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Post by Deleted on Nov 21, 2012 0:43:03 GMT
Hi Allan As usual, very interesting, true spirit DIY work. Kind Regards Alex
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Post by Deleted on Nov 21, 2012 1:23:48 GMT
Hi Alan just the LS/OP devices to go and it's test time. great work especially on those nice hand wound chokes which are truly inspiring. take care
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Post by Deleted on Nov 21, 2012 9:47:16 GMT
Hi Alex and Shaun, nothing like DIY, thanks for your comments and as usual wouldn't have done it without RG........... should rephrase that as there's quite a bit still to do. Four transformers ordered from Airlink yesterday, ally for two cases to order and heatsinks for the power amp...............now's when you realise just how much it all costs. Shaun.............I'm going to buy a bit more copper clad board from our local supplier, not enough left to cut the PSU boards for the HA/Pre do you need any? Regards, Alan PS any recommendations for heat-sink supply?
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Post by Deleted on Nov 21, 2012 10:28:08 GMT
You still have 4 weeks, what's your problem I wish I had your get up and go Alan! Superb work as usual Syd
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Post by Deleted on Nov 21, 2012 10:32:10 GMT
Hi Alan Shaun.............I'm going to buy a bit more copper clad board from our local supplier, not enough left to cut the PSU boards for the HA/Pre do you need any? those boards that you sent me last time where super quality thick copper and made my etching efforts look pretty good. so yes I'd love two or three more sheets. let me know the cost and I'll PP you some funds. take care
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Post by Deleted on Nov 21, 2012 11:33:28 GMT
Hi Shaun, that's fine then I'll buy enough for both of us and let you know when I have it. Hi Syd, my problem is that I've toooo....much time on my hands, although I do manage to fill all my waking hours. MGLW runs a tight ship here brooks no interference in her domain and mollycoddles me no end. ;D ERGO..............Alan has only minor duties to perform and time for whatever takes his fancy. Regards, Alan
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Will
Been here a while!
Ribena abuser!
Member since 2008
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Post by Will on Nov 21, 2012 19:03:04 GMT
Hi Guys,
I've just emailed everyone on the GB for pcb's/parts, can you please have a read and get back to me?
Ta.
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Post by jeffc on Nov 21, 2012 20:40:52 GMT
Me too !!!!!! in my next life..... Alan.. nice soldering and DIY PCBs plus leading the field by a good 2 furlongs as usual... I predict my build to be completed second quarter 2014 or thereabouts.... cheers.. jeffc
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Post by Deleted on Nov 21, 2012 22:27:30 GMT
Hi Jeff, thanks, just think along these lines..................... in twenty years time............... "the Old Farts" Alex's words................... will be in their ninety's....................... and "you Younger Bloods" ........................... just the age the "Old Farts" are now. You've got a bit of catching up to do, enjoy the catching up period, cos you can't go back. Regards, Alan
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Post by Deleted on Nov 22, 2012 0:17:23 GMT
It's not a big deal, but I have found recently that the AD744 in the offset corrector of both the preamp and 15W Class A, which Shaun originally reported as sounding a little better in the 15W Class A, can be further improved by replacing them with OPA134s for a further improvement in S/N.When done in the preamp, there is a small but worthwhile improvement in clarity, naturallness and soundstage. I will also replace the AD744 in the 15W Class A when I receive more OPA134s from ebay. This is quite surprising as the original offset corrector design in the David Tillbrook AEM6000 which was a 240W/Ch Mosfet PA used a simpler offset corrector with the noisier TL071, but didn't try to attenuate opamp noise with the addition of a bypass cap to earth at it's output resistors. Attachments:
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Post by Deleted on Nov 22, 2012 0:42:52 GMT
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Post by Deleted on Nov 22, 2012 0:48:01 GMT
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Post by Deleted on Nov 22, 2012 0:50:26 GMT
Hi All Alex asked me to check out some work that he had been doing around the opamp used in the DC servo of his Class A pre. But greenhouse duties got in the way just a little bit. This morning I finally found time to play some music through my speakers due to a flood that seems to be engulfing the area that I live in. it’s going to be even worse tomorrow. Good I say no more out door work. Ok I started off with the AD744’s that I was currently using and then let everything warm up a little just to get a handle on the sound. Then I tried the OPA134’s that Alex had suggested. The first thing that I noticed was a slight drop in the noise floor (it was quiet before but now it has a little more of that inkiness). A little more fine detail. Remember that Sandy Deny track that I mentioned? Well it’s even easier to hear the way the guitar is being played. Plectrum and finger work is more vivid. The vocal also seemed to stand out a little further forward in the soundstage than I remember. Overall the sound was a little cleaner, more refined and natural. One interesting effect that I heard was that the sound stage shape had changed a little. I’d always found my soundstage a little larger than life with a slightly ‘’land of the giants’’ feel to it. I’d put that down to room acoustics and got used to it over time but with the OPA134 In the soundstage lost a little height but gained depth and width which made things a little more normal size wise. All a little more obvious through my speakers which IMHO give me a little more special information compared to the HP’s. I found that whilst none of the changes where huge they were still noticeable in my set up and worth the little time it took me to unplug one and replace it with another. thats what i call plug and play So I have two more OPA134 on order for Alex’s PA. Take care
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Post by Deleted on Nov 22, 2012 1:06:29 GMT
Hi Alan Those from a U.S.A. ebay supplier were quite cheap in a lot of 4 too. I ty to avoid RS and Element14 wherever possible, as they don't accept Paypal. I have accounts with both, but I don't like using my credit card any more than necessary.I would love to be able to not have to use a Credit Card, pay it off and get rid of it. Around 20% interest is a bloody rip off, as is the yearly card renewal fee. Regards Alex P.S. Yes, I could immediately use phone banking to transfer funds into my credit card to cover the payments, but it is a PITA, and I often forget. Regards Alex
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Post by Deleted on Nov 22, 2012 12:43:57 GMT
Hi Alex, seems you need to find a better card provider. Without a doubt RS and Farnell provide a great service, RS has the edge on Farnell as they don't seem to have a minimum order value on credit card use. Comparison of product cost between them is always worth doing as they can differ wildly. RS is offering the OPAs at a price that is certainly as good as, if not better than Ebay sellers delivered free next day, reputable trustworthy business. Many purchases via Ebay are as you know fraught with danger. Payment through PayPal still requires use of either credit or debit card unless you keep funds in your PayPal account (am I mad?) . Disputes with buyer/seller and PayPal are a PITTA, I've been there they just give you the run-around. If your card provider allows it (and most of them do), best and easiest method to get your money back from a recalcitrant seller is to use CLAWBACK. PayPal don't like it and come down heavily on bad sellers. I cant see any good reason to prefer Ebay sellers over RS in this instance. Your Ebay States seller is just 2p per item cheaper than RSUK at today's rates whilst RSAU is 60p under the RSUK price. On your recommendation, which we all value with regard to our audio nirvana, I've just bought 4 OPAs @ £2.29 each total delivered for the new build. Of course from RS, delivery tomorrow. (Have I got shares in this Company?) Regards, Alan PS I'll stick e'm in the old build which is regaling me with that AKSCMODS magical sound as I type. Just to see if I can discern any diff. I'll not read back on your or Shaun's comments before I listen, wouldn't want to be unduly influenced.
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Post by Deleted on Nov 22, 2012 21:07:18 GMT
Alan I was in no hurry for these OPA134, as I now have 2 in the preamp. Benefits of the OPA134 in the 15W will be less obvious, but beneficial.I use RS and Element 14 for the bigger stuff and ebay for stuff under $20 that I am in no great hurry for. I pay using my debit card. Most Credit Cards in Au. are now close to 20% Interest which is why our Banks are solid as a rock and highly unlikely to collapse like so many foreign banks. The bastards even kept posting disgusting record profits right throughout the recent world financial meltdown. Alex
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Post by Deleted on Nov 22, 2012 21:15:00 GMT
Hi Alex,
I currently have TL071's in my A class and had no background noise at all. Can I expect a greater benefit in changing to OPA134's from this status?
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Post by Deleted on Nov 22, 2012 21:35:01 GMT
Hi Alex, I currently have TL071's in my A class and had no background noise at all. Can I expect a greater benefit in changing to OPA134's from this status? Hi Chris With the preamp I wasn't aware of any background noise either, but through my speakers the gains were clearly obvious. It just sounded cleaner and a little more natural, and even surround sound/ ambience from DTV sounded more natural too. It's a subtle improvement but worthwhile if your speakers and the rest of the signal chain are revealing enough. Before trying the OPA134 I tried the reportedly low noise OPA27GP, and it seemed to improve treble, but on a local soapy with good beachside surround sound, voices seemed to have a weird grainy envelope around them. Very low level noise can sometimes give the false appearance of a little added treble detail. Regards Alex P.S. I tried to be more technical about this by looking at the noise contribution of the various types of opamps with a C.R.O. but the C.R.O. ran out of "grunt". Even at maximum sensitivity when using the OPA27GP I could only see about + and - 1/3 of a division of noise.I would need a very low noise shielded preamp ahead of the C.R.O. to see the differences.
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Post by Deleted on Nov 22, 2012 22:14:20 GMT
It has to worth a try then!
I'm currently putting my shopping list together for the power amps so it's no bother to add a few chips.
I may even get a case for the pre! Earlier plans of using an old integrated's case didn't work out so well, so thinking again...
Cheers
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Post by Deleted on Nov 22, 2012 22:27:11 GMT
It has to worth a try then! I'm currently putting my shopping list together for the power amps so it's no bother to add a few chips. I may even get a case for the pre! Earlier plans of using an old integrated's case didn't work out so well, so thinking again... Cheers Hi Chris I have been sitting on this one for a little while, until I got confirmation from Shaun that he heard similar improvements. BTW, I now have the 1PPM TCXO running in the SC DAC, but as I half expected, I haven't noticed any further improvement over the existing outboard Xtal oscillator. I will put that one back again later this morning and save the TCXO for something else. Regards Alex
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Post by Deleted on Nov 22, 2012 22:55:38 GMT
Talking SC DAC and your recent post it seems I have only the odd tweak left to do. Outboard xtal, extra earth strap, cap change on DAC board JLH. Then, yet another outstanding case.....
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Post by Deleted on Nov 22, 2012 23:10:43 GMT
I look forward to seeing just how individual, but functional, you can make this one!
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Post by Deleted on Nov 22, 2012 23:32:25 GMT
Talking SC DAC and your recent post it seems I have only the odd tweak left to do. Outboard xtal, extra earth strap, cap change on DAC board JLH. Then, yet another outstanding case..... Chris Do you already have the 3.3V Paul Hynes series regulator ? You should be able to appreciate it better when you have all the Class A area working.It's not designed to have a grab you by the short and curlies sound about it, just a natural and easy going sound with nothing accentuated, and a much better than average 3D presentation with good material. I will UL a few good surround type selections to test it out when more of you have completed the build of the 15W Class A . Kind Regards Alex
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Post by Deleted on Nov 23, 2012 0:03:10 GMT
Errr, no. I haven't gone down the PH reg route. The CKT is the only one I have played with, on anything. There seems to a mine field of them out there.
I guess an easy DIY on plain board version would be interesting to do if rated better than the CKT or is that just more ma capable?
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Post by Deleted on Nov 23, 2012 1:10:04 GMT
Errr, no. I haven't gone down the PH reg route. The CKT is the only one I have played with, on anything. There seems to a mine field of them out there. I guess an easy DIY on plain board version would be interesting to do if rated better than the CKT or is that just more ma capable? Hi Chris I used the PH reg because Syd kindly sent me a couple. I wouldn't call the difference earth shattering, but it was worthwhile. Like many shunts you need to be careful not to "over sauce the egg" otherwise the sound gets too focussed and fatigueing. The PH reg is VERY fast and low impedance. David2vk from Sydney is now using the alternative Belleson regs to replace the 7815 and 7915 in his W4s with apparently very good results. We hope to revisit the W4s and SC DAC , along perhaps with Allan's new toys at my place in the not too distant future. Regards Alex
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