The Stax thread (New) - Page 390

I found these photos on my HDD: hope they help (as they say round these parts: a picture is worth a thousand words... )







(My first go at posting snaps in a posting! It's so easy when you know how! Thanks for the info on how to do it: TBH I don't know why I'd not worked it out for myself!)

This is exactly what I needed. Thank you very much. Stax did change the wiring and I can change it back now. I'll study the pictures and post my findings when I'm done.

Nice transformation, for sure!
Another Stax 'phone I have not heard, but are really tempted to give a go.

Ok it looks like I've cracked it and my SRM-1 Mk2's are playing off 230v.

First off the disclaimer. This is live AC voltage you are working with so do this at your own risk. If you do not know what you are doing have somebody that does take a look at it. While I've tested the 240v and 117v versions and it works fine this is posted without any responsibility on my part for any damage due to Stax changing the design at some point. This works with my two C-series SRM-1 Mk2's and my B-series SRM-T1. This is only intended for those amps that didn't ship with a voltage selector plug. If it did come with one... then use that then!


The picture above is how the rear of the socket should look like but Stax often changed them around to have the component only for one voltage. If it reads 100v (or 117v, 230v etc.) only on the back and there is no plug in the voltage selector socket odds are that the socket is wired differently. It needs to be changed to the above configuration or the amp can catch fire or worse.

Since there are two white wires I marked them on the picture, AC power in and from transformer. The AC power comes from the power switch and is in the upper row. It is connected to 3 pins while the other white wire is in the bottom row and only connected to one pin. That one is connected to the primary of the transformer. The only other pin that has more then one connection is the gray one. You can connect to any of the joined pins as they are all the same.

Here is the list. You need to put a jumper wire between different colors where the + sign is. There are always two different connection per voltage with either two or three different colors.

240v configuration

Gray + Purple
AC power in + Blue

220v configuration

AC power in + Blue
Green + Gray

117v configuration

Blue + Purple + AC power in
White + Gray

100v configuration

AC power in + brown + green
Gray + White

Generally absolute phase is not going to be detectable. I have a Denon DCD3000 cd player with a phase switch and I generally can't tell any difference between either setting. On a rare occasion you might think you hear some difference in a transient, such as cymbal crash. Here I think the transient could be effected by phase because an initial compression of the sound wave would be replaced by a rarefaction and this could sound different.

Of course you have no guarantee that the recording process preserves phase or that all the microphones or tracks in any particular recording had the same phase.

It's one of those stimulus characteristics that could be significant in a few situations but in practice is probably not.

Have to sneak in a question.
I had a Signature II system, but sold it ! Now I am thinking about Stax again, but, the prices are horrific here so I thought about buying somehwere else, AudioCubes, NeedleDoctor, whatever really.
But, my question, the SRS-4040 II system comes with the 006tII (or seem to have the 006tA some places) and I was wondering, my 006t had a voltage switch on its rear panel, but on the Stax netsite I dont see this switch on the 006t II. Anyone knows anything ?
On the AudioCubes site it says it comes with an adaptor, but I would rather not have that.
We have 230 volts here.

niels. Stax amplifiers sold in Japan (though PriceJapan, EIFL, Audio Cubes II, ...) are set to 100 volt, with no easy way to alter this. Hence the need of a voltage converter to use with out 230 volt mains.

Stax amplifiers used to have a switch/jumper on the back, to select your local voltage. But Stax removed it some years back, in an attempt to protect their international dealers from the Japanese grey market.

A few of my sources have had phase switches but it doesn't make much of a difference to me. My only concern is that the drivers are firing away from the ear but it doesn't seem to matter.

You can alter the voltage but Stax has made it a whole lot harder to do. With more and more gray imports they dropped the plug you mentioned and I'm talking about in the post above in favor of a fuse board with metal bars instead of the fuses. There was no color coding on the wires to make it even harder to figuer out the correct setup. Now they've abandoned the fuses in favor of a PCB where the wires are soldered. They will even cut the extra wires away at the transformer so the transformer has to be opened up to replace the wires.

Koss ESP 950 driven by Stax Amps

I just tried the trick of "borrowing" the bias from the Koss E-9 while driving my 950's from a Stax SRM3. It didn't actually help. In fact signal levels actually dropped and distortion on loud passages increased.

Evidently the overload distortion I hear with the 950 SRM3 is not the result of the bias being a bit lower with the Stax amp.

I generally don't hear distortion with rock/pop music but it is more evident in loud classical passages. I wonder if the classical music sucks more bias, possibly because the loud passages are generally more sustained whereas the rock passages have fairly short bursts of loudness such as drum beats?

Maybe it's not a bias issue at all, but some sort of impedance mismatch?

One question, did you have a source connected to the E/90? When I tried it with my Blue Hawaii I lost all bias as there wasn't any input connected to the Koss amp so there must be a sensing circuit that drops the bias when no signal is flowing. I haven't opened it up yet but that would be my guess.

Okay, I am going to check out dealers in germany then, maybe, just maybe....
I can always buy the phones themselves in Japan, and the amp in Europe.

Stax SR-404s pop up from time to time on German eBay (without the SRM-006T amp) and you can then use them with the older (and according to many around these parts, better) SRM-1/Mk2 amp, which turns up quite regularly in Germany, Netherlands and the UK eBays.

My main Stax rig is the 404s driven by the SRM-1/Mk2, and this combo is a step up from the 3030 II system (303s and 313 amp); I can firmly recommend this combination, especially for the price (mine cost about €420, you might have to pay a bit more now, but it would still be a lot less pricey and risky than importing from Japan). (Risky in terms of potential extra duty and import charges, but I don't know how hot the Norewegian customs are on this kind of thing!)

Hello,

Aren't the Stax earspeakers dangerous ?
With the electrostatic technology, hundreds volts pass through the phones... Isn't dangerous ?

Ah, yes, extremely dangerous - just look at the damage evident by who posts in this thread...

Only if you listen while taking a shower

I've been listening to electrostatic headphones since the late 60's without a single shock. I don't think that Stax would be in business if it posed a heath risk. Just enjoy them!