eXStata DIY Electrostatic Amp for Intermediate DIYers

[manaox2]

Quote:

Originally Posted by minivan /img/forum/go_quote.gif a local is generous enough to give me a commerical version of kgss from headamp for a week to compare with the exstata.

Thank you so much for the review. Man, I need to get on this.

 

[Scooba]

Greetings everyone, I have spent my last 4 days reading this thread . Thanks everyone for their input (and especially the design team) .
I am very interested in building the SS version and maybe even the hybrid. Please count me in for the next batch of boards (or if anyone has some unused spare boards please PM me).

 

[les_garten]

Quote:

Originally Posted by marcus1 /img/forum/go_quote.gif Hi Alex I posted a query a few days ago about using the Lightspeed Attenuator with the eXStata (hybrid) but didn't get an answer. The criteria for using it are: 1: Low source impedence (cd player) <50ohms 2: High input impedence (amplifier) > 50k. What is the eXStata input impedence? Thanks

You seem to be on the Lightspeed thing and nobody else has really chimed in on it. So, I'll give you what I found and why I'm not interested in it.

1) You have to match the devices closely, this gets expensive with each added device. So balanced setups become high dollar.
2) These devices drift their performance relatively quickly. So you have 4 devices that may all drift at different rates. Expect frequent tweaking, measuring, replacement and maintenance. You into that? I wasn't.

I found a balanced setup on ebay, "cheap" and started asking questions and looking into it on DIYAudio.

Of course everyone has to make their own path. The Lightspeed option was booted out of my path.

The quest continues, I thing we need a really good, flexible, cheap, relay/resistor based attenuation system.

 

[studeb]

Quote:

Originally Posted by marcus1 /img/forum/go_quote.gif Hi Alex I posted a query a few days ago about using the Lightspeed Attenuator with the eXStata (hybrid) but didn't get an answer. The criteria for using it are: 1: Low source impedence (cd player) <50ohms 2: High input impedence (amplifier) > 50k. What is the eXStata input impedence? Thanks

See post #965 from the master

i do not think the Zin has ever been measured or hypothesized

 

[digger945]

Input impedance will be dominated by, and ever so slightly less than(in most cases), the input attenuator chosen.

 

[Lou Erickson]

Quote:

Originally Posted by runeight /img/forum/go_quote.gif Resistors in the PS are ok. CCF55 can handle the wattage requirements for the intended use.

Excellent! Thanks runeight! Hope your trip goes smoothly and you make it back to where you want to be.

Now... if I can just find what I did with those other parts...

Hey! I found them. Also, ordered a couple of nabu cases to make sure they're in a box of some sort.

Now I can match some JFETs... whee!

 

[studeb]

Quote:

Originally Posted by digger945 /img/forum/go_quote.gif Input impedance will be dominated by, and ever so slightly less than(in most cases), the input attenuator chosen.

right, but what is the Zin of the amp? The poster was saying the lightspeed (input attenuator) will want to see an Zin of at least 50k.
So what is the Zin of the PCB?

 

[Beefy]

A JFET input stage should have a very high impedance.

 

[macm75]

Quote:

Originally Posted by les_garten /img/forum/go_quote.gif 1) You have to match the devices closely, this gets expensive with each added device. So balanced setups become high dollar.

We have ears! Balance for free!

 

[ericj]

Took my eXStata SS prototype to the Salt Lake City mini-meet today, along with my ESP/950 and SR-Lambda.

Seemed to be very well received with the ESP/950 the big hit - but i was the sole attendee with any experience with 'stats, and all we had to compare them with was the E/90 and SRD-7 (SRD-7 powered by my Hitachi HMA-6500 mosfet power amp, with my old SOHA 1 with lm4562 doing preamp duty).

I also had my Sony ECR-500 powered off the same speaker amp as the SRD-7, and about three dozen misc orthos and dynamics (mostly AKG studio stuff).

 

[runeight]

Quote:

Originally Posted by studeb /img/forum/go_quote.gif right, but what is the Zin of the amp? The poster was saying the lightspeed (input attenuator) will want to see an Zin of at least 50k. So what is the Zin of the PCB?

1M

 

[jcx]

I hate to see so much mental energy and money wasted on balanced input for the exstata - having a high impedance differential front end it can accept single ended signals and still give the same output performance - up to the limitations of its low loop gain and consequent sensitivity to matching just about all of its components

it is unlikely that enough have been built that that even one exits (by statistical chance) that actually would give a "better balanced" output with balanced input vs single-ended input given device and component parameter distributions - that are not being measured/matched/trimmed

even with balanced source you could save money with dual attenuators with little to worry about in loss of "sound quality"

 

[pabbi1]

I believed the discussion was more the relative QUALITY of attenuation, not how to get there, but, hey, I am so oblivious to all that anyway.

What I detest is using an ALPS rk27, regardless of the number of decks. This amp deserves better.

Now, the SOURCE might be a crisis, and require much mental anguish, not to mention peer validation. But, heck, that is almost every DIY build discussion...

In other news, I did the follower mod to the 'red board proto'. and really can't tell any difference with the 'black board prod'. So, Marc, I think the ccs, the only remaing difference, really is not audible. Maybe using the WPS/Amphenol jack instead of your jack is a more likely difference.

 

[BoilermakerFan]

Quote:

Originally Posted by pabbi1 /img/forum/go_quote.gif I believed the discussion was more the relative QUALITY of attenuation, not how to get there, but, hey, I am so oblivious to all that anyway. What I detest is using an ALPS rk27, regardless of the number of decks. This amp deserves better. Now, the SOURCE might be a crisis, and require much mental anguish, not to mention peer validation. But, heck, that is almost every DIY build discussion... In other news, I did the follower mod to the 'red board proto'. and really can't tell any difference with the 'black board prod'. So, Marc, I think the ccs, the only remaing difference, really is not audible. Maybe using the WPS/Amphenol jack instead of your jack is a more likely difference.

I haven't spent enough time sorting the switches, but I think I'm going to use a PVA with 1:2 trafos and basically a shunted pot behind it. Nobel 10K for the pot. I don't have any balanced sources yet, so most of the time it will be fed by SE, when a Balanced source is available, I'll just bypass the trafos. They'll actually be part of a pre-amp that will also feed my F5(s).

For guys using the eXstata with electrets like the SR-30 and SR-40, how far are you pushing the volume? Are you concerned about over-voltage? I have ATH7s (SR-30s) on the way with eyes on another 'tret and AT-706s and KH-82s already in the house. The AT-706s are playing very quietly relative to the volume on my CR-620 compared to the KH-82s and SR-Lamda through a SRD6. I used Deoxit in the AT transformer box switches and contacts on the socket/plug and that helped, but they distort and clip pretty quickly after getting to a listenable level. I knew they were quiet cans when I bought them and did so mainly for the transformer box to use with the KH-82s after mods to Stax jacks and a recable on the KH-82...

I'm tempted to reterminate the 706 cable to a Stax plug and try them through the SRD6 before I mod the AT box...

 

[ericj]

Quote:

Originally Posted by BoilermakerFan /img/forum/go_quote.gif For guys using the eXstata with electrets like the SR-30 and SR-40, how far are you pushing the volume? Are you concerned about over-voltage? I have ATH7s (SR-30s) on the way with eyes on another 'tret and AT-706s and KH-82s already in the house. The AT-706s are playing very quietly relative to the volume on my CR-620 compared to the KH-82s and SR-Lamda through a SRD6. I used Deoxit in the AT transformer box switches and contacts on the socket/plug and that helped, but they distort and clip pretty quickly after getting to a listenable level. I knew they were quiet cans when I bought them and did so mainly for the transformer box to use with the KH-82s after mods to Stax jacks and a recable on the KH-82... I'm tempted to reterminate the 706 cable to a Stax plug and try them through the SRD6 before I mod the AT box...

I have SR-30 and SR-80 'trets but i haven't listened to them with the eXStata prototypes. I can give it a try.

Last year or so there were some pics of the inside of a Signet electret that make it appear that Stax and Audio-Technica were sourcing electret drivers from the same production line, so, there's a good chance the AT-706 can be driven just fine by the eXStata.