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Stax SR-507 investigation


spritzer

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Considering the huge difference in signal chains, I'm not sure that a meet comparison between my 507's amd n3rdling's O2's means much. What we should have done at the last NorCal meet was plug my 507's into the B.H. and done a direct comparison. Hopefully we'll get another chance. What is pretty clear is that the 507's are substantially closer to the O2's than any previous Lambda. I'm curious what the rest of the updated Stax line sounds like.

I had a go with the SR-507s and the O2Mk2 recently and i primarily went with the SR-507s because i felt getting the SR-507s weren't gonna be such a huge compromise as with the earlier lambdas and didn't wanna totally commit into the O2s with the C32 looming around the corner.

I had a brief comparison with the SR-207s as well and the 507s were definitely fuller and more mature sounding than the 207s but haven't had a go with the 407s yet which i read to be really close to the sound of the 507s.

Anyone had a go with the 507s and 407s or even 307s for that matter?

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You guys need to get your feet wet and build something. There are plenty of cost effective, easy to implement, and surprisingly effective DIY designs out there if you dig a little. Make a ton of mistakes, go through a learning curve, and get something successful under your belt before attempting anything as complex as the T2. Got to learn how to crawl before you can run. Consider it the start of a journey.

I aint no engineer.

My abilities fall under the "tech" level.

I built a MSSH. No problems. It works wonderful.

Admittedly a beginner's project.

I am now tackling a KGSSHV.

Due to a couple of fuck-ups i am going through DIY hell.

I am making a ton of mistakes. Aint done with the learning curve yet.

No T2 for me, thanks.

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I had a go with the SR-507s and the O2Mk2 recently and i primarily went with the SR-507s because i felt getting the SR-507s weren't gonna be such a huge compromise as with the earlier lambdas and didn't wanna totally commit into the O2s with the C32 looming around the corner.

I had a brief comparison with the SR-207s as well and the 507s were definitely fuller and more mature sounding than the 207s but haven't had a go with the 407s yet which i read to be really close to the sound of the 507s.

Anyone had a go with the 507s and 407s or even 307s for that matter?

The 507 and 407 are indeed very close. The only thing that I notice is that the bass on 507 is a little bit better.

Wachara C.

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The easy version of the T2 is the Blue Hawaii. They are pretty similar over all and the sound is certainly close enough.

As for the 507, I never got over how bright they are but I do think they complement the SR-007Mk1 well, that's certainly how Stuart feels (who now owns my set).

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For 507 (or 407) what's a good starter amp? SRM-323, SRM-006t, or other?

I'm getting started with an old STAX classic, the SRM-1/Mk2 PP that Spritzer sold from his collection just a while back. And having compared the SRM-1 with the SRM-007tii (stock) at an audio shop, i didn't feel i was missing too much but adopting the older STAX amp.

Sorry to say i've no other experience with those amps you listed (SRM-323, SRM-006t or the works).

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More power means the amp is less of a factor in the over all sound. That's the whole point of designing better amps IMO. Feed the transducer properly and you'll get the most from it.

I'm also talking about the older versions of these amps, nobody knows what the S thing stands for or even if there are any real changes.

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The SRM-323 ouputs +/- 400 volts to the rails, what is the rating on the SRM-006t?

EDIT: Found the answer. SRM-006t = +/- 300 volt rails.

Regarding the "S" thing, you are referring to the older stuff, right?

As of late, it seems the "S" suffix relates to 120volt mains input. (States?-for the U.S. market)

While the "A" suffix denotes 100 volt mains for the Asian (japanese?)market.

I could be wrong here, as I see conflicting vendor info on ebay.

Would probably be smart to buy the amp from an established vendor in the USA

to avoid the stepdown transformer hassles needed for a 100 volt mains unit.

Edited by livewire
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Voltage swing and the rail voltages don't go hand in hand like that but the SRM-323 doesn't just swing more voltage, it is also more tolerant of the load it "sees".

The S is the export code while the Japanese models are named M. The old code was II and A which just confused everybody.

I wouldn't personally pay extra for the same amp when the Japanese units can be changed to either 120 or 230V.

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Spritzer speaks the truth, power matters. (see post #62 above)

Case in point, I have a low-end Stax setup.

SR-202 Lambdas with a SRM-252II amplifier that has +/-280 volt output rails.

The sound is incredible, but I have no headroom.

The phones max out with SPL of ~85 to 90 dB depending on the source.

I am currently building a KGSSHV with +/- 450 volt output rails.

That should do the job (and then some). I really need MOAR POWER!

I do plan on upgrading to the SR-507's in the near future as well.

EDIT: I just saw your last post. I certainly do not claim to know

everything as you do, but I do know that I need MOAR POWER!

(and I want to keep it SS)

Edited by livewire
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I wouldn't personally pay extra for the same amp when the Japanese units can be changed to either 120 or 230V.

Yes, but not everone is tech saavy as you are, and handy with a soldering iron.

Then there is the issue with violating the warranty,

that is if one is given when buying from a japanese vendor.

Also the newer units are not "voltage switched" on the backside like some of the older units are. Right?

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Power and volume have very little to do with one another. Sure if you drive the amp flat out then it will compress quite badly, same goes for the 006t since the 6CG7's are run past their limits. What you are descibing is just gain which can easily be increased or just convert the amp to a balanced input to double the input voltage. I'm all for more power but it is all about control over the diaphragm and load tolerance but not volume.

Converting the amps can be difficult but some are very easy. Solder two wires from the transformers to the PCB and change the jumper settings. Minimal skill involved.

As for the US warranty, that's a none issue. There is nobody to service the amps should they fail as Yama's doesn't answer the phone.

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The 727 often has the windings cut which can be a pain to fix. Then you need to remove the lacquer on the winding, add some solder to it and then fashion a jumper to the external pin on the trafo. Not all that hard to pull off.

I've had two 323's here and both simply lacked the 117V wires from the transformer so once they were installed all you need to do is change the jumper settings. Those are soldered on the main PCB but are easy enough to change.

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Someone please tell me that a WES will drive the 507s better than the SRM-323.

The Peak->HD800 sounds awfully close to SRM-323->SR-507 right now. I assume the 507s will scale.

Did you order a WES?

I thought my old GES was excellent with my SR-Lambda, SR-Lambda Pro and SR-Lambda Signature, as well as ESP-950; but it seemed to need more power with HE-60 and O2 Mk1/2. So the GES might be a cheaper alternative for the 507. I know my WES sounds very good with LNS, giving a nice warm euphonic tone and big soundstage, and it drives my HE-60 and O2 Mk1 better than my old GES; but the WES's power, micro-detail, and air was not as good as the BHSE at RMAF. So I'd worry the WES might be overkill in price just for the 507. The biggest improvement to me is the WES soundstage width and depth is certainly bigger than my old GES which was more narrow and closed in sounding, although the GES soundstage wasn't what I'd call small. And the WES seems to give me that extra 3-4dB in headroom that I was always wishing for in my GES.

All my brothers-in-law who compared the O2 Mk1/WES to my re-cabled HD800/ZDT over last thanksgiving liked the WES rig more (same PWD DAC/Bridge source). They all preferred the O2 Mk1 over the HE-60 as well, citing better warmth/bass and a richer more natural sound.

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I haven't heard the SR-507 but I've heard pretty much the other Lambdas out there and in this man's opinion, I think a tube-based energizer should suit a Lambda better. Something that can "moisten" the sound a bit should work extremely well.

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Someone please tell me that a WES will drive the 507s better than the SRM-323.

I'd say no. Even if we look past just how fubar the WES is in terms of design then the 323 simply has more voltage swing and is more immune to the load it sees. The WES has more power but that advantage is largely lost due to those stupid inductors and any DC offset present at the output.

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It's certainly a conundrum for me. I've had a lot more time to appreciate the 323/507 combo. The 323 doesn't seem to have a problem driving the 507 - plenty of bass, impact, control, and detail. Also 323/507 sound has opened and warmed up quite a bit since when it was brand new. I've heard better amps drive the SR-507 though - mainly Frank Cooter's plutonium powered amp - but that thing's a beast.

My plan was to pick up a WES (no BHSE because I don't want to wait a few years), and consider an O2 or C32 later this year. As K3cT mentioned, I would just like throw tubes in the way - just a personal preference. On the other hand, as Spritzer mentioned, the WES does have a couple of reactive elements in the signal path (I believe there are a lot of caps in the way - between stages and at the output? And no, I'm not into magikcal V-caps either), which makes me think it wouldn't be as clear and detailed as even the 323.

LOL, maybe for now, I'll just DIY a simple tube buffer stage between my DAC and the 323.

Anyone know if KGSS turnaround times are truly 4 weeks?

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