[PointyFox]

Which STAX amps are mid-tier to you? The Koss energizer is without a doubt lacking.

Let's use what most would consider an upper mid-tier Stax energizer, the SRM-353X.

Stax SRM-353X bias voltage: 580V
Koss E/90 bias voltage: 600V

Stax SRM-353X max voltage output: 400 Vp-p
Koss E/90 max voltage output: 2300 Vp-p

Stax SRM-353X THD + noise at 100Vrms/1kHz: 0.01%
Koss E/90 THD + noise at 100Vrms/1kHz: 0.001%

I A/Bed the Koss E/90 with a SRM-717 and found the SRM-717 to be lacking in bass extension and dynamics compared to the E/90.

So explain to me why "The Koss energizer is without a doubt lacking."

 

[buke9]

Let's use what most would consider an upper mid-tier Stax energizer, the SRM-353X.

Stax SRM-353X bias voltage: 580V
Koss E/90 bias voltage: 600V

Stax SRM-353X max voltage output: 400 Vp-p
Koss E/90 max voltage output: 2300 Vp-p

Stax SRM-353X THD + noise at 100Vrms/1kHz: 0.01%
Koss E/90 THD + noise at 100Vrms/1kHz: 0.001%

I A/Bed the Koss E/90 with a SRM-717 and found the SRM-717 to be lacking in bass extension and dynamics compared to the E/90.

So explain to me why "The Koss energizer is without a doubt lacking."

Where does the SRM1 MK2 fall into this as I do think it sounds better than the stock E90 or am I missing something?

 

[Amish]

@PointyFox It's lacking for me in the power dept. SQ is fine at low to mid-volume but when really cranking up the volume it just falls apart. Loses steam, fails to perform to my standards. I bought several STAX amps and the SRM-T1 was without a doubt better sounding to me but still lacked the power I was craving. I owned the woo audio wee as well and that got plenty loud with the emotiva amp I was using but ultimately it was not until I purchased the Octave III that I really found out what both my Koss and Stax stats could do. The Koss energizer just doesn't perform as well, at all. It gets the job done for sure but its not for me.

 

[PointyFox]

@PointyFox It's lacking for me in the power dept. SQ is fine at low to mid-volume but when really cranking up the volume it just falls apart. Loses steam, fails to perform to my standards. I bought several STAX amps and the SRM-T1 was without a doubt better sounding to me but still lacked the power I was craving. I owned the woo audio wee as well and that got plenty loud with the emotiva amp I was using but ultimately it was not until I purchased the Octave III that I really found out what both my Koss and Stax stats could do. The Koss energizer just doesn't perform as well, at all. It gets the job done for sure but its not for me.

Could be that I listen at a lower volume. Do you know how the Octave 3 compares to the Octave 2 SE?

 

[Amish]

Could be that I listen at a lower volume. Do you know how the Octave 3 compares to the Octave 2 SE?

I'm sure they are not too far off from each other but I have no experience using both. If you reach out to Birgir at Mjolnir Audio, I am sure he will explain the difference if any.

I'll quote what he said to me about the Octave design: "The Octave was designed to go head to head with the SRM-353X and the 727 (also the T8000 as that is so similar to the 727) and offer better performance."

One of these days I will upgrade to a better electrostatic amp but until then the Octave III works beautifully. SQ is fantastic and I can crank it up as loud as I can stand it and the sound remains clean.

 

[PointyFox]

I'm sure they are not too far off from each other but I have no experience using both. If you reach out to Birgir at Mjolnir Audio, I am sure he will explain the difference if any.

I'll quote what he said to me about the Octave design: "The Octave was designed to go head to head with the SRM-353X and the 727 (also the T8000 as that is so similar to the 727) and offer better performance."

One of these days I will upgrade to a better electrostatic amp but until then the Octave III works beautifully. SQ is fantastic and I can crank it up as loud as I can stand it and the sound remains clean.

I'll be getting the V2 SE in the mail in the next day or two.

Birgir told me this about the Octave V2 SE "The Octave V2 was designed to surpass the SRM-353X in every way so yeah… it is better. More neutral sounding (as the 353X is very bright and edgy) with more power and a far better power supply. I have yet to get the new SRM-400S but based on the internal pics I’ve found, the Octave V2 will run in circles around it."

 

[Amish]

@PointyFox That's sweet! I'm sure you will really enjoy the Octave when it arrives. I bought mine in August 2019 and it's been used every day since. I just love it. My Koss sounds great paired with this amp but My L700's sound amazing with it.

I have not seen an Octave III for sale in a very long time now. Back when I bought it, his site stated it was an improved design with the same power rating as the Octave II (or something like that) and I bet the Octave II SE might be improved since my III came out. Birgir would know.

Anyways, enjoy it when it arrives!

 

[PointyFox]

@PointyFox That's sweet! I'm sure you will really enjoy the Octave when it arrives. I bought mine in August 2019 and it's been used every day since. I just love it. My Koss sounds great paired with this amp but My L700's sound amazing with it.

I have not seen an Octave III for sale in a very long time now. Back when I bought it, his site stated it was an improved design with the same power rating as the Octave II (or something like that) and I bet the Octave II SE might be improved since my III came out. Birgir would know.

Anyways, enjoy it when it arrives!

Got a response already :

"The V3 was an offshoot of the original V2 amp, designed to be a power amp with no built in volume control. They weren’t all that popular so I dropped the idea and kept on with the V2. Then the V2 SE is a further development of that basic circuit with a bunch of improvements along the line. "

 

[Amish]

Got a response already :

"The V3 was an offshoot of the original V2 amp, designed to be a power amp with no built in volume control. They weren’t all that popular so I dropped the idea and kept on with the V2. Then the V2 SE is a further development of that basic circuit with a bunch of improvements along the line. "

Ahhh that's right! I remember now that one of the features was no volume control. How could I forget that? I didn't need one as I run everything through my w4s ST preamp.

 

[PointyFox]

Just got the Octave V2 SE. I started playing a song where it starts off with vocals then a drum comes in. The vocals normally sound a little recessed to me with the Stax amp and turning the volume up just makes them sound harsh. The vocals come in and they're not recessed at all and have more definition and texture to them. Normally I have to turn the volume UP when it gets to the drums so they have impact. I had to turn it DOWN when it got to the drums!

In the past I had a KGSSHV and I had ranked the L700MK2 above the Focal Clear. I eventually sold the KGSSHV and got a SRM-353X I thought the Clear was better. Now with the Octave V2 SE the L700MK2 is better again.

 

[Amish]

I own a lot of headphones but I can't deny the L700mk2 is the very best in my collection (with a proper amp).

 

[JimL11]

The Koss energizer sounds better than the mid-tier Stax energizers on the Koss headphones. I think it's due to the higher bias voltage.

Well, the Koss energizer has a bit higher bias voltage and power supply voltage, but it has pretty low current capability (according to Kevin Gilmore it only has 2 mA standing current per channel, while the portable Stax SRM-252 has about 4 mA/channel), not surprising as plastic doesn't make good heatsink material. My modified SRM-T1 sounds significantly better IMHO.

 

[jotaku]

Nice idea - Thanks!

Just wondering... Who gets the Stax SRM-323a ??

My wife will be the first person to say that I have a more discerning ear. Do if you asked her she would say I should get the 323a.

 

[jotaku]

The Koss energizer sounds better than the mid-tier Stax energizers on the Koss headphones. I think it's due to the higher bias voltage.

My 323a is a marked improvement over the Koss Energizer.

 

[Brahmsian]

Any definitive answer on what causes the squealing?

On the ear pad swap I wrote about earlier (Vesper sheepskin vs. stock 95X), after more than a year of going back amd forth I finally decided to stick with the stock pads. Although the Vesper sheepskins added some crispness and punch, they also added glare in the treble that I ended up disliking too much. I have really grown to love the rich, smooth, chocolatey sound of the stock pads. It’s like using a tube amp. Also, I felt that the tight seal produced by the sheepskin might damage the diaphragms. Breaking the seal often caused the diaphragms to pop.

Now if only I knew what caused the intermittent squealing!