The Headcase Stax thread

[spritzer]

The thermistors can go bad and do all sort of funny things to the amps. 

 

Try bending the arc to get a better fit on the SR-40.  Most of these were designed to be bent into shape. 

[ktm]

I don't see anything obvious. Thermistors appear ok, but that's pretty hard to really check. I'm going to have to unsolder them

There's two on each channel in parallel. The rest of it looks ok. There are some differences in how they are built.

The srd4 has larger, single thermistors on the input. it also  has  5 watt 27 ohm resistors in parallel with the transformers.

The srd6 has a spot on the board for them, but doesn't have them installed.

This is the big difference (other than bias tapped off one channel). I could see where this might change the

sound signature. Guess I just need to accept the fact they have a different sound.

[DefQon]

They would be the same except the SRD-6 box has a bias supply for full blown Stax electrostatic models. The SRD-4 don't have bias which suits exactly the SR-80's electret nature as it has a fixed/charged bias. 

 

I think the original SR-80 Pro's came with a pro-bias solution box. (Again the Pro was just purely for marketing because it came with a pro-bias capable adaptor and not the standard SRD-4 electret adaptor).

[ktm]

I really am going to have to build a decent energizer. I built an exstata hybrid,

which is ok, but with all the great designs out there it's about time to move up a couple of levels.

The sr-80 and srd-4 should hold me over for a while. I think I'll gut out parts from the exstata

and drop in some new boards.

[spritzer]

The SR-80 Pro shipped with a bog standard SRD-4 except it had gold printing on it.  Well that and the SRM-Xs too which was just a Xh minus the bias supply. 

 

There is no difference between the boxes whether they have bias or not.  The SRD-6 not having protection resistors almost guarantees that it has suffered some damage.  The SRD-6's also didn't have a power switch which has caused some problems though mostly on the headphone side. 

[ktm]

Ok, I've played with vintage stuff for years, so I should of done this 1st.

Clean 30+ years of crud out of the switch, clean out the socket connections,

I also cut back the wires to fresh copper and crimped on copper pins.

Bass is there now. But the srd-4 still has the warmer sound. I didn't have 27 ohm

wirewounds, so I doubled-up 68 ohm 3 watt for 34 ohms. Now both boxes pretty

much sound the same. That was the only real difference, and with them in place

on the srd-6 it changed the sound. The 4 is still just a bit warmer, but I prefer it this way.

If I change my mind, I'll go find the proper 27 Ohm ones. In a pinch I could use the 6 with

the 202's as well.

[DefQon]

Such a rare sight to see something like this:

 

But overpriced

 

 

http://buyee.jp/item/yahoo/auction/r126553633

[spritzer]

You do know these are our boards so not that rare.  Silly expensive though. 

[mwl168]

The description says the boards are 4mm thick. Wonder how much the accounts for the high price?

[spritzer]

Not much.  Most of the Chinese boards are silly thick. 

[GeorgeP]

Such a rare sight to see something like this:

 

But overpriced

 

 

http://buyee.jp/item/yahoo/auction/r126553633

Those look like the boards Tran made with other people 's money.

[kevin gilmore]

for that price you could have 5 sets made, no problem.

 

Some of this is beginning to upset me, people making money

for stuff I give away. The Chinese ksa5 clones also piss me off,

they are hacked up garbage. They have no idea why the

original sounded so good.

[Tachikoma]

Heh, if you look on Taobao now, there's an ad for the Megatron as well. 

[nopants]

http://tw.taobao.com/item/43870740416.htm

 

Description taken straight from mjolnir audio's site. Those sinks aren't even the right size. Wasn't there a guy on this forum asking about the use of AMRG resistors?

 

Edit: same exact pictures from xianghao's bs, with those undersized sinks used in the megatron supply

Edited April 13, 2015 by nopants

[wink]

Gents.

 

How do you tell a Stax SRE-725 extension cable from a SRE-925S..?

 

The new ones are both black and don't have any differentiating marks like model number on them.

[padam]

White vs yellow lines on the cable just like on the headphones

[edstrelow]

" There are at least 4 very different versions of the SR-007Mk1 but they never changed the name.  The SR-Omega came in three versions and that was with Stax on their last legs. "

 

I am curious as to what these differences were?

 

"It has also been confirmed why Stax altered the headphones."

 

Confimed? How and/or by whom?

[DefQon]

You do know these are our boards so not that rare.  Silly expensive though. 

 

Ah didn't know only have seen the green ones from Tran's GB. I thought the pcb's were original Stax SRM-T2 ones. 

[spritzer]

A Stax T2 has about 8-10 different PCB's and is built in no way like ours. 

 

Also black PCB's are just stupid.  We do green for a reason. 

[chiguy]

Just curious, what benefits would one PCB color have over another? 

[spritzer]

It's better to be able to see arcing and other burns should they occur.  Also the traces are all but invisible on a black board which is far from ideal. 

[kugino]

I picked up a used 717 that is a Japanese 100v model that the seller said was adjusted to 117v. is there any way to verify this? if I were to use it plugged into my US outlet, will I damage the amp or earspeakers if it has not been converted properly?

[rx79ez08]

I picked up a used 717 that is a Japanese 110v model that the seller said was adjusted to 117v. is there any way to verify this? if I were to use it plugged into my US outlet, will I damage the amp or earspeakers if it has not been converted properly?

Open up the amp and see if the jumpers are set correctly. A guide to the jumper can be found here:

http://www.head-fi.org/t/223263/the-stax-thread-new/23625#post_9627206

[spritzer]

Post a picture of the transformer board and we can tell you. 

[kugino]

thanks...so it looks like the jumpers are on 2, 4, 6, which corresponds to 120V, correct?