brat Posted May 27, 2008 Report Share Posted May 27, 2008 I use this popular thread to share an observation: After long term troubles with my STAX system I listen to the Omega II mk2 + SRM-727II with great pleasure while waiting the KGSS to be built. But sometimes while listening to classical music I feel something wrong... Last night I compared the staxes to my Corda Prehead+k701 system and the problem cleared: the stax system lacks dynamics. All orchestral moments that must be LOUD and accented sound somewhat suppressed. The same thing appear when I listen to classical piano works - all "wild" moments are somewhat smoothened and void of emotions. The same parts are much more realistic ( in this respect ) with the dynamic rig. Has anyone noticed such an effect? I suspect it's a question of amplification but I'm not sure... Quote Link to comment Share on other sites More sharing options...
Smeggy Posted May 27, 2008 Report Share Posted May 27, 2008 Yes It's definitely a problem with some Stax amps. It's one of the reasons I went back to transformers. Also, I can't afford the real hi-end offerings and a good speaker amp plus transformers is, to my ears, more dynamic, more edgy with good bite. I don't find my Staxes lacking dynamics or life in any way now. I personally don't line the super smooth, relaxed sound some prefer, I like mine to have some spiky bits and a touch of sharpness. Even if I lose a little in the way of detail it's a worthwhile tradeoff for me. I've been modding and tweaking my Staxes to tune them for my preferences and they are killer now. Those wild moments come with aplomb. I don't really care what type of transducer I listen to as long as it sounds great to me, so far it's just working out that 'stats are doing it best, they produce the ideal sound for me and when you get it sorted there's no lack of dynamics or musicality going on. I was giving myself a good blast of classical last night and the hairs on my back still go up and when a crescendo comes, you know it. Quote Link to comment Share on other sites More sharing options...
brat Posted May 27, 2008 Report Share Posted May 27, 2008 What transformer are you using? Quote Link to comment Share on other sites More sharing options...
Smeggy Posted May 27, 2008 Report Share Posted May 27, 2008 What transformer are you using? I'm using a SRD-7MkII, though even my SRD-6SB sounds good with my SR-Lambda. Running a big-ass power amp through them gives them big balls. I don't have an Omega and the Omega may well need more juice than the SRD's can provide from what I've read, however, for the rest, they're great. As I've said previously, I'd put these up against anything else I've heard with confidence. Quote Link to comment Share on other sites More sharing options...
Tachikoma Posted May 31, 2008 Report Share Posted May 31, 2008 My builder is having some trouble with this amp http://gilmore.chem.northwestern.edu/head3.htm, he said something about the "getting insufficient voltage" at certain stages (with the net result being horrible sound), it wasn't very clear over the phone but I've asked him to write down a list of all of the problems he's having. One of his complaints was that the schematic seemed ... incomplete. Could someone add more annotations to the schematic for me? >_> Quote Link to comment Share on other sites More sharing options...
justin Posted May 31, 2008 Report Share Posted May 31, 2008 My builder is having some trouble with this amp http://gilmore.chem.northwestern.edu/head3.htm, he said something about the "getting insufficient voltage" at certain stages (with the net result being horrible sound), it wasn't very clear over the phone but I've asked him to write down a list of all of the problems he's having. One of his complaints was that the schematic seemed ... incomplete. Could someone add more annotations to the schematic for me? >_> I tried, but failed, to build this a few years ago. I didn't have as much test equipment as I do now or as much experience, but what I found was i might have around 40Vrms audio signal at the cathodes of the 2nd stage tubes. However, each 0A2 tube was losing about 10Vrms audio, so there was almost nothing left for the 6S4A to amplify. I had RCA 0A2 tubes but never tried any others. You may want to try Russian equivalents that may be newer. Also, you can try neon lamps or zener diodes, i never tried either of those to see if it solved my problem. Also, at least for testing, you can capacitor couple the output of the 2nd stage but by removing the 0A2s you'll have to change the circuit so the voltage on the 6H30 isn't exceeded and add a grid resistor for the 6S4A The only thing I see incomplete in the schematic is that power ratings aren't given for the resistors but if you can't calculate these you'll have a lot more problems later. There's also no way to adjust DC voltages, you may want to replace the 1.2K resistor with a resistor+pot in series, to adjust points A and B to be 0VDC, and replace the 600 ohm degeneration resistors with resistors + a pot for a +/- DC offset adjustment. You should also split the 300K resistors into 3x 100K or 2x 150K or at least make sure the single 300K is rated for high voltage Quote Link to comment Share on other sites More sharing options...
justin Posted May 31, 2008 Report Share Posted May 31, 2008 oh and most importantly, you need at least 3 filament supplies (input 6H30, 2nd 6H30, 6S4As can share one) Quote Link to comment Share on other sites More sharing options...
Tachikoma Posted May 31, 2008 Report Share Posted May 31, 2008 I'm using zeners for the build for now, so that part shouldn't be the problem. I'll forward that info to my builder, thanks! Quote Link to comment Share on other sites More sharing options...
spritzer Posted May 31, 2008 Report Share Posted May 31, 2008 Make sure that he's using enough heater supplies and then swap in some NE-2's or 0A2's to test. Also what PSU is being used? Quote Link to comment Share on other sites More sharing options...
Tachikoma Posted May 31, 2008 Report Share Posted May 31, 2008 I'm not too sure about the PSU, I gave him the schematics for the BH's PSU but he might have improvised something on his own since we lost the BH PCB to USPS/malaysian post. He's an experienced tech when it comes to "normal" tube amplifiers, but this is his first electrostat amp so I can't say I didn't expect any screw-ups Quote Link to comment Share on other sites More sharing options...
spritzer Posted May 31, 2008 Report Share Posted May 31, 2008 I'm not too sure about the PSU, I gave him the schematics for the BH's PSU but he might have improvised something on his own since we lost the BH PCB to USPS/malaysian post. He's an experienced tech when it comes to "normal" tube amplifiers, but this is his first electrostat amp so I can't say I didn't expect any screw-ups That could be the reason as the amp might be drawing too much power. I hope that Kevin will chime in and help as I have a lot of 0A2's and 6SA's that will be perfect for this amp. Quote Link to comment Share on other sites More sharing options...
luvdunhill Posted May 31, 2008 Report Share Posted May 31, 2008 You should also split the 300K resistors into 3x 100K or 2x 150K or at least make sure the single 300K is rated for high voltage Xicon resistors would work fine here (700 VDC if I recall), or even better are Mini-Mox resistors as they have a very high HV rating. Both are available at Mouser. Quote Link to comment Share on other sites More sharing options...
Voltron Posted June 1, 2008 Report Share Posted June 1, 2008 As a result of Jack Wu's kindness, I have had the Woo GES prototype in my house since CanJam ended. I have not spent as much time as I might have hoped with the GES, but it is a big improvement over the Stax 007t and made me actually think the Omega II was enjoyable (right before I sold them!). Although the prototype is an old model (obviously) and is not supposed to be up to the current production model's standard, it is a very good match with all of the Stax cans I have thrown at it. That would include the O2, 4070s, Lambda Pro, Lambda Signature, and Stax SR-5NB Gold, and each of them improved with the GES over the 007t. That is also saying something special because the 007t was being fed a balanced signal from the EMM Labs rig, while the GES got merely single-ended signal from lesser cables. Anyway, I cannot do a full review of this wonderful amp for lack of time spent and time to commit to it, but I can definitely say that its greater power and increased finesse both add greatly to the listening experience. When I upgrade or add to my electrostatic setup, the Woo GES will be at the top of the list. Even upgraded in a few ways that Jack recommends and with top-notch tubes, it is still a much more affordable option than other available high-end amps. Also, it is a one-box and compact unit in the stock configuration, which is another plus in my book and given my overcrowded racks! Congratulations to Woo Audio for another fine amp in their line-up. In fact, there is a rumor circulating (and I have not spoken to Jack about it yet) that there will be another Woo electrostatic amp in the near future. It is a higher-end model and I know basically nothing about it other than it is supposed to be on the way. I will be watching for sure! Here are a couple pics of the Woo and Stax 4070s. I didn't have room on the rack for a solo spot so the GES is sitting on top of the VPI SDS speed controller. Enjoy (I know I do!): Quote Link to comment Share on other sites More sharing options...
deepak Posted June 1, 2008 Report Share Posted June 1, 2008 I spent some time comparing the SR-Lambda and Omega 2 last night. I hadn't listened to the Lambda in a long time prior to this mostly because of not having much free time. Confirms my suspicion that the Lambda is an excellent entry into the world of Stax. Even though the Omega 2 beat them in every way (resolution, detail, holographic soundstage, midrange/bass quality) the Lambda are still damn fun to listen to and more forgiving of lesser systems. Quote Link to comment Share on other sites More sharing options...
postjack Posted June 1, 2008 Report Share Posted June 1, 2008 In fact, there is a rumor circulating (and I have not spoken to Jack about it yet) that there will be another Woo electrostatic amp in the near future. It is a higher-end model and I know basically nothing about it other than it is supposed to be on the way. I will be watching for sure! This is great news, thanks for the heads up Al! If the 4070 was my can, the GES would be my amp. Quote Link to comment Share on other sites More sharing options...
spritzer Posted June 1, 2008 Report Share Posted June 1, 2008 In fact, there is a rumor circulating (and I have not spoken to Jack about it yet) that there will be another Woo electrostatic amp in the near future. It is a higher-end model and I know basically nothing about it other than it is supposed to be on the way. I will be watching for sure! It will be fun to see what they come up with. I hope they use some cheaper tubes and at least direct couple some of the stages. If it's just a GES with a differential input as has often been talked about then that will only mean more ECC83's (rather expensive for the good stuff) and even more caps in the signal path. Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted June 1, 2008 Report Share Posted June 1, 2008 If it's just a GES with a differential input as has often been talked about then that will only mean more ECC83's (rather expensive for the good stuff) and even more caps in the signal path. The extra capacitors in the signal path part is not necessarily true. It can also be done with the same number of tubes, and slightly higher distortion. Quote Link to comment Share on other sites More sharing options...
spritzer Posted June 1, 2008 Report Share Posted June 1, 2008 The extra capacitors in the signal path part is not necessarily true. It can also be done with the same number of tubes, and slightly higher distortion. Thanks for clearing that up. I do hope they come up with something new, hell I'll settle for another take on the SRX circuit but built to the standard of the rest of the Woo gear. Now if they were to use something new like GU50's for output duty I'd buy one on the spot. Quote Link to comment Share on other sites More sharing options...
The Monkey Posted June 1, 2008 Report Share Posted June 1, 2008 It will be fun to see what they come up with. I hope they use some cheaper tubes and at least direct couple some of the stages. If it's just a GES with a differential input as has often been talked about then that will only mean more ECC83's (rather expensive for the good stuff) and even more caps in the signal path. Based on some correspondence with Jack Wu (a really nice guy, btw), he plans to introduce the new offering in 2-3 months (depending on how busy they are). It will be a two-box, all-tube rig. It appears that Woo Audio is aiming for the high end with the new amp, and the price likely will be significantly higher than the GES. Quote Link to comment Share on other sites More sharing options...
spritzer Posted June 1, 2008 Report Share Posted June 1, 2008 Based on some correspondence with Jack Wu (a really nice guy, btw), he plans to introduce the new offering in 2-3 months (depending on how busy they are). It will be a two-box, all-tube rig. It appears that Woo Audio is aiming for the high end with the new amp, and the price likely will be significantly higher than the GES. Though it will be more expensive it should be good value. Woo don't just jack up the price like some other manufacturers do to make the amps look more high-end then they really are. Quote Link to comment Share on other sites More sharing options...
The Monkey Posted June 1, 2008 Report Share Posted June 1, 2008 Though it will be more expensive it should be good value. Woo don't just jack up the price like some other manufacturers do to make the amps look more high-end then they really are. Agreed. I think it's a good opportunity for Woo Audio to make a real statement about price to performance. Quote Link to comment Share on other sites More sharing options...
Smeggy Posted June 2, 2008 Report Share Posted June 2, 2008 When is someone (reliable) going to make a decent cheap stat amp to compete with the lower end Stax models? Quote Link to comment Share on other sites More sharing options...
The Monkey Posted June 2, 2008 Report Share Posted June 2, 2008 When is someone (reliable) going to make a decent cheap stat amp to compete with the lower end Stax models? Yes agreed, there is an opportunity there (provided that it can be done, I am ignorant about the tech of stat amps). Perhaps now that Stax fever has grabbed many of us firmly by the [insert word of choice here], someone will realize the opportunity. Of course, we're all marching steadily toward the O2, so the cheap amps may not be forthcoming when we so obviously will cave in and pony up whatever it takes. Quote Link to comment Share on other sites More sharing options...
justin Posted June 2, 2008 Report Share Posted June 2, 2008 When is someone (reliable) going to make a decent cheap stat amp to compete with the lower end Stax models? It's not possible to beat the Stax SRM-313 for the price Quote Link to comment Share on other sites More sharing options...
Jon L Posted June 2, 2008 Report Share Posted June 2, 2008 I welcome any and all new developments in the 'stat/amp arena. About 20 years more of constant new products in the 'stat arena should get us close. Direct-coupled new Woo 'stat amp with 5-pin XLR for HE Audio eh1.2b sounds just..about.. Quote Link to comment Share on other sites More sharing options...
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