FritzS
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Sound of Blue Danube
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Post by FritzS on Jan 31, 2011 5:43:04 GMT
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Will
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Post by Will on Jan 31, 2011 8:42:33 GMT
I've always found it best not to argue with SWMBO, and in this case yours is spot on  |
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Will
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Post by Will on Jan 31, 2011 8:55:09 GMT
Nice links, thanks for those!
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Will
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Post by Will on Jan 31, 2011 9:00:01 GMT
Hi Guys,
I've had a potential difficulty pointed out when assembling the board.
Now, 3mm thick pcb's look nice and do double up well as burglar deterrents, but they can cause a problem if using a dip socket for mounting the op-amp in the offset corrector, as the pins of the mount can be on the short side. If they are, then it's advisable to use a thin tip in your soldering iron, and flow the solder in.
My apologies for the over-sight on this point, and hope it doesn't cause too much grief.
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Post by Deleted on Jan 31, 2011 9:51:35 GMT
when Wife number 7 complained that ''we don't do things togerther any more'  '. i booked her into and electronics course for her birthday.  that did it  my generosity knows no bounds  take care Chong. |
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Post by Deleted on Feb 2, 2011 16:30:40 GMT
Hi Alex
I've just swapped out the 100pf input filter caps for some 47pf to use with my 50k switcher and it does make a difference. not a huge one but a bit more sparkle and air to the top end.
I'm going to be trying the two TX setup tomorrow so it will be interesting to see what that does.
thanks
take care
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Post by Deleted on Feb 2, 2011 20:35:10 GMT
Hi Alex I've just swapped out the 100pf input filter caps for some 47pf to use with my 50k switcher and it does make a difference. not a huge one but a bit more sparkle and air to the top end. I'm going to be trying the two TX setup tomorrow so it will be interesting to see what that does. thanks take care Hi Shaun Good luck ! The method of earthing used is critical for good results when using dual transformers. I earth both TX centre taps to the metalwork directly at the AC sockets, but Will gets good results with his method too. You don't get an earth loop due to the transformer isolation between primary and secondary, so it should still be dead quiet, even when used as a preamplifier for a power amplifier. Alex P.S. If using a rack case, it is a good idea to run wires from the AC sockets' earth connection to the front panel and base plate. Anodised panels need extra care to achieve proper bonding. |
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Will
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Post by Will on Feb 2, 2011 21:31:07 GMT
Shaun, nice update on the cap change. I must admit I wasn't aware of it until Alex mentioned it recently. I'll get me some on them 47pF in. Hope the dual traffo goes well, it'll be worth it  |
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Post by jeffc on Feb 2, 2011 23:37:48 GMT
Hi Alex, Thanks for the tips on grounding. A question on this, in the Audiowind PSUs, as per the circuit diagram, I've inserted a 0.1uf film cap from the 0V output to one of the standoff holes that when used with metal standoffs is designed to ground this to the metal chassis, apparently in Chinglish for "0V (GND) to Chassis DC Blocking, High-Frequency Equivalent Short-circuit".  I was wondering whether this might be a problem with ground loops/hum, particularly with the use of 2 transfomers, so seems a good time to ask. cheers.. jeffc PS. PSUs + JLHs as well as the 12 x 100 uf caps for the Class A PCBs have been cooking since Sunday. Ages ago I made a little 15V DC cap pre-former to the design you sent me so a perfect opportunity to make some use of it.  |
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Post by Deleted on Feb 3, 2011 0:09:50 GMT
Hi Jeff I would try it with, and without. No, it will not cause an earth loop. Not having looked at your PSU schematic, I expect that my method of earthing will make it redundant. Alex Attachments:
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Post by Deleted on Feb 3, 2011 2:33:40 GMT
Hi Alex I've just swapped out the 100pf input filter caps for some 47pf to use with my 50k switcher and it does make a difference. not a huge one but a bit more sparkle and air to the top end. I'm going to be trying the two TX setup tomorrow so it will be interesting to see what that does. thanks take care Hi Shaun Good luck ! The method of earthing used is critical for good results when using dual transformers. I earth both TX centre taps to the metalwork directly at the AC sockets, but Will gets good results with his method too. You don't get an earth loop due to the transformer isolation between primary and secondary, so it should still be dead quiet, even when used as a preamplifier for a power amplifier. Alex P.S. If using a rack case, it is a good idea to run wires from the AC sockets' earth connection to the front panel and base plate. Anodised panels need extra care to achieve proper bonding. Hi Alex I totally agree with the method above. i star earth as much as i can. on anodized Ali i usually give it a good rub with coarse wet and dry to get a good bond and then measure the resistance to ground just to be sure.. ;D well just to say i have both transformers up and running (well it is tomorrow )with no issues. it's soooo quiet (like no noise at all that i can hear )now and really shows the thought put into it.  so now for a listen.  I'm not really expecting the channel separation to be that much better with vinyl due to the limits of cartridges (very poor Chanel separation) but i may try some Flac (yes i know you don't think much of it) as it may do the Chanel separation thing better. it will be interesting to hear. as for the case the PSU is still in a scavenged instrument case but he's going to get a nice suit to. I'm going to use the same PSU for the pre and as i won't be using the pre and HA at the same time it's just a question of swapping the power leads (not hot swapping though). pretty cool. take care |
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Post by Deleted on Feb 3, 2011 2:38:12 GMT
Hi Shaun
Nice going !
If you need a few high quality .wav files to test with, let me know and I will UL some.
Regards
Alex
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Post by Deleted on Feb 3, 2011 3:05:27 GMT
Hi Shaun Nice going ! If you need a few high quality .wav files to test with, let me know and I will UL some. Regards Alex Hi Alex Nice going yourself is more to the point .initially i did get a very small amount of hiss but after a few days it just dropped away. now with the two TX using the method you outlined above it's still quiet as can be. yes some nice .wav would be greatly appreciated. even after a quick listen I'm very happy with the sound (understatement ). I'll have a better listen tomorrow and post some thoughts if i can drag myself away from the music (a quick listen can easily turn into three hours). what i have noticed with the Class A is that i get no listener fatigue whatsoever. I've listened to some HA that leave my ears ringing after half an hour or so. The K701 and the Class A are just perfect together. so all good take care |
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Post by Deleted on Feb 3, 2011 3:22:37 GMT
Hi Shaun
I will UL a few in the morning (Aus. time) when it's cooler , as it's 33.7C here and still slowly climbing.For best results I turn off the PC's front and rear PWM controlled fans during ULs, but I don't want to do that when it's so warm outside.
Regards
Alex
P.S.
Now 37.1C at 2.25PM
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Post by Deleted on Feb 3, 2011 4:55:13 GMT
Hi Will, Make that 3 sets!!! mine were waiting for me when I got back home this afternoon. And some other stuff as well. A BIG thanks to you for all your efforts!!! The boards are, well, a work of art, tbh. I have never seen FR4 so thick!! This should be fun!! Cheers Jon I will have to repeat what Jon said above. Will I thought you were exaggerating about the IC socket pins possibly being a fraction too short, although still usable .  I have never seen FR4 so thick before either ! Thanks again, for all your time and effort with this project. Regards Alex |
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Will
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Post by Will on Feb 3, 2011 8:48:56 GMT
I'm glad that you've said that as well. It's exactly what I think of the amp. There does seem to be a synergy between the amp and K701, which I have mentioned before. When working from home, I've spent up to 8 hours listening to music via this amp and headphones, and not felt anything odd at all. It's a clear indication of how good this amp is, and a massive thanks to Alex for doing the hard bit and coming up with this HA design, tweaking it until it's perfect and then sharing it with us |
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Will
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Post by Will on Feb 3, 2011 8:51:21 GMT
No problem, Alex, it's been an absolute pleasure!
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Post by Deleted on Feb 3, 2011 14:09:55 GMT
They're heeeerrrrre! Will, many thanks. They are the most substantial boards I've ever seen. (A PM on the way in a min.) Shall we rename the amp the "2011 Monolith Odyssey"? Size and quality together, don't tell the wife! ;D Once my PSUs arrive I'll be able to join in on the fun Chris |
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Post by Deleted on Feb 3, 2011 14:28:21 GMT
Hi Alex and Will I’ve been trying to collect some thoughts regarding the Class A and let me tell you it’s not easy. Usually I’d listen to a piece of kit and think yes this or that part of the sound is great or not and this or that could be better. Well with this HA it’s just so even-handed with no parts exaggerated in any way. It just has honesty to the sound which just lets the music speak for itself without imposing on the sound. It has the sort of clarity, cohesion and musicality that at times just takes my breath away. I spent 2 years at college learning recording techniques (from rocking and rolling cut and splice analogue to 24bit digital and ambisonic) so am interested in listening to that work on recordings. The Class A just totally reveals what’s going on in the recording without being in anyway forensic or unmusical. It’s just crystal clear without being clinical, smooth without being boring and musical in the best sense of the word. It’s just plain lovely to spend time with. Out of curiosity I had a small techno and trance party last night and anyone who say’s that the K701 can’t do that stuff should get themselves a listen to this amp. I just kept on keeping on and just sounded soooo effortless and almost liquid in its ability to deal with the all important fine detail. A real party monster with the Hallucinogen – twisted Flacs ( I do like alsorts)that I tried. Bass was tuneful and appropriate to the rest of the recording and just sounded spot on. The Class A just takes you deeper into the mix and I just remember in between the wows thinking I don’t remember hearing that before. So the dual mono switch in Well with my turntable it had more of an effect than I was anticipating with a deeper soundstage (not sure what the word for that is it head stage) which was kind of domed with so much air and space (out of head listening experience). I think also that clarity and cohesiveness improved noticeably. With Flac, well that was just a huge jump in SQ with a wide open but flat sound stage. I must say that the level of difference was much more marked with my Squeeze box duet and CA Dacmagic. It really did sound like I’d totally upgraded my front end to something much more expensive. The thing that impresses me is that the same cohesion, liquidity and plain rightness exists with analogue and digital playback which is some achievement. I think that all of the work balancing the transistors and regulated PSU’S along with the JLH just creates a stunningly good sound (what a recipe what a cake) ;D The down side (and there’s always at least one) I love to build but won’t be building another HA for the foreseeable future. I do think that the SCHA DAC looks interesting so may need some help with that. So no review of this or that track or album I’d fall asleep doing that but I do feel that I’ve had long enough with this amp to make some comments. So the question just how good is it? The best HA I had listened to previously was the WAD tube one which I like but the Class A does so much better than the WAD but without the sugar and cream. It has to be the best piece of equipment in terms of getting so much right that I’ve EVER heard. Will and Alex are Audio heroes for making this amp a real possibility even for dullards like me. Their hard work and ability to suffer all of my stupid questions just speaks volumes to me about the sort of people they are. (Top banana's) Inadequate as it is THANKS SO MUCH to Alex and Will for all of your work on the SCHA (the sound of which really made me take note) and the Class A. so no review but some initial thoughts. Those building this amp are in for a real treat. I’ll give my wife the final say ‘’Just a work of pure genius’’ Well it started as just a few words.ramble ramble take care |
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Post by gommer on Feb 3, 2011 14:57:19 GMT
I've been hesitating but under the motto "Everything I always wanted to know about the SC classA, but was afraid to ask", here goes:
How does this amp compare to the Panda HA? (yeah, I know, Panda is China designed and this one is Rockgrotto designed).
Cheers, Marc
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Post by Deleted on Feb 3, 2011 15:55:33 GMT
I've been hesitating but under the motto "Everything I always wanted to know about the SC classA, but was afraid to ask", here goes: How does this amp compare to the Panda HA? (yeah, I know, Panda is China designed and this one is Rockgrotto designed). Cheers, Marc Hi Marc i have both HA just as a moment of madness can i use a quote from Spartacus (film) to address your question? Lawrence Olivier to Tony Curtis in the famous bath scene ''some people prefer Snails and some prefer Oysters. some prefer to eat both, have you ever wondered why that is?'' ;D its just a question of personal taste and preferences isn't it? i would rather limit my remarks on this thread to SCHA related stuff if just to keep the build process moving along and fun. i really hope that a further group build may be a possibility in the future as this would allow people to build the Class A for themselves and make comparisons if they wish. take care |
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Post by gommer on Feb 3, 2011 16:07:27 GMT
Yeah, I understand it must almost sound insulting to ask, since this amp's history is one of several years of tweaking in one huge group effort to reach the holy grail.
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Post by Deleted on Feb 3, 2011 17:33:21 GMT
Yeah, I understand it must almost sound insulting to ask, since this amp's history is one of several years of tweaking in one huge group effort to reach the holy grail. Hi Marc no not insulting, it's just better to build and hear for yourself than taking anothers word for it. how are your DIY skills ? if you like you could build a SCHA to start off with (as many did and still happily use) which would put you a third (IMHO) of the way there in caparison to the ClassA (no insult intended to the SCHA). the SCHA was a great starting place for myself and many others also. there are plenty here myself included who would be happy to help you with that. then if another Class A group build comes up you can jump in. Marc i have seen some of your posts and Know you are a cool guy so please don't take my comments as an insult as none was intended. just my way of saying each to their own i guess that what i was trying to say was that one of the great things about DIY is that for comparatively little cash you can find out for yourself and be helped along by people who want you to have fun and build nice things. that's the real beauty of this place just cool people who want to help. take care |
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Post by gommer on Feb 3, 2011 18:03:56 GMT
Hey, I wasn't offended in any way, I'm just being sincerely humble in my wording. DIY is fun and cheap, agreed, but it's terribly time consuming when you start tweaking. On top of that, I don't have a place of my own to work. I have a desk for administrative stuff and the PC, that's it. Everything else must be executed on the kitchen table and must be out of sight by the end of the day. Woman, love them and hate them I'm living with hope though, within 4 years time I'll have my own permanent electronic workshop corner set up in the new house that we're building. |
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Post by Deleted on Feb 3, 2011 18:20:03 GMT
Hi Marc
yes me to. I'm a kitchen table surgeon also but the new house sounds great.
we're thinking of building a garage for the same sort of DIY use. strangely enough my wife finds it all quite fascinating (in a psychologist studying her subject kind of way) and thanks god i did not take up motorcycle or car rebuilds as a hobby.
take care
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I was wondering whether this might be a problem with ground loops/hum, particularly with the use of 2 transfomers, so seems a good time to ask.
