icnaiwhimor1975
New Head-Fier
looks like my 6FQ7\6CG7 tubes in stax T1S are dead
is looking for some analogues to them a good idea
is looking for some analogues to them a good idea
The Stax Thread III
SolarCetacean
500+ Head-Fier
I use RCA Clear Top 6CG7s in my 006tS. Not cheap, but I read reviews that they were better than the stock 006t tubes. I didn't really notice much of a difference, but that was over a year ago when I wasn't as good at picking out sound changes, and I haven't switched back to the stock tubes for comparison (biasing the amp is too much of a hassle). Though I'm not sure if they'd be an upgrade over the T1S tubes; I've read that certain units back then used really nice tubes.
Another thing you can do is buy 6SN7 adapters for the amp. Stritt Audio in Germany makes and sell right-angle adapters so that the 6SN7s fit horizontally inside the case and you don't need to remove or mod the top cover. That gives you more options for tube rolling, as there are a lot more 6SN7s plus new production and they are electrically compatible with 6CG7s. A more advanced mod that a few people have done is adjust the amp to run the 6SN7s at a higher power (more output current) since they can handle more power than 6CG7s.
Another thing you can do is buy 6SN7 adapters for the amp. Stritt Audio in Germany makes and sell right-angle adapters so that the 6SN7s fit horizontally inside the case and you don't need to remove or mod the top cover. That gives you more options for tube rolling, as there are a lot more 6SN7s plus new production and they are electrically compatible with 6CG7s. A more advanced mod that a few people have done is adjust the amp to run the 6SN7s at a higher power (more output current) since they can handle more power than 6CG7s.
+1 on the 6SN7 conversion. I've used these popular Tung Sol tubes in multiple devices and always been happy with them.
https://www.tubedepot.com/products/tung-sol-6sn7gt-new-production-preamp-vacuum-tube
SolarCetacean
500+ Head-Fier
Tung-Sol GTBs are also what Stax uses in the SRM-700T. And even Spritzer thought that amp sounded good after he did the CCS mod on it. I've been thinking of doing the 6SN7 mod and adjusting the CCSes for higher output current and thus getting something like the 700T on the cheap, but I haven't gotten around to that yet.
Nice! Looking forward (with bated breath) for the comparisons!
myheadHz
New Head-Fier
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What are peoples opionions on the SRD-X pro?
Personally not noticed much difference sonically from SRD6, is the SRD 7 much better than SRD6 or SRD-X pro? However lots of info seem to recommmend SRD7 as the best STAX enigizer (not amp), is this mainly due to the transformers it uses?
Also, the extension cable SRE-725 uses OOC (copper), yet the signature models (& L700) use silver OOC. Does this mean not advisable to use extension cable with 'silver' cabled models as this limits them to the constraints of copper OOC cables (if there is any difference)?
Personally not noticed much difference sonically from SRD6, is the SRD 7 much better than SRD6 or SRD-X pro? However lots of info seem to recommmend SRD7 as the best STAX enigizer (not amp), is this mainly due to the transformers it uses?
Also, the extension cable SRE-725 uses OOC (copper), yet the signature models (& L700) use silver OOC. Does this mean not advisable to use extension cable with 'silver' cabled models as this limits them to the constraints of copper OOC cables (if there is any difference)?
padam
Headphoneus Supremus
I have an SRD-X Pro. Performs as advertised, meaning not very well, there are a few Staxes which work reasonably well with it, and it is one of the cheapest and most portable ways to have the vintage Stax sound, so considering those things, I can't see myself not keeping one around.
You can't really evaluate the SRD-7 as a standalone product. You can hook it up to a 100$ speaker or integrated amp or a 1000$ speaker amp or a 10000$ pair of monoblock amps - you get the idea.
I wouldn't care too much with extension cables. They work. Maybe a tiny difference, but there are other things, which are much more important to good sound.
You can't really evaluate the SRD-7 as a standalone product. You can hook it up to a 100$ speaker or integrated amp or a 1000$ speaker amp or a 10000$ pair of monoblock amps - you get the idea.
I wouldn't care too much with extension cables. They work. Maybe a tiny difference, but there are other things, which are much more important to good sound.
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IIRC the SRD-X Pro uses the actual headphone signal to generate the 580v bias which is pretty poor design.
SRD-7 doesn't do this and has bigger/better transformers but is still not optimal, you'll get some roll off above 15khz with the SRD-7 as the transformers saturate. It's possible you may actually find this enjoyable but yeah, it's not accurate. One thing you should do with the SRD-7 that helps a lot is remove the thermistors and replace with resistors since they add unnecessary distortion in the signal path. Takes 15 minutes with a soldering iron. I go over the process starting with this post: https://www.head-fi.org/threads/the-stax-thread-iii.677809/page-1605#post-17658579
Only way to get "optimal" performance from a transformer is DIY using something like Lundahls or Edcors. Reason I put optimal in quotes is some would still argue it's suboptimal due to some odd transformer effects but you can at least get big voltage swings and flat frequency from a large enough and well built enough transformer.
You could also buy an SRD-7 already modded with Lundahl transformers from Mjolnir Audio if you're ok spending $1500 instead of the $500 to do it yourself.
Tyler Durden
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How will you use it with the Stax?
aokman
100+ Head-Fier
Definitely ditch the STAX SRD transformer thermistors if they exist / but you must run with resistors, if you try to run them directly, the FR will be completely out of whack and there is a sharp voltage rise as frequencies increase. Ironically the Edcors perform almost identically. The problem is getting non inductive wire wounds these days, not that I noticed a difference in the real world.
The SRD transformers work…. Ok I guess… but leave a lot on the table at low frequencies, you can technically fit 2 Lundahl 1630s inside an SRD7 enclosure also.
I will have a video out on this soon
Would love to hear why transformers are suboptimal also because I haven’t found any downsides yet though I haven’t got into measuring phase etc… yet.
This graph is only very early quick testing still with Edcors and I hate using external resistors, I have a lot of work to go…. The LL1630s always gave me the warm fuzzies with how well behaved they are out of the box with no screwing around.
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With a transformer like the one mentioned in the post you quoted and the post above yours
I think simconn posted about in somewhere in this thread. Weird second order type stuff not readily apparent in voltage swings or frequency responses.
I don't think it's an issue really. I mean, a simple way to think about it is that 95% of amps have output transformers anyway and they're fine.
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KDS315
100+ Head-Fier
Google “Hysteresis” … (hint: causes low frequency distortions)
icnaiwhimor1975
New Head-Fier
all these transformer things are just a cheap way to listen to hp, hold out until waiting for a package with a real amplifier like Megatron or Carbon
After listening to them just once - you will no longer want to return to transformer boxes
It makes sense to use transformer boxes with something cheap like cheapest lambda series if the main goal is to save as much money as possible
aokman
100+ Head-Fier
Ahuh…. I keep hearing such things then you try to decide what direct drive amp to buy and the crap fights begin about what direct drive amp. KHSSHV, BHSE, Z10e and god knows what else and no one was willing to subject one to analytical measurements vs a high end transformer setup, let alone each other…
I have 2 transformer setups and counting now and 3 high end amplifiers and still haven’t got near the price of a BHSE alone…
Whatever floats your boat I guess but I'm betting you cannot hear any difference between a reference direct drive amp and a high end transformer setup in a blinded comparison. Then again Im expecting all the usual audiophile caveats at that point of “your source isnt good enough” you need “better estats” “you cannot measure the differences analytically”
etc6849
100+ Head-Fier
You're welcome to your opinion, but it's not objectively true. I have a used BHSE I bought which is superb, but was curious about transformer mods after seeing old posts on them and videos like this:
I've measured square waves and sine waves, etc... comparing the two setups below. BHSE's square wave was slightly better when fed from a signal generator, but once you feed it using a signal from a DAC, the square waves look identical between the two. Plus the transformer setup has more headroom too, a lot more in fact!!! While off the shelf energizers/transformers may or may not compete, modding them can easily compete if you have decent amps driving things. Some measurements are below.
I stopped testing the transformers at 2kV peak to peak, but the setup can go higher no doubt. The BHSE clips ~1500V peak to peak. You can easily drive the X9000's to 1500V peak during transients and I've heard clipping on a few tracks before (admittedly only able to notice it on maybe 2/100 tracks, but it's there and repeatable). Plus I have clipping indicators now on the Benchmark AHB2 amps, while all the SS or tube driven options have no clipping indicators (a huge drawback in my mind as I like to know if my amps are clipping).
Qualitatively, I highly doubt any one can hear the difference between the two setups; unless you drive the BHSE into clipping, and have the transformer setup not clip which again is possible with the hard to drive X9000's on a few tracks. It really does sound superb. Used price, I realize the Benchmark setup + transformers is more versus the BHSE used price. However, I already had the Benchmark gear for my speakers, so they now perform dual duties in my office. Essentialy, the comparison is iFi Pro iESL plus the transformers versus the BHSE which is a huge price difference.
Transformer measurements:
Transformer square wave thru the DAC3 B:
Transformer fed from signal generator:
BHSE Square wave thru the DAC3 B:
BHSE fed from signal generator:
I've measured square waves and sine waves, etc... comparing the two setups below. BHSE's square wave was slightly better when fed from a signal generator, but once you feed it using a signal from a DAC, the square waves look identical between the two. Plus the transformer setup has more headroom too, a lot more in fact!!! While off the shelf energizers/transformers may or may not compete, modding them can easily compete if you have decent amps driving things. Some measurements are below.
I stopped testing the transformers at 2kV peak to peak, but the setup can go higher no doubt. The BHSE clips ~1500V peak to peak. You can easily drive the X9000's to 1500V peak during transients and I've heard clipping on a few tracks before (admittedly only able to notice it on maybe 2/100 tracks, but it's there and repeatable). Plus I have clipping indicators now on the Benchmark AHB2 amps, while all the SS or tube driven options have no clipping indicators (a huge drawback in my mind as I like to know if my amps are clipping).
Qualitatively, I highly doubt any one can hear the difference between the two setups; unless you drive the BHSE into clipping, and have the transformer setup not clip which again is possible with the hard to drive X9000's on a few tracks. It really does sound superb. Used price, I realize the Benchmark setup + transformers is more versus the BHSE used price. However, I already had the Benchmark gear for my speakers, so they now perform dual duties in my office. Essentialy, the comparison is iFi Pro iESL plus the transformers versus the BHSE which is a huge price difference.
Transformer measurements:
Transformer square wave thru the DAC3 B:
Transformer fed from signal generator:
BHSE Square wave thru the DAC3 B:
BHSE fed from signal generator:
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