Will
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Post by Will on Jun 1, 2009 19:53:15 GMT
If you have been following the SC Class A head-amp thread, then you may be aware that to get best results, you need to match the BC560C and MPSA18 transistors in particular. When matching, it is best to match both hfe and vbe. This takes a lot of time and a lot of transistors. A solution to this is to use the Linear Systems LS313 and LS352. Each device consists of two very tightly matched transistors, doing away with the need to match them. However, they are very difficult to get hold of. I've contacted the UK suppliers, and they are willing to sell the devices directly to us. The minimum number is 25 of each, which is quite a low number, considering that you need two of each to make the SC Class A. They will be supplied in TO-71 cases. We've been quoted a price of £3.58 each device, ex VAT and delivery. The cost for a full set (Qty 2 LS313, Qty 2 LS352 inc VAT and delivery to me) is £17.80, although this will go down if we buy more than the minimum of 13 full sets. The next price break is at 100 devices (£3.03 ex VAT and delivery), so if we buy 50 full sets, it'll go down in price again. I'll advise when that happens! So if you are interested in buying a set, please post here, or PM me. Here is how I plan to do the purchase. 1. We'll wait until we have the 13 full sets needed to go ahead, and then wait one week, just in case any stragglers want to join in. 2. Once we have the right numbers, I'll advise of the final price. 3. As I do not have the spare cash, I would like to be paid for the number of sets you require. Once all payments have been made, I will place the order. 4. Once I receive the LS313/LS352s, I will contact you to discuss how you wish to have them posted. I recommend that any overseas buyers look at insured postage. I will try and arrange the most cost-effective postage for you. Once postage options have agreed, I will post to you once payment for postage has been made. I'm doing this as I know that there are a few who want these devices, so it seems the best way to try and get them. I'll post a running total of who wants what. So, who wants some, as they say? www.linearsystems.com/datasheets/LS310-3.pdfwww.linearsystems.com/datasheets/LS350-2.pdf |
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Post by Deleted on Jun 1, 2009 22:00:14 GMT
Will
As previously advised, I will take 4 of each, or settle for 2 of each if quantities are limited.( That's for Class A amp + preamp)
Alex
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Will
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Post by Will on Jun 2, 2009 5:59:51 GMT
OK, current state of play.
Me - 1 full set.
Alex - 2 full sets.
Juke - 3 full sets.
Jon Clancy - 1 full set.
Pretty good going. Just need another 6 sets and we make minimum quantity to make this work!
By the way, if anyone wants some sort of proof that I'm honest, please contact me for my ebay username. Only 114 feedback, but the majority gained through selling stuff, mainly when clearing out the cupboards/garage etc!
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Spirit
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Post by Spirit on Jun 2, 2009 9:33:49 GMT
Congrats on 500th post Will  I would.. but.. yeah... you know =P |
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Post by Deleted on Jun 2, 2009 15:45:27 GMT
X2!  |
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Will
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Post by Will on Jun 2, 2009 22:42:32 GMT
Congrats on 500th post Will I would.. but.. yeah... you know =P Thanks, Phil! No probs, I think I would do what you are doing, given the chance! |
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Spirit
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Post by Spirit on Jun 2, 2009 22:55:52 GMT
X2! Are you heading to Indonesia too?   |
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Post by Deleted on Jun 2, 2009 23:33:45 GMT
 only in my dreams, though there are tentative plans for Thailand in 4 to 5 years. I was referring to my lack of electronic savvy! Edit = Good luck in Indonesia
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Spirit
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Post by Spirit on Jun 3, 2009 3:45:51 GMT
only in my dreams, though there are tentative plans for Thailand in 4 to 5 years. I was referring to my lack of electronic savvy! Edit = Good luck in Indonesia Hehehe... Thailand is lots of fun - mate of mine was there for New Years. I built a SCHA... This doesn't look too much harder . As long as there are pretty pictures, chances are I can emulate it ;D Thanks! </hijack thread> |
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Will
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Post by Will on Jun 3, 2009 6:05:01 GMT
Chris, from what I've seen, you are more than capable of making this amp (SCHA/your recent modifications to your amp)
It really is a case that If I can do it (with the help of the circuit diagram, pretty pictures and a couple of E-mails) then anyone who made the SCHA can. I'm more of a board stuffer than one of these ninjas that now which way around a cap goes, due to the closeness of the nearest transistor etc, but I am learning.
I've put up a few diagrams in the thread, that I created during my build, that have been now proven to be correct (ie my amp works!) that really should help.
The only extra 'technical bits' over the SCHA are probably the transistor matching (which is straight forward with a DMM or the circuit you posted) and the board etching.
I'll be trying a method of board etching this week that Jon Clancy has tried. It is not very technical at all. A bit of etch fluid and two plastic bags! No real investment in pieces of equipment at all.
I have a post half written detailing how I etch boards. I'll post this soon, so perhaps it may encourage some to have a go, and hopefully help people make the SC Class A. If all else fails, I sure I can be persuaded to help with etching boards.. (oh jeez, did I just post that?!)
If anyone else feels that this may be a bit too technical, please post to your questions. I'm sure that they can be answered to help people feel that they can build this amp.
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Post by Deleted on Jun 3, 2009 7:45:49 GMT
Will, Thanks for the encouragement! I've certainly learned plenty too, especially during the SCHA build, thanks to all here. The main amp is still pending, just got the psu Robert built powered-up off the amps transformer (all measured well) and decided on a spot to cut into the power rails for the opamps. Not enough time as usual, once done I still have the SCHA to finish modding! Etching method sounds interesting... Spirit, Yep, Thailand's fun alright. I lived on Phuket around '93-'95, had a bar in Patong, need I say more  Been back for holidays but the whole family is itching to move back. Never got closer than Malaysia (to Indonesia), are you going for short a holiday or longer? |
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Spirit
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Post by Spirit on Jun 3, 2009 8:16:04 GMT
had a bar in Patong, need I say more You needn't Only a short trip... 28 or so days. Already skipping the first week of uni when it goes back... (Mate who I'm travelling with can't do my summer holidays... so these are the restrictions I have to work with ) |
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jonclancy
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Post by jonclancy on Jun 5, 2009 7:06:26 GMT
A quick question: Is is possible to configure a set of boards to run as headphone amp and, by changing the output devices, to 15W Class A?  If this was possible, it would make this project ultimately flexible, and would be a brilliant forum project. We have the expertise here to redesign boards as required, etch them using various methods, construction hand-holding, troubleshooting and advice on ancillaries and casework. So come on folks, don't be shy!!! Cheers Jon |
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Post by Deleted on Jun 5, 2009 7:47:05 GMT
Jon
The PCBs are identical, but with a few minor component changes, and supply for front end split for JLH only for front end instead of the lot in the preamp.
Should be entirely feasible . You will of course need a bigger PSU regulator board etc.for the 15W Class A.
Alex
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Post by clausdk on Jun 5, 2009 9:03:06 GMT
A quick question: Is is possible to configure a set of boards to run as headphone amp and, by changing the output devices, to 15W Class A? If this was possible, it would make this project ultimately flexible, and would be a brilliant forum project. We have the expertise here to redesign boards as required, etch them using various methods, construction hand-holding, troubleshooting and advice on ancillaries and casework. So come on folks, don't be shy!!! Cheers Jon I would be happy to supply wodden boxes, for a small fee ofcourse, but it will still be cheap.. |
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Post by Deleted on Jun 5, 2009 9:45:48 GMT
clausdk
A wooden box would go well with the preamp, but the Class A amplifier uses big heatsinks either side, as total power dissipation is close to 100W.
Alex
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Post by clausdk on Jun 5, 2009 14:29:57 GMT
clausdk A wooden box would go well with the preamp, but the Class A amplifier uses big heatsinks either side, as total power dissipation is close to 100W. Alex 100 W That could be causing some problems. Maybe I can let the heatsinks stickout on the sides ? But to find a good solution I would have to see the Finished PCB in real live. |
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leo
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Post by leo on Jun 6, 2009 1:31:55 GMT
I'll have a set please
You compared the SQ to the BC560C and MPSA18 Will out of interest? I sat ages matching them up in mine
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Will
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Post by Will on Jun 6, 2009 7:57:48 GMT
I'll have a set please You compared the SQ to the BC560C and MPSA18 Will out of interest? I sat ages matching them up in mine No problem, 5 sets until we can buy! To be honest, Leo, I didn't match my BC560C or MPSA18 at all, as I had the LS devices ready to drop in. I used the BC560C and MPSA18 to try the board out and any de-bugging. I didn't want to risk the LS313/352 as they are pretty scarce to come by. When I put the LS's in, I also did the LTP mod as well, so the improvement may have been a cumulative thing. It certainly is not a backwards step, from what I have heard so far. |
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Post by Deleted on Jun 6, 2009 8:07:35 GMT
Will
Did you by any chance check the HFE of the LS devices before installation ? Actually, I would expect matched high HFE MPSA18 to perform better in the current mirror, but the use of the LS313 would make it easier for the average constructor. I hope to trial LS301 in that location. Their typical HFE is 2,000 (!) at 500uA.
Alex
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Will
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Post by Will on Jun 6, 2009 8:30:01 GMT
Aaargh!  Don't say that, you'll put people off buying the devices! Seriously, though, If you find that the LS301 is a better device for the application, I can find out what the difference would be, cost wise. Do you now when you may be able to try them out? In answer to your original question, I didn't have chance to measure the HFE. Build fever got in the way. |
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Post by Deleted on Jun 6, 2009 8:38:56 GMT
Aaargh! Don't say that, you'll put people off buying the devices! Seriously, though, If you find that the LS301 is a better device for the application, I can find out what the difference would be, cost wise. Do you now when you may be able to try them out? In answer to your original question, I didn't have chance to measure the HFE. Build fever got in the way. Will I would stick with the LS313 for ease of use. As Leo said , it's very time consuming to match high gain MPSA18 especially. Their HFE varies quite a bit with temperature/air movement. Personally, I would have chosen the LS302 to experiment with, (HFE1,000) but my friend wanted to try the HFE 2,000 variety in the CM. Alex |
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Post by cyteen on Jun 6, 2009 8:54:30 GMT
I'm in for a set when the GB goes through.
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Will
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Post by Will on Jun 6, 2009 11:04:32 GMT
I'm in for a set when the GB goes through. Good Man! Current state of play. Me - 1 full set. Alex - 2 full sets. Juke - 3 full sets. Jon Clancy - 1 full set. Leo - 1 full set. Cyteen - 1 full set. 4 sets 'till take off. |
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jonclancy
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Post by jonclancy on Jun 6, 2009 19:27:18 GMT
Thanks Claus!! Your workmanship is first class, and would set off the pre nicely. I also think it would be possible to mount a large heatsink down either side of a wooden enclosure. You could use a metal sub-chassis to spead the heat evenly, perhaps? Cheers Jon A quick question: Is is possible to configure a set of boards to run as headphone amp and, by changing the output devices, to 15W Class A? If this was possible, it would make this project ultimately flexible, and would be a brilliant forum project. We have the expertise here to redesign boards as required, etch them using various methods, construction hand-holding, troubleshooting and advice on ancillaries and casework. So come on folks, don't be shy!!! Cheers Jon I would be happy to supply wodden boxes, for a small fee ofcourse, but it will still be cheap.. |
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only in my dreams, though there are tentative plans for Thailand in 4 to 5 years.
Been back for holidays but the whole family is itching to move back. Never got closer than Malaysia (to Indonesia), are you going for short a holiday or longer?
Don't say that, you'll put people off buying the devices! 