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The Stax Thread III - Page 101

post #1501 of 2674
I find it quite interesting with the amp requirenments of stats. With 'ordinary' headphones you want to have at least 10dB more headroom before you can say they are 'well driven' compared to what you have with stats
post #1502 of 2674

Honestly the fear of channel imbalances has been the biggest deterrent to ordering a 009.  Would be the most expensive gear I've bought....and could fail apparently.  I kind of think that's unacceptable for the price of them.

post #1503 of 2674
Not so much a failure as a temporary but silly inconvenience for what is a luxury product. Unfortunately it seems to be based on electrostatic principles but I'd be thrilled if Stax figured out a way to prevent parasitic charges in the future. It really is unacceptable to have to deal with an issue that compromises the core functionality of such an expensive product.

Temporary imbalance typically coincided with seasonal/temperature/humidity changes.

DefQon, you should get your friend to stow the Omega for a month or two until the imbalance is resolved and then consider whether you'll settle back to the 009. Not many people have ready access to snap up an Omega when they please, but the 009s will come and go.
post #1504 of 2674

Chances are I will sell the 009 before even giving it some head time.


Edited by DefQon - 2/8/14 at 1:48am
post #1505 of 2674
Quote:
Originally Posted by DefQon View Post


It's all planned out to be purchased in the future so it's all good. I would buy a set of Megatron boards if Lilknight would respond on the other site I'm not reluctant to drop the $ on boards knowing that I won't receive them in a long time. And I still need to find time to complete my offboard KGSSHV lol.

Speaking offboard PSU is this one of the new mini KGSSHV psu board or another one I'm completely not familiar with?
Nope too risky owning them.

 

Doesn't matter which version of the PSU board. The tubes draw about 2-3 times more than the KGSSHV - which is why you need to remove the current limiters for the Mosfets. It'll work with the onboard sinks - it just eats the LT1021s for me when cased up cause of the heat (and I use it in an air conditioned room).

 

Since you're building the offboard kgsshv, I'm certain you'll get the megatron up before that :P I think LilKnight is caught up in some stuff, he's always been a class act to me. I do hope he's okay, though.

 

Re alternatives to Sumr... try http://www.toroidy.pl/ I had a good experience with them.


Edited by RiStaR - 2/8/14 at 7:14am
post #1506 of 2674

Question about storing the 009s long-term:

 

I'm going to be moving soon, and I have 2 options:  Either take my 009s with me on a trans-Pacific flight using a Pelican case, or store the 009s in the original wood box where they'll be transported through humid climates and on board ships for about 2-3 months.

 

Which is the safer option?  Is the wood box really as good as Stax claims it is for limiting the potential damage of humidity?

post #1507 of 2674
Quote:
Originally Posted by dj nellie View Post
 

Question about storing the 009s long-term:

 

I'm going to be moving soon, and I have 2 options:  Either take my 009s with me on a trans-Pacific flight using a Pelican case, or store the 009s in the original wood box where they'll be transported through humid climates and on board ships for about 2-3 months.

 

Which is the safer option?  Is the wood box really as good as Stax claims it is for limiting the potential damage of humidity?

You could include some of those small bags made to keep the air dry within the case/box. Dunno what they are called or what they are for that matter.

post #1508 of 2674
Quote:
Originally Posted by davidsh View Post
 

You could include some of those small bags made to keep the air dry within the case/box. Dunno what they are called or what they are for that matter.


desiccant pouches

post #1509 of 2674

Hi all, Looking for some feedback regarding the  SRM-007T II.  I currently have a SRM T-1 which is partnered to a Koss ESP-950 and it sound really nice but sometimes seems to lack a little drive on some material.

 

Would going to a SRM-007T be a big step forward or more of a sideways move, I know both amps share the same 6CG7 type tubes but the 007T has four of them vs the single pair in the T-1. Do they share the same sonic signature ?

 

Any comments would be appreciated.

post #1510 of 2674

I very much like my 007t/ii with my 009 phones. The slightly rounded, reticent highs I hear in the amp (which was a weakness with the SR007 mk1 phones, making them sort of flat) 

is just what the doctor ordered I sense with the 009s. Bass is very high quality, just not thunderous, about the same amount of bass-power and depth as my HD800s, but with more

bass detail and bass-life. Nice tube signature, with a great inner glow and silkiness in the mids.


Edited by rgs9200m - 2/8/14 at 11:43am
post #1511 of 2674

I agree totally with rgs.  I think he has exactly nailed the sound quality of the 009/007TII combination.  I very much enjoy it.  It's the best headphone sound quality I've ever come across.

post #1512 of 2674

Thanks for that greggf.

post #1513 of 2674

can the bias be changed on an amp like the T1 or srm1mk2 to accommodate something other then the stax pro line?  like maybe a koss 950 or jade?

post #1514 of 2674
The 950 works fine off 580vdc pro bias
post #1515 of 2674
Quote:
Originally Posted by milosz View Post
 

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.

 

======Additions======

(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

 

=====Tips====

 

#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.

Thanks for the in depth directions.. Since you took the time to put in so much work for me I will definitely be tackling this project.. Thanks again

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