The Stax Thread III
May 23, 2018 at 11:17 AM Post #15,256 of 21,404

JimL11

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I've just ordered a 727, and I hope it'll arrive by the end of the week. Concerning the gain mod (i.e. replacing R5 and R6 with 200ohm parts):

Are there any sonic benefits, or is this just for consistency in case one owns multiple Stax amps? If I perform this mod, I'd like to use the same size of MELF resistor for the replacement. Does anyone know what size, power rating etc. would be the right choice?

I believe that spritzer, who first did the feedback mod, later dropped the gain mod and only recommended doing the global negative feedback mod, although I can't seem to find that post. In any case, it is easy to just turn up the volume a bit. You should use 350V rated resistors for the global feedback mod, BTW. You should also check the output voltages after the modification, when the amp has warmed up for 30min or an hour with the cover on, you may need to adjust the balance and offset pots if the output voltages are more than 10-15 volts with respect to ground (balance adjusts the voltage between the positive and negative outputs of the same channel, offset adjusts the voltages of both outputs up or down with respect to ground). Note that the voltage may shift a bit when you remove the cover to do the adjustment so there's no point in being obsessive about it.
 
May 23, 2018 at 5:45 PM Post #15,257 of 21,404

gilency

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damn it! i just noticed a simple fact. i cound notice this simple fact as a hard fact until today.....

computer audio = sound not so good....

many posters/contoributers suggested this simple real fact many times before.
I just codnt realize it. damn it. really sad. lol
Stax is not bad. computer is not so good.

Thank you very much for your advices/posts! thanks again!

chao(Anakchan and JimL may understand this Oyaji joke lol)

That premise is plain wrong.
It depends on what you are using.
 
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May 23, 2018 at 8:36 PM Post #15,258 of 21,404

Pokemonn

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yeah i know it depends on gear.
its just "in my experiences". so its not right or wrong thing.
my iMac 5k retina(120W power consumption which emit huge digital/RF noises) really doesnt cut my job imo.
cheap traditional CDPs just cut it FOR ME.
even Suzuki-san(chief engineer of Stax) hinted me that directly out of CDP sound best in his e-mail..
 
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May 23, 2018 at 11:08 PM Post #15,259 of 21,404

SeaWo|f

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As a broad statement I think it's fair. General purpose off the shelf computers are not optimised for isolation on the usb and have relatively poor clocking. The prevalence of boxes to address this I think is the best evidence.

When going from a PC to dac my preference is optical. But the only time I do that is gaming and music videos on YouTube so not exactly great quantity..
 
May 24, 2018 at 12:47 AM Post #15,260 of 21,404

Pokemonn

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I agree.
any high-end source system are still CDPs. Chord Blue mk2 Accuphase dCs vivaldi etc.
Monster company Sony just restart manufacuturing vinyl LPs.
also monster Toshiba released High rez cassette tape deck plan.
Denon just removed USB/digital inputs from their latest CDP lineups.
Schiit audio going to start to sell turntables!
Stax is planning to sell build in phono EQer(not DAC) for their latest amp. SRM-T8000.

Things are throwback! they know people hates digital noises. muhahahaha :D
 
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May 28, 2018 at 12:24 AM Post #15,261 of 21,404

Rhamnetin

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As a broad statement I think it's fair. General purpose off the shelf computers are not optimised for isolation on the usb and have relatively poor clocking. The prevalence of boxes to address this I think is the best evidence.

When going from a PC to dac my preference is optical. But the only time I do that is gaming and music videos on YouTube so not exactly great quantity..

Yeah it's not even just general off the shelf computers, even these higher end motherboards with "gaming audio" have the issue. I need a digital interface between my PC and the DAC when using USB, otherwise the sound is highly distorted and noisy. Maybe just a ground loop isolator would do, but all I know is that any digital interface (had a Gustard U12, now a Breeze DU-U8) fixes the issue.
 
May 28, 2018 at 1:40 AM Post #15,262 of 21,404

SeaWo|f

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Yes the high-end onboard sound for gaming mobos is more about the software suite from either realtech, creative labs or asus, and a more powerful opamp. In recent years they have started trying to isolate the audio part of the board but using usb would obviously negate this, most of these boards to have an optical out for hookup to a surround sound receiver. I have an msi board that has this setup. Never have bothered to compare sound quality with my dedicated server, or the tos vs usb vs coax on the board. I just figure the tos keeps my dac isolated from electrical noise on my pc.
 
May 28, 2018 at 6:58 AM Post #15,263 of 21,404

Whitigir

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Computer does not suck....if you know what you are doing and build one for the purpose...like mine. It is the best for digital transportation in sound quality. There are build that cost $16,000 Sound Gallery for example
More to come
45EB607A-C911-4535-86ED-D7345886DEA9.jpeg
3DB7A0DE-9E70-4F1B-BAA8-A5D1EBF13E7B.jpeg
7C249552-59D9-479B-B833-1FA300D2D043.jpeg

Take a look at Sound Gallery streamer here
https://www.audiostream.com/content/sound-galleries-sgm-2015-music-server
 
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May 28, 2018 at 10:21 AM Post #15,265 of 21,404

SeaWo|f

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Computer does not suck....if you know what you are doing and build one for the purpose...like mine. It is the best for digital transportation in sound quality. There are build that cost $16,000 Sound Gallery for example
More to come

I like the case.

My point was that what you built is exactly what one has to do to optimize for clean audio. You cant just go out and buy something off amazon or even build your own in a normal way. It has to be a well though out process with steps that are unique to audio pcs.

My music server is exactly that too, I just didnt DIY it.
 
May 28, 2018 at 10:35 AM Post #15,266 of 21,404

statfi

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Could someone tell me the material that is used to make rings that holds the ear pads in place in the SR-009? These are flat rings with an outer diameter of ~4" that are right under the dust screens that slip into the ear pads. Are they aluminum, steel, ...?
 
May 28, 2018 at 11:34 AM Post #15,268 of 21,404

JimL11

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I have an SRM-007tA on the way, could anyone please provide me (or point me towards) a schematic of the 007tA (or 007t ii)? I've searched but haven't found anything useful thus far.

AFAIK, the input and intermediate sections of the SRM-007 are the same as the SRM-T1. You can find schematics of the latter on the internet w/o too much problem. Some of the transistors have been changed due to the originally specified ones becoming obsolete, etc. Also, the power supply has been upgraded in that the zener regulation of the low voltage front end has been changed to 7815/7915 IC regulators. The output stage is the main difference between the T1 and 007.

Here is a schematic of the output stage, along with the upgraded power supply. Because the output stage uses two dual triode 6FQ7 tubes, there are two additional pots (TVR3 and TVR4) to balance the tube sections, as well as the previous balance (TVR1) and offset (TVR2) pots. TVR1 is not shown as it is (probably) located in the intermediate stage. In addition, the bias supply of the 007 has a 4.7 megohm safety resistor after last capacitor. Note this shows the earlier version that had Normal as well as Pro bias output sockets. HTH.

Stax SRM-007 output 1998.gif
 
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May 31, 2018 at 9:20 PM Post #15,269 of 21,404

Ronsanut

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Does anyone use tube preamp/buffer amp/DACs for your Stax rig? what is your favorite tube units?
I found tube pre amp makes sound much smoother.

Marantz SA11S3 -> Schiit Lyr2(as pre amp) -> Stax SRM-717 -> SR-009/007 = eargasm heaven!

I also understand today why...

* astrostar uses Audio Note UK tube DAC.
* Senheiser HE1(aka orpheus 2) uses so many tubes.
* hifiman shangri-la use 300B tube amp.
* TOTL electrostatic amps are all tubes (DIYT2 BHSE etc)
* most expensive Stax amp is also tube amp(SRM-007tII)
* Jude loves frank cooter tube amp for stax.
* Tyll love/recommend BHSE.

Thank you very much

I use a Schiit Gungnir Multibit DAC -> Schiit Mjolnir 2 (with Tubes) -> Stax 353X -> SR L700 = Unbelivably awesome!
 

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