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Post by Deleted on Jan 19, 2012 23:23:27 GMT
Javier Good luck ! It is a very satisfying feeling to bring something like this to life. As the name infers, it is highly configurable, and IMHO, markedly superior to the design from Frans evil twin.Don't be afraid to experiment with the output resistance settings to see what best suits each type of headphones that you own.I am looking forward to reading your impressions after the PSU electrolytics have had a chance to stabilise.(Perhaps after 48 hours of use ?) Regards Alex
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Post by Deleted on Jan 19, 2012 23:46:20 GMT
Alex, that was not my own CHAmp board, is the 2nd CHAmp I've built and is Mick's (I built it for him). I won't get be able to listen to it because Mick has my Alps pot, I have no other and even at its lowest gain setting it'll blow up my ear drums without some attenuation. I'm afraid I'll only be doing basic tests to check all is in order (voltages, no DC on outputs, nothing overheating, relay working, etc.). I've been enjoying my own CHAmp for quite some time and love it. I can't use it ATM due to the mentioned lack of vol pot. Until I get back I'll be enjoying Frans' G2 instead which is not bad either .
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Post by Deleted on Jan 22, 2012 9:28:42 GMT
Mick's CHAmp PCB testing finished.
Results:
Left Channel:
Unregulated: +24.0 -24.0
Regulated: +16.36 -16.37
Right Channel:
Unregulated: +24.0 -24.0
Regulated: +16.35 -16.35
DC Offeset with JP18 and J28 in place: 0.00 on both channels
All relay tests passed OK.
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FritzS
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Post by FritzS on Feb 1, 2012 8:45:52 GMT
The LME49990 has better tecnical papers then the OPA2132/2134/LM4562 and will give a very wide FR in BW-0 mode. Myself, I only use the amp in BW-1 mode so all of the above will do, but have another 'religion' then most in the Grotto/hifi community. I really cannot say if the LME49713HA would be applicable but suspect they might. There is always the chance of oscillation lurking which can only really be seen with a fast oscilloscope. It could be hard to check for operation without the proper gear. Should you want to apply them, contact me, as you can use only 2 of them in each channel and do not have to use 4 of them. resistor values have to be changed in this case, and the metal cans should be connected in a certain way. Hi, hase anyone use the metal can LME49713HA instead of the LM6172? I know LME49713HA are single and LM6172 are dual, I think this is not a great problem for using. LME49713HA could drive +- 90 ... 100 mA each and two in parallel could be adequate as LM6172 (four amps in palallel). Why not AKG K1000? Today I have an AKG K1000 as guest (loaned) ... and my Solo could drive them with much loudness ... Solo use only a single 15V Voltage inside. (my +-10V WNA MKII could drive them too, but sounds muddy)
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Post by Deleted on Feb 1, 2012 9:52:56 GMT
The LME49713HA are not very suited as a 1 on 1 replacement for this as they are not designed/intended to be used as 'followers'. Oscillations are more than likely to occur as it is not stated in the data sheet to be unity gain stable but can be used in -1x amplification provided the feedback resistor is at least 1k2. They need to see a minimal resistance in their feedback loop (output to - input), which in the case of the CHAmp is 0 Ohm. Since it cannot be mounted directly anyway you could make an adapter that includes a resistor in the feedback path (recommend 3k3) and use only 2 of them but the 270 Ohm resistors need to be changed or on the adapter the 2 (former) output pins have to be connected.
You can connect the K1000 as well as the K340 but will not come anywhere near it's maximum SPL. When NOT played very loud they can be used of course, you just cannot get the most out of them as a higher voltage is needed for that (to reach full potential at higher SPL)
I do not claim this is the best headphone amp nor that it sounds worse as the better amps. The CHAmp is primarily designed to provide a low noise and low distortion amplification in a safe manner so most headphones can safely be used without a chance of blowing them up (accidentally) as the output power is max 200mW for all impedance headphones. Most headphones can handle 200mW max. It can be configured easily to suit more different headphones to your needs/optimal performance.
The K1000 is a rare breed in the world of headphones and may be more picky about how it is driven than most other headphones.
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Post by Deleted on Apr 1, 2012 9:31:35 GMT
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Post by PinkFloyd on Apr 1, 2012 9:59:43 GMT
Nice job Mick! I see you still have the NAD... that was a good buy @ £199 wasn't it?
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Post by Deleted on Apr 1, 2012 10:17:34 GMT
Great job, Mick! I like the idea of the adjustments sheet taped in the lid, about to copy you Did you farm out the panel work or do it yourself? Its certainly distinctive Syd
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Post by Deleted on Apr 1, 2012 10:35:40 GMT
Good build !
Does that exquistely crafted Stirling engine already run on the warmth generated by the ASUS soundcard ?
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Post by Deleted on Apr 1, 2012 11:10:46 GMT
Nice job Mick! I see you still have the NAD... that was a good buy @ £199 wasn't it? Thanks Mike, Yes it certainly was, use it specifically for my HP set up through the Asus dac, which brings up to another level. Great buy indeed, superb!!. ATB.Mick.
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Post by Deleted on Apr 1, 2012 11:30:06 GMT
Great job, Mick! I like the idea of the adjustments sheet taped in the lid, about to copy you Did you farm out the panel work or do it yourself? Its certainly distinctive Syd . Hi Syd, Long time no speak!! Yes, but for the anodising which was sent to a contact i know to be carried out. The enclosure started off much the same as yours, but was then re-machined to suit. Worked a barter system with Javier, he did the pcb population, i machined his enclosure and face plate, which is essentially the same as mine with a more conservative black anodised finish face plate. Mine has the engraved (nc milled, to be black filled ) name above the HP socket, Javier chose to be inscription free. Great Amp this, sounding better all the time (approx 6hrs). Frans`s knowledge just blows me away, bl""dy genius if you ask me!! Hope you and yours are keeping well. Regards Mick.
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Deleted
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Post by Deleted on Apr 1, 2012 11:39:31 GMT
Good build ! Does that exquistely crafted Stirling engine already run on the warmth generated by the ASUS soundcard ? Great design Frans, sounds superb. Yes it is a modified copy of one commercially available, i made 5 of them shortly before i retired, gave the other 4 away to friends and family for Xmas presents. The heat from the palm of your hand is enough to keep it running, so it works a treat on top of the Assus. Mick.
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Deleted
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Post by Deleted on Apr 4, 2012 11:26:09 GMT
Its a brilliant amp, Mick. I find it works particularly well with the fully modded Superlux 681s, suitably set up for them of course. Pity is though that I can't wear the 681s for very long, compared to any of my other 'phones. Well as can be expected given the marching years Mick. Syd
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Deleted
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Post by Deleted on Apr 13, 2012 10:45:17 GMT
Hi Mick
That 'adjustments' sheet in the lid of your C.H.Amp - I finally got around to printing a copy to do the same, but I can't see that particular sheet - did you compose it yourself? I've tried to cut and paste from Frans' manual but its not possible.
Syd
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Deleted
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Post by Deleted on Apr 13, 2012 10:59:18 GMT
Hi Syd,
I can mail you the original pics. I always intended to make such a sheet myself but never got around to it.
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Post by Deleted on Apr 13, 2012 11:13:44 GMT
That's great, thanks Frans.
Syd
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Post by Deleted on Apr 13, 2012 11:37:46 GMT
I made the composition Syd, I think I do still have the Powerpoint file somewhere, I can email it if you are interested.
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Post by Deleted on Apr 13, 2012 11:55:25 GMT
Thanks Javier, I'd be glad to have it. As you'll see above Frans offered already, but if you have the job done that'll do nicely.
Thanks again to both of you.
Syd
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Deleted
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Post by Deleted on Apr 13, 2012 12:15:00 GMT
Mail sent Syd.
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joethearachnid
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Post by joethearachnid on Apr 14, 2012 18:36:59 GMT
I am (belatedly and with much fussing) putting in my order for my C.H.AMP BoM and seem to have everything except the BF245B transistors. They seem to be no longer manufactured, so getting them from anywhere would probably be a pain. Is there another transistor I can use instead?
-JoetheArachnid
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Deleted
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Post by Deleted on Apr 14, 2012 20:49:24 GMT
Let me have a look around in my part boxes.
Otherwise you can also use the BF244B
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joethearachnid
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Post by joethearachnid on Apr 14, 2012 21:38:55 GMT
Also Frans, I'm assuming that the BC557Bs you sent me are to be used in place of the B556Bs? The PDF is very specific about only using B556Bs, so I just wanted to check before I explode anything.
I must warn you, this may be the first of many possibly silly questions (though I'll probably just send PMs in future).
-JoetheArachnid
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Deleted
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Post by Deleted on Apr 15, 2012 9:20:05 GMT
yes they can be used in the PS section. They act as low power/very low noise zeners and the ones I sent have been tested and have the correct 'zener voltage'. This voltage is dependent of manufacturer/batch.
No problem PM ing or posting.
I have 5x BF245B packed in a bag.
Other parts you have missing ?
PM me.
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joethearachnid
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Post by joethearachnid on Apr 15, 2012 21:58:14 GMT
Thanks Frans. Your postmarket support is top notch. I think I'm okay on all of the other parts, the only problem I'm having is with ordering the resistors, since Rapid don't have all the ones I need in stock and ordering small numbers of resistors from Farnell is a pain. Why buy just one resistor when I can get 4,000 different types in packs of 100? I'd left the resistors until last because I figured they'd be the easiest bit... Oh well, I shall bravely persevere. -JoetheArachnid
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Deleted
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Post by Deleted on Apr 16, 2012 5:07:25 GMT
PM me the values and qty you look for.
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