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Post by Deleted on Jun 18, 2010 21:09:11 GMT
I must remove my SS Class A amplifier from it's cabinet during winter then !
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Post by Deleted on Jun 18, 2010 21:36:18 GMT
Mine goes in a sleeping bag, so it gets plenty of rest as well.
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Post by Deleted on Jun 19, 2010 8:50:08 GMT
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Post by Deleted on Jun 19, 2010 10:37:59 GMT
Well done Frans. A great article. The picture of the G2 made me chuckle - It's looking like Atlla the Hun's helmet. Very 'Chinese' looking with those big cooling fins.
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rowuk
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Pain in the ass, ex-patriot yank living in the land of sauerkraut
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Post by rowuk on Jun 19, 2010 14:04:37 GMT
A brilliant article. I am getting an itch to DIY this with point to point wiring. A second thought is to have a switchable discrete transistor and tube front end. Then I could switch as my mood or the music demands. No more discussions about what is better.
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Post by rmouser on Jun 25, 2010 0:14:33 GMT
Has anyone noticed on eBay that a G2 6N23P Tube version is out has the IRF510 installed in it?
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Post by Deleted on Jun 26, 2010 9:22:27 GMT
Yes ... Judge Buff mentioned it.
Luckily the specs did not change at all ;D
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Post by Deleted on Jun 26, 2010 10:28:56 GMT
A BIG THANKS TO FRANS, I returned home yesterday, and this morning the postman arrived with my moded Miri. After only 15mins of listening, i can tell that this is now a very special sounding little Amp , you are a very talented man Frans. Thank you PM to follow. Will post some photo`s when i get a minute, and made some NEW FEET, the bugger has pinched my originals
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Post by Deleted on Jun 26, 2010 14:24:19 GMT
This is where your original FEET now reside. Moved the power switch to the front too, so annoying to have to reach for it in the back of the amp. The switch has to be used in order for the output disable circuit to work...
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Post by Deleted on Jun 26, 2010 14:47:25 GMT
looks like a little friendly flying thing Frans, almost got a personality with its nose , eyes and wings, and of course feet ;D BRILLIANT Update. My fully Frans modified Miri, kicks the backside of my partially modified G2 big time, the clarity and attack of the guitars on Rodrigo y Gabriela "Stairway to Heaven" and "Orion" has to be heard to be believed. I have all the parts required to complete the similar upgrade on the G2, which i am looking forward to "trying my best to do" with Frans excellent tutorial. I have a huge grin on my face listening while i type this, simply amazing. Thank you Frans
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Post by Deleted on Jul 1, 2010 13:13:30 GMT
Hi Guys, I didn't know whether to start a new thread with this or add it here - eventually decided it might be best to keep G2 things in one place. I am very happy with my G2, no mods other than a few holes in the top plate to aid ventilation, but fed by 24v linear PSU, courtesy of Lang Technical on eBay. But I have recently begun to notice when adjusting the volume there is a loud 'rustle' whilst the knob is being turned, and it's getting louder . Once the knob is stationary (correct volume reached) the 'rustle' sound disappears. In the scale of things this is not really a problem for me UNLESS it is a sign that the pot is on the verge of failure . Can any of you more knowledgeable guys offer any opinion on this please? Thanks for any replies, Dave.
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robertkd
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Post by robertkd on Jul 1, 2010 14:05:59 GMT
Well mmmm let me simply say this is a classic indication of DC on the volume control can't say I didn't raise this issue. The good news is it shouldn't go belly up it's simply a function of the way the circuit is connected wrt to the volume control, if it's not a sealed type you might find a small application of some deoxit to the inards of the volume control will reduce the effect or fix it for a while
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Post by Deleted on Jul 1, 2010 16:19:01 GMT
Robert is right.
Like to add the possibility of the source being the DC culprit. Is it doing the same with a source connected ?
If it is the source (no rustling when nothing is connected or at least very low volume) then there is a DC component present on the source and thus the input of the amp. IF this is the case the DC bias will also be screwed up depending on the position of the vol pot.
It might be the pot needs cleaning (do you live near salty water or smoke a LOT ?) like Robert says.
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Post by Deleted on Jul 2, 2010 10:59:05 GMT
Hi Frans and Robert, Thanks for your helpful responses. I tried it last night without a source connected and it still made the rustling sound. Hopefully Robert is right when he says it shouldn't go belly up. I'm sure it's only coincidence but this morning my Cyrus XPA power amp packed up and it just happens to be the next link in the chain downstream from the G2. No voltage across the output terminals but all the LEDs light up. The headphone out from the G2 works fine and replacing the XPA with my Marantz integrated restored the music so it looks as though I'm going to have to spend some money on the Cyrus . Would anyone have any clues as to what might be the problem, common faults etc?? Cheers, Dave.
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Post by Deleted on Jul 2, 2010 13:11:19 GMT
Looks like a scratchy pot. Cleaning might help or replace it if it becomes annoyingly much.
Very unlikely the G2 destroyed the Cyrus. But maybe if the G2 was switched on AND it was switched on by applying power to it (being mains being switched on or adapter plug inserted) with the on/off switch in the 'on' position a rather big DC voltage peak of around 18V would have appeared on the input of the cyrus.
Dependent on the input topology/volpot arrangement of the cyrus this MIGHT or MIGHT NOT have presented a pulse destroying the input stage of the cyrus. hard to say without a schematic.
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Post by Deleted on Jul 2, 2010 13:59:36 GMT
Looks like a scratchy pot. Cleaning might help or replace it if it becomes annoyingly much. Very unlikely the G2 destroyed the Cyrus. But maybe if the G2 was switched on AND it was switched on by applying power to it (being mains being switched on or adapter plug inserted) with the on/off switch in the 'on' position a rather big DC voltage peak of around 18V would have appeared on the input of the cyrus. Dependent on the input topology/volpot arrangement of the cyrus this MIGHT or MIGHT NOT have presented a pulse destroying the input stage of the cyrus. hard to say without a schematic. Hi Frans, Thanks for that. I'll give the vol. pot on the G2 a quick squirt with DeOxit but in the meantime I'm more concerned with the Cyrus. My local Cyrus dealer tells me that Cyrus will not even send their (the dealer) service engineer any circuit diagrams - ALL Cyrus repairs can only be done by Cyrus at their factory, so the chances of seeing a schematic are a bit slim . I cannot recall exactly how I switched everything on this morning but it is quite possible that I inserted the power adapter into the G2 with it live and the Cyrus live but there was no noise at all from the speakers when I did so, so if a DC volt pulse did appear at the Cyrus input it arrived silently. I have at least learned one lesson from this, namely only connect things with all the power being off Thanks again, Dave.
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Post by Deleted on Jul 2, 2010 15:52:39 GMT
Hi Frans, I've just looked under the bonnet of the amp. The signal paths appear to be completely seperate and run down each side of the PCB. About halfway down each side is a 20mm x 5 mm glass fuse rated at 250v 4 amp fast blow. The fuse on the right channel has blown. Questions: - 1) could a blown fuse on one channel cause the whole amp to shut down? AND 2) could the possible scenario you outlined earlier with regards to a DC surge cause such a fuse failure? Thanks again, Dave.
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Post by Deleted on Jul 2, 2010 17:34:00 GMT
1: Yes if there is a common 'error' circuit that switches off both channels if one is faulty. 2: Maybe... I guess you should have heard something on switching on.
replace the fuse with a 4A fast blow fuse and see what happens. In most cases a fuse is there to prevent fires inside when something goes wrong and not to protect the components. It being fast MAY have saved the parts in the event of a surge.
If a DC pulse destroyed the input of the cyrus it is very well possible that you would not have noticed anything and the thing went to amp-heaven in sillence. Doesn't quite explain the fuse being blown as you would expect a DC on the output and the error amp not releasing the outputs and not blowing a fuse.. This usually points in the direction of a short on the speaker terminals or blown powertransistors/FETs whatever.
if the fuse has blown without a big flash (deposits on the glass) the amp may well be working after replacement and looks to be blown by a short on the output. If the glass is tainted and the fuse is blown horribly the output stage is gone (shorted) and replacing the fuse will result in another big flash in the fuse.
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Post by Deleted on Jul 2, 2010 21:14:27 GMT
Hi Frans, Thanks for your continuing input. The fuse that is obviously blown (the other one MAY also be blown but if so it isn't so obvious) has blown gently, no flash or bang and no deposit on inside of the glass, just a 2 to 3 mm gap in the middle between 2 frazzled ends of fuse wire. I don't have any 4 amp fuses so I've just bought some on eBay but it will probably be mid next week before they arrive. I'll keep you posted. Meanwhile I've reinstated my Marantz PM6010 OSE KI integrated amp in place of the Cyrus pre and power amps and much to my surprise I'm very much enjoying it. I don't know whether it's just the different sound I'm noticing but I now have another problem - which amp(s) do I stick with? I planned to eBay the Marantz but I now may be reluctant to part with it . Cheers, Dave.
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Post by PinkFloyd on Jul 2, 2010 21:20:56 GMT
Dave,
Are you running the unit through a surge protector?
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Post by Deleted on Jul 2, 2010 22:33:57 GMT
Hi Mike, No surge protector - my leccy comes into a 1500mA UPS and out from there through a shielded power lead into an audio distribution block (almost vintage) into which are plugged both the pre and power amps amongst other bits of kit. Can I ask why you ask? Cheers, Dave.
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Post by PinkFloyd on Jul 2, 2010 22:45:40 GMT
"if" it was a surge that blew the fuse then make sure you are protected against surges in the future...... a good surge protector will take the "hit" and ensure that your equipment remains OK....
If you're an el cheapo (like me) solder a 275V MOV between the live and neutral input on all of your devices.... let "it" take the hit.... it will protect the other components downwind of it.
Mike.
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Post by Deleted on Jul 3, 2010 6:05:56 GMT
Maybe best to keep this thread clean (about G2).
With a surge I meant the output 'plop' of the G2 when the output disable relay is not activated (powered on NOT using the power switch on the amp) which has a 'surge characteristic' in this case. It being about 20V and having plenty energy (about 0.5A so 10W) this will bring the amp in saturation at least and might destroy the input stage. HP's don't like it either, especially low ohmic. That's why they installed the output relay (in a el-cheapo way if they had put some more parts/ thought into it this would not have happened) Fitting 2 anti-series 3.3V zener diodes on the input of the Cyrus will protect it in the future IF this is what destroyed it (the fuses)
Fitting a 275 V MOV over the power line (Live to Neutral) is always a good thing. Actually 2 of them is better in case there is a used ground lead. 1 from Live to Neutral and 1 from Neutral to ground. or: 1 from L to ground and 1 from neutral to ground. These can 'clip' 4kV pulses with tremendous currents (1000A) in a very short time period. keeping the pulse below 1kV whixh most devices can handle.
Better PM me for this.
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Post by tacoboy on Apr 17, 2011 21:12:07 GMT
Have the headphone amps from China been improved at all in the past 10 months?
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Post by Deleted on Apr 18, 2011 5:22:08 GMT
Some have gotten IRF510 so the bandwidth is not that limted anymore.
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