Looks like these are finally EOL, and I think it’s been on the cards for a while. Anybody considered other alternatives in the same TO-126 packages?
I’ve looked at the Toshiba TTA/C 004 devices. The hFE vs Ic is nice and flat but Cob is about 2.2x the KSA/KSC devices. fT is about the same at 100 MHz.
I will open up my ax-Amp and try the TTA/TTC devices. May require tweaks to the compensation and re-characterisation of distortion etc.
Looks like for VAS duty another option will be to go for a SOT223 type device but I’m not aware of anything out there at this point.
I’ve looked at the Toshiba TTA/C 004 devices. The hFE vs Ic is nice and flat but Cob is about 2.2x the KSA/KSC devices. fT is about the same at 100 MHz.
I will open up my ax-Amp and try the TTA/TTC devices. May require tweaks to the compensation and re-characterisation of distortion etc.
Looks like for VAS duty another option will be to go for a SOT223 type device but I’m not aware of anything out there at this point.
I use MJE243/253 in my designs and schematics.
Unfortunately I am not happy with the SPICE models of TTC004B/TTA004B.
Unfortunately I am not happy with the SPICE models of TTC004B/TTA004B.
Hi Bonsai
Maybe you read this:
here:
or ask brain92fs
i changes my KSC/KSA to TTA004B_Q because i have got wrong hfe group at my FX8. i am happy with the sound with this VAS transistors.
it is a group by (last call) existing for the correct hfe group by brain92fs.
i am not able to measure the difference as brain wrote in this thread, but it is very interesting for me to have an idea to compensate the "wrong" hfe group transistors as good as possible.
kr
chris
Maybe you read this:
here:
or ask brain92fs
i changes my KSC/KSA to TTA004B_Q because i have got wrong hfe group at my FX8. i am happy with the sound with this VAS transistors.
it is a group by (last call) existing for the correct hfe group by brain92fs.
i am not able to measure the difference as brain wrote in this thread, but it is very interesting for me to have an idea to compensate the "wrong" hfe group transistors as good as possible.
kr
chris
The Toshiba models are a joke. Check these out:
I made a comment specifically about the Toshibas in the first post.
BTW true that they have higher Cob than the KSx, but they have much better quasi-saturation, at least at low currents. I can post my measurements if anyone is interested.
Equivalents are still available from KEC (https://www.keccorp.com/) as KTA1381 and KTC3503.
They sent me free samples a couple of years ago and they work fine.
They sent me free samples a couple of years ago and they work fine.
Here are some relevant curves that cabirio kindly provided via his constructive device modeling in other threads. Thank-you very much!
Yes, the Cob's differ, but my optimistic swag is that difference is almost compensated by the higher Beta...and then the global feedback will reduce that difference to near naught. For me, the tipper was the beautiful TTA4003B curve with no quasi-wazi anomalies. This could mean the single VAS may obtain a couple of volts extra clean headroom when the VAS is run into the rails.
No testing has been done by me to substantiate these swags.
-David
Attachments
Yes, I lifted those very same plots to post here... thanks again for helping us with useful real data.
The KSA1381 was originally destined for a singleton VAS application due to its low Cob and traditional VAS use.
I was going round and round with the Tosh part also, and your trace curves finally answered the tradeoff questions I had about the VAS choice.
-David
The KSA1381 was originally destined for a singleton VAS application due to its low Cob and traditional VAS use.
I was going round and round with the Tosh part also, and your trace curves finally answered the tradeoff questions I had about the VAS choice.
-David
Here we have it again. Sound is coming from loudspeaker or headphones not from transistors.
I downloaded your models of KSC1845 and KSA992.The Toshiba models are a joke. Check these out:
I made a comment specifically about the Toshibas in the first post.
BTW true that they have higher Cob than the KSx, but they have much better quasi-saturation, at least at low currents. I can post my measurements if anyone is interested.
They are super!!!
KSC and KSA have almost the same VBE