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Posted

Stay far away from that AMRG crap imo.  They alone are the reason 25% of the SRM-600's have failed while I've never heard of the TKD units failing in any of the other T1/006t amps. 

 

Coming back to this topic. I own a SRM-600, so this sentence makes me slightly nervous. Should I exchange anything as a precaution, or do these parts fail without entraining other parts so that it would be safe to wait until they fail (if ever)?

Posted

If they short then they could do serious damage.  I think they just go up in resistance or just stop working.  If so then the damage should be minimal. 

Posted

So the question remains which is the usual failure mode. :confused:
Maybe I should at least open the amp and check the necessary values soon, just to be prepared. ::)

Posted

The failure mode is that the resistors open up, the outputs go to -350V, the resulting bias

gets close to 900, and makes the headphones very unhappy.

 

This is reason enough to do some maintanance better sooner than later. :unsure:

 

They are 30K/2W.   Eight units in total. 

 

This value should be easy to get, not sure if I find the recommended TKDs. But if not it would be still better to use some proven industry grade stuff (Vishay, Panasonic, ...) than risk to keep the unreliable parts I assume.

Posted

I'm not even sure the TKD's are made in this value.  That could explain why Stax changed as the 6CG7's need 66k for the plate load so two 33K units per plate. 

 

Interestingly Stax emphasized these resistors in their advertising: "a straight uncolored dynamic sound has been realized by using non-magnetic audio-grade carbon film resistors for load resistance". Probably a good example how marketing works, every trifle can and will be bloated. ;)

 

 

Exactly these I had also in mind. Unfortunately my last Mouser order just arrived this week (with KGST parts - to return to the original topic :) ), so it will take some time for the next one, but obviously there is no hurry - after all the years the amp won't blow up next week.

Posted

@headincoulds. I have not done an extensive comparison, since I have changed the output transistors of my kgsshv to 4686 (which was a very big improvement over the ixys mosfets). My current impression is still that the KGST fits the 009 a bit better for my taste. 

 

@earspeakers. The KGST is a slimline case from modushop with 10mm front, the KGSSHV is a pesante case from modushop with a 10mm front. Both frontpanels were sent to schaeffer in germany (FPE in the US) for machining. After working with both types of cases, I think the slimline is superior in every way. 

Posted (edited)

Here are some more pics of the internals

I have some additional venting holes drilled under the tubes, but I guess with a 3U case, this would not have been necessary. Furthermore I didn't have the US screws for the small heatsinks. I had to use m3 with a washer all the way on the rear of the sinks (looks crappy, but... whatever). The voltage reg near the washer has some shrinking tube over it, just to be safe. 

Pot is an alpha from Birgir with the corresponding pcb. The brown pcb on the left is for star ground and mains. 

Because I wanted that pcb mounted inside as is, I had to use the side panels of the case the "wrong" way around. This is why there are some additional holes on the mounting brackets of the front panel. 

post-4130-0-79234200-1423763874_thumb.jp

post-4130-0-58595000-1423763899_thumb.jp

post-4130-0-67369400-1423763904_thumb.jp

post-4130-0-97022200-1423763910_thumb.jp

Edited by insanity
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