jonclancy
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Post by jonclancy on Jan 15, 2013 23:54:15 GMT
That's the one - 10K. I paid a little less than 695 Euros, though!
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Post by Deleted on Jan 23, 2013 17:28:34 GMT
Well here it is number two build to partner the 15watt for my elder son.............might just keep this one and give him the first build. Still a bit to do but half is working "ACE". One channel fully operational after a slight hiccup with the DC offset being 269mv with the OPA installed and 7mv with it out. DC offset now -3mv and music brilliant. So on to channel number two.
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Post by Telstar on Jan 23, 2013 18:12:15 GMT
Another - note the resistors on the attenuator. Which spacers and screws did you use to bolt the PCBs to the bottom of the case? Can you point me to some kit on Mouser or RS?
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Post by Deleted on Jan 23, 2013 22:12:17 GMT
Well here it is number two build to partner the 15watt for my elder son.............might just keep this one and give him the first build. Still a bit to do but half is working "ACE". One channel fully operational after a slight hiccup with the DC offset being 269mv with the OPA installed and 7mv with it out. DC offset now -3mv and music brilliant. So on to channel number two. Hi Alan The work is up to your usual high standard well done take care
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Post by Deleted on Jan 24, 2013 10:16:23 GMT
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jonclancy
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Post by jonclancy on Jan 30, 2013 17:55:15 GMT
Nice work again!!! I can report I am currently having a rest to allow my bleeding eyes to recover after soldering uo one end of my power umbilical. I have, taaa-daaah, finished the amp wiring. Just one end of the umbilical to go then I'll gash together the trafos and se if I can coax this amp into life!! The modules are tested, so as long as the psus are ok, then we should be in the ball-park. I'm smewhat excited. It's been a while since I was doing audio stuff. I think that my recently developing crap eyesight and fat fingers isn't helping. Glasses sort the first problem out. The second...? Who knows!!! No brain surgery or filigree jewellery projects for me!
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Post by Deleted on Jan 31, 2013 1:28:36 GMT
What a load of bollocks Installed the supposedly good amp module as a permanent fixture in the case. Check voltages again and offset is back up and higher than before. So after a thorough check of layout and soldered joints I threw the thing to the side and had a go at it's mate. That was a real disaster with one OPT nicely warm and the other cold and high dc offset to boot. Well before I could take any more voltages I noted a curl/wisp of smoke rising from the JLH section both C/L Trs cooked. Time to install fuses. Not all bad news though as the main PSU REG section is okay just the JLH both sides Pos/Neg a bit worn. No visual reason for the blow out that remains to be sorted. Tonight I returned to the original working amp module for another session at the high offset with the OPA installed and low with it out and found I'd placed C22 across earth and input of the 79L instead of earth and output. Fixed that and DC offset is now 0.1mv and hopefully no more grief from that side. The other amp module has the same error so that should fix the high Dc on it also. Hopefully I'll get it's other faults rectified soon. Alan
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Post by Deleted on Jan 31, 2013 1:42:34 GMT
Hi Alan You have done very well, as you even made your own PCBs, so a few hiccups are to be expected. The rest of us are spoiled due to Will's very nice PCBs making it much harder to make simple mistakes. Kind Regards Alex
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Post by Deleted on Jan 31, 2013 1:59:59 GMT
Hi Alex, getting late here so I'm off to bed, I quite enjoy the fact that I've looked at the circuit worked out a layout carved out the boards and the thing actually works well. With the boards for this build I reworked part of the layout to make the ground run with as few links as possible and did away with a link on the offset line from pin 6 /R35 to R11, that required a bit of a jiggle around the offset section. I'm more concerned with the high current drawn by the other board which cooked the CL section but since it made me realise that I should have made provision for fuses on the PSU boards it's a lesson learned. I've bought fuse holders for all the PSU modules so they will be installed ASAP. Nothing ventured nothing gained. Perhaps it's a bit of Mike's Karma. Alan
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Post by Deleted on Jan 31, 2013 3:05:04 GMT
Hi Alan Did you have small heatsinks fitted to the CL Toshibas, and the Toshibas with the 33 ohm emitter resistor ? What value emitter resistor were you using in the CL ? Also, you can get 1% MF .25W resistors in the 1 -10 ohms range that could be worthwhile in the CL emitter resistor position. I will be using 1 ohm 1% .25W resistors in the emitters of the power output devices. Kind Regards Alex
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Post by Deleted on Jan 31, 2013 11:42:07 GMT
Hi Alan ''so a few hiccups are to be expected''. yup i totally agree with that and you've built the whole thing from scratch which is quite some achievement. when i think of the fun and games i had initially with my build (transistors the wrong way round ) and the hours of uncle Alex's valuable time i used. you've done really well. so hopefully now you are good to go. now just think what an utterly superb pre/power you have made take care
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Post by Deleted on Jan 31, 2013 12:16:22 GMT
Hi Alex, the penny just dropped Current limit ;D As I quite like my Combo...PSU/JLH.........compact, all on the one board and easily configurable for a variety of voltages and currents.................did I just say currents with an ssssssssssss.....................shi..t.t.t.t.t.t yes the penny drops So replace the Toshibas in the CURRENT LIMITER SECTION drop the emitter resistor value to 1R as per scheduled for the Preamp/HA not wot's init at the moment set for the 15Watt at 150R fit the fuse holders with .5a fuse in place of the present link between the Reg section and JLH and it should be good to getting on with finding out what caused the high current draw in the right hand preamp board. I've hooked the good section up to the #2 build 15Watt and am now listening to half of #2 build Preamp via the 15Watt and TL speakers...............sounds as good as if not better than #1 build. So when I've got this one fully functional I'll revamp the #1 build new case as per this build with switches and Vctrl at the case rear much shorter internal cables and much neater, of course PSU boards will be replaced with the better combo version and all with no music down time. Are heatsinks in the C/L section JLH required for the Pre/HA? I thought that was for the higher current draw of the 15 Watt. Regards Alan
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Post by Deleted on Jan 31, 2013 12:29:46 GMT
Hi Shaun, with what I'm listening to at the moment and with only one side of the new Pre working it looks as if this build will perform better than the first and that's quite an achievement in that the first build is so good. Lots of hobby work ahead getting the first build revamped. Still following your exploits with interest.................. sometime soon hopefully I'll move on. Third call to lunch.................better go. Regards, Alan
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Post by Deleted on Jan 31, 2013 13:06:06 GMT
Hi Alan I didn't feel the need to use heatsinks on the CL device in the preamp, but in view of what happened to you it wouldn't hurt in combo with a 1/4W emitter resistor. That resistor could even be as high as 1.5 ohms as we don't need a current limit of >500mA with either.It must have been a decent s/c to overheat the CL device when it was limited to <600mA by the CL. (20V at >500mA perhaps across the CL transistor?) A small heatsink is a good idea at +-20V, but not needed at say +-15V. Perhaps that event helped prevent major damage to the amp PCB ? Kind Regards Alex
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Post by Deleted on Feb 1, 2013 0:48:14 GMT
Hi Alex, combo PSU repaired and working, just the toshies in the CL section and replaced the out of step emitter resistors. Had to parallel three reading at around 2.6R to get it down to 1.4R but it's a working unit with fuse holders in place of solid links. Well no more soldering till Monday as we are off curling for the weekend. Starts with lunch 1pm at the Grouse and Claret Kinross tomorrow Friday and ends with curling final on Sunday afternoon. Guaranteed to be totally shagged out by the Sunday evening. Perhaps not the best phrase but you get the drift. Regards, Alan
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jonclancy
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Post by jonclancy on Feb 1, 2013 15:49:41 GMT
I have POWER ON!!! But, have lost my set up instructions.
Will be emailing my Antipodean Guru for guidance. More later.
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jonclancy
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Post by jonclancy on Feb 1, 2013 16:07:19 GMT
Unless anyone here has them please??? I can't wait the 5 hours until Alex get's online!!! I'll have a flick back through the thread....
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jonclancy
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Post by jonclancy on Feb 1, 2013 16:28:41 GMT
Ah, of course!!! Linked to in Will's signature.
However, in the near two years it has taken me to get this far, I have dicovered that I have already bench-set the bias and checked the dc offset. Power on for a good old cook, methinks!!!! Then front-end balancing. Then....
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Post by Deleted on Feb 1, 2013 17:17:36 GMT
Ah, of course!!! Linked to in Will's signature. However, in the near two years it has taken me to get this far, I have dicovered that I have already bench-set the bias and checked the dc offset. Power on for a good old cook, methinks!!!! Then front-end balancing. Then.... Hi John fingers and toes crossed you'll be joining the super sound club pretty soon. i hope it all goes well take care
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jonclancy
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Post by jonclancy on Feb 1, 2013 17:44:42 GMT
... no sound!! Amp heatsinks are warming nicely. I seem to have pre-set 400mV bias previously, but I have double the sinking in my build. It's a wiring check that'll need to be done tomorrow. Never mind!!! Hopefully I'll get come Class A soon. It's taken two years thus far, so another day or two won't hurt...
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jonclancy
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Post by jonclancy on Feb 1, 2013 18:06:58 GMT
Wow!!! This thread was started by Leo nearly FOUR years ago!!!
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Will
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Post by Will on Feb 1, 2013 19:08:56 GMT
Hi Jon,
If I remember right, you had tunes out of this a while back, before building it up into the case?
Check your wiring again, try checking GND continuity between various part of the PCB and see what you get.
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jonclancy
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Post by jonclancy on Feb 1, 2013 20:37:39 GMT
Hi Will,
Just set up the bias and voltages, but I didn't get round to getting it on the scope. I suspect my mad wiring scheme!! I'll get the sig-gen and scope fired up tomorrow and just trace the wiring. But yes - probably a ground out!
Cheers
Jon
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jonclancy
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Post by jonclancy on Feb 2, 2013 17:57:56 GMT
Got tunes. And a wigging for me for being thick!! Just some mis-wiring on the signal side. A bit more tweaking tomorrow. Jobs for the future include converting box (pre-drilled) to DC only, with JLH in there. Currently running AC through the umbilicals. Did I mention it sounds GREAT!!! Very pleased to hear it sing - and I confess me ol' eyes sweated a bit!! Peg - Steely Dan Aja (Hoffman mix). Niiice!
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Will
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Post by Will on Feb 3, 2013 8:34:29 GMT
Nice one Jon! very pleased to hear that it's working!
It's worth while getting it nice and warm through use and then rechecking the bias and front end balance a few times, and it'll be fully on song, as well as getting the JLHRE's in?
Using your k701's?
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