Does the SS1122 have the integral heatsink like the 404XX types? Some people have
stated that the 404XX are slow but they are actually 100 MHz ft.
The higher voltage BD139 and BD140 should work just fine, they don't see the full
42+42 voltage due to the voltage gain output stage. Use a quality part like Onsemi or similar.
You'll have to be sure to get the pinout right and to use a bolt on heatsink.
There are some newer/faster options for drivers.
MJ15003/4 are good outputs if you want to keep the speed about the same, let us know if you try them.
I've not tried re-building with any different drivers or outputs so no experience here.
MJ21193/4 Are the faster possibility.
stated that the 404XX are slow but they are actually 100 MHz ft.
The higher voltage BD139 and BD140 should work just fine, they don't see the full
42+42 voltage due to the voltage gain output stage. Use a quality part like Onsemi or similar.
You'll have to be sure to get the pinout right and to use a bolt on heatsink.
There are some newer/faster options for drivers.
MJ15003/4 are good outputs if you want to keep the speed about the same, let us know if you try them.
I've not tried re-building with any different drivers or outputs so no experience here.
MJ21193/4 Are the faster possibility.
21193/4 will likely work. But 15003/4 are a little higher gain. That was The Big Deal with the original MJ802/4502 but the SOA is garbage.
BD139/140 will likely work as drivers too, but they CAN see the full 84V under overdrive. Best check ‘em to be sure they’re good for 100 before using. If any doubt, use a modern Jap driver pair or MJE243/253.
BD139/140 will likely work as drivers too, but they CAN see the full 84V under overdrive. Best check ‘em to be sure they’re good for 100 before using. If any doubt, use a modern Jap driver pair or MJE243/253.
MJE15031/032 have “horrible” SOA too, but that doesn’t stop them from driving four pairs of C5200. They are only good for a couple of watts at VCE=40, but that is all that is needed. The output transistor beta falls off at high current, but at that point (near clipping) VCE is low. Even MJ15003 beta is pretty good at 2 amps, requiring less of the drivers at full VCE.
wg_ski, thanks for the suggestion to use the MJ15003/15004 pair. I will pick some up and give them a try. Let me know your thoughts on using the BD137/138 in place of the SS1122/1123?
EDIT: Just searched and most of these are now NLA that's unfortunate, and I would not buy
from ebay or any other less reputable sources. BDent has been okay for me but I didn't check them.
I wrote this in 2019 not sure if they're still readily available:
I'd use 2SC4883A / 2SA1859A devices that are available, cheap at Digikey and perhaps others.
They are fast 2A parts with excellent SOA, discussed here:
We discussed drivers in Bob Cordell's Book thread but I can't find the page in that super long thread.
Here's another post that I made in 2019 about drivers, note that the above parts have the best SOA:
Very Good: Last I checked KSA1220A/KSC2690A SOA was 220mA @50V and 90mA at 100V,
2SA1552 is 150mA @50V and 40 mA at 100V, this is decent but not as good, there
are many parts that are far worse.
Not good: 2sa1930/2sc5171 only do 100mA@50V, 35mA@100V but are rated for 2A.
These have been talked about recently, but are TO-220 with very good SOA:
Best: 2SC4883A/A1859A - TO220-F 20W 180V 2A 30pF 120 MHz 300mA@50V 75mA@100V
These also are TO-220 with very good SOA:
2sa1837/2sc4793 -TO220 1A 20W 220mA@50, 85mA@100V
from ebay or any other less reputable sources. BDent has been okay for me but I didn't check them.
I wrote this in 2019 not sure if they're still readily available:
I'd use 2SC4883A / 2SA1859A devices that are available, cheap at Digikey and perhaps others.
They are fast 2A parts with excellent SOA, discussed here:
We discussed drivers in Bob Cordell's Book thread but I can't find the page in that super long thread.
Here's another post that I made in 2019 about drivers, note that the above parts have the best SOA:
Very Good: Last I checked KSA1220A/KSC2690A SOA was 220mA @50V and 90mA at 100V,
2SA1552 is 150mA @50V and 40 mA at 100V, this is decent but not as good, there
are many parts that are far worse.
Not good: 2sa1930/2sc5171 only do 100mA@50V, 35mA@100V but are rated for 2A.
These have been talked about recently, but are TO-220 with very good SOA:
Best: 2SC4883A/A1859A - TO220-F 20W 180V 2A 30pF 120 MHz 300mA@50V 75mA@100V
These also are TO-220 with very good SOA:
2sa1837/2sc4793 -TO220 1A 20W 220mA@50, 85mA@100V
Not looking good for parts:
https://www.diyaudio.com/community/threads/ksc2690a-and-ksa1220a.336650/page-5
https://www.diyaudio.com/community/threads/ksc2690a-and-ksa1220a.336650/page-5
No it’s not looking good. No more KSA1220. And I thought it was going to be one of the survivors. We’re not too awfully far away from designing/redesigning everything around MJE1503x. I wonder if they would work in an original Tiger without the fat lady singing.
The last few years when I’ve been looking for Sanken anything (drivers, outputs, darlingtons) at least one of the pair has been out of stock, no backorder, no estimated delivery date.
The last few years when I’ve been looking for Sanken anything (drivers, outputs, darlingtons) at least one of the pair has been out of stock, no backorder, no estimated delivery date.
BD139/140-16 are typically at Arrow, Digikey, and Mouser.
I would only get Onsemi or Fairchild, don't know about STmicro - anyone?
Would like to get Phillips but NLA as far as I know.
I have some of these but will probably stock up on more, too bad they're so low voltage.
I'd probably use the TTA004B and TTC004B in the VAS and current source location since
they should be faster. Or a better small signal transistor, any suggestion on current parts?
BD139/140 should also work in the VAS and comp as a last resort, they will probably want
a bit more bias.
I would only get Onsemi or Fairchild, don't know about STmicro - anyone?
Would like to get Phillips but NLA as far as I know.
I have some of these but will probably stock up on more, too bad they're so low voltage.
I'd probably use the TTA004B and TTC004B in the VAS and current source location since
they should be faster. Or a better small signal transistor, any suggestion on current parts?
BD139/140 should also work in the VAS and comp as a last resort, they will probably want
a bit more bias.
How are transistors from Nexperia and Infineon good quality? Anyone?
Seems Nexperia is the old Philips, might be a good thing:
https://www.nexperia.com/about/company-timeline
Seems Nexperia is the old Philips, might be a good thing:
https://www.nexperia.com/about/company-timeline
Last edited:
I wrote this in the APT1 thread PZT parts are still available from usual sources.
300V, low CCB and decent Ft probably good enough for VAS and comp even with .5A rating:
Solder to a heat sink if needed.
Also, while the MPSA92/A42 are not readily available from Onsemi (MOT) the PZTA92/A42
versions are in production. They are large surface mount parts that one could easily solder
leads to. The lead pitch is the same as a TO126.
You can use Octopart to find parts, stay away from odd ball distributors.
300V, low CCB and decent Ft probably good enough for VAS and comp even with .5A rating:
Solder to a heat sink if needed.
Also, while the MPSA92/A42 are not readily available from Onsemi (MOT) the PZTA92/A42
versions are in production. They are large surface mount parts that one could easily solder
leads to. The lead pitch is the same as a TO126.
You can use Octopart to find parts, stay away from odd ball distributors.
Last edited:
Nothing wrong with NXP, Infineon, or ST. But everybody’s thru hole is either gone already or dwindling fast.
MPSA42,92 are generic enough you could probably use anybody’s. At least those that still make ‘em in a TO-92. It’s a conspiracy to keep the guys that make all these 1 inch fans in business. Your PCB needs a fan blowing directly on it or it reaches 115C. And thats the small signal part of it.
MPSA42,92 are generic enough you could probably use anybody’s. At least those that still make ‘em in a TO-92. It’s a conspiracy to keep the guys that make all these 1 inch fans in business. Your PCB needs a fan blowing directly on it or it reaches 115C. And thats the small signal part of it.