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Post by Dickybottle on Aug 5, 2010 10:53:52 GMT
Many thanks guys - Much appreciated. Will - I know, that gap is massive - I don't know what all the fuss was about The Opamp coolers are here: uk.farnell.com/jsp/search/productdetail.jsp?sku=1319816and are 2.17 GBP. Alex, I know they are a bit pricey, but why spoil the ship for a ha'porth of tar? They not only look good but they perform much better than those cheap moulded heatsinks, and the Opamp does seem to be the warmest running component. They fit like a shell held with a sprung wire, so it is possible to use some heatsink compound without it squidging out. What the photo's don't show well are the "mods" I had to make to the regulator board, which had to be cut to allow clearance for the input jack - So fitting a 5V regulator is now completely out of the question Ken
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Post by Deleted on Aug 5, 2010 11:04:59 GMT
Hi Ken I prefer them to look good too, but you can't see them when the case is closed. The main point is that considering a normal DIP8 LM4562 doesn't need a heatsink, and you will not see them with one either, the metal can LME49720HA/LM4562HA with exactly the same chip inside, doesn't really need a heatsink either, so maximum heatsink efficiency is not a big deal here. Still, it's nice to know they are running a little cooler with a heatsink. Alex
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Post by Deleted on Aug 5, 2010 11:08:41 GMT
Alex, is this stackable version of the JLH an improvement over the single board version? Thanks. Miguel No, it is no different in performance. It is just more convenient in some circumstances where room is minimal, or you only need a single polarity JLH. Alex
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Post by Dickybottle on Aug 5, 2010 11:17:27 GMT
Hi Ken I prefer them to look good too, but you can't see them when the case is closed. The main point is that considering a normal DIP8 LM4562 doesn't need a heatsink, and you will not see them with one either, the metal can LME49720HA/LM4562HA with exactly the same chip inside, doesn't really need a heatsink either, so maximum heatsink efficiency is not a big deal here. Still, it's nice to know they are running a little cooler with a heatsink. Alex I think what I am saying is that if I going to use a heatsink at all, I may as well use one that actually works well and looks decent. Ken
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Will
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Post by Will on Aug 5, 2010 17:40:39 GMT
Alex, is this stackable version of the JLH an improvement over the single board version? Thanks. The only real difference between this new JLH and the ones that Canjunkie made for us is an extra resistor on the collector of a transistor. The one that Alex made for use in your SCHA has this extra one. Mind you, your SCHA should sound better than most, as it's been 'touched' by Alex On the hot topic of costly (or not) to-5 sized heatsinks, I throw this one into the mix. uk.farnell.com/fischer-elektronik/kk-504/heat-sink-clip-on-to-5-65-c-w/dp/1222495?Ntt=1222495 It's a whole 44p, although not as nice as Ken's.
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Post by Deleted on Aug 5, 2010 22:27:10 GMT
Will I think the point that Ken is making is that the type he is using are more efficient, as they have a temperature rise of just over half of that of the cheap ones. Not that it is so important when using opamps of these types , compared with TO5 transistors that could be used at much higher current levels. Alex
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Post by jonclancy on Aug 7, 2010 22:31:33 GMT
Dunno, Alex. I think we'd need the disspation specs. The sale I originally linked to was for 5 pieces, so not too much of a rip off....
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Post by Deleted on Aug 7, 2010 23:21:56 GMT
Jon You are most likely correct, but although the picture shows 5, the text does not state 5. The dissipation of all the other types , except for those that Ken posted are likely to be similar at around 65C/1W. (Ken's are 35C/1W) The Opamps don't normally need heatsinking, but transistors that could run at fairly high collector currents often do. Excessive non essential cooling may even reduce performance ? Transistors have higher HFE and Ft as the temperature is increased. (within limits) It's debatable whether single devices like the LME49710HA, which has around half the power dissipation of the dual LME49720/LM4562, would even benefit from having a heatsink fitted, as the metal can devices already have better thermal management. Alex
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Post by punkjr on Aug 8, 2010 7:56:01 GMT
i've got a heap of t05 heatsinks if anyone needs one
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Post by jonclancy on Aug 9, 2010 13:36:43 GMT
TO-5, TO-99 = 0.35 and 0.325 ins. Now I'm confused!! LM4562HA is a TO-99. Ambiguously, the ad I linked to says: Up for sale is 5pcs Aluminum Heatsink for TO-99 package Transistor/ Opamp But, if a TO-5 will fit OK, then super. Mine runs pretty hot - not so that I can't hold my finger on it, and probably doesn't need sinking, but I'm with Ken on this one!
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Post by jonclancy on Sept 3, 2010 17:25:41 GMT
I got my heatsinks. They are nicely machined and fit snugly over the top of the metal can. There is a slot for the can skirt milled in. Seems to do a good job with the dissipation as I can hold my finger on it for ages. On another note, do your Jaycar PSU heatsinks get hot? Mine are ROASTING!! I'm thinking about returning it to standard config and removing the higher voltage, low ESR caps I installed (as I wanted to use it for 24VDC as well). Cheers Jon
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Post by mrarroyo on Apr 10, 2011 12:53:13 GMT
Ok, I am resurrecting this thread since yesterday I pulled the amp that Alex built and used it to drive an ATH ESW9 and an AKG K501. The sound is superb even though I am using a portable USB type DAC the iBasso D4 "Mamba" with iTunes lossless files. Very nice sounding indeed!
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Post by Deleted on Apr 10, 2011 21:46:34 GMT
Hi Miguel I am pleased that you are still enjoying it. I hope that you are able to try the Class A HA/preamp, as it builds on the strengths of this one. Regards Alex
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Post by mrarroyo on Apr 10, 2011 23:18:46 GMT
As you may know I am in conversations with ...
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Post by Deleted on Apr 19, 2011 23:35:35 GMT
Ok, I am resurrecting this thread since yesterday I pulled the amp that Alex built and used it to drive an ATH ESW9 and an AKG K501. The sound is superb even though I am using a portable USB type DAC the iBasso D4 "Mamba" with iTunes lossless files. Very nice sounding indeed! Hi Miguel i built my SCHA a while back and still use it with my K701. IMHO it's just a great sounding amp. no flash caps or resistors just good engineering and a great PSU. as you say ''superb''. and a good example of what can be done with a relatively inexpensive kit and a lot of know how. mine's a keeper. take care
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Post by Deleted on Apr 21, 2011 15:30:15 GMT
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Post by Deleted on Apr 21, 2011 17:06:28 GMT
As you may know I am in conversations with ... Doctor Who? Roger Rabbit? Jesus?
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Post by lark on May 5, 2011 10:37:18 GMT
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Post by Deleted on May 5, 2011 12:05:20 GMT
lark My preference would be for the 30VA one in this case. I am not sure what it is, but I usually find the 30VA toroidals sound better with preamps and headphone amplifiers. A 30VA even sounded better in an outboard regulated supply for my Musical Fidelity X-DAC V3 than a 50VA that I replaced a 30VA with. It only lasted a day in there ! Alex
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Post by lark on May 5, 2011 12:28:37 GMT
Thanks again Alex, You're like a omni-present guru here... Sorry for so many questions - I'm just a little excited I want to use the APLS 27 50k pot that's been recommended but it seems to cost about $AU50 here in Aust. I see that it is not that expensive $11 here ( www.analogmetric.com/goods.php?id=1129 ), but I'd much rather try and source one locally. Any idea on where to get them cheaper here? I also can't find Wima caps here either, any ideas? They are cheap on ebay but come with a $5 postage fee..... I'm also wanting the JLH ripple eater - but again, can't find a PCB anywhere.. I've looked over the tweaks thread and I'm wanting to implement your mods here ( rockgrotto.proboards.com/index.cgi?action=gotopost&board=chitchat&thread=3622&post=38795 ) but I'm somewhat confused as which mods I should do (the best bang for bucks mods). Any hints on where to start? Since I haven't started building this yet, I want to do any simple ones as I build it (no point ripping out components later if I can do it from the start).. Given that I can't get the JLH PCB, what mods would you make to the stock AMP and Powersupply to give the the best results with parts that I can get and may get locally? I'm a bit limited here in Adelaide, there's only really Jaycar left that stock any components, and they don't seem to have much these days... Thanks for you help again. If there is any way I can replay you for your assistance, just let me know, It's much appreciated. Cheers.
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Post by Deleted on May 5, 2011 12:40:45 GMT
Hi Lark I don't know of any Aussie source of Alps pots. Have you considered the 23 or 24 position attenuators from Valab etc. ? They sound better anyway ! Several of us in RG have used them., If there is no more than a couple of mV DC from your sources (usually isn't) you can dispense with the input capacitors. You can get the 2SA1930 and 2SC5171 from ebay, or with a week or so delay from RS Components.You can use the 1uF from Jaycar in place of the 2.2uF in the JLH. Alex P.S. Check your Private Messages.
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Post by lark on May 6, 2011 8:52:17 GMT
Great stuff. I've ordered my kit and bits (as you've suggested) I should have it all next week.. In case anyone else if looking for these kits the cheapest supplier I could find is a site called photonage ( www.photonage.com.au/studio-series-pre-amp-headphone-amplifier-kit-p-3322.html ) just $AU25. They look to be an Altronics supplier - I can't vouch for the quality as I haven't got it yet, but the prices seem good: 1 x Studio Series Pre Amp Headphone Amplifier Kit (K5503) = $24.95 1 x Studio Series Pre Amp Power Supply Module Kit (K5501) = $14.95 1 x Transformer Toroid 240/15+15 30VA (M4915A) = $22.95 1 x Chassis Mount Male IEC With Fuse And Switch Mains Socket (P8340A) =$3.95 1 x delivery = $14.14 Total: $80.94 Seems like a bargain to me.. Cheers.
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Post by lark on May 6, 2011 14:29:00 GMT
Hi Lark I don't know of any Aussie source of Alps pots. Have you considered the 23 or 24 position attenuators from Valab etc. ? I like the idea of these attenuators but the log 50K valab log ones here ( cgi.ebay.com.au/Valab-23-Step-Attenuator-Potentiometer-50K-Log-Stereo-/290554533710 ) have a graph of the log scale - this looks awfully steep at the start.. I like to listen at rather low volumes at times - is that scale actually inverted on the attenuator? As I understand the change in volume will be less perceivable as the volume increases linearly, such I would have thought a log pot would be inverted (exponential) ... This log attenuator looks like it would provide even less control than the linear version.. Am I missing something? Lark.
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Post by Deleted on May 6, 2011 22:40:07 GMT
Hi Lark I don't know of any Aussie source of Alps pots. Have you considered the 23 or 24 position attenuators from Valab etc. ? I like the idea of these attenuators but the log 50K valab log ones here ( cgi.ebay.com.au/Valab-23-Step-Attenuator-Potentiometer-50K-Log-Stereo-/290554533710 ) have a graph of the log scale - this looks awfully steep at the start.. I like to listen at rather low volumes at times - is that scale actually inverted on the attenuator? As I understand the change in volume will be less perceivable as the volume increases linearly, such I would have thought a log pot would be inverted (exponential) ... This log attenuator looks like it would provide even less control than the linear version.. Am I missing something? Lark. I have the 50k log valab in my scha. Obviously I can only speak from my own personal experience but I find the first half of the rotation pretty useless, I like it loud! I have a small tweak to the gain on mine because I like it loud. My volume control is always beyond the 12:00 position because I like it loud. Oh, and did I mention that I like it loud?
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mrarroyo
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Post by mrarroyo on May 6, 2011 22:51:27 GMT
WHAT! Can't hear cause you are not loud enough.
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