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The Stax Thread III - Page 98

post #1456 of 11926

Boy, I wish I could work wood as well as Frank Cooter.  I do OK with metal, and can design some circuits, but I can't do joinery for the life of me, even though I have access to a full custom hardwood cabinet-maker's shop. Even making a chassis base with 4-corner miter joints, which is fairly simple joinery, by the time I cut the final 45 degree miter things are just a little out of kilter, either in terms of length or angle, leaving a slight gap in one corner no matter how much I tighten the clamps when gluing. Now, in my defense this wood is bubinga, very very hard and dense, so that I needed to apply considerable pressure to the miter saw when cutting; this pressure distorted the geometry of the saw ever so slightly.... also I used urethane glue which expands in the joint as it cures..... yeah! That's what it was- that's the ticket!




Pretty wood, though-  bubinga.  This is a phono preamp.

Edited by milosz - 2/4/14 at 3:59am
post #1457 of 11926
What a coincidence! I might have an srm t1 I can get my hands on.

Thanks for the reply I'm gonna look into all options. Especially the DIY. Oh and a sub $30 amp? SOLD.
post #1458 of 11926
Originally Posted by milosz View Post

A lot of people like the T- amp stuff- based on the Tripath chips.  For the price ($90) , the Dayton Audio DTA-100 is a damned good 50 watt/ channel amp.  Really you don't need that much power for an SRD-5  so you might try the Lepai LP-2020A+ 
 20 watt/ channel tripath amp from Parts Express for $24 (!!)  These are switching amps, and I think they sound better than many of the solid state amps out there; not quite as nice as the better class-A amps but better than almost all mid-fi receivers, integrated amps etc. For $24  you can hardly go wrong.  If you don't like it on your SRD-5, you can use it as a spare / troubleshooting / utility amp. (The Lepai is the amp I would use if I wanted to stick to a budget.)  Many listeners have said that the Tripath amps have a "class A-like"  sound.  I have a DTA-100, and I agree.  Sounds better than it has a right to at the price.

If you are capable of some light D-I-Y, another route would be to use a pair of the 10-watt class A solid state amp boards from eBay seller jims_audio, the amp boards sell for about $57 a pair and you'll need   +  and - 12-to-18 volt supplies at 5 amps or so per rail.  These are VERY nice sounding amps, I have a bunch. For $150 all-in (amp boards, power supply, casework from Par-Metal etc) you could have a high-end 10 watt/ channel amp, along with the satisfaction of building something yourself.  I use 5 of these for L/R/C/LR/RR speakers for my surround speaker setup in my "computer office." (They also help heat the room- class A amps always run hot.)

AS far as a dedicated electrostatic-only amp for a future upgrade, I can highly recommend the Stax SRM-T1. It's a VERY GOOD sounding amp, has both low- and high-bias output jacks, and there are many of them around so they come on the market fairly regularly. I think it sounds just about as good as ANY Stax brand amp, save the rare T2.  The newer Stax tube based amps sound a LITTLE better, but not really THAT MUCH better, and given the price, the SRM-T1  is a clear winner in terms of sound per dollar.

Upgrading from the SRM-T1  is an expensive proposition. To get a MARKED increase in sound quality, you need to go to a KGSS or KGSSHV amp, Blue Hawaii, etc.  $$$$$$$$

Feel free to post a complete part list and directions for the DIY build smily_headphones1.gif
post #1459 of 11926
Frank, you are the best.
post #1460 of 11926

2 channel 10 watt class A amplifier - suitable for driving Stax SRD-5. SRD-7  etc.  Also works well with speakers, although power is limited to 10/ channel watts at 8 ohms. 20 watts/ channel at 4 ohms.


Pair of  assembled 10-watt class-A MOSFET   boards from eBay seller jims_audio  CLICK HERE


Power supply board from jims_audio click HERE contact jims_audio via eBay, they will give you a list of the parts needed to stuff this board.


Standoffs  / hardware to mount boards to chassis from eBay click HERE


Neutrik RCA input jacks, 2 needed  MOUSER  click HERE


2A slo-blo 5x20 mm fuse, MOUSER get 2 or 3, good to have spares Click HERE


Four TO-220 transistor mount kits MOUSER  click HERE


IEC  AC input jack w/ fuseholder Parts Express click HERE


On-Off Switch  Parts Express Click HERE


Two  HS-0606-b heatsinks from PAR-METAL  Click HERE


Pick a size  Par-Metal chassis that will fit.  I suggest you buy all the parts first, and then collect them together on a desk and measure how large a space they require, and then order the appropriate size from Par-Metal in your favorite color.  Click HERE


You will also need:


TOOLS - power drill, files, screwdrivers, soldering pencil, small diagonal cutters or nippers, needlenose pliers


OTHER SUPPLIES  - the thinnest 60/40 rosin-core solder you can find, some electrical tape to put around the bare AC line connections inside the amp, some misc screws and nuts etc.  


To mount the heatsinks, place them over the ventilation slots in the chassis, and drill holes from the bottom of the chassis into the heat sinks, then use some sheet metal / self tapping screws to mount the heat sinks to the chassis.  What you want is for air to be able to rise through the ventilation slots on the bottom of the chassis, pass over the fins of the heatsink, and then rise out of the vent slots on the top cover of the chassis. So you want to place the fins so that they have the most exposure to the vent holes possible given the space.


You can also find some fancier chassis on eBay that have heatsinks built in to their sides, if you prefer.



(Stuff I forgot)


5-way binding post output terminals - Parts Express - click HERE


Hook up wire - I suggest using some 18 ga. Teflon insulated wire.  Most hookup wire is 22 ga, but I think here you have a bit higher current on the DC side, so 18 ga might be a good choice.  Probably OK to use 22 ga. wire from the AC power inlet to the on/off switch and from the switch to the primary of the power transformer, but I would use the heavier 18 ga wire for the power supply connections to the amp boards, and for the speaker output wires from the amp boards to the binding posts.  Search eBay for some Teflon insulated wire, you don't need much, perhaps 5 feet.  Teflon is best because the insulation doesn't melt or burn when you solder it. 


You might want an LED pilot light, see Mouser HERE


The power transformer I originally specified might be a little too small.  This one from Mouser would be better, 30 V CT, 150 VA  Click HERE




#1 TIP - DO NOT WORK ON THE AMPLIFIER WHEN IT IS PLUGGED IN TO THE POWER LINE!!!! Close the chassis up before plugging the thing in!


I suggest wiring the power supply first, without connecting it to the amp boards. The close the chassis up, plug the thing in and hit the power switch. If the pilot light LED lights up and stays lit,  then disconnect the power cord, open the amp chassis up and wire the power supply to one channel at a time.....


The hardest part of this build will be cutting the rectangular hole in the chassis to mount the IEC power inlet/fuseholder.  My suggestion for this is to make a cardboard template the proper size, and trace around it with a pencil onto the chassis where you want to mount the power cord. Now, drill the largest holes you can drill that fit inside the outline.  After these are drilled, use a file or a chassis nibbling tool to enlarge and square the hole. (see http://www.parts-express.com/nickel-plated-nibbling-tool--360-022 )  The AC power inlet is press-fit. You push it in to hole until the thing snaps in place.


This => http://makezine.com/2006/04/10/how-to-solder-resources/  is a soldering tutorial. Practice a little before you build, if you're not used to soldering. 


In wiring the AC line,  connect the hot lead from the AC input socket to the fuse and then to the power switch in series with the HOT lead going to the power transformer's primary; and don't forget to connect the power cord's safety ground wire to the chassis.  See http://www.ampmaker.com/pp-18-chassis-wiring-part-3-1043-0.html


The output transistors of the amplifiers need to be bolted to the heatsink, but the transistors must not make electrical contact with the aluminum metal of the heatsink- that's why you use the TO-220 mounting kits. ("TO-220" is the standard designation for this type of rectangular, tab-mount transistor)  See http://www.turkiyefagor.com/semi/pdf/rultiris.pdf  for instruction on how to mount the transistors.


Note that this is a POWER AMP; if you want to add a volume control to it, I suggest a 50k audio-taper stereo pot like the Alps Blue Velvet, available on eBay for about $16 if you shop around ( like THIS ) - and although the Blue Velvet has a reputation for quality, reliability and close channel balance, it is perfectly acceptable to use a less expensive pot like THIS one from Parts Express for $2.40;  you'll need some kind of knob for the volume control like THIS budget one from Parts Express or THIS nicely machined one from Mouser.  ( or pick one out from THIS selection guide from Mouser; be sure it will fit the 1/4" shaft of the volume control.)  HERE is a tutorial on how to wire the volume control.


You might want to get a book like Circuitbuilding Do-It-Yourself For Dummies from your local library if you've never built any electronics.  It's really not that hard to do, but there is a bit of craft involved.

Edited by milosz - 2/4/14 at 3:54am
post #1461 of 11926
Originally Posted by karlgerman View Post

1:     5 days a week
2:     3-4 hours

3:     100% electrostat others are in boxes and stay there for at least the next 3 months :o2smile:


By the way, i picked my new KGSS, a used one i bought from someone in this forum.

So this is almost Headphone-heaven for me.

As far i can tell right now, it is very nice but there is a hum after the amp is turned on.


Not in the signal, but one could hear it sitting next to the amp.

So it could be the transformer??  It is a european voltage model build by Spritzer, maybe a year old????


I´m not into electronics and DYS amps.... but my HIFI-dealer,

which is also a friend of mine (and for all that stuff i bought in his shop, i´m his friend as well)

will help me for sure.


Maybe one of the specialists in this forum could be so kind to give me a hint to solve this problem in front of asking my hifi-dealer.


Thank´s in advance:bigsmile_face:

I had the same problem with my Cayin tubed DAC. Mechanical hum. I solved it by removing the mounting screws of the transformator and packing it in bubble plastic w/o screws. It;s dead quiet now.

post #1462 of 11926
Originally Posted by 3X0 View Post

Thanks; this is just the type of answer I was seeking. I don't suppose it was converted as I received it brand new.


I guess the other option would be to open it up with the intent of switching to 120V, with the potential of being pleasantly surprised.


It sounded "better" than either my 120V SRM-T1 or SRM-T1S ever did, but seems significantly less sensitive on the dial than the latter of the two. Guess it's time to crack it open...

My US-made Empire Troubador turntable  has a sticker of US voltage/frequ. but in fact is their export model for Europe. I'm living in Holland and ordered it in 1975 new through an American PX outlet. So sometimes the statements on the box are not correct. I wonder about Stax though. They are usually very thorough.

post #1463 of 11926
SR-009 question:

Has the 009 been unchanged since launch or has there been small revisions?
post #1464 of 11926
Originally Posted by ardilla View Post

SR-009 question:

Has the 009 been unchanged since launch or has there been small revisions?

No revisions.

post #1465 of 11926
Originally Posted by ardilla View Post

SR-009 question:

Has the 009 been unchanged since launch or has there been small revisions?

Nope. SR-009 has always been the same. 

post #1466 of 11926

Instead of going through 90+ish page of discussion, I would like to seek advice from anyone with experience on SRM-600TS amp driving Airbow SC-21. Currently, I am using Woo Audio WA2 with Beyer T1.

post #1467 of 11926
Defqon, I think I read in in the LCD2 thread that you will be getting a pair of 009s. You've tried out so many headphones, so I'd be wipe curious to know your impressions. Do you plan to share them?
post #1468 of 11926
Here's a semi-hypothetical: if you had to choose only 1 combo, what would you rather have, a well driven 007 Mk2 ( not Mk1, just because the Mk2 is the current production and more readily available, and driven by a KGSSHV or BHSE) or a 009 with a mid-tier amp (for all available e-stat headphones, that is) , something like the 323s, Woo GES, srm-007. If you get either headphone from PJ then I think the prices are similar (1800 + 2500-5600 = 4300- 7400 for 007 setup, and 3800 + 700- 2000= 4500-5800).
post #1469 of 11926

The 009+midtier amplifier. Why: The 009s are not hard to drive to sound great and the 007MK2s aren't that great to begin with.

post #1470 of 11926
Originally Posted by FrankCooter View Post



As long as we're discussing "home-brew" DHT electrostatic amps, here's my 845 based amp. It's a single-ended 3 stage design. 1st stage is a CCS loaded 6N7 direct-coupled to a 45. 2nd stage is a 45 driving an interstage transformer connected to the 845 grid. The 845 output drives a custom high level Electra-Print phase-splitting transformer.Running the 845 with fixed-bias at 650V@60mA. Power supply was originally based on mercury rectifiers, but am currently working on a hybrid solid-state/tube regulated supply. Not the most practical project, but definitely a lot of fun and a completely different presentation from most other electrostatic amps.

My current favorite is my own SR 3n with 5n membranes driven by a Wavac 572 50 watt single ended amplifier using 572b tubes with a normal bias Stax SRD 7 using new production dyna z565 trannies.


For my taste this setup is much better than the 009/blue hawaii/cavalli combos or the Abyss/Cavalli Liquid Gold setups I have heard many times now at shows.  Deep, rich, fast, nuanced bass, transparent midrange, lovely upper mids and highs. It is reminiscent of HE90 sound but faster and deeper.


 I think I like the Abyss/Cavalli LG better than any of the 009 setups I have heard, I just could not bond withe the 009/Blue Hawaii sound for some reason.

Edited by cjfrbw - 2/6/14 at 1:19pm
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