I have moved all the GB posts here:
http://www.diyaudio.com/forums/group-buys/156811-aaks-symasym-pcb-group-buy.html
This thread should be about the design & performance.
Thanks
Hi Al,
I have a design question here:
2SC4793 is out of stock at both mouser & digikey.
Can I use 2SA1930/2SC5171 to replace the 2SA1837/2SC4793?
2SC5171 is a Toshiba 180V-2A driver, the spec looks quite good except that the base current (Ib) is 1A compared to 0.1A on C4793. I don't know how to read the SOA charts.
Do you have any other suggestion?
Best regards, Stanley
I have a design question here:
2SC4793 is out of stock at both mouser & digikey.
Can I use 2SA1930/2SC5171 to replace the 2SA1837/2SC4793?
2SC5171 is a Toshiba 180V-2A driver, the spec looks quite good except that the base current (Ib) is 1A compared to 0.1A on C4793. I don't know how to read the SOA charts.
Do you have any other suggestion?
Best regards, Stanley
Hi All,
I finally got around to finishing the new Rev_1.4 PCB for the GB, the amplifier schematic, and the BOM with updated prices from Mouser. Check out the pics. The amplifier section has already been prototyped and works great.
While updating the BOM I found four components out of stock at Mouser. The 4700uf PS caps (C3-C6), the 2SK170s (Q1,Q2), the 2SC4793 (Q21), and Terminal Block TB1. I found replacements at Digikey for all except the 2SK170s which I can't seem to find anywhere in the states. I've been told that Toshiba is no longer manufacturing them.
I could use some help in finding a cross reference device for the 2SK170 or a place where I can buy them in quantity? I'd be happy to match and ship Q1&Q2 along with the replacement parts from Digikey. I'm also thinking of doing a components GB that will include all the components with the SST, and OT matched and ready to go for a reasonable fee for those interested. I'll provide more info on the GB thread found here.
http://www.diyaudio.com/forums/group-buys/156885-symasym-sequel-aaks-pcb-gb-15.html
Getting back to the PCB, it measures 6.375" x 2.87" which is about 0.375" longer the my Rev_1.3 board. Some differences with the original Rev_1.3 PCB includes mounting holes for the OTs for those that would prefer using a 3" heatsink. I rotated Q1&Q2 so that it reflects the correct orientation, and added some extra space for C10 to accommodate a larger capacitor on the PCB to reduce crossover distortion, and put back the VAS load resistors. I also added a new input differential bias circuit that reduces the parts count without influencing the sound in anyway when compared to the Rev_1.3 design. The new PCB also provides the option of separating the PS from the amplifier by simply cutting between the vertical lines labeled on the board. This option could come in handy if you want to build a multi channel amp let say for an active crossover speaker system, or a home theater amp where the on-board PS length may prevent you from installing several amplifiers on a single heatsink.
Here's the pics.
Regards,
Al
I finally got around to finishing the new Rev_1.4 PCB for the GB, the amplifier schematic, and the BOM with updated prices from Mouser. Check out the pics. The amplifier section has already been prototyped and works great.
While updating the BOM I found four components out of stock at Mouser. The 4700uf PS caps (C3-C6), the 2SK170s (Q1,Q2), the 2SC4793 (Q21), and Terminal Block TB1. I found replacements at Digikey for all except the 2SK170s which I can't seem to find anywhere in the states. I've been told that Toshiba is no longer manufacturing them.
I could use some help in finding a cross reference device for the 2SK170 or a place where I can buy them in quantity? I'd be happy to match and ship Q1&Q2 along with the replacement parts from Digikey. I'm also thinking of doing a components GB that will include all the components with the SST, and OT matched and ready to go for a reasonable fee for those interested. I'll provide more info on the GB thread found here.
http://www.diyaudio.com/forums/group-buys/156885-symasym-sequel-aaks-pcb-gb-15.html
Getting back to the PCB, it measures 6.375" x 2.87" which is about 0.375" longer the my Rev_1.3 board. Some differences with the original Rev_1.3 PCB includes mounting holes for the OTs for those that would prefer using a 3" heatsink. I rotated Q1&Q2 so that it reflects the correct orientation, and added some extra space for C10 to accommodate a larger capacitor on the PCB to reduce crossover distortion, and put back the VAS load resistors. I also added a new input differential bias circuit that reduces the parts count without influencing the sound in anyway when compared to the Rev_1.3 design. The new PCB also provides the option of separating the PS from the amplifier by simply cutting between the vertical lines labeled on the board. This option could come in handy if you want to build a multi channel amp let say for an active crossover speaker system, or a home theater amp where the on-board PS length may prevent you from installing several amplifiers on a single heatsink.
Here's the pics.
Regards,
Al
Attachments
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Zhoufang has the 2SK170's
Hello Al!
http://www.diyaudio.com/forums/vend...ted-but-hard-get-they-here-5.html#post2227651
He is on "vacation" 'til August 8. He is responding to posts on his thread.
I bought 100 for ~$36 on cut tape and matched my own.
Lovin' the amp...
Hello Al!
http://www.diyaudio.com/forums/vend...ted-but-hard-get-they-here-5.html#post2227651
He is on "vacation" 'til August 8. He is responding to posts on his thread.
I bought 100 for ~$36 on cut tape and matched my own.
Lovin' the amp...
Last edited:
Or, from Spencer http://www.diyaudio.com/forums/swap-meet/131284-toshiba-2sk170bl-sales.html. I bought from Spencer and Zhou before. Both are good.
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