The Stax Thread III

[TheAbyss2022]

I almost forgot this important point regarding amplification: Max voltage defines the maximum movement, so to speak, while current is needed to move the driver. In other words, we need both, which is why amplifiers usually are spec'ed in Watts. And as Ohms law makes it clear, the lower the resistance, the higher the current draw.

For reference, I just saw that Mjolnir KGSSHV Carbon is said to be spec'ed to 1550V swing (peak to peak) while being able to deliver 22mA.

Birgir confirmed the Carbon delivers 23mA.

I will ask the builder of the Polaris what the mA is on that amplifier.

 

[Svperstar]

I redid the wiring on my audio setup. Now I have a UPS + Power Filter running everything.

Anyway I touched my Carbon and it was really warm, not as hot as the Asgard 2 but still warm. Forgot to plug these fans back in:
SCCCF Dual 80mm USB Speed Control Fan, 5V Portable Cooling Fan for Flat-Screen TV Receiver Router DVR Playstation Xbox Computer Cabinet Cooler https://a.co/d/cSHsA6W

On the lowest setting I have one fan on the left and one on the right and the Carbon is room temperature to the touch. Zero noise.

 

[elitico]

Hello,

I have ordered a pair of L700MK2. I will use a Mjölnir Audio SRD-7 to begin with (standard version).

I will later need a dedicated amplifier to save space on my desk.

Just wondering about Stax's current models that can be bought easily new in my country.

I've briefly listened to the Stax SRD-400S and the Stax SRD-500T and I've read a lot but haven't gotten any wiser as to which one is the better buy with the L700mk2. According to my memory, I thought 500T did something magical with voices in particular. I think I missed that while listening to the 400S on a later occasion. But I've also read that the Stax SRD-400S is the better amplifier in almost every regard (many people seem to prefer Stax S amplifiers to tubes?).

Then there is the SRD-700T/S, which is a clear step up in terms of price at least. I briefly compared the 700T and 500T and heard that everything was possibly a little better with the 700T, but maybe not a huge differences (just listened to two songs)? Does it perhaps have to do with the fact that I read that lambada and L700 mk2 are not so hard to drive and therefore sound good with Stax's entry-level stuff? Or is maybe the 700S the model to go for?

 

[Svperstar]

It's a lot cheaper than the Carbon as well. Do you reckon it's better than the Carbon CC?

I think I remember reading Mjolnir saying that the Polaris amps are "what Stax was doing 30 years ago". He isn't a fan. Those are his direct competitors tho so I wouldn't expect him to have much nice to say.

Was close to ordering one and if I didn't like it selling it then I found the BH/Carbon used for good prices so I passed.

 

[TheAbyss2022]

I think I remember reading Mjolnir saying that the Polaris amps are "what Stax was doing 30 years ago". He isn't a fan. Those are his direct competitors tho so I wouldn't expect him to have much nice to say.

Was close to ordering one and if I didn't like it selling it then I found the BH/Carbon used for good prices so I passed.

That's a competitor so I would expect there to be some bad mouthing on other products. At the end of the day its all about the users experience and impressions of the amplifiers so regarding the comments by @Thomsen132, it seems the Polaris is more transparent with more treble extension and a wider soundstage compared to the darker/warmer tuning of the Carbon. For me, I value treble, air and space in estats so the Polaris seems to be the choice for me. Additionally the bass is apparently is very similar between the two with the Polaris having a slightly tighter bass.

I'll give the Polaris a try and see how big of an improvement it is to my current amplifier. For the price, as I am outside the EU, It will be less than £1,900 so a very good price for the specs.

 

[Svperstar]

I'll give the Polaris a try and see how big of an improvement it is to my current amplifier. For the price, as I am outside the EU, It will be less than £1,900 so a very good price for the specs.

Good idea. If you don't like it ask about the return policy. I would test how a bass boost sounds. That was the big difference I noticed on the 007mk2 going from a "entry level" Stax amp to a Gilmore amp.

 

[TheAbyss2022]

Good idea. If you don't like it ask about the return policy. I would test how a bass boost sounds. That was the big difference I noticed on the 007mk2 going from a "entry level" Stax amp to a Gilmore amp.

It says there is a 14 day right of return with a 2 year guaranteed warranty so it shows the builder is confident in the amplifier.

I always bass boost with every headphone however, using the Phantom has essentially relegated any use of digital EQ with the xBass feature. I will just have to return back to digital EQ once I acquire the Polaris so no big deal.

 

[shabta]

It says there is a 14 day right of return with a 2 year guaranteed warranty so it shows the builder is confident in the amplifier.

Not exactly. It's required by EU law.

 

[KDS315]

My Mjolnir Carbon has 1550 V, Polaris is 1720 V (both stator to stator, not Vrms)
Specs of Carbon can differ as not every builder probably uses the same power supply. There might be other differences.
As i alreay mentionend, i like both amps. The Carbon is more on the slightly warm and smooth side, the Polaris V3 is more transparent and clear. It depends on my mood, which one i prefer.
Both amps have more power than i will ever need and great extended bass.

That test we have done then was with the X9000, correct Thomas?

It says there is a 14 day right of return with a 2 year guaranteed warranty so it shows the builder is confident in the amplifier.

I always bass boost with every headphone however, using the Phantom has essentially relegated any use of digital EQ with the xBass feature. I will just have to return back to digital EQ once I acquire the Polaris so no big deal.

I would recommend to ask Andreas Rauenbühler about that, since you seem to be located within the UK, which is no longer part of the EU, so EU regulations do not apply. And there is a shipping issue with export paperwork to be done as it is >EUR2.000 which will be some effort on his side, and possibly import tax issues on your side.

 

[shabta]

Perceptively the Mjolnir Carbon might seem a little warmer in comparison to Polaris due to its treble roll off, and that could also enhance bass.
But objectively both do bass very good.

This is a surprising statement, since the general feedback about the Carbon is that the treble is endlessly extended. That is also my experience. I haven't heard the polaris, but I can't imagine using the term treble roll off in relation to the Carbon.

 

[Thomsen132]

That test we have done then was with the X9000, correct Thomas?

Yes

This is a surprising statement, since the general feedback about the Carbon is that the treble is endlessly extended. That is also my experience. I haven't heard the polaris, but I can't imagine using the term treble roll off in relation to the Carbon.

For Mjolnir Carbon it is safe to say, that is rolled off a little vs Polaris a bit. I have both and compared them extensively. Also measured that.

 

[Svperstar]

Yes

For Mjolnir Carbon it is safe to say, that is rolled off a little vs Polaris a bit. I have both and compared them extensively. Also measured that.

Do you have the measurements handy? So few measurements of estats around compared to dynamic/planar

 

[LarsHP]

Frequency response of the Mjolnir KGSSHV Carbon is about 0.08 dB down at 20kHz. I highly doubt that is audible.

Measured by Bob Katz. Published originally by Inner Fidelity, now available at Stereophile.com.

EDIT: Note that he says the noise at about 70kHz is caused by something in his setup.

 

[LarsHP]

Note the comment Bob Katz has to his measurements of the KGSSHV Carbon:

"Measuring a Stax amplifier (row 8) is a bit of a challenge. I had to build a special jig which terminates the amplifier in a balanced 170 kOhm resistive load, the stated impedance of an SR-007. But this is not authentic since the headphones present a capacitive load which is specified by Stax as 170 kOhm at 10 kHz. Perhaps someday I can construct a load that emulates the complex impedance of the Stax. This jig attenuates the high voltage output of the amp to normal voltages and presents a low output resistance to the measurement gear so we can measure it without cable-induced high frequency losses. I wonder if this is the first time that an independent reviewer has published performance measurements of a Stax amplifier."

 

[KDS315]

Wonder why he did not use an approx. 120-140pF condensator for that (??) and then divide it down to measure...hmmm