The Headcase Stax thread

[n_maher]

We wouldn't have it any other way Mike.

I'm similar: build it, sell it, build it again, sell it again, lather, rinse, repeat.

[jp11801]

Rocking a 404le powered by Pabbi's original ExStata hybrid amp, for a roughly $1400 set up it sounds really stunning. Very clean and detailed, while there are build choices (not a huge fan of steppers, I much prefer shunted pots and a normal bias would be swell) I would have done different, solder hacks like myself can't be too choosey when buying a diy only amp. I consider myself fairly fortunate to get the amp from Pabbi as they are not falling off the trees in the FS forums over at the fi. Overall it is a really sweet looking build with a really nice wood chassis. At first I was unsure if I liked the combo but the sound is very different from the JH13 or Ad2k from the Stacker ll. I love the vocals on the Stat rig but crunchy guitar or juicy bass lines are done better by the JH13s. It took about three days to acclimate but I am really digging the sound.

I can't wait to hear other stats on this amp and compare it to other Stat amps in the under $2000 range.

[spritzer]

Quick question...... what is the easiest way to measure/check the bias voltage being produced by an SRD7-SB?

Can I measure from bias to one of the outputs with no music playing, then calculate the actual voltage assuming a 5M ballast resistor in series and 10M multimeter input impedance?

It's rather more complicated then that as you have to account for the load presented on the voltage multiplier as well. The 10M load presented by DMM is very low compared to the diaphragm so I'd personally not go this route. I'd rather measure the AC input input in the the bias supply, see what the value of the transient suppressor is (i.e. the two zener's back to back) and then do the math.

[Beefy]

It's rather more complicated then that as you have to account for the load presented on the voltage multiplier as well. The 10M load presented by DMM is very low compared to the diaphragm so I'd personally not go this route. I'd rather measure the AC input input in the the bias supply, see what the value of the transient suppressor is (i.e. the two zener's back to back) and then do the math.

Well the reason I ask is that the highest I can measure from the bias pins out of the SRD7-SB is 60V relative to the outputs, which then slowly drops. It seems very low to me, even considering any effect of the voltage sagging through the multimeter.

And the reason I am measuring this is that the 'crackling' problem I am having with my Exstata and Lambdas doesn't happen on the SRD7-SB. But I'm quite sure it isn't the amplifier, because the crackling only ever happens when the bias is up and the rear stator on one particular driver is connected to the amp. I have recabled, removed the diodes, get no apparent continuity between this stator and the bias wire, but still it crackles away when connected.

My idea was that perhaps the bias on the SRD7-SB is much lower than the Exstata. At the higher bias, something is shorting or arcing. I will drop the bias on the Exstata to its minimum and see if this helps, and consider cracking open the SRD7-SB to get a better assessment of the bias voltage.

[cetoole]

The way the SRD7 generates it's bias supply is quite hacky, and only really works because there is absolutely no load at all on the multiplier to drag it down. Nothing bit a very small amount of capacitance to ground. In comparison, 10Mohm is huge. I imagine the SB is even worse about this.

[Beefy]

The way the SRD7 generates it's bias supply is quite hacky, and only really works because there is absolutely no load at all on the multiplier to drag it down. Nothing bit a very small amount of capacitance to ground. In comparison, 10Mohm is huge. I imagine the SB is even worse about this.

Awesome. I love how everything is just so damn easy in this hobby

*

I just progressively dropped the bias on my Exstata from 230 to 140V while listening carefully. The lower the bias, the more intermittent and quieter the crackling, until it seems to disappear somewhere between 150-170V. It comes back as the bias hits 180-190V. I am 100% sure that I am measuring correctly before the ballast resistor (the Exstata has a test point here for this purpose), and 99% sure that my meter isn't bogging down the voltage in the first fraction of a second. And surely if was just that the bias was actually much higher than I am measuring, the crackling noise would be in both drivers - or at the very least, in both stators on the same driver.

I'm not ready to call it yet because the symptoms have been intermittent...... but have I found my problem? At the higher bias, I am getting a short or arcing from the bias to the rear stator, and the Exstata holds the bias well enough that it just keeps on happening. If the bias on the SRD7-SB is indeed that easy to bog down, the slightest short is enough to constantly keep the bias down, thus I don't hear the crackling.

[spritzer]

The only semi sensible readings I've been able to get when measuring any of the SRD supplies is with my VTVM and they are still a bit off. The Mk2 SB unit has an 82V transient suppressor and a 7 stage multiplier but I can't find my schematic of the Mk1 SB unit so I don't know if they stuck to the two stage design with an 82V entry and thus only having 160V bias.

As for the diaphragm shorting out into either stator, I've never heard that present as crackling. More like squealing as the diaphragm is oscillating due to the forces acting on it not being equally distributed. Crackling has always been due to excessive bias.

Also if the diaphragm were shorting out then you would get drops in volume but only gradual as the high resistance of the diaphragm stops and real amount of power from moving across it. You can normally listen to an ESP with no bias for at least a couple of minutes until the charge is fully drained.

[Hopstretch]

So, roughly how much are my O2s being under-driven by the 007t right now? Because they still sound pretty damn good.

I will accept either percentage estimates, "a lot" or "don't be a freaking douche", but am semi-serious as I've not yet had the chance to try any other amps with them except under meet conditions.

[aardvark baguette]

Having never heard electrostats, I'd say 'to a degree'.

[Hopstretch]

I knew this wouldn't go well.

[tyrion]

You are still using a 007t? I see a BH in your future. It's a shame that Al will have to witness your grin, I think it was.

[mypasswordis]

[morphsci]

Ω2 + 007t => orgasmic

Ω2 + KGSS => multi-orgasmic

Ω2 + BH/BHSE => mega-multi-orgasmic

Ω + BH/BHSE => mega-multi-orgasmic screamer

[igorst]

Ω2 + 007t => orgasmic

Ω2 + KGSS => multi-orgasmic

Ω2 + BH/BHSE => mega-multi-orgasmic

Ω + BH/BHSE => mega-multi-orgasmic screamer

Nice!

[n_maher]

So, roughly how much are my O2s being under-driven by the 007t right now? Because they still sound pretty damn good.

I will accept either percentage estimates, "a lot" or "don't be a freaking douche", but am semi-serious as I've not yet had the chance to try any other amps with them except under meet conditions.

Perhaps what you really should be considering is how many drinks will be required this coming weekend to convince a certain out of town visitor for a loaner program?

[The Monkey]

So, roughly how much are my O2s being under-driven by the 007t right now? Because they still sound pretty damn good.

I will accept either percentage estimates, "a lot" or "don't be a freaking douche", but am semi-serious as I've not yet had the chance to try any other amps with them except under meet conditions.

Compared to a KGSS, they are being under-driven by a relatively wide margin. I loved the O2 (both mk1 and mk2) out of the 007tii. In fact, I still love that amp. But I felt a certain "hollowness" in comparison to the KGSS, which just seems to kick those phones into another gear. I feel like the O2 is much more nimble and "sings" more out of the KGSS.

Whatever the fuck any of that means.

[Deadneddz]

Plants vs Zombies avatar FTW!!! Is this the game little monkey has been playing, or have you been playing it yourself?

[spritzer]

I'd say 36.345%, with a margin of error of 0.003%...

For me the music just snaps into focus with more power. The imaging is more precise, bass is more linear, treble extends further etc.

[n3rdling]

I'd say 36.345%, with a margin of error of 0.003%...

Repeating, of course.

[Elephas]

Haha, poor little 007t, it's supposed to be a Stax top-line amp but doesn't seem to get any love.

Well, I don't even want to listen to the O2 with a 717 or KGSS, so I guess a 007t doesn't really have a chance. I still recall the KGSS fondly (I sold it a long time ago) but don't miss it much.

I remember thinking, "How much difference could there be amping the O2 anyway?" before I heard the O2 + KGSS. Those Stax-brand amps are bundled with the O2 after all, so that's the "official" sound, right?

I think the Stax amps are the best they can do, given cost constraints, and selling through dealers and manufacturing the amps in Japan doesn't help in the cost dept. So the amps are not really very good values, but then not many commercial amps are good values compared to DIY-designed and built. The Stax engineers most probably have built a BH in-house to try, so they know how the O2 sounds driven by those amps... which is NOT DARK.

[spritzer]

Stax probably have a few T2's still in use and given how similar it is to the basic BH design, they sure know how the phones sound when properly driven. I do think that a redesigned 007t with ECC99's and a simple CCS would put the Stax amps back in the running, especially if the Yen finally drops a bit in value.

[The Monkey]

Plants vs Zombies avatar FTW!!! Is this the game little monkey has been playing, or have you been playing it yourself?

Both.

[Salt Peanuts]

So Stretch, when are you buying a BHSE?

[Hopstretch]

When there's one for sale.

Just out of general interest, where does the Woo GES stack up against the Stax offerings? Seems like there are a few of those on offer right now as people trade up to the WES.

http://www.head-fi.org/forums/f42/fs-woo-audio-ges-474962/

[The Monkey]

When there's one for sale.

Just out of general interest, where does the Woo GES stack up against the Stax offerings? Seems like there are a few of those on offer right now as people trade up to the WES.

FS: Woo Audio GES - Head-Fi: Covering Headphones, Earphones and Portable Audio

The GES is nice, but it will suffer from similar problems to the 007t--it's underpowered for the O2. I wanted very much for that not to be the case, but listening to the combo at several meets convinced me.