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Post by dicky on Aug 10, 2011 19:41:02 GMT
The socks are fine - they are stuck half way up the wall ;D
I'll play with the settings but I need to make the changes slowly as I don't think my ears/brain are as well tuned in as most of you guys on here.
I have a question regarding the LED. I have a 2mA red LED but I don't like red - it really iritates me. Can I use a 20mA LED in place of the 2mA LED if I add further series resistance? I can't seem to find a high sensitivity LED in blue but I have some 20mA blue LEDS. I wondered if I could add maybe 5k in series?
Cheers,
Dicky
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Post by Deleted on Aug 10, 2011 19:50:45 GMT
Just pop in any LED you like and see how bright it is.
You don't need to mount resistors in series with it. There are already 2 resistors doing that. 1 (R55) will determine how bright the LED is in 'error' or directly after switch on and R54 determines how bright the LED is once the relay is activated.
The bigger these resistor values (R54, R55) the dimmer it will be lit. The smaller the values the brighter..
High effieciency 20mA LED's also are quite bright already on low currents so can be used. You can have a play with the 2 resistors mentioned in the BOM list to make it as bright as you want. If you increase the current (by using lower value resistors) it will become brighter but at the same time the 4 zener diodes will become a bit hotter.
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Post by dicky on Aug 10, 2011 20:01:30 GMT
OK, Frans. I thought the resistor values (R54 and R55) were optimised for a 2mA LED and I was trying to avoid upsetting the diodes.
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joethearachnid
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Post by joethearachnid on Aug 10, 2011 23:12:38 GMT
Gosh, I come back from five weeks away and suddenly it's all going down today! Glad these little discrepancies in the BoM are getting sorted out before I start my build though. If my A-level results turn out bad then I'll definitely have plenty of spare time available to work on it...
Dicky, looking forward to your detailed impressions.
-JoetheArachnid
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Post by Deleted on Aug 13, 2011 17:28:59 GMT
Dicky, have you tinkered with different settings yet? have you compared it with another amp? Cheers
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Post by Deleted on Aug 13, 2011 23:02:51 GMT
Dicky, have you tinkered with different settings yet? have you compared it with another amp? Cheers Javier Assuming that the Panda meets Frans minimum specifications requirements,and that the bandwidth,output levels and output impedance settings are closely matched, then this amplifier and the Panda should sound absolutely identical. ;D Alex
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Post by Deleted on Aug 13, 2011 23:12:10 GMT
I don't have a Panda, in fact I don't have any 100% SS amp just two hybrids...
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Post by Deleted on Aug 13, 2011 23:20:29 GMT
I don't have a Panda, in fact I don't have any 100% SS amp just two hybrids... Javier I believe that there are likely to be a couple of members that own both the Panda and Frans C.H.Amp.Perhaps they would like to post the results of a comparison between them ? It should be quite interesting, because they are very different designs (Discrete vs. a very good I.C. ) Alex
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Post by dicky on Aug 16, 2011 14:47:45 GMT
Hi Frans, I read in the CHAmp manual ' .... if used as a preamp also, 2 (RCA) outlets'. Is it possible to connect another set of (output) RCAs somehow to be used as a feed-through (for daisy chaining into another HP amp)? Not necessarily as a pre-amp - unless there is no difference. I'm currently dry-fitting the CHAmp into a shoe box to determine what size box I need - the wife's already been poking it. She can't help herself Still, she's insured Regards, Dicky
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Post by dicky on Aug 16, 2011 15:01:40 GMT
Hi Javier, I have had a play but I lost track of what jumpers I had set. So I've drawn up a 'switching matrix' to have a proper 'scientific' play. However: - I didn't notice any effect when by-passing the input coupling capacitors. - Gain effects were obvious. - Output resistance had a definite effect on response - most notably bass (Senn HD250) - although I can't quantify it. I need to listen for longer as I think, for me, the effects might have an impact on fatigue more than anything. I like bass and the CHAmp seems to extend nice and low. If I can hook-up some output connectors I'll daisy chain it to my Panda so I can do some direct comparison. - I haven't played too much with the bandwidth - only to check the amp works in all modes. My overall impression at the moment is that it is more clinical than a V2 and more subtle than a Panda. My priority now is to get it into a box - otherwise I'll be doing my own ironing again.
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Post by Deleted on Aug 16, 2011 15:54:13 GMT
yes... simply hardwire the through-put RCA's directly to the input RCA's. As long as the 2nd amp doesn't load the source too much it doesn't matter (it probably won't)
So the in and feedthrough RCA's are simply connected and in case you also want to use it as a pre-amp the out-RCA's for that are connected to the output of the amp (through resistors between 50 and 100 Ohm)
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Post by dicky on Aug 16, 2011 17:09:00 GMT
Thanks Frans. Is this configuration normal for any amp with feed-through - e.g. X-Can? If so, there's no need to label input and output.
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Post by Deleted on Aug 16, 2011 17:12:11 GMT
Thanks Dick, Hi Javier, I have had a play but I lost track of what jumpers I had set. So I've drawn up a 'switching matrix' to have a proper 'scientific' play. However: - I didn't notice any effect when by-passing the input coupling capacitors. - Gain effects were obvious. - Output resistance had a definite effect on response - most notably bass (Senn HD250) - although I can't quantify it. I need to listen for longer as I think, for me, the effects might have an impact on fatigue more than anything. I like bass and the CHAmp seems to extend nice and low. If I can hook-up some output connectors I'll daisy chain it to my Panda so I can do some direct comparison. - I haven't played too much with the bandwidth - only to check the amp works in all modes. Input caps? do you mean output (J10 & J20)? My overall impression at the moment is that it is more clinical than a V2 and more subtle than a Panda. Could that be due to lower noise and distortion Frans? My priority now is to get it into a box - otherwise I'll be doing my own ironing again. Any enclosure you like? I found this pics of a beatiful black Galaxy at head-fi:
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Post by Deleted on Aug 16, 2011 17:39:25 GMT
yep similar to Xcan..
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Post by Deleted on Aug 16, 2011 17:48:11 GMT
a V2 adds a pleasant type of distortion with the emphasis on ADDS. This is pleasant though, not experienced as distortion. The Panda and CHAmp add nothing so the 'extra niceness/warmth' is also not added. It is clean as a whistle. The Panda ia a 2 stage design with somewhat 'unmatched' parts in it. The CHAmp uses opamps that are extremely well matched (internally I mean and this is many times better than can ever be obtained using discrete designs) and are multiple stage, hence the noise and distortion are many, many factors lower... The PCB design (4 layer with separated double ground planes) and low noise wideband power supply (it is ultra clean and very low Ohmic) helps too The AC coupling is indeed JP10/JP20 If 100nF is used the cutoff freq is 30 Hz. Depending on headphone and musical content this may just be detectable. 30Hz is already unbelievably LOOOOWWW and it rolls of from that point. For a more 'dramatic' effect the cap could be made smaller, say 47nF, to get a more substantial lows roll-off effect.
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Post by dicky on Aug 16, 2011 18:17:43 GMT
That's a nice box, Javier.
I've been looking at Galaxy enclosures. I want to keep the front as plain as possible so I'll be putting the switch on the back (a switched, fused inlet). So just a knob, small LED and HP socket on the front.
So far, according to my shoe-box mock-up, it'll all fit comfortably in a 230x170mm box. I was going to contact the GB'ers with my findings as there was some initial interest in a box GB.
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Post by Deleted on Aug 17, 2011 16:27:01 GMT
Some more B22 builds HPAs using Hifi2000 Galaxy enclosures: Minimalist black (beautiful vol knob): Aluminium: Same but with knob's LED on:
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Post by Deleted on Aug 20, 2011 21:29:03 GMT
For those that have not completed the build of the C.H.Amp yet I just finished updating the article about it. It now has elaborate (checking) tutorials and some info is added. The error in the parts list, layout (2 components were swapped) have been corrected. a MUST for those who have to build or finish it yet. It can be downloaded here: www.mediafire.com/?ix63elqpci2hn9eIt now has 21 pages filled with info. file size is about 5 MB.
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joethearachnid
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Post by joethearachnid on Aug 20, 2011 22:44:02 GMT
Thanks for the updated manual, Frans. I was wondering whether I was going to be able to keep track of all the changes and tweaks that had been mentioned in this thread, so having it all in one place will make things easier. My C.H.AMP is still just a bare PCB, but given that I'm suddenly finding myself with a lot of free time on my hands and probably some income if I can find a job, this build is definitely something I'll be working on.
-JoetheArachnid
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Post by Deleted on Aug 21, 2011 10:38:33 GMT
@ JoetheArachnid
If you want to have some already Vbe checked transistors let me know. I have loads of suited transistors (and checked)
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Post by dicky on Aug 21, 2011 16:09:10 GMT
Hi Folks (CHAmp GB'ers in particular - you know who you are). Boxing the CHAmp.I've just knocked up a front and rear panel design and sent it off to Modu in italy for a cost estimate (they're on holiday so I don't know when I'll hear back from them). It's a simple design using their 230x170x80mm Galaxy Maggiorato box with 10mm front panel. The front panel has a 10mm hole in a 28mm x 5mm deep recess for a standard 26mm volpot knob towards the left of the panel (to keep the wires as short as possible), a 3mm hole smack in the middle for the LED and a 24mm hole on the right hand side (symmetrically to the volpot position) for the locking Neutrik jacks we all bought. The rear panel has 4 off 11mm holes for RCA in and out and a 60 x 29mm cut-out for the switched/fused IEC inlet that I'm using. This may be a problem area for a GB as I don't know if you guys will be using a switch on the front panel etc... The reason I've asked for a quote for the machining is because I want a black front panel and if I machine it the volpot recess will be silver - these guys will anodise it afterwards so it'll look reasonably professional. I also added some engraving to see what the cost might be 'Configurable Headphone Amplifier'. I didn't see any point labeling the volume knob and headphone socket. I'll see what they come back with and see how much of a language barrier there is before I add any tweaks. Anyhoo, watch this space. If you guys are interested and we can agree a design I'll run with this for the group. Warning: I don't think it'll be cheap, but it would be a shame not to do Frans' design justice.
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Post by Deleted on Aug 21, 2011 17:26:22 GMT
I'l be waiting for the info Dick, thanks. What vol knob are you getting? the one they sell? I'd love a Copland style kbob like this: Can you post some pics of your finished amp? Cheers
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Post by dicky on Aug 21, 2011 18:40:01 GMT
Hi Javier, I have an Audio Note knob that I was going to use - the same size as the Panda knobs about 25mm diameter. Hopefully some pictures attached. The cardboard box is the size of the Galaxy Maggiorato (230mm x 170mm x 80mm) case. The large space at the front of the PCB is for a stepped attenuator I have. Unfortunately, it is quite bulky and quite a bit of clearance is needed for the PCB so I can still get to all the jumpers safely without fouling. The phono in and volpot are just a lash-up for now and are just tacked on the surface of the holes. The RCA inputs will be on the left of the rear panel (as viewed here) and the cables will run to the left of the PCB. The volpot will be on the left-hand side of the front panel to keep the wires as short as possible. The HP socket will either be in the centre or on the right of the front panel. I guess the centre would be better to keep it away from the trafos? (Frans? ) The IEC inlet is quite bulky but it has a built-in switch, fuse and filter so saves on a bit of mains wire floating about inside the case. If a GB is likely and we can agree on knobs and such like I can modify the design to suit. Anyhoo, the PRon:
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joethearachnid
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Old head on young shoulders.
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Post by joethearachnid on Aug 21, 2011 20:17:54 GMT
@ JoetheArachnid If you want to have some already Vbe checked transistors let me know. I have loads of suited transistors (and checked) The transistor matching looks like quite a pain, so if you gave some prematched that would be very useful. I'm currently running up some spreadsheets and looking on Farnell to see how much I'm going to have to budget to get it up and running. I'd probably be aiming for the same Galaxy case as Dicky, though I daresay that I'd probably go for the thinner fronts to save cash make drilling easier. -JoetheArachnid
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Post by Deleted on Aug 21, 2011 21:08:16 GMT
The centre will be O.K. and will look good too I reckon. You can move the trafos a bit closer to the PCB also to create room at the front. Mine are very close to the PCB and there is no hum. I wouldn't route my input and output wires near the trafo's though @ Joe, PM me...
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