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Post by loupy31 on Aug 5, 2009 22:10:37 GMT
Hi Guys, Wow, that was a flood of info thanks for that, I am still not too familiar with the terms used JLH, and others but I will learn, once again thanks, I will keep you guys in the loop as I build and test, BTW the headphones I received for my birthday are the ATH AD900 hope they are good.
Regards Peter
Ps. How can I get hold of a JLH upgrade board?
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Post by Deleted on Aug 6, 2009 0:06:31 GMT
Peter See the thread at the attached link, and send Jon a PM. Remember though, that you will need 2 of these small PCBs, as they are designed for universal use with a single supply voltage. They would be positioned side by side normally, with one PCB built as a -VE supply rail version, and the other PCB as a +VE supply rail version. Alex rockgrotto.proboards.com/index.cgi?board=786345&action=display&thread=4333&page=3
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Post by Deleted on Aug 15, 2009 16:43:00 GMT
Another daft question.... If I wanted to configure a modified (Alex) PSU to twin +ve, I would; need to reverse the caps on the neg rail change the LM337 to a LM317 and re-twiggle the legs to get the right BCE arrangement, reverse D7. resistor value change, which I know is stated somewhere in this thread. BUT, what do I do to the rectifier diodes? and have I missed any other change(s). PLUS, is that ok running off +12 - 0 - -12 transformer? (Bracing myself as gut feeling says that's a really plonky question )
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Post by Deleted on Aug 15, 2009 21:19:30 GMT
Another daft question.... If I wanted to configure a modified (Alex) PSU to twin +ve, I would; need to reverse the caps on the neg rail change the LM337 to a LM317 and re-twiggle the legs to get the right BCE arrangement, reverse D7. resistor value change, which I know is stated somewhere in this thread. BUT, what do I do to the rectifier diodes? and have I missed any other change(s). PLUS, is that ok running off +12 - 0 - -12 transformer? (Bracing myself as gut feeling says that's a really plonky question ) Chris Most of what you are saying is correct, but the rectifiers would need to remain as a normal bridge rectifier feeding both sides in parallel. The junction of D2 and D3 would need to be connected to the 0 volts (earth) rail, and the junction of D1 and D4 connected to the +VE side of both 2,200uF electros. A 12-0-12 transformer is inadequate to maintain regulation with a 15V DC output. Perhaps Robert can come up with a more appropiate solution ? Alex
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Post by Deleted on Aug 15, 2009 22:22:54 GMT
No worries there, I'm after 12vdc o/p (which I neglected to mention b4) I assume I would cut their existing track connection to the upstream circuit? Thanks and enjoy your caffeine hit
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Post by Deleted on Aug 16, 2009 12:29:38 GMT
Chris Yes, that would do, then use insulated links to the new locations. Alex
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Post by Deleted on Aug 16, 2009 12:45:55 GMT
that's great, cheers Alex.
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Post by Deleted on Sept 6, 2009 0:42:49 GMT
Ok, here's another one Bearing in mind I'm using a stepped attenuator, and within the context of the SCHA. Is there any real SQ advantage to rewiring the vol pot as "shunt" as shown HERE. I remember seeing it mentioned here and there but wasn't sure if it was worth it. Especially as I slightly increased the gain to get the required volume on low level recordings, so I guess I'd need to increase it a little again to counter the drop caused by using the shunt? Chris
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Post by Deleted on Sept 6, 2009 0:50:04 GMT
Chris You could always give it a try with an Alps potentiometer. Would I do it ? No. There are too many trade offs for my liking, especially in Signal to noise, and increased source impedance seen by the amplifier. Alex
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Post by Deleted on Sept 6, 2009 0:51:48 GMT
Alex,
Nuff said! I'll leave as is.
Cheers!
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Post by johnmclean on Sept 7, 2009 13:26:03 GMT
I made an amp for a friend of mine who owns K701’s he’d like more gain. The build is an Sandyk modded version but does not have the JLH. What parts need to be replaced and what value should they be?
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Post by Deleted on Sept 7, 2009 14:12:27 GMT
John I have sent you an email. Alex
P.S. John, it bounced.Seems your mailbox is over quota. Send me an email when you are able to receive the details from the SC article.
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Post by vidaraus on Sept 17, 2009 9:32:40 GMT
Hi, I have been reading through this topic for a number of days, and really wanted to give this thing ago! Sounds amazing! So I went down to my local JayCar in Canberra and picked up the headphone amp kit, power supply kit, instrument box, IEC socket, the recommended tord transformer e.t.c I have soldered a bit before, modifying xbox's and building basic battery powered kits e.t.c - but never anything that involved playing directly with 240VAC. After looking through all the bits, I have some questions at this point: 1) How do you be safe with 240VAC? What precautions do I take. Any do's and don'ts? 2) How do you wire up the transformer? What colours go where? 3) How do you mount the transformer in the plastic instrument case? Does it just bolt direct into the case or must it sit on top of something? 4) How do you wire one of these: www.jaycar.com.au/productView.asp?ID=PP4003&keywords=IEC+switch&form=KEYWORDCorrectly with this project? How do you wire it so that the fuse works and the switch works e.t.c? What wires go where? 5) How do things get grounded in a plastic case? Just back to the earth wire? How does this work? What wires where? 6) What is the best opamp to upgrade to if you want a flat response? I want to use this amp for studio monitoring and mixing. 7) Could someone please send me a copy of the original Silicon Chip article? Please PM me for email address. Very much appreciated. 8) Lastley (for now !!) could someone recommend a really good volume pot? I have read about a velvet something or other on these forums. How do you wire this correctly? Apologies for all the dumb questions. I am a real n00b with a great interest in electronics. I will need a fair bit of step-by-step and hand holding! I would love it if there was a step-by-step guide for the standard project somewhere. Is there??? Thanks so much. You all sound like a fantastic bunch of people!! VidarAus
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Post by Deleted on Sept 17, 2009 9:57:56 GMT
vidaraus I have sent you a couple of emails with further information.
SandyK
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Post by vidaraus on Sept 17, 2009 12:41:36 GMT
Thanks Sandy. You have been most helpful. Another question, has anyone used this IEC socket: www.jaycar.com.au/productView.asp?ID=PP4003I have attached a picture of the back of it. How do I wire this up with the recommended tord? I am really stuck as to how to wire up the transformer - what colours go where, and how do they connect to this socket with a built in switch and fuse holder? Thanks
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Post by Deleted on Sept 17, 2009 12:59:19 GMT
Joshua Re the Jaycar MT2086 15-0-15VAC 20VA Toroidal transformer : The 2 orange wires (transformer Primary)connect to the mains switch. The red and white wires are joined together, and connected to the centre terminal of the PSU PCB's lone 3 pin connector. The purple and yellow wires go to either side of the same 3 pin block. Which way around does not matter. Don't forget to remove the 2 big 5W resistors and 7805 regulator I.C. etc. from the PSU PCB ,as per the "Tweaks" thread. This smaller transformer will have more in reserve without those additions which were meant for the full Studio Preamp project only. Alex P.S. I live in hope, that one day they will come out with a simple IEC socket version with only 3 rear connections. i.e. Switched "Active" via the inbuilt fuse, Switched "Neutral," and EARTH. But that would make matters too simple, as well as much safer !
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Post by vidaraus on Sept 17, 2009 13:35:57 GMT
Thanks. So you mean the two orange wires connect to the N and L of the IEC socket? Does not matter which way around they go?
How is this thing earthed? Is the earth pin in the socket connected to anything? Sorry I am such a n00b.
Now just to work out how the fuse and switch is incorporated into this thing.
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Post by Deleted on Sept 17, 2009 13:45:41 GMT
Joshua The 2 orange wires will connect to the switch contacts at the LHS, but there will be some interconnecting wiring required with the other side of the socket. The earth of the IEC socket will be wired via a lug and mounting screws to the aluminium base plate that the transformer is mounted on. An earthing lug will also need to slip over the mounting thread of the potentiometer, and then also connect to the aluminium base plate to stop any hum problems. Alex
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Post by dean0 on Oct 24, 2009 21:23:26 GMT
what 3m product would that be?
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Post by PinkFloyd on Oct 24, 2009 21:50:59 GMT
what 3m product would that be? It's a special damping tape.
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Post by Deleted on Oct 24, 2009 21:54:23 GMT
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Spirit
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Post by Spirit on Nov 12, 2009 22:52:57 GMT
I'm still discovering new things in pieces I've listened to many times prior to the amp.... Loving it Cheers Alex
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jonclancy
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Post by jonclancy on Nov 13, 2009 12:45:17 GMT
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jonclancy
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Post by jonclancy on Nov 13, 2009 12:48:54 GMT
A quick Jaycar PSU question:
How hot does your +ve rail run? Mine's hot, -ve rail is pretty cool.
Cheers
Jon
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Post by Deleted on Nov 13, 2009 20:06:18 GMT
A quick Jaycar PSU question: How hot does your +ve rail run? Mine's hot, -ve rail is pretty cool. Cheers Jon Jon Do you still have those 5W resistors there ? Alex
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