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Post by PinkFloyd on Jun 3, 2007 22:07:39 GMT
I've got more headphone amps than I can shake a stick at and need another one like a hole in the head but the Channel Islands VHP.2 headphone amp looks so cute I think I'll pull out the stops and order one. Yeh, I know "cute" isn't really a reason for buying an amp but, what the hell, only round this way once so may as well give it a go www.ciaudio.com/They claim it doesn't use an opamp but, from what I can make out from the picture looks like they are employing a Texas Instruments TPA6120A2 High Fidelity Headphone Amplifer (see here: focus.ti.com/docs/prod/folders/print/tpa6120a2.html) so this amp should be compatible with most headphone impedances. Far from unique but certainly a different approach from the majority of the head amps that are on the market at the moment will be interesting to see how it sounds. Have you listened to one mrarroyo?
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leo
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Post by leo on Jun 4, 2007 23:08:33 GMT
Look forward to reading your opinion on this one Mike, The TPA6120A2 is a nice looking chip reading the specs, it looks similar to the AD815 and these make great pre-amps with lots of drive, they sound best with a nice supply. Looking at the picture on CIA I hope those big electrolytics near the jack socket are not coupling caps
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xerxes
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Post by xerxes on Jun 5, 2007 23:39:19 GMT
CIAs Digital power amps are supposed to be very special. They use Hypex amplifier modules, which along with all the other parts you need are available for DIY class D amps. The original Hypex amps have had some really positive reviews and they have now improved them with better caps and the LM4562 op amps in place of the original AD6820. I'm very tempted.
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Nigel
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Post by Nigel on Jun 6, 2007 9:56:48 GMT
Where are they from, Mike? The US? I immediately thought they were hand built in Jersey or something.
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Post by PinkFloyd on Jun 6, 2007 9:58:07 GMT
Where are they from, Mike? The US? I immediately thought they were hand built in Jersey or something. Yes Nigel, from the USA.
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leo
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Post by leo on Jun 7, 2007 21:37:29 GMT
CIAs Digital power amps are supposed to be very special. They use Hypex amplifier modules, which along with all the other parts you need are available for DIY class D amps. The original Hypex amps have had some really positive reviews and they have now improved them with better caps and the LM4562 op amps in place of the original AD6820. I'm very tempted. Yes I have a pair of modified Hypex UCD mono's, fantastic amps if your handy with a soldering iron
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xerxes
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Post by xerxes on Jun 18, 2007 20:15:56 GMT
Which modules do you have and what modifications did you make? I'm interested in the UCD 700HGs, when they release them. I'm also wondering what the "super regulators" will do. Sorry if I'm thread jacking a bit here.
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leo
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Post by leo on Jun 20, 2007 1:05:20 GMT
Which modules do you have and what modifications did you make? I'm interested in the UCD 700HGs, when they release them. I'm also wondering what the "super regulators" will do. Sorry if I'm thread jacking a bit here. Currently have the 180's but soon will have the newer 400HG's too I've done a lot of mods but as I understand the newer HG modules will have most of these mods already implemented according to Bruno, the super regs as an extra are a nice touch, going by the mods I've done to the input stage of mine these will be a very worthwhile mod;) LM4562's do sound the best in these amps IMO and I've tried quite a few, only thing I think will be missing from the newer HG modules is the CRD on the output of the LM4562's to rail with worse PSRR. Also if you can get away with it bypass the coupling caps, it makes a big difference. I've heard the CIA mono's and they sound quite different to my own modules My UCDs are also run as monoblocks using MBR20200 schottkies and 4-pole T-network caps (simply the best capacitors I have tried) Please delete this post if it clogs up the thread
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xerxes
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Post by xerxes on Jun 20, 2007 2:46:32 GMT
If I knew what CRD and PSRR stood for, that might mean something. Which were better?
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Post by PinkFloyd on Jun 20, 2007 8:27:10 GMT
If I knew what CRD and PSRR stood for, that might mean something. Possibly "current regulating diode" (CRD) and "power supply rejection ratio" (PSRR)
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Deleted
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Post by Deleted on Jun 20, 2007 8:55:08 GMT
Now try and explain what "power supply rejection ratio" is ! It's much easier said than done isn't it ?
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leo
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Post by leo on Jun 20, 2007 11:04:42 GMT
Yes, PSRR is Power supply rejection ratio, you get +/-v on the op-amp, one of these supplys in the op-amp is better than the other at rejecting noise etc, so say if the -v is the better you fit the current regulator diode from the output of the op-amp to the +v pin, or the -V pin if the +v is better. Op-amps like the LM4562 do have very good PSRR for both supplies but one is still slightly better than the other. You see some people always put them to the -v pin, you need to look at the datasheet to see which one to fit them to, probably why some op-amps sound worse when people try this mod How does the CIA compare against my mono's, well I'm in no rush to sell mine They are both run different though, the psu's are certainly different, the CIA uses Blackgate coupling caps and the ones I heard used the AD8620's which I personally don't like
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Deleted
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Post by Deleted on Jun 20, 2007 11:25:03 GMT
What is this current regulator diode that you are referring to ? Do you have a diagram? I am aware of the difference in PSRR between the + and - supply rails, although it is pretty academic with devices such as the OPA2134 and LM4562 etc.Wouldn't it be preferable to provide a cleaner,low impedance supply to both the opamp supply rails in the first place? SandyK
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leo
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Post by leo on Jun 20, 2007 11:48:09 GMT
What is this current regulator diode that you are referring to ? Do you have a diagram? I am aware of the difference in PSRR between the + and - supply rails, although it is pretty academic with devices such as the OPA2134 and LM4562 etc.Wouldn't it be preferable to provide a cleaner,low impedance supply to both the opamp supply rails in the first place? SandyK Normally the J511 www.datasheetcatalog.com/datasheets_pdf/J/5/1/1/J511.shtml , yes a better supply in the first place is good, not everybody wants to go to the trouble of adding extra regulation and supplies so they try to make best of whats there. I use ALW super regs in mine but it takes a fair bit more space in the case
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Post by Deleted on Jun 20, 2007 12:28:35 GMT
They are virtually carefully selected FETs. I use FETs (3mA) for the same reason in a plugin version of a combined opamp and discrete buffer stage. The FETs replace the usual 5K resistors of the buffers, for better linearity. SandyK
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leo
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Post by leo on Jun 20, 2007 12:34:23 GMT
Yes, with a J-fet you can set the current yourself, I've never tried doing it with just a fixed resistor tbh, the CRD's now seem to be discontinued so the next time I need any I'll use something like a 2sj309+resistor to set the current
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Fergus
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Post by Fergus on Jun 20, 2007 18:11:37 GMT
Wasn't CIA started up by the guy from the now defunct AUDIO ALCHEMY?
If so, they do cram quality into very small boxes. I had one of the rather grandly entitled Digital Decoding Engines a few years back and it was a fantastic little DAC. Also had a AA transport - very good also, but very unreliable.
The CIA headphone amp is a lovely looking piece of kit and with the dedicated PSU almost irresistible. I see they also make a little DAC - and with AA's experience with DACs I would love to hear this also.
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Post by PinkFloyd on Jun 20, 2007 20:42:30 GMT
I've contacted CIA (the audio firm, not the Central intelligence agency ) and have asked if there are any review samples kicking about in the UK.... if not I'll buy one from them and have a listen to it.... either / or I'd like a few select ears to have a listen too so will arrange for it to be sent to a few Rock Grotto members (in rotation)..... I think it better to do a "group" review rather than a singular "I think blah blah blah" review.... a "group" review will expose the amp to a lot of different ears and a lot of different partnering equipment. leave it with me.
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xerxes
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Post by xerxes on Jul 4, 2007 16:15:32 GMT
Exciting new stuff at Hypex: www.hypex.nl/I'm getting an itchy soldering iron.
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