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Post by Deleted on Jun 8, 2011 12:26:51 GMT
I don't mind paying if its the norm, but this is outrageous. I'll scout around, order off ebay if necessary. Thanks Alex.
Syd
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Post by Deleted on Jun 8, 2011 12:28:56 GMT
I don't mind paying if its the norm, but this is outrageous. I'll scout around, order off ebay if necessary. Thanks Alex. Syd Syd Check your PM Alex
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Post by Deleted on Jun 8, 2011 13:22:14 GMT
Syd, I'm also using TL071 s, to good effect. I just happened to have a supply of them from another project. As for the Wimas I'm using Banzai in Germany more and more. RS Spain (Amidata) provide patchy service at best and Farnell Spain are a bit screwy on prices for some unknown reason. Banzai 3.3uf 63v 5mm (Don't know why but that reminds me of; in Arnie Schwartzie voice "The Uzi 9mm" )
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Post by Deleted on Jun 8, 2011 13:42:31 GMT
Hi Chris
Thanks for the link. I'll keep it for future reference but for now it looks like I'll go with the crazy Farnell price. Its only £6 as I only need two but the unit price is such a rip off it really annoyed me. As I am paying a P&P charge already for my Farnell order for their reasonably priced other items I would just be spiting myself on a point of principle!
I've ordered a couple of the OPA 134s. It wasn't the price, it was the case type but I now know they're OK, thanks.
Syd
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Post by Deleted on Jun 8, 2011 23:13:20 GMT
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Post by Deleted on Jun 9, 2011 9:30:58 GMT
Hi Alex, just thought I'd throw that in, after five hours solid relaxed listening, to my revitalised "BLACK HOLE'y stuff via the Sandy K plus your balanced phono stage. That's a revelation that is. The low hum is only apparent at the highest setting on Jeff's DACT not likely to listen up there. TT earth best spot appears to be 0v into the phono just about kills it dead. Not hitched it up to the Quad for speaker test yet evening listening has to be by HP. I'm sure it will get even better once it's cased up.......gee I'm slow. Thanks for your help Alex never thought I'd have such good SQ. Strange my internet access dropped out just as I was about to post this last night so I retired for the shut eye however black stuff through the Quad this morning is first class.....or should that be.....Class A......? Alan
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Post by Deleted on Jun 9, 2011 10:04:07 GMT
Hi Alan I am pleased to hear that you were able to get rid of most of the hum. I will be interested in hearing how it sounds through speakers after it is all cased up. Regards Alex P.S. Did you notice much difference after the front end balance was fine tuned ? Also, how is the JLH connected to the RIAA preamp's power input now ?
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Post by Deleted on Jun 9, 2011 11:57:53 GMT
Hi Alex, RIAA preamp's power is as block dia. Did you suggest another JLH before the IRAA. Balance was very close from start so I can only say that the sound is superb. Wont be around till tomorrow we are off for an all day lunch with our friends. Regards, Alan
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Post by Deleted on Jun 9, 2011 12:05:31 GMT
Hi Alan O.K. You are still using a dropping resistor to drop around 5V followed by a 1,000uF to 0 V. It would be interesting to try feeding 7815 and 7915 from +-20V followed by a CL dual JLH with the series dropping resistors removed, and the 1,000uF reduced to 100uF. Getting a little unwieldy though .You could try 7815 and 7915 instead of dropping resistors though, with 100uF instead of 1,000uF Alex
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Post by Deleted on Jun 9, 2011 23:30:47 GMT
Hi Alex, not sure what your suggesting here.....I have +-20v coming out of the PSU into dual JLH and 19.78 or there abouts out of the dual JLH being fed to AKH/preamp...(SandyK)...power for the dual IRAA is therefor 19.78 output from dual JLH going into 7815/7195 fronting the IRAA with a reg. 15v-+ into 47R the 1000uf have been dropped to 100uf as per your original suggestion. Listening to Elkie Brooks as I type and must say it seems to get better the more I listen Should I remove the 47R? Boy if you can improve on what I'm hearing now you'll never see the end of these little fellows Regards, a devotee of the "SandyK" Alan
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Post by Deleted on Jun 9, 2011 23:34:00 GMT
Hi Alan Yes, seeing you are already using the 7815 and 7915, try it with the 47R bridged out. Alex
P.S. Have you tried increasing the value of the 1.5uF output capacitors? Only try it if the low end appears slightly rolled off due to the input impedance of the HA/ preamp. Especially if you are using a 20K volume control/attenuator instead of 50K.
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Post by Deleted on Jun 9, 2011 23:52:57 GMT
Hi Alex, uptodate on block diagram
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Post by Deleted on Jun 10, 2011 0:04:36 GMT
Hi Alex, okay but not tonight .... good Australian red wine good food and good friends add up to a good day. Yes low end is as you say, must tighten up Thelma Houston's bottem end. Now on "Thelma Houston I've Got The Music In Me" direct to disc recording from late seventies....superb....thanks Alex, Alan
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Post by Deleted on Jun 10, 2011 0:15:16 GMT
Hi Alex, okay but not tonight .... good Australian red wine good food and good friends add up to a good day. Yes low end is as you say, must tighten up Thelma Houston's bottem end. Now on "Thelma Houston I've Got The Music In Me" direct to disc recording from late seventies....superb....thanks Alex, Alan Hi Alan Further down the track you should try a JLH between the 7815/7915 and the phono preamp without the 47 ohm resistors. Even if it doesn't do much more there, another reserve JLH never goes astray. I hope you have a designated driver after all that food and wine ? Have a good day ! Regards Alex P.S. When you have finished tweaking the phono preamp to the max, perhaps you should use it to digitise your vinyl to 24/192 before you wear them out !
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Post by Deleted on Jun 10, 2011 0:23:28 GMT
VC is 20K would 50K be more appropriate. Gee haven't listened to such good music in a long time.......I'd be mad to put all this back under the bed. Alan
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Post by Deleted on Jun 10, 2011 0:29:33 GMT
Hi Alex, must get to bed before I'm ex-communicated....no driver we walked to the Choo...Choo train about half a mile then train ride of ten minutes, seniors pass gets low rates on train fares then .....pub...sorry good pub just outside station, train home no need to drive just find a good rolling gait. Alan
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Post by Deleted on Jun 10, 2011 0:30:10 GMT
VC is 20K would 50K be more appropriate. Gee haven't listened to such good music in a long time.......I'd be mad to put all this back under the bed. Alan Alan Let's see if the low end improves without the 47 ohm resistors Alex. P.S. Shouldn't you be in bed ?
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Post by Deleted on Jun 10, 2011 19:47:31 GMT
Hi Alex, bridged the 47Rs.......volume up.....low end much fuller everything much more detailed. I'm beginning to appreciate the sad fact that much of the "Holey Black" stuff that I have is only fit for turning into plant pots......that is of course a product of the SQ of your circuits where the old adage.....shite in shite out never rang truer. Equally good quality recordings really shine, as I write this I'm listening to Eric Clapton Slowhand....last night it was Elkie Brooks Pearls.....and a handful of others that had seduced me into the wee sma hours as I marveled at the detail being reproduced from well recorded vinyl.....yes the phono stage is a well worth addition to the "SandyK". Alan
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Will
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Post by Will on Jun 10, 2011 20:36:19 GMT
15W/Ch. Class A Upgrade. Looking good Alex! Did you notice much difference when the input caps were removed, along with the feedback cap? Good to hear it works well in this application as well. Also, did you use normal 0.5w resistors for the group of 8 1R resistors? Would you or Frans offer any advice on whether it'd be OK to mount the output zobel (4.7uH inductor and 6R8 resistor) off the pcb and hardwired to the speaker outputs, seeing as an offset corrector lives where the zobel used too Also, any recommendation on sourcing a suitable inductor would be very useful. At a later date, it might be a good idea to break out the 15W stuff to a separate thread, if I can get the 15W pcb closer to completion.
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Post by Deleted on Jun 10, 2011 21:02:46 GMT
Hi Will My BP has been a bit variable lately, so I haven't had a chance for extended listening sessions. However, I have been surprised with the SQ from DTV in the evening, as it is more pinpoint, and with a further improvement in dimensionality.The low end sounds more precise too.The improvement is enough to want to make me upgrade the preamp using the other completed pair of those lovely black PCBs. I used 1 ohm 1% .5W MF resistors in the output stage. I haven't tried an offboard Zobel network, but I would keep it very close to the PCB.I used the supplied formers and wire from the SC HA kits for the Zobel inductors.I reduced the number of turns a little though.(from memory 20T instead of 24 1/2. ?) Regards Alex P.S. I found out by accident that a suitably heatsinked LM317T is more than capable of use by itself, without the series pass transistor when dual PCBs are used.Quality LM317T such as those from Fairchild are specced for maximum current in excess of 1.5A.
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Post by Deleted on Jun 10, 2011 21:27:39 GMT
Hi Alan Now you can see why I got out of vinyl.I really liked my half speed masters, but you can't just play the same stuff over and over again. The average LP at the start of the CD era had become horribly compressed in order to fit more on a side, and they often used recycled vinyl.(with paper labels still stuck on ?) Some of the brand new vinyl releases of today will be much better, but again, much of it is old catalogue stuff. Alex
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Post by Deleted on Jun 19, 2011 15:00:28 GMT
JLH - For use with the Class A HA, do I just need to swop the 16V caps for 25V. What uF?
Thanks
Syd
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Post by Deleted on Jun 19, 2011 21:12:46 GMT
JLH - For use with the Class A HA, do I just need to swop the 16V caps for 25V. What uF? Thanks Syd Hi Syd Only the 10uF and 100uF need to be upgraded to 25V. The large electros only have around 600mV across them. Alex
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Post by Deleted on Jun 19, 2011 22:15:11 GMT
Hi Alex
That's great, thanks Alex. I have a good stock of both those. Glad I hadn't ordered the 'big ones'!
Syd
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Post by Deleted on Jun 22, 2011 23:58:08 GMT
Work in progress. I am presently constructing a new Class A preamp to replace the present preamp in my main system. It is also using the Class A HA/preamp PCBs as used in the Class A HA, and designed by Will. The delay PCB is capable of being used to switch to headphones, but I haven't yet decided whether that facility is needed in the main listening room. I intend using the rotary switch as shown at the attached link for Input switching, instead of relay switching of the Inputs.The main reason being that I wish to retain maximum channel separation, as well as being also able to switch the "Earth" side of all of the inputs to avoid any added noise from other devices using internal SMPS. If I had decided to use relay switching, I would have needed an additional relay PCB, as well as using more screw type connections than I would like to use. The rotary switch shown, not only has ceramic wafers, but it also has 2 separate wafers, which will aid with maximising channel separation. I intend reclaiming the DACT CT2 from the existing preamp for use as a volume control. Alex cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=120731587552&ssPageName=ADME:L:OU:AU:1123URL=http://imageshack.us/photo/my-images/713/workinprogress.jpg/] [/URL]
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