spritzer Posted February 11 Author Report Share Posted February 11 Yup... Apex. 2 Quote Link to comment Share on other sites More sharing options...
usa_love Posted February 11 Report Share Posted February 11 thnaks for the photos, so it turns out the only difference is in the availability of the DAC and the price Quote Link to comment Share on other sites More sharing options...
spritzer Posted February 11 Author Report Share Posted February 11 Yeah and this one has more power it seems. Still pitiful but a bit more. Quote Link to comment Share on other sites More sharing options...
Kung Posted February 16 Report Share Posted February 16 (edited) yes，build everything that can make sound into a fancy box，and sell them to those audiophiles in china for over $10K，that is what these high-end brands are doing right now. Edited February 16 by Kung Quote Link to comment Share on other sites More sharing options...
spritzer Posted February 16 Author Report Share Posted February 16 So I should cram a Koss E/90 into a gold box and charge 20k$? 1 Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted February 16 Report Share Posted February 16 (edited) you mean like this there was another koss circuit on ebay from a guy in ukrane, i did not save that picture. it was even worse. the soviet era toroid transformer is a real gem. Edited February 16 by kevin gilmore 2 2 1 Quote Link to comment Share on other sites More sharing options...
usa_love Posted February 17 Report Share Posted February 17 16 hours ago, kevin gilmore said: you mean like this there was another koss circuit on ebay from a guy in ukrane, i did not save that picture. it was even worse. the soviet era toroid transformer is a real gem. the appearance is not very good, but it is powerful and bias there is 1300 volts I saw his scheme - on the technical side it looks good Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted February 17 Report Share Posted February 17 here is another koss circuit. this one seems built better. Quote Link to comment Share on other sites More sharing options...
usa_love Posted February 17 Report Share Posted February 17 28 minutes ago, kevin gilmore said: here is another koss circuit. this one seems built better. I'm not sure if this is the koss circuit or if it has anything to do with it Quote Link to comment Share on other sites More sharing options...
usa_love Posted February 17 Report Share Posted February 17 they will definitely be better than any Chinese in which you get just a pair of power transformers as sound transformers for $600 Quote Link to comment Share on other sites More sharing options...
usa_love Posted February 17 Report Share Posted February 17 and this thing for $1200 Quote Link to comment Share on other sites More sharing options...
usa_love Posted February 17 Report Share Posted February 17 or this fot 700$ Quote Link to comment Share on other sites More sharing options...
usa_love Posted February 22 Report Share Posted February 22 On 2/17/2023 at 1:06 PM, kevin gilmore said: here is another koss circuit. this one seems built better. it looks like it's really a koss scheme found this photo from one of those who used this amp and found a photo from the coss - the same transistors and capacitors and I think the power is small there - the transistors are too small https://www.head-case.org/forums/topic/3816-koss-esp950-electrostat-thread/page/19/#comment-803295 Quote Link to comment Share on other sites More sharing options...
spritzer Posted February 22 Author Report Share Posted February 22 The Koss unit draws 9W from the wall, max so factor in PSU losses, very high rail voltages, that you driving 4 amplifier channels and yup, there is not a lot of power there. So Woo has a new electrostatic amp out, WA7e... who wants to guess that it is a tube pre driving some Apex modules? 1 1 Quote Link to comment Share on other sites More sharing options...
usa_love Posted February 22 Report Share Posted February 22 4 hours ago, spritzer said: So Woo has a new electrostatic amp out, WA7e... who wants to guess that it is a tube pre driving some Apex modules? at least it's not just 2 transformers - it's already better Quote Link to comment Share on other sites More sharing options...
spritzer Posted February 23 Author Report Share Posted February 23 I'd take a transformer solution, that is properly driven, over the the Apex garbage. Just look at the specs of those modules, they are truly terrible. Quote Link to comment Share on other sites More sharing options...
usa_love Posted February 23 Report Share Posted February 23 2 hours ago, spritzer said: I'd take a transformer solution, that is properly driven, over the the Apex garbage. Just look at the specs of those modules, they are truly terrible. what exactly do you not like why then does stax use them in their D10 Quote Link to comment Share on other sites More sharing options...
spritzer Posted February 23 Author Report Share Posted February 23 The specs, go read the datasheet. Because Stax, under Chinese control, doesn't give a shit? The D10 and D50 have very little to do with Stax in Japan. Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted February 23 Report Share Posted February 23 are you so clueless that you cannot read a datasheet. the apex opamp used in the woo is a class C device. with 450v power supply rails. so loud and horrible. the apex opamp used in the d10 is a class a/b device with 175v power supply rails. so too quiet for most people. Quote Link to comment Share on other sites More sharing options...
usa_love Posted February 23 Report Share Posted February 23 10 minutes ago, kevin gilmore said: used in the d10 is a class a/b device with 175v power supply rails. so too quiet for most people. This is still a portable device with a power supply of 12-16 volts that you can take with you in your pocket. And its power is enough for the lambda series. It's still better than some Kingsound M03 with a couple of flooded trances and a $0.1 class D amp. Quote Link to comment Share on other sites More sharing options...
usa_love Posted February 23 Report Share Posted February 23 if someone does not have enough power - you can always use the bridge mode I don't know if this is a good idea my friend once had an idea to do something similar on opa464 but I think the opamps themselves are worse in terms of signal slew rate are even worse than apex Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted February 23 Report Share Posted February 23 this is how it is already done. the headphones are balanced drive only. Quote Link to comment Share on other sites More sharing options...
spritzer Posted February 23 Author Report Share Posted February 23 Indeed, the rails are just not high enough. Even the old SRM-001 has a single 600v rail for the output Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted February 26 Report Share Posted February 26 Contrails said: @Ciggavelli did you ask Woo about their 3ES amp and their false advertising? I did. He confirmed it’s not a 300B output. He said the 300B isn’t powerful enough so it needed a Mosfat for the output, but I’m not really sure what that means. reference: CanJam NYC 2023 Impressions Thread (February 25-26, 2023) | Page 16 | Headphone Reviews and Discussion - Head-Fi.org so lets be specific 1) mosfet for output. lets rephrase that. 4 x apex class C high voltage power opamps. 2) 300B not powerful enough? pair of tubes is good for 18 watts. more than enough to damage your hearing. All of my tube designs that use el34 you can substitute emission labs 300b. with an adapter and extra filament transformers. Works great. plenty of power. including bh, gg, t2 and megatron. and justin's grand cayman. just because jack does not know how to correctly design amplifiers with 300b... 5 1 3 Quote Link to comment Share on other sites More sharing options...
spritzer Posted March 1 Author Report Share Posted March 1 Well he's right about one thing, a 6SN7 feeding a 300B hasn't got a hope in hell of driving electrostatics simply because of the voltage gain. Why anybody would want to use 300B's for this role though when the 20B exists is beyond me. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.