[Sundance]

Wow, thank you! I thought of this suggestion but it was too stiff at first. Secondly, how would you rebalance both channels if you do not wish to keep the setting? Would you twist both segments back to zero?
 
Your 717 is a bit different from mine. Mine has vents on top. Won't the machine get hot or are there other vents that I'm seeing?

 

[Gu Sensei]

Quote:

Wow, thank you! I thought of this suggestion but it was too stiff at first. Secondly, how would you rebalance both channels if you do not wish to keep the setting? Would you twist both segments back to zero?

Yep, just twist each dial all the way back to zero.
 
Quote:

Your 717 is a bit different from mine. Mine has vents on top. Won't the machine get hot or are there other vents that I'm seeing?

That is not my 717 (or even a 717!) It is just a picture with a good angle on the knob that I grabbed from the web.
 
Glad it worked for you though.

 

[3210]

Quote:

Quote:

the main concern is if the internal temp gets too high it will greatly reduce electrolytic's life expectancy. It is not an immediate failure.
 

105 *C caps inside for all of them, unless you replace with lower grade ones... I suppose the difference is whatever the manufacturer rates the caps for 50 vs 70 *C
Is cap life quoted a straight figure? (i.e. say 2000h without pause at 105 *C) or some sort of dodgy weighted average, where the real life at 105 *C is something like 200h, and progressively gets more as the temperature is lowered?
Or is it 2000h at 105 *C then a set of multipliers for lower temps?
Also, 10-20 hours/year at higher temp, would it make that much of a difference since the quoted expected lives are for conts use for the rated time (no storage, or lower temp cycles?)

The speed of chemical reactions doubles when the temperature is increased by 10 degrees celsius (Arrhenius Law),
so the lifetime doubles with every 10 degrees less working temperature (thereby, just for example, 
105°C caps will live four times longer than 85°C caps (at 85°C)).
 
 
 

 

[schorsch]

Some usefull information on old stax equpment
 
It's mostly German
 
http://new-hifi-classic.de/Gallery_MO/thumbnails.php?album=246
 
Regards Georg

 

[heycarnut]

"The speed of chemical reactions doubles when the temperature is increased by 10 degrees celsius (Arrhenius Law),
so the lifetime doubles with every 10 degrees less working temperature (thereby, just for example, 
105°C caps will live four times longer than 85°C caps (at 85°C))."
 
 
Nope. That is a *very* rough rule of thumb that has little applicability for capacitor lifespan. Use of the Arrhenius equation requires real data, usually experimentally derived, to give valid results, Otherwise, thumbtimes true, thumbtimes not.
 
You can find operating T / Rated T vs failure time datasheets at many manufacturer / distributor sites.
 
Here's some typical data from a manufacturer of hardware, comparing electrolytics to solids. Note it is more like 2-3X per 10C:
 

	Average Lifespan of Solid Caps. vs. Electrolytic Caps
	Temp°C Electrolytic Capacitors (Working Hours) Solid Capacitors (Working Hours) 95◦C 4,000 Hrs 6,324 Hrs 1.5X longer 85◦C 8,000 Hrs 20,000 Hrs 2.5X longer 75◦C 16,000 Hrs 63,245 Hrs 4X longer 65◦C 32,000 Hrs 200,000 Hrs 6.25X longer

 

 

[3210]

The data you posted shows that lifetime of electrolytics doubles with every 10°C.
 
I'm focussed on lifetime vs temperature here without regarding other parameters/effects/types etc.
 
Laws of nature don't require real data to be right, even reality is typically complex by use.
 
If you are an engineer, it will be probably best to look at datasheets.
 
 
 
 
Quote:

"The speed of chemical reactions doubles when the temperature is increased by 10 degrees celsius (Arrhenius Law),
so the lifetime doubles with every 10 degrees less working temperature (thereby, just for example, 
105°C caps will live four times longer than 85°C caps (at 85°C))."
 
 
Nope. That is a *very* rough rule of thumb that has little applicability for capacitor lifespan. Use of the Arrhenius equation requires real data, usually experimentally derived, to give valid results, Otherwise, thumbtimes true, thumbtimes not.
 
You can find operating T / Rated T vs failure time datasheets at many manufacturer / distributor sites.
 
Here's some typical data from a manufacturer of hardware, comparing electrolytics to solids. Note it is more like 2-3X per 10C:
 

	Average Lifespan of Solid Caps. vs. Electrolytic Caps
	Temp°C Electrolytic Capacitors (Working Hours) Solid Capacitors (Working Hours) 95◦C 4,000 Hrs 6,324 Hrs 1.5X longer 85◦C 8,000 Hrs 20,000 Hrs 2.5X longer 75◦C 16,000 Hrs 63,245 Hrs 4X longer 65◦C 32,000 Hrs 200,000 Hrs 6.25X longer

 

 

 

[soundoholic]

In relation to the post of K3cT from the last page I cannot agree with the conclusion "any proper Stax amp would be better than a combination of a transformer and a speaker amp." It´s simple false. Actually I received an energiser including the Lundahls LL-1630. This LRT-1630 of my design with many options, I can switch optionally from 580V to 630V BIAS. I must say, this box with Accuphase 406 amp provides unbeatable sound for my many lambdas and omegas. I forgot my 717 and a new 007t II. The stage, air, reality, bass, dynamics and more I receive now, let me easily forget other Stax amps. Not only with the reference SR-Omega (temporary in my stuff),  but also with the 007 Mk1 at this combo I hear now to the new unknown world.
 

 

 

[svyr]

In relation to the post of K3cT from the last page I cannot agree with the conclusion "any proper Stax amp would be better than a combination of a transformer and a speaker amp." It´s simple false. Actually I received an energiser including the Lundahls LL-1630. This LRT-1630 of my design with many options, I can switch optionally from 580V to 630V BIAS. I must say, this box with Accuphase 406 amp provides unbeatable sound for my many lambdas and omegas. I forgot my 717 and a new 007t II. The stage, air, reality, bass, dynamics and more I receive now, let me easily forget other Stax amps. Not only with the reference SR-Omega (temporary in my stuff),  but also with the 007 Mk1 at this combo I hear now to the new unknown world.
 

 

hehe, Peter's build? How much did that set you back, if you don't me asking? (4-600 EUR?). Basic idea from http://www.audiodesignguide.com/my/stax_transf.html (I think spritzer previously mentioned that one), but obviously with the adjustable bias and input switches?

 

[soundoholic]

Yupp, you´re right, svyr. It is Peter´s new box thanks Ciuffoli old project, but with another supply solution and options.

 

[svyr]

Yupp, you´re right, svyr. It is Peter´s new box thanks Ciuffoli old project, but with another supply solution and options.

m, some sort of linear PSU with a toroidal by the looks of it? (what sort ?) I presume the PSU is for the bias/leds, since the rest look passive(input->L+L- and R+R- via the Lundahls )?
Looks very nice. Haven't seen previous Peter's builds use leds to indicate selected input.

 

[soundoholic]

PSU is regulated, two BIAS voltages (the second one can be variable: "S-PRO"), Lundahls feeded directly, special cables, relais and, and.

 

[padam]

How much better do you think it is compared to the SRD7Mk2?

 

[TruBrew]

Do most of you guys cover your stax, or do you just leave them sitting out?

 

[soundoholic]

Padam, what a difficult question. And not so much. On second terminals sits SRD-7 Mk2, so I can quickly change. I hear a real difference, my friend does the same. It would be hmmm.. to describe as more clarity, lucidity - especially in low mids; more strong bass and more precise more fast; 007 Mk1 plays without veil, with full dynamics... And Lundahls need another 50 houers to be much more better. But just now, it is a fable.

 

[K3cT]

Quote:

In relation to the post of K3cT from the last page I cannot agree with the conclusion "any proper Stax amp would be better than a combination of a transformer and a speaker amp." It´s simple false. Actually I received an energiser including the Lundahls LL-1630. This LRT-1630 of my design with many options, I can switch optionally from 580V to 630V BIAS. I must say, this box with Accuphase 406 amp provides unbeatable sound for my many lambdas and omegas. I forgot my 717 and a new 007t II. The stage, air, reality, bass, dynamics and more I receive now, let me easily forget other Stax amps. Not only with the reference SR-Omega (temporary in my stuff),  but also with the 007 Mk1 at this combo I hear now to the new unknown world.
 

 

That's nice and all but the real question is can it beat the KGSS or BHSE?