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post #24211 of 24765

Note that it's only rated for 35W, so that rules out many Stax amps.

post #24212 of 24765
Quote:
Originally Posted by miceblue View Post

Yup. Okay the step-down transformer works after all. Iono what's up with the Kill-a-Watt thing; it might be the third grounding plug that the transformer doesn't have.

 

Phew.

 

So I can finally say the Kashimura TI-101 step-down transformer works with North American voltages. :)

There are some instances on amazon reviews of that kill-a-watt thing going bad and reading weird...blink.gif

post #24213 of 24765

Umm... the fact that my imbalanced channel is buzzing... isn't a good thing right?

post #24214 of 24765
Quote:
Originally Posted by n3rdling View Post

Note that it's only rated for 35W, so that rules out many Stax amps.

Hm, you're right about that. I didn't know other STAX amps draw so much power.


 

A couple of questions:

    1. Does anyone have measurements for the SRS-2170?

 

Yes the treble is better-extended than my K 701, but I think I hear a peak at around 9-10 kHz, similar to the HE-500 but in a less annoying way. Or maybe the peak is at a higher frequency since it does kind of remind me of the non-offensive, yet fatiguing treble of the SRH940, which has a bunch of higher-frequency peaks. Sure, this kind of treble makes rock music much more engaging compared to the rather dull-sounding treble of the K 701 (the SRH940 was the headphone king for a fun rock experience), but it does get fatiguing after some time.

 

 

    2. What's the gain on the SRM-252S? I have the digital volume on maximum, the potentiometer at 9:00, and this thing is insanely loud for me. The potentiometer and it's dead-zone + channel imbalance zone is worse than that of the Objective 2.


Edited by miceblue - 8/1/13 at 10:54pm
post #24215 of 24765
Quote:
Originally Posted by miceblue View Post


    2. What's the gain on the SRM-252S? I have the digital volume on maximum, the potentiometer at 9:00, and this thing is insanely loud for me.

 

About the same for me.

 

The Stax USA website, says Gain: 58dB (x800)

https://www.staxusa.com/stax-srm-252s.html

post #24216 of 24765

There are no 3rd party measurements of the 207s that I know of.  I have a measuring rig now, so really I could measure a crapload of Stax headphones...

post #24217 of 24765
Quote:
Originally Posted by n3rdling View Post

There are no 3rd party measurements of the 207s that I know of.  I have a measuring rig now, so really I could measure a crapload of Stax headphones...

 

So a group of Stax headphones is known as a 'crapload'? Is it because of the Stax fart?

post #24218 of 24765
Quote:
Originally Posted by n3rdling View Post

There are no 3rd party measurements of the 207s that I know of.  I have a measuring rig now, so really I could measure a crapload of Stax headphones...

Looking forward to your measurements, but getting the data stable is a pita

post #24219 of 24765
So, I have modified my SRM-727A after KG's advice. I had formerly modded the amp with the "spritzer" mod (by changing local feedback to global), but Kevin helped me making the modification much more radical.
Basically, we fixed his 727 schematic together (I provided pictures eheheh) in order to have a complete idea of how to overhaul the output stage and make it better.
He gave me instructions to replace 10 transistors on the board a few resistors with eight pieces of 2sc4686a (or 2sc4686) transistors (the same as the KGSSHV) and some shorts. I will post the instructions here after Kevin's permission.

The result is a 727A that not only has its feedback 'restored', but also the same identical output stage of the KGSSHV. My 727A (which I rebaptised "KGSS-A") is basically a KGSS with current source modification (which was the "better" part of the feedback modded 727 over the 717), and better (faster, more modern) transistors than the older KGSS.
Or, the other way around, this modified 727 is a KGSSHV minus the higher voltage, since there was no room for a better PSU.

The sound has improved in transparency and overall extension. The bass has more control and the treble is smoother. I am using a SR-007 Mk1 and a SR-Lambda (the latter, after modifying another output after KG's advice).

Also, really interesting, the newer transistors get much less hot. My 727A is barely hot now, even after much time of usage, while the 717 I used to have, the older version 727 and even the SRM-Mk2 Pro I used to have here ago used to run noticeably hotter. I guess it depends on the newer transistors being capable of handling much higher voltage than what I am squeezing from the 727A psu, hence having very good efficiency.

I can take some dirty pictures, and will be waiting for Kevin's blessing to post the mods.
post #24220 of 24765
That sounds very interesting. Looking forward for pictures and details. Arturo
post #24221 of 24765
Quote:
Originally Posted by SoupRKnowva View Post

 

I left it playing for quite a few hours, and I think it got a teeny bit better.

 

I'm also trying to figure out a buzzing issue I am having in the left channel of my KGSSHV, this is the first time I have ever plugged headphones into it, you guys don't think the buzzing and the imbalance in the left channel could be related do you?

 

When I had some noise when I turned the pot to the minimum (grounding wire of the pot was loose) it was always both channels. So I doubt it's the amp... but I can think of a way to test out your assumption.

 

Swap your left right inputs. See if the buzzing still stays on the left. If it does it's your headphone and nothing to do with the amp.

 

Edit: Just thought about it, it may be better to rewire the outputs (L+- with R+-) to ensure it's definitely not the amp. Just swapping inputs, the right channel source will still go to your left on your headphone. 


Edited by RiStaR - 8/2/13 at 6:33am
post #24222 of 24765
Quote:
Originally Posted by miceblue View Post

Yup. Okay the step-down transformer works after all. Iono what's up with the Kill-a-Watt thing; it might be the third grounding plug that the transformer doesn't have.

 

Phew.

 

So I can finally say the Kashimura TI-101 step-down transformer works with North American voltages. :)

 

Very wierd, I did think that it was rather odd that your line voltage (the voltage on the wall receptacle) was 126-127 Vac.

Usually it's closer to 115-120 Vac.

Even if you were getting 126-127 olts from the receptacle, you would (or should) read approx. 105 Vac out of the step down transfromer.

It should not matter that the step down transfromer doesn't have a ground pin, the Kill-A-Watt should be reading voltage from line to neutral:  the other two pins.

 

What do you measure with the DMM? Line voltage, transformer output voltage, wall wart DC voltage?

 

Quote:

Originally Posted by miceblue View Post

Hm, you're right about that. I didn't know other STAX amps draw so much power.


 

A couple of questions:

    1. Does anyone have measurements for the SRS-2170?

 

Yes the treble is better-extended than my K 701, but I think I hear a peak at around 9-10 kHz, similar to the HE-500 but in a less annoying way. Or maybe the peak is at a higher frequency since it does kind of remind me of the non-offensive, yet fatiguing treble of the SRH940, which has a bunch of higher-frequency peaks. Sure, this kind of treble makes rock music much more engaging compared to the rather dull-sounding treble of the K 701 (the SRH940 was the headphone king for a fun rock experience), but it does get fatiguing after some time.

 

 

    2. What's the gain on the SRM-252S? I have the digital volume on maximum, the potentiometer at 9:00, and this thing is insanely loud for me. The potentiometer and it's dead-zone + channel imbalance zone is worse than that of the Objective 2.

 

More weirdness.

I've used my SRS-2170 with a CD player and two different DACs, and typically I have the volume at 11 o'clock on the SRM-252S and I don't think I listen very loud.

I do think the Stax is less fatiguing and less mechanical sounding than my Q701.

The Stax also sounds flatter in the mids and treble than my DT880.

post #24223 of 24765
Quote:
Originally Posted by Chris J View Post

 

More weirdness.

I've used my SRS-2170 with a CD player and two different DACs, and typically I have the volume at 11 o'clock on the SRM-252S and I don't think I listen very loud.

I do think the Stax is less fatiguing and less mechanical sounding than my Q701.

The Stax also sounds flatter in the mids and treble than my DT880.

 

With my Stello DA100 DAC I usually only had the 252S volume on 10 o'clock and really never get past that except on some classical tracks where I cranked it up to 11 (and with digital volume on max of course)... I'd think anything past that would be ear splitting.  I do think that the default gain may be a little too high, but I personally didn't have any problems regarding channel imbalance due to being so low down on the pot (since it wasn't around the 9 o'clock area but more like 10 where it usually becomes free of that problem).

 

I did not hear any 9-10khz treble peaks (isn't that more of the usual Beyer headphone peaks? definitely didn't hear it) on the 207 but I did notice a midrange peak somewhere lower down causing some vocals to sound "shouty" at times. No sibilance at all though. I would actually prefer a bit more treble because the very top sounded somewhat rolled off.

 

I'm thinking these differences among users may be more down to the source used perhaps.  I probably need more listening on my friend's rig though as it was only for 4-5 hours total.


Edited by K_19 - 8/2/13 at 5:25am
post #24224 of 24765
Quote:
Originally Posted by K_19 View Post

 

With my Stello DA100 DAC I usually only had the 252S volume on 10 o'clock and really never get past that except on some classical tracks where I cranked it up to 11 (and with digital volume on max of course)... I'd think anything past that would be ear splitting.  I do think that the default gain may be a little too high, but I personally didn't have any problems regarding channel imbalance due to being so low down on the pot (since it wasn't around the 9 o'clock area but more like 10 where it usually becomes free of that problem).

 

I did not hear any 9-10khz treble peaks (isn't that more of the usual Beyer headphone peaks? definitely didn't hear it) on the 207 but I did notice a midrange peak somewhere lower down causing some vocals to sound "shouty" at times. No sibilance at all though. I would actually prefer a bit more treble because the very top sounded somewhat rolled off.

 

I'm thinking these differences among users may be more down to the source used perhaps.  I probably need more listening on my friend's rig though as it was only for 4-5 hours total.

Maybe it's the source thing.

Who knows?

Keep in mind that I often use el cheapo DACs with the SRS-2170.

I have an iBasso D12, $285 and a FiiO E17, $150.

The D12 is pretty smooth and clear, the FiiO sounds a bit rough next to it, a bit of treble grunge.

 

I keep thinking I should get something better..........DAC wise. Like maybe a fully loaded Schiit Bifrost or an Audiolab. 

post #24225 of 24765

Has anyone ever had a Stax headphone custom-painted by a third party?

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