but I'm starting to understand.

https://youtu.be/afkYRJU0Dlw
 
Aug 23, 2015 at 7:22 AM Post #5,783 of 26,473
 
I finally decided to check the temperature on my KGST. It's a 2U build, with the tubes just a few millimeters away from the fully-vented top panel. I never thought it ran particularly hot — I wouldn't keep my hand on it indefinitely, but it certainly doesn't burn. The temperature probe that comes with the Fluke 179 measured around 45degC tucked just inside a vent above one of the amp boards, between the two tubes, or around 20degC above ambient. FWIW, I run the PSU at 350V, and I used the largest Aavid heatsinks that fit in the available footprint where needed.

 
Looks right, 45C = 113F. Those 'lytics are rated for a shortened lifetime at 100F.
 
You're right in that it doesn't feel particularly hot on top, but neverthless is quite hot inside. I put a PC rear vent chassis fan on all my amps as a simple solution. It blows the heat away on top, giving the heat inside an easier time to come out keeping the whole unit cooler. 
 
Aug 23, 2015 at 12:19 PM Post #5,784 of 26,473
   
Looks right, 45C = 113F. Those 'lytics are rated for a shortened lifetime at 100F.
 
You're right in that it doesn't feel particularly hot on top, but neverthless is quite hot inside. I put a PC rear vent chassis fan on all my amps as a simple solution. It blows the heat away on top, giving the heat inside an easier time to come out keeping the whole unit cooler. 

I you sure re 100F? That sounds a bit low, most caps are ok till 85°C which is 185F. A typical cap that has 2000 hours at 85°C should have (for example) 10,000 plus at 45°C.
IMO it is not good to have components hitting their temperature safe zone in normal usage.
 
In many tubed amplifiers the heat generated and the way a design negates that has a marked effect on reliability and life of the component i.e. nobody wants to spend 3K + plus on a product and have it fail inside say 5 years minimum. Besides, components start to tank out of spec as the temp reaches their limits, so the SQ goes to all to hell .....
 
Aug 23, 2015 at 1:17 PM Post #5,786 of 26,473
Looks right, 45C = 113F. Those 'lytics are rated for a shortened lifetime at 100F.

You're right in that it doesn't feel particularly hot on top, but neverthless is quite hot inside. I put a PC rear vent chassis fan on all my amps as a simple solution. It blows the heat away on top, giving the heat inside an easier time to come out keeping the whole unit cooler. 


Does the pc fan bother you noise level wise! I tend to use louder/faster fans that push a lot of air but I feel like it could go either way on being audibly distracting or not
 
Aug 23, 2015 at 1:37 PM Post #5,787 of 26,473
Does the pc fan bother you noise level wise! I tend to use louder/faster fans that push a lot of air but I feel like it could go either way on being audibly distracting or not

 
It's variable, on the lowest setting it gives a nice cooling breeze and is basically silent. Comes with a 12V adapter so just plug into the wall. 
 
Aug 24, 2015 at 9:11 PM Post #5,790 of 26,473
Somebody(s) is obsessing about getting old 
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Doesn't bother me. Other than Beethoven all musicians keep going into their late years with no apparent loss of enjoyment or skill. It's all about the midrange anyhow, the upper freqs are for overtones you don't hear much anyhow. 
 

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