The Stax thread (New) - Page 57

Is there any difference in sound between Mullard XF2's and XF2's manufactured by Mullard with other brand names like Rogers or Philips?

Spritzer, we have similar Blue Hawaii's, always on bias and black gates. I'm currently running Telefunken EL34 Wing Plates in my BH which sound great to me, have you ever heard this tube, would you know how the XF2's would differ in sound.

I'm also very interested in improvements you might be making to your Blue Hawaii, I might try the same with mine. The only minor complaints I have so far is the always-on-bias makes a slight buzzing sound, only external, not throught the phones.

Thanks!

When I use my SRX-III’s on my SRA-12S amp the usual listening level is about 10 o’clock on the dial. Using the same source on my SRM-1mkII the volume dial is at 2 o’clock on the dial. With some low output sources I can turn the volume control all the way up on the SRM and it still is not driving the amp to full output. This would give the impression that the 12S is more powerful than the SRM. Not true. What is true is that the 12S has considerably more gain (amplification factor). The only real way to test an amps ability to drive the phones is measure the actual high voltage output into a dummy electrostatic element load and run it up to clipping and measure the voltage. You could also use a sound level meter coupled to the earpad and run it up. That would be a dangerous procedure that would likely arc the elements. The procedures would be the same for a conventional amp driving a step-up transformer.

I made them this tensioned for a reason. I'm experimenting with my own DIY two driver per cup electorstats, one for bass and the other for treble but both driven full range because crossovers are the devils work... I can control the frequency output with the tensioning of the diaphragm and the coating material used. It's a fun project but nobody I know understands what the hell I'm doing...

The MS-2 are among the most high end non Stax stat ever made. The stators have hexagonal openings and the driver is clamped into place with enormous force even though it is only held together with tape. The original diaphragms were white polyethylene and while some sound came from them they fell too pieces when I disassembled the drivers.

All XF-2's are the same despite the name but the Mullard branded are often more expensive.

My amp doesn't have always on bias since it wasn't an option back then but they are very similar. It's been a while since I did my tube tests so the exact impressions aren't still fresh but I remember what they did to my system.

I've tried two types of Telefunken's, the real ones that Telefunken actually made and the ones with the hole or "dimple" on the top of the tube. Those were made in East Germany for Siemens but they are dozens of different names on them, I've got AEG, Telefunken, National and Siemens here. From the picture in the New York meet thread I gathered that you were using these. The original Telefunken's are good but the Mullards do everything better and they are cheaper too. It's more of a collectors tube and I simply didn't warm up to it. The "dimple" version is a good, cheap NOS tube and while better then the current production they can't match the extension and the liquidity of the best tubes. The XF2's are the best tube for the SR-007 because both are very truthful but at the same time musical and involving. Both tell it like it is and while that doesn't work with the He90 the SR-007 flourish.

I don't really like stepped attenuators so I'm going to replace them with a single 4-gang P&G pot and remove the RCA input and switch. All of the wiring will be upgraded with solid core soft silver covered with cotton or teflon where the high voltages demand. All connectors will be removed and every thing wired directly to the boards. I've also been toying with the idea of getting some custom made R-core transformers to replace the torroid. It won't be cheap but it will be a huge improvement. I'm also going to add two new bias supply's for the He90 and low bias Stax.

Interesting discussion regarding the gain factor and actual power. So here is my question: with an amp-to-energizer combo, how do you determine (on paper, that is) whether it has a high gain factor or if actually has more power.

If I'm not mistaken, I know there is an issue with dynamics where the ability to drive a can to loud volumes does not necessarily translate to having the ability to drive a can with authority/power. How does this theoretically work and how would this translate to the world of electrostatics? (For dynamics, my intuition was that high gain factor = high voltage, high volume; high power = high current.)

Also, on the back of energizers, there is a power rating in watts. What does that refer to?

When driving dynamic speakers we need power (watts). Amps with big power transformers, huge capacitors and lots of output devices can punch their way through difficult loads to provide the correct amplified voltage to the speakers. This same amp driving a Stax step-up transformer is like a Chevy 454 engine revving to 6000 rpm in neutral. Not much power is being used but the same voltage is being delivered. Very little current (muscle) is required to drive a SRD. There are small amps (low wattage OTL tube amps) that can swing big voltages and Big monster high current amps that are very limited in voltage swing.

You also need to remember that amp gain and amp power are not the same. Most conventional power amps (for driving speakers) have between 20 and 30 db of gain. That means that a few volts in will give max volts (or power) out. If your source will not drive to that level you will need a preamp in between. All you need to drive a SRD is 15-20 volts (30-50 watts into 8 ohm load). All the current in the world will not get you anymore dynamics. More voltage will.

The watt rating on the back of the SRD-7 is how much the bias supply draws from your house current.

Well, I'm nobody, and sure enough, it's not too hard to understand what you're doing. Sounds like AKG in the '70s with a little of Acoustat founder Jim Strickland thrown in.

Speaking of Strickland, I think he was the one who pointed out to me that 'stat 'phones don't need a high-resistivity coating, since they're too small for charge migration to be a problem. Still, doesn't the MS-2 use a resistive coating? or is it impossible to tell?


Here's Charivari's struggle with his Infinitys. See if the guts are the same.
http://www.sound-thinking.org/index....&hl=headphones


I'm not up on the details of xformer design, but don't toroids have the best HF passthrough? Why would R-cores be better?

Agreed! I've been banging on about this for ages now: I've been shocked (and disappointed) to discover how much better are the transformers than an SRM-313 or an SRM-1 Mk 2. I've used an SRD-6 SB and an SRD-7 (mains-bias) driven by a 20-year old Naim pre-/power combo, and they're louder, more dynamic, more musical, just plain better, than the Stax amps.

All this churning over numbers is a waste of time: I thought Naim (and Linn) had laid all this to rest years ago, when the tiny Nait integrated amp sounded louder (and better) than 100w-specified Jap amps...

Thanks for the help audiod. When shopping for amplifiers, how do I know what the voltage gain will be? (Which spec should I look at, or is there no clear number.) Or is looking at the watt-into-load spec enough?

It's more like Quad with the original ESL but you've got the gist of it. I would never run without a resistive coating in the mega ohms per cm2 to make sure they are working in constant charge mode and for safety reasons but you can go with high conductivity. I do not see any reason to do so but it's ok in theory.

I can't see if these are phones are the same design from these pictures. The film in my set fell into little pieces and I didn't bother measuring. A simple "5 minute made" diaphragm with a pencil as a resistive coating works fine so I'm guessing they treated the film with something.

I don't really know why R-cores are better but when you see company's where pure performance is the only criteria (Kondo, Shindo) and cost be damned they all use R-cores. The only reason toroids are used is that they are cheaper and with 99.999999% of audio company's thats all that counts.

I was going to say that, but didn't the original Quad have a conventional crossover network?

I’m an old style audiophile that believes that our ears are the final judge. Putting together a great system is not just an art, there is some science involved. I’ve owned low powered tube and solid state amps all my life. We’re not talking about amps driving conventional speakers. We’re talking about amps driving step-up transformers. What good is an audiophile grade amp if it clips when listening to music driving the SRD-7. This discussion is not about the subtleties of an amps sound quality but compatibility. We are discussing whether a amp is likely to under voltage drive the SRD-7. We all want the best sound quality (using our ears) but there are some audiophile grade amps that are not suited for this purpose no matter how good they are driving conventional speakers. If you understand what we are talking about you will see that it is not a waste of time.

Veniogenesis,
I don't know if you need a basic amp (no controls) or a integrated amp (control functions and switching). Whatever you get I would recommend a power output of 30-50 watts into 8 ohms. I would stick with the known audiophile brands. Take your phones to a good dealer and listen.

AudioD

That's certainly my take on things. I don't believe the numbers are meaningless, especially when just trying to find out what just will outright not work. An under driven SRD-7 is not going to sound great no matter how nice the amp may otherwise be. A well driven SRD-7 may or may not sound great either but that doesn't mean the numbers have no value at all.

Oh the numbers have meaning, but I wouldn't get too hung up on them. In the end I think we would all probably agree to the phrase "let your ears decide" over any other factor(s). Am I wrong ?
And what was that one phrase -If it sounds bad and measures good - it is bad. If it sounds good and measures bad - you measured the wrong thing.