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Post by gommer on Feb 12, 2013 14:53:01 GMT
Hey guys,
I'm not sure if i should have started a new thread for this or not, time will tell and it can move wherever it's more appropriate in the (near) future.
Anyway, what i wanted to ask.
I know -correct me if i'm wrong- that the SC HA is a (top) class A HA/Pre, which is derived from a SC 15W amplifier and improved on (DC coupling, DC bias servo added,...). The original SC kit is no more available from Jaycar. I've seen photo's of 'AK SC HA' PCB's, probably RG/DIYA brewing with all improvements incorporated. What I don't know: was there ever a group buy for the AK version PCB's? If so, where? Here or on DIY audio? A collection of thread pointers would be welcome, i'll list those that i know of at the bottom to start with.
Are there any boards left available and if not, is there enough interest for a new run of PCB's. If a kind soul would lend me Eagle or Gerber files, i could consider arranging for production myself.
Cheers, Marc
/edit: follow up post with links removed because it caused confusion. All threads are correctly linked further down.
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Post by Deleted on Feb 12, 2013 17:35:37 GMT
Hi Marc, From your post and links I think you are getting different builds mixed up. The Silicon Chip Heahphone Amplifier is a design in its own right, as per your second, third and fifth links. The SC 15w amp is the one that has been modified and improved to be used as a headphone amp, a pre amp or as a power amp. As your first and fourth links. From your description it is the latter you are after. I hope that clears some confusion for you. You'll need to drop Will a line to see if there are any boards remaining. If, however, you do mean the SCHA headphone amplifier, Jaycar in the UK are still showing stock. code = KC5417 www.jaycarelectronics.co.uk/productView.asp?ID=KC5417&keywords=headphone+amplifier&form=KEYWORD |
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Post by gommer on Feb 12, 2013 18:41:26 GMT
Hi Chris, I was probably a bit hasty in linking. I did realize there is a difference in the SC HA and the modified SC 15W amp. The modified version resuulting in the following desired object:  Cheers on the heads up, I'll see what Will tells me. Marc |
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Will
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Post by Will on Feb 12, 2013 19:30:14 GMT
Hi Marc, you've got PM!
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Will
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Post by Will on Feb 12, 2013 19:45:26 GMT
..and as Chris mentions above, the main thread for the pre/Ha version is here SC Class A (turns into the AK Class A HA/pre) Grab a cup (or glass) of something nice, sit yourself down and have a read through the thread. Among other things, you'll learn never to have pcb's made that are 3mm thick!! |
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Post by gommer on Feb 12, 2013 21:10:22 GMT
3mm thick PCB's, I'v honestly never seen one. It must be as awkward as alu substrate or 105µm copper.
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Post by Deleted on Feb 12, 2013 21:35:50 GMT
3mm thick PCB's, I'v honestly never seen one. It must be as awkward as alu substrate or 105µm copper. Hi Marc It was a great PCB, and beautiful looking, but it was unforgiving of errors. It would have gone very well in a premium product from an automated production line.  Although the LS dual devices are becoming harder to obtain, , the LS352 can be replaced by the original Motorola/ON 2N3811A from stores.ebay.com.au/UTSOURCE-STORE and another ebay store. The 2N3811A are what I started out with in the beginning with the original 15W design. They are superb devices that were originally used in amplifier designs along with the 2N2920A by Erno Borberly. Perhaps Will can supply a copy of the necessary artwork for the HA PCB, but using a standard thickness PCB? Kind Regards Alex |
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Post by Deleted on Feb 12, 2013 23:16:49 GMT
''The 2N3811A are what I started out with in the beginning with the original 15W design''
Hi Mark
i'm still using them in my build of Alex's superb class A PA and they are nice devices.
the matching HA/PRE is outstanding also
how are your etching skills?
take care
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XTRProf
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Post by XTRProf on Feb 13, 2013 4:11:10 GMT
Hi Marc,
The last MO from Will, I'm surprised you didn't order one to keep even if you didn't populate it. It's relatively cheap. Now you will have to have enough members buying before you can have another run. Quite tough given that most already have 1 or 2.
Anyway, as Will had written, don't ever do the 3mm version. You will have a nightmare desoldering if you made a mistake.
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Post by gommer on Feb 14, 2013 12:59:15 GMT
Yeah well, I'v only registered end of 2010 on here and was brought here because of the Panda amp. The Panda, being a nice amp, that i love. It works well with my K701, but it's still coloring a little on the warm side. It's only the last year that I've learned about the merits of the (AK) SC class A and became really interested.
Anyway, anyone reading here and wanting to join in on a next round of PCB's, should speak out load. Maybe here is better, in order not to further clutter up the 'official' thread.
Anyone who is a regular on other forums that could raise interest, feel free to point to this and the other thread, we might even gain some new members.
Let's get the ball rolling. I'm in for 2, no idea on the price point yet, i'll try to find out and report.
Cheers, Marc
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Post by Deleted on Feb 14, 2013 16:35:31 GMT
Yeah well, I'v only registered end of 2010 on here and was brought here because of the Panda amp. The Panda, being a nice amp, that i love. It works well with my K701, but it's still coloring a little on the warm side. It's only the last year that I've learned about the merits of the (AK) SC class A and became really interested. Anyway, anyone reading here and wanting to join in on a next round of PCB's, should speak out load. Maybe here is better, in order not to further clutter up the 'official' thread. Anyone who is a regular on other forums that could raise interest, feel free to point to this and the other thread, we might even gain some new members. Let's get the ball rolling. I'm in for 2, no idea on the price point yet, i'll try to find out and report. Cheers, Marc i've have the pleasure of using Alex's lovely Class A pre/HA for some time now and with K701 it's just heaven. but i'll be up for building another with you Marc i'd like to have one as a dedicated Pre and one for HA use. put me down for 2 boards please. lets make a list gommer x2 shaun x2 and i think that someone was asking on the class A thread so i'll have a look. take care |
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Post by Deleted on Feb 14, 2013 16:40:51 GMT
Yeah well, I'v only registered end of 2010 on here and was brought here because of the Panda amp. The Panda, being a nice amp, that i love. It works well with my K701, but it's still coloring a little on the warm side. It's only the last year that I've learned about the merits of the (AK) SC class A and became really interested. Anyway, anyone reading here and wanting to join in on a next round of PCB's, should speak out load. Maybe here is better, in order not to further clutter up the 'official' thread. Anyone who is a regular on other forums that could raise interest, feel free to point to this and the other thread, we might even gain some new members. Let's get the ball rolling. I'm in for 2, no idea on the price point yet, i'll try to find out and report. Cheers, Marc i've have the pleasure of using Alex's lovely Class A pre/HA for some time now and with K701 it's just heaven. but i'll be up for building another with you Marc i'd like to have one as a dedicated Pre and one for HA use. put me down for 2 boards please. lets make a list gommer x2 shaun x2 and i think that someone was asking on the class A thread so i'll have a look. ok i think that it was florian i'll drop him a PM take care |
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Post by gommer on Feb 15, 2013 11:09:27 GMT
Hi Shaun,
Thanks for your support.
I'm also looking at the hard to get components. It seems the LS352 and LS313 are both hard to get, with only a single ebay source for the 2N3811A. But LS313 and LS352 are both distributed by Micross.
They could be added to the group by, which might make it more attractive for some. Let's hope we reach at least 20 pieces. Quick cost calculation results in around €6 per PCB.
Cheers, Marc
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Post by Deleted on Feb 15, 2013 16:27:34 GMT
Hi Shaun, Thanks for your support. I'm also looking at the hard to get components. It seems the LS352 and LS313 are both hard to get, with only a single ebay source for the 2N3811A. But LS313 and LS352 are both distributed by Micross. They could be added to the group by, which might make it more attractive for some. Let's hope we reach at least 20 pieces. Quick cost calculation results in around €6 per PCB. Cheers, Marc Hi Marc no worries it should be fun to build another. the 2N3811A is a very good device by the way and if it's from tubeshunter well i've had two from him without issue but Alex had a few problems if i remember rightly.  if it's just going to be me and you then no worries i'll get the etch kit out and do us some boards so you will be building this fine HA/PRE what ever. if we get no other takers then well er letting the chance to hear this outstanding amp will be slipping though the fingers again. ho hum.  just to say that this is the best HA/PRE i've heard full stop and Alex's PA is likewise so come on in and join us solder slingers.  take care |
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Will
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Post by Will on Feb 15, 2013 18:18:31 GMT
Well, if you are going to to do all the hard work, I'm up for a few pcbs!
I'll have 4 please, and if you do a GB for the LS devices. It's really easy to order from Micross, just need to meet the minimum qty of 20 I'd be up for 4 of each ls device. Before hand, you had to get quotes and raise pro-formas. You'll find the TO71 size cases cheaper as well.
Come you lurkers, this is a chance to build a fantastic head amp, especially if you have K701* headphones.
*other headphones are available, but you don't get to look like a cyberman.
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Post by gommer on Feb 15, 2013 18:33:05 GMT
Hehe, with only 3, we're at 10 pcs. already, that's half way. I'll increase my own count because I'll probably regret only being able to build one pre/HA.
gommer x4
shaun x2
will x4
________
total 10
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Post by Deleted on Feb 15, 2013 18:37:49 GMT
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Post by Deleted on Feb 15, 2013 18:48:05 GMT
I can't believe I'm doing this after giving my spare pair of black slabs to Chong but the thought of one of these at work as well is too tempting.....
gommer x4
shaun x2
will x4
juke x2
cj x2
total 14
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Post by Deleted on Feb 15, 2013 19:10:43 GMT
I can't believe I'm doing this after giving my spare pair of black slabs to Chong but the thought of one of these at work as well is too tempting..... gommer x4 shaun x2 will x4 juke x2 cj x2 total 14 oh go on then gommer x4 shaun x4 will x4 juke x2 cj x2 total 16 to good to pass up ''Come you lurkers, this is a chance to build a fantastic head amp, especially if you have K701* headphones.'' spot on take care |
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Post by pingu on Feb 16, 2013 0:49:01 GMT
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Post by Deleted on Feb 16, 2013 1:38:21 GMT
Hi Marc,
I'm up for the LS devices if you are doing a GB on them.
LS352 and LS313 4 each # 8 total
Alan
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Post by Spirit on Feb 16, 2013 7:40:59 GMT
gommer x4 shaun x4 will x4 juke x2 cj x2 pingu x4 Spirit x2 total 22  |
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Post by Will on Feb 16, 2013 8:12:17 GMT
What do people think of me bringing the HA/pre pcb's into line with the PA pcbs? (Swap the 7xlxx regs in the servo for the to220 package versions, small load resistor in the same area, remove the smaller LS device location and put the feedback cap in) Shouldn't take more than 8-9 months to do that! |
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Post by gommer on Feb 16, 2013 8:21:46 GMT
Wow, I'm off to sleep and come back to see we've already reached the threshold. Nice.
Alan, I'll definitely count you in for the LS devices.
I presume everyone else wants one each(LS 352 and LS313) per PCB?
Will, could you send the artwork over as it is right now? I've only made presumtions about size (extrapolated on T0220 size), and many PCB makers only quote when they receive gerbers. I'll send you an email that you can reply to.
What benefit do you see, bringing the pre/HA in line with the PA? You still won't be able to turn one into the other, right?
Cheers, guys, keep'em coming, the more the merrier.
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Post by Will on Feb 16, 2013 8:31:40 GMT
Will, could you send the artwork over as it is right now? I've only made presumtions about size (extrapolated on T0220 size), and many PCB makers only quote when they receive gerbers. I'll send you an email that you can reply to. What benefit do you see, bringing the pre/HA in line with the PA? You still won't be able to turn one into the other, right? Hi Marc, The main benefit in bringing the pcb in line with the PA is making the whole circuit a bit more robust. A few people had the to92 style regs in the servo die on them, causing problems. Frans mentioned that he had had this problem in the past in other circuits, so I moved to the to220 type regs in the PA version. The feedback cap helps with fault-finding, and removing the small LS holes was just a tidying exercise. No difference to the actual PCB size physically, just improving the circuit a little. Thinking on it, there is also an improvement in the servo (extra cap?) that needs doing, which improves performance further. Off to get my hair chopped now, so will fire the original eagle files over to you when I get back, and we can discuss on the changes later. Cheers, Will |
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