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Post by Deleted on Jun 17, 2007 11:14:18 GMT
yrh0413 Have you tried the OPA 2134 instead of the OPA2107 ? It is quieter,wider bandwidth, and extremely low distortion.I have also tried the LM4562 in a preamp, but found it fatigueing,despite all the extra detail. For this reason, I fitted a SOIC OPA2134 in my X-FI soundcard with excellent results. IMHO,in a dulller sounding piece of gear the LM4562 could be worthwhile, but it isn't a good universal choice. SandyK
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Post by PinkFloyd on Jun 17, 2007 12:23:14 GMT
IIRC OPA2107 (one of my favourite BB chips) sounded pretty chocolaty and congealed in the Heed, the AD-823 offered up a bit more sparkle and zing though not enough to make it sound bright.... more organic and raw sounding with the AD-823 on board. You could try the opa2134 it's one of the best drop in replacements for the 5532 you can get and is one opamp that never really offends. Opa2132 is another good one from the same stable. I really love the Opa 2107 and have always classed it as sounding "as good as damn it close to two OPA627's on a Bdog" but in the Heed it really didn't perform at its best simply "dropped" in with no additional circuit tweaking. I think Nigel went through quite a few opamps in his Heed 0pa627 (B-Dog), Lm4562, DY2000 etc. etc. and has ended up where he started with the AD-823, hopefully he will chip in with his impressions. Another one you may wish to try is the OPA-2111, one of my all time favourites from BB but nobody else seems to share my opinions.... a beautiful sounding chip if implemented correctly and I'm surprised it isn't used in a lot more amps. Spec sheet here: focus.ti.com/docs/prod/folders/print/opa2111.html
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Post by yrh0413 on Jun 17, 2007 13:27:58 GMT
I have a handful of opamps with me: LM4562, LM6172, OPA2107, AD823, DY2000, and LME49720. My browndog has arrived, and my OPA637s will be here this weekend. LM4562 -:- damn detailed, but quite sterile. It made my favorite music genre (classicals) sound very unimpressive. Moreover the lower frequencies are a bit too thin to my liking. LM6172 -:- a better version of LM4562. Bass is stronger and i prefer this opamp over the 4562. OPA2107 -:- warmth and lively, perfect match for classical pieces. AD823, DY2000, and LME49720 -:- haven't really compare them yet. Now my CanAmp is still on the surgery table. p/s: did you guys notice the implementation of the PSU by Heed Audio is very very "cheap"? My next mods will focus heavily on the PSU section
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Post by yrh0413 on Jun 17, 2007 13:30:46 GMT
p/s: holy cow! i checked Farnell and to my horror the OPA2111 is almost USD 20 per piece!
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Post by dc on Jun 17, 2007 14:26:58 GMT
let us know how the power supply mods go
i'm toying with new transformers atm
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Post by PinkFloyd on Jun 17, 2007 14:40:29 GMT
p/s: holy cow! i checked Farnell and to my horror the OPA2111 is almost USD 20 per piece! £10.74 each from RS in the UK ($21.22) As it happens, whilst on the subject, I'm gonna pluck one of these babies out of the vault and plunk it into to the Graham Slee Solo for a road test
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Post by yrh0413 on Jun 17, 2007 14:53:03 GMT
sure, i'll keep you guys updated with my mods.
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Nigel
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Post by Nigel on Jun 17, 2007 15:24:36 GMT
Hiya,
I'm back with the DY2000 at the moment. It doesn't sound bright to me anymore with my HD650's, (lid removed, with my current isolation fetish) I love the AD823 though in the Heed & could easily live with either. In fact, if some gremlins swopped op amps overnight, I probably wouldn't notice the difference.
I'm very interested in any potential power supply improvements & have mentioned it before. I know Mike was looking at the possibility of a better transformer amongst other things. In fact, I'd love an ultimate power supply for the Heed in a different enclosure.
Cheers, good luck with your experiments.
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Post by yrh0413 on Jun 17, 2007 17:36:16 GMT
Nigel, i'm going to mount some regulators and tantalums at the rear of the transformer (as you can see from my picture above, the rear of the tranny has quite a big space), and perform P2P soldering on the components. Going external is the best solution, but i can't stretch my budget that far though . Now i'm still cracking my head figuring how should i mount the Nichicon KZs LOL!
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leo
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Post by leo on Jun 17, 2007 20:05:19 GMT
Surprised to see the Heed uses a raw supply. Regulation should certainly make quite a big difference, if it sounds better or worse in this amp is hard to say. If your going to add regulation to the existing circuit I'd use a transformer with higher secondary voltages and then drop this down to the Heeds original voltage through the regs. I see your using higher capacitance in the supply, the standard transformer is only 6vA per winding so a higher current transformer would be better anyway with higher uf's
Wish I had one of these amps, theres quite a lot of things I'd like to try with it, say regulation for the op-amp and raw supply for the driver transistors, or even VBE's which would clean the supply
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Post by dc on Jun 18, 2007 13:44:42 GMT
using a couple of AD843s on a browndog at the moment in the heed, slightly less top end sparkle, but overall smoothness and resolution is better in my system.
recently got the Ori Modded Zhaolu which really put things on another level from the source side, so might go back to the DY2000 see how it fairs
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Post by yrh0413 on Jun 19, 2007 15:23:21 GMT
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leo
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Post by leo on Jun 19, 2007 20:39:16 GMT
Looking good mate, what voltage out you set the regs? just a couple of volts drop? Its hard to see the track from the picture but are those two electrolytic caps at the front of the amp in the feedback loop? it looks like C1 and the cap behind the vol pot are input DC coupling caps? Only local decoupling capfor the op-amp I can see is that 100nf that seems to have track that goes across the +/-v of the op-amp
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Post by yrh0413 on Jun 20, 2007 1:49:43 GMT
ah crap, done a silly mistake. I thought the tranny outputs at 18-0-18, but it turns out to be 9-0-9. Have to rebuild the regs!
p/s: i'm still wondering where should i mount those Nichicon KZs >.<!! behind the tranny?
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Post by Deleted on Jun 20, 2007 2:50:30 GMT
yrh0413 Try to allow for a minimum of 3V DC above the regulators rated voltage output.Using ceramics as a parallel bypass usually results in metallic sounding treble. Better to use ordinary polys, unless you are using premium type electros. Even then you can try it and see. SandyK
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Post by yrh0413 on Jun 20, 2007 6:16:52 GMT
thanks for the input guys. I got a job interview next week and my mods need to be put aside for the weekend.
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Post by yrh0413 on Jun 20, 2007 15:06:44 GMT
Mods done: 1st phase:- 10,000uF 35V Panasonic - 10uF and 100uF Panasonic FCs - MUR820s - Opamp socket 2nd phase:- 3.3uF 100V metalized polyester - replaced the cable at the bottom with silver wires - 10uF and 100uF FCs removed - installed the wrong regulators 3rd and final phase:- 1000uF 25V Nichicon KZ - optimized the final layout with ceramics and thin wires - front input decoupling caps bypassed Special thanks to my buddy Ijan, all the mods are done by him. I received my dual-to-single browndog earlier this week; gonna try rolling 627/637s. That's all folk, no more modding on the Heed
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FritzS
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Post by FritzS on Jun 22, 2007 7:48:16 GMT
off topic who is the manufacturer of the DY2000? where I can get a data sheet? where I can get it? in google I don't find this
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Nigel
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Post by Nigel on Jun 22, 2007 8:16:40 GMT
FritzS, DY2000 can be purchased from diykits.com.hk/He charged me 13 US dollars including the postage. Cheers, Nigel
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FritzS
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Post by FritzS on Jun 22, 2007 8:27:41 GMT
Dear Nigel, and who is the manufacturer of the DY2000? Gives datasheets too - I dont found any on diykits.com.hk/what typ you buy? DY2000 (Ceramic) HK$ 100.- YD2100 (Ceramic) HK$ 100.- DY2000 ( Metal can) HK$ 250.-
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FritzS
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Post by FritzS on Jun 22, 2007 8:55:19 GMT
I got some new OP's for test Analog AD827, AD828, AD847 / TI OPA211, OPA827 / Linear LT1055, LT 1056, LT1006, LT1010 and will try them next time in some of my HiFi equipment Unfortunately I don't have a Heed CanAmp
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Post by dc on Jun 22, 2007 11:33:15 GMT
the DY2000 are made by analog devices (has their logo on top) supposedly for the Filipino government iirc. it definitely has the AD house sound
read it in the huge zhaolu thread over @ h43d-f1 a long long time ago. originally discovered by Zhaolu owners as it was thrown in as a freebie with Zhaolus bought from Eddie Wu over @ diykits.com.hk
not sure where he's sourced it or if there are any data sheets but outside of use with the Zhaolu/Heed it's largely unknown. maybe he could get hold of the data sheet...
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Nigel
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Post by Nigel on Jun 22, 2007 12:44:31 GMT
FritzS,
I have the DY2000 ceramic, as recommended & first pioneered by dc. The metal version is said to be much superior, however, it is not easy to fit. It doesn't look like a usual opamp & will require a degree of skill to fit inside the amp.
Cheers.
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Post by Nigel on Jun 22, 2007 12:46:42 GMT
dc,
I hear you have fitted a new transformer? Any improvements in overall sound quality?
Nigel
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Nigel
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Post by Nigel on Jul 12, 2007 23:02:39 GMT
I bought a metal DY2000................. this is the best I've heard yet. It's easy to fit, comes already soldered to the socket. It's a beauty.
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