[number1sixerfan]

All the mods that I've mentioned are actually to make mkII's have same driver setup with mkI.(same port, same ear-driver distance) And with these mods mkII's sound very close to mkI. mkII drivers have better treble performance.(probably they upgraded the material they have used for diaphragm?) If you'll send the to repair they'll put mk2.9 drivers which are really good.

These are going to an individual for repair. He'll assess and then repair, but I'm not sure if that includes driver replacement. In either case, I was potentially thinking of a used MK2 or such to replace for now. Given the need for mods, I'll just wait or wait for a used MK1 pair to come available. Thank you for the help!

 

[John_M]

For electrostatic amplifiers, voltage is all that is really required for volume. Multiplying voltages is actually easy for amplifiers. Even Stax 252S can make your headphones can go very loud. You probably wouldn't find it's sound very pleasant though. The current that amplifiers can deliver determine how capable they are in driving electrostatic headphones. On higher sound volumes, amplifiers tasked to deliver higher voltage and as the voltage goes higher the amount of current required to have full 20-20khz extension goes higher too.

Electrostatic headphones have very high impedance, for example 007's impedance is 170k at 10khz. Probably it's around 350k at 20hz or even more. The amount of current needed which can go through such impedances is high. The bass rumble, the bass impact becomes much more prominent with stronger amps.

Again for treble extension electrostatic headphones need current. Because in higher frequencies, the amplifier has to rush faster and fill stators with enough statical charge in the given time. Current is the rate of the flow of statical charge. If the flow isn't enough, the voltage sags. (Voltage = volume, things you can gear = detail) First thing people notice when comparing Stax amps and Carbon is that how treble detail becomes more accessible and how it sounds more transparent in treble region. The soundstage expansion can be a result of this too.
Here are some examples,

STAX D50 has 300V power supplies, it requires 9ma of output of current for full extension. However, it's limited to 6ma.
350V power supplies require 10.6mA of output current.(T1, 717, 727 etc) They are limited to 7mA.
500V power supplies require 15mA. Megatron & T2 can do that. Carbon also has 20-22mA current output.
(amplifier measurement data is taken from Kevin Gilmore)

My recommendation is, if your budget is limited, get a good powerful speaker amp and pair it with a stax srd trafo. With this solution, you can get more voltage, more current than you can ever need for 1/3 price of Carbon or Megatron. There are reasons why direct drive amps are better and I had a post about it. I won't repeat myself again.

Thanks for the response. The trafo idea is interesting.

I noticed that the poster cited earlier (tabness) responded to a post which was substantially the same as this on the other thread as follows:

Those values seem to be calculated for both full voltage swing available by the amp and the full 20 kHz sine wave.

In real world usage the required output stage current would be far lower because most music power bandwidth would be in the range of 3 to 5 kHz (there was a study cited earlier in this thread that found one example of music requiring 15 kHz) and there shouldn't really be a need to swing that much voltage on the amp anyway (not to mention I have read that slew rate limitation distortion isn't the easiest to hear anyway).

Using 95 dB to 101 dB as the sensitivity of the 009 at 100 Vrms (as Stax measured at 1 kHz where there is a peak) the 353X at lower than the max output voltage (200 Vrms) would still give an extra 6 dB of headroom basically allowing for for 101 to 107 dB peaks which if you're listening close to the upper limits of reasonable average levels (75 dB to 80 dB) gives you 20 to 25 dB of headroom for peaks which covers the tough requirements of classical nevermind other stuff.

Do you have a response to this?

 

[Sviatoslav]

All the mods that I've mentioned are actually to make mkII's have same driver setup with mkI.(same port, same ear-driver distance) And with these mods mkII's sound very close to mkI. mkII drivers have better treble performance.(probably they upgraded the material they have used for diaphragm?) If you'll send the to repair they'll put mk2.9 drivers which are really good.

Does anybody know when Stax started using the new, current drivers on the SR-007 Mk II? I reckon that Stax now scramble serial numbers so that they are no longer dependable for determining age. One would, then, have to know the production date to know which transducers were installed, I figure. Or is there any other way, besides listening, to reliably determine the driver type used in a pair of SR-007 Mk II's?

 

[John_M]

No idea what your budget is. But assuming you want among the best amps for this I would consider one of the following:

1) KGSSHV Carbon: These are typically made by individual custom makers. But the most "company" like of these is Mjolnir Audio whose owner had significant part in the design of the amp. He is also one of the foremost experts in all things electrostats.
https://mjolnir-audio.com/

2) Headamp BHSE: Even though this is a tube amp, it is considered very neutral. Go look at the thread on BHSE Many would consider it one of the best available amps for 009/007 as well as being very nice eye candy.
https://www.headamp.com/products/blue-hawaii-se

Hope that helps.

Thanks for the reply. I'm not ruling out spending this much but I'm trying to avoid it if possible. Currently I'm thinking maybe just to go with something like a 727-ii which can be picked up much more cheaply than the SRM-700S and has more power than the amp I originally suggested. But it's interesting that there seem to be clear differences of opinion on what improvements a more powerful amp would give - will keep following the thread...

The tube vs solid state is another can of worms entirely. Like I said, I'll be using this with a Realizer and so would want the minimum possible distortion - if someone tells me confidently that a tube amp can deliver this, that would be interesting too...

 

[Tugbars]

Does anybody know when Stax started using the new, current drivers on the SR-007 Mk II? I reckon that Stax now scramble serial numbers so that they are no longer dependable for determining age. One would, then, have to know the production date to know which transducers were installed, I figure. Or is there any other way, besides listening, to reliably determine the driver type used in a pair of SR-007 Mk II's?

Nobody knows for sure, rumors say since 3 years all the new models are mk 2.9 which is considered as the best 007 model for some. You still gotta do the port mod though. It is a very simple mod and unless you don't intend to, it's impossible to damage anything within the driver. Taking pads out can be a bit tricky, luckily STAX has launched a video on their official youtube channel guiding how to take pads out and how to put them back.

Thanks for the reply. I'm not ruling out spending this much but I'm trying to avoid it if possible. Currently I'm thinking maybe just to go with something like a 727-ii which can be picked up much more cheaply than the SRM-700S and has more power than the amp I originally suggested. But it's interesting that there seem to be clear differences of opinion on what improvements a more powerful amp would give - will keep following the thread...

The tube vs solid state is another can of worms entirely. Like I said, I'll be using this with a Realizer and so would want the minimum possible distortion - if someone tells me confidently that a tube amp can deliver this, that would be interesting too...

Unless you mod it, 727 is really bad.

Do you have a response to this?

Totally true, those values are for full 20-20khz extension, Even most of contemporary classical music pieces have nothing going on after 14khz.

 

[John_M]

Totally true, those values are for full 20-20khz extension, Even most of contemporary classical music pieces have nothing going on after 14khz.

Thanks for this reply... but what does this mean in terms of how much power is actually needed? It sounds like even though you agree with this part of his reasoning, you don't agree with his conclusion, which was "...the 353X really seems to have enough to drive the 009 unless you start listening to really loud levels." Is there something else about his numbers that you don't agree with?

Note your comment about the 727 - I'm still thinking about this...

 

[AudioThief]

Ah yeah, I remember you were also saying that L300 is better than SR007. I see no reason to change your opinions but I don't agree with them. I gave you the numbers of how much power these amplifiers are lacking. Things get messy for amplifiers as you turn the volume higher, at extremely low sound levels even SRM-252S should be able to drive SR007 to it's "fullest".That's one of the reasons why frequency response of headphones from different amplifiers show almost no difference. However, the volume levels where they can deliver enough power is quite low. After a certain volume level, they start only adding compression artefacts to sound.

Nice strawman, I've never in my life said L300 are better than SR-007. I've said I prefer their forward sound signature, which is something completely different. Looking at the numbers, you can see that the 252s cannot actually drive the 007, but the 727 and 007t can.

 

[Tugbars]

If you say so.

 

[PJJK]

Hi all. This is my first post, so perhaps I’m about to resurrect an issue that has been dealt with in the past. I apologise if so.

What I want to talk about is an issue I am having with a CCS mod on a 006T, but before I detail this, I must thank Kevin Gilmore for sending me his Gerber files so that I could have some PCB’s manufactured.

My issue relates to the voltage across the DN2540 source resistor and because of this I have not ventured beyond the first CCS module. I’m using a 9V battery to set the current and started with a 430 Ohm resistor in parallel with a 5k Ohm pot. The result was a drop to 7V's no matter where the pot was set. I then dropped out the pot and replaced the 430 Ohm resistor with a number of resistors of different values, with the same result. I can only assume that I am doing something incorrectly or perhaps I have a faulty component. I’m not quite sure where to go from here, so any help I can muster would be greatly appreciated.

 

[Deolum]

Hello,

i need some help. I never heard a Stax and now i want to buy a used Stax Set. I need some suggestions which of the following ebay offerings is the best and which would be a good entry in the Stax world (i live in Europe)

Lamda Pro + SRM-1/MK 2 = 720 €
SR 303 + SRM 310 = 550 €
SR 303 + SRM 323 II = 800 €
SR 207 + SRM -1/MK II = 750 €
SR 202 + SRM 212 = 370 €
Lambdra Pro + SRM-T1 = 720 € (i like tubes but is it safe to buy 20 year old device with tubes? Do i have to change them?)
SR 202 + SRM 310 = 550 €

Is there anything else i have to take care of? Can i just plug in my DAC via RCA to the Stax Amps like any other Amp too?

Thanks !

 

[afgmjkl]

Hi all. This is my first post, so perhaps I’m about to resurrect an issue that has been dealt with in the past. I apologise if so.

What I want to talk about is an issue I am having with a CCS mod on a 006T, but before I detail this, I must thank Kevin Gilmore for sending me his Gerber files so that I could have some PCB’s manufactured.

My issue relates to the voltage across the DN2540 source resistor and because of this I have not ventured beyond the first CCS module. I’m using a 9V battery to set the current and started with a 430 Ohm resistor in parallel with a 5k Ohm pot. The result was a drop to 7V's no matter where the pot was set. I then dropped out the pot and replaced the 430 Ohm resistor with a number of resistors of different values, with the same result. I can only assume that I am doing something incorrectly or perhaps I have a faulty component. I’m not quite sure where to go from here, so any help I can muster would be greatly appreciated.

DN2540 has different pin configuration between TO-92 and TO-220.
Did you use TO-92 version?

 

[AudioThief]

Hello,

i need some help. I never heard a Stax and now i want to buy a used Stax Set. I need some suggestions which of the following ebay offerings is the best and which would be a good entry in the Stax world (i live in Europe)

Lamda Pro + SRM-1/MK 2 = 720 €
SR 303 + SRM 310 = 550 €
SR 303 + SRM 323 II = 800 €
SR 207 + SRM -1/MK II = 750 €
SR 202 + SRM 212 = 370 €
Lambdra Pro + SRM-T1 = 720 € (i like tubes but is it safe to buy 20 year old device with tubes? Do i have to change them?)
SR 202 + SRM 310 = 550 €

Is there anything else i have to take care of? Can i just plug in my DAC via RCA to the Stax Amps like any other Amp too?

Thanks !

I'd go for the Lambda pro in best condition possible. Any of the stax amps can drive it. The DAC connects into the amp normally. If you go for tubes, you might need to change them, yes. You need to watch out for if the amp needs a transformer or not, but beyond that its nothing. By the list you put up, I would say get the Pro + SRM-1/MK 2 and call it a day.

 

[AceMew]

Just ordered Sr 007, does anyone here in Europe have a 353x or equivalent for sale?

 

[o7brother]

Anybody compared the 009 and 007 MK2.9 in terms of bass "detail"? Obviously the 007 is much warmer, but I'm finding my 009 actually has faster bass attack and decay than my 007 MK1, but what about the MK2.9?

 

[AceMew]

I’m also taking suggestions if there’s anything better out there around the same price