I'm going to try to see is there anything suspicious at most right pic
in a meantime - solder those resistors in 1-pin headers , just in case
even if one wants later to remove them , it's easy
in a meantime - solder those resistors in 1-pin headers , just in case
even if one wants later to remove them , it's easy
I communicated with Chris yesterday about this bracket and poked around my local Ace this morning. They have a few choices, and my first try is with a: 5" Corner Brace Zinc, with a part number of 5290671, which seems perfect (right down to bolt hole size) for an Antek 300VA transformer. There is also a 6" version, if you're a crazy person. I haven't yet verified the compatibility with the Store chassis, but will do so when I tear this amp down to rebuild it into the next big thing. 😉
Since I don't have my thread wading boots on, can SissySit be made with Sony VFET instead of Tonkin? Sorry if question has been asked and answered.
I am still contemplating trying to get SissySit to work in Sony TA4650 chassis/power supply (blown boards but preamp still works). I have an extra heat sink (built in heat sink for one channel, extra heat sink for second channel) and some working Sony VFET's rattling around, but I have to measure size of circuit boards and consider implementation logistics. I could put some components external to the chassis as well if necessary.
The Sony PS has 43V rails DC + and - at the diode outputs.
I am still contemplating trying to get SissySit to work in Sony TA4650 chassis/power supply (blown boards but preamp still works). I have an extra heat sink (built in heat sink for one channel, extra heat sink for second channel) and some working Sony VFET's rattling around, but I have to measure size of circuit boards and consider implementation logistics. I could put some components external to the chassis as well if necessary.
The Sony PS has 43V rails DC + and - at the diode outputs.
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I do have a Sony TA-4650 as well as having built a SissySIT.
From my estimate, building SissySIT into TA-4650 case / PSU wouldn't work. SissySIT is a typical FirstWatt-style Class A amp. It runs about 100W per side, bias curent of around 2A at 24V. The heatsinks of the 4650 are way too small, even two of them, and the transformer / PSU has too much voltage and way too little current capability. Also, it is a C only PSU, not CRC or CLC, so it has way too much ripple.
As to using a Sony 2SK60 as the SIT in a SissySIT, I don't know how happy that would be dissipating 50W at idle ... a lower current SissySIT may need significant alterations in the circuit - maybe ZenMod can step in if the bias circuitry could be adapted to regulating to a lower bias current ?
But in my view, the good thing about the 4650 was its output stage, not necessarily its preamp stage ... I have used it as power amp only, with preamp bypassed 🙂.
Regards, Claas
From my estimate, building SissySIT into TA-4650 case / PSU wouldn't work. SissySIT is a typical FirstWatt-style Class A amp. It runs about 100W per side, bias curent of around 2A at 24V. The heatsinks of the 4650 are way too small, even two of them, and the transformer / PSU has too much voltage and way too little current capability. Also, it is a C only PSU, not CRC or CLC, so it has way too much ripple.
As to using a Sony 2SK60 as the SIT in a SissySIT, I don't know how happy that would be dissipating 50W at idle ... a lower current SissySIT may need significant alterations in the circuit - maybe ZenMod can step in if the bias circuitry could be adapted to regulating to a lower bias current ?
But in my view, the good thing about the 4650 was its output stage, not necessarily its preamp stage ... I have used it as power amp only, with preamp bypassed 🙂.
Regards, Claas
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not likely , from few reasons:
- less important - circuit is optimized for usual FW format PSU , which means twice 18Vac secs. resulting in somewhat as +/-22V5dc
-more important - without actually checking , but by memory of resurrection and full service of few Sony amps I made in last decade , Sony VFets are most likely having greater Ugs than allowed , to be able to meet with regular mosfet gate ...... in short - count that mosfet's gate is circa 4V bellow it's source/output node , so VFet's gate can be anywhere from output node to said 4V bellow output node ....... practical limit being ,say, -3V7 - so we still have some voltage window to squeeze opto inside of it
making it functional (Sony VFet in SissySIT) could be making entirely new amplifier ....... buying a pair of Tokins is certainly more effective , and cheaper 🙂
of course - it is possible that I'm wrong , judging Ugs by use in B class amp , with highish rail - it's is possible to check Ugs values in Papa's Sony amps threads , but I'm sleepy ...... Monday morning 🙂
I'm going to do few most urgent things , then I must check something on my pillow ......
- less important - circuit is optimized for usual FW format PSU , which means twice 18Vac secs. resulting in somewhat as +/-22V5dc
-more important - without actually checking , but by memory of resurrection and full service of few Sony amps I made in last decade , Sony VFets are most likely having greater Ugs than allowed , to be able to meet with regular mosfet gate ...... in short - count that mosfet's gate is circa 4V bellow it's source/output node , so VFet's gate can be anywhere from output node to said 4V bellow output node ....... practical limit being ,say, -3V7 - so we still have some voltage window to squeeze opto inside of it
making it functional (Sony VFet in SissySIT) could be making entirely new amplifier ....... buying a pair of Tokins is certainly more effective , and cheaper 🙂
of course - it is possible that I'm wrong , judging Ugs by use in B class amp , with highish rail - it's is possible to check Ugs values in Papa's Sony amps threads , but I'm sleepy ...... Monday morning 🙂
I'm going to do few most urgent things , then I must check something on my pillow ......
Thanks, ZenMod for bringing up the other issue - in my case, all the 2SK60 I have tested had a Ugs at 100mA bias point between 18V and, say, 11V ... so I think it highly unlikely that you could get them down to less than 3V5 Ugs at 24V / 2A.
I also have the larger transformer from a Sony TA 8650 as well as the 8650 heat sinks with some large caps. I suppose I could purchase the Tonkin SITs and gut and revamp the insides of the chassis, or cut holes in the cage if necessary. That's why I would have to measure and see if possible. It's purely for nostalgia, but if it doesn't work it doesn't work. I might try the "simple SIT" route instead with single ended SIT.
if complete revamp of your Sony amps is out of question , just sell them and invest in parts to make your own clean amp , from scratch ..... whichever you choose
Thank you, just spitballing. I am thinking if I go into a different scheme than the revamp, then the 8 to 10 watt single ended SIT approach might work better for the ergonomics of the amp.
The preamp portion still works and sounds quite good, and the single ended SIT would have enough power for my application intended.
Thanks again for tolerating my fantasy.
The preamp portion still works and sounds quite good, and the single ended SIT would have enough power for my application intended.
Thanks again for tolerating my fantasy.
hm...... Fantasy
aren't we all here from same that reason
?
8 to 10W SE SIT/VFET/Sand ...... in a best way count on 30W of heat, per channel
best , efficiency/heat-wise , if using big honkin choke as load , but then you're restrained with space inside mainly for chokes , while still slim with heatsinks and ventilation
no Bubba , physics still dictates , so you're pretty much coral-ed with form-factor - amp is made for so-so watts in aB class , and that's it
been there, done that , flopped heavily not just once
🙂
aren't we all here from same that reason
?8 to 10W SE SIT/VFET/Sand ...... in a best way count on 30W of heat, per channel
best , efficiency/heat-wise , if using big honkin choke as load , but then you're restrained with space inside mainly for chokes , while still slim with heatsinks and ventilation
no Bubba , physics still dictates , so you're pretty much coral-ed with form-factor - amp is made for so-so watts in aB class , and that's it
been there, done that , flopped heavily not just once
🙂
... because pictures or it never happened
It was late and the lighting was pretty bad but I will post better pictures as this progresses.
Some things I learned from stuffing these:
- MZM gives you 10 diodes (1N4148) but you only use 6 for M25 (D1, D2, D3) and 6 for Sissysit (D3, D4, D5) so you really only need 6 and the extra 4 are gifts. If this is totally wrong please let me know.
- don't think you can be cute and replace the series resistance at R21 with a single 200R until you've read the post where it says to put 100R as close to the gate as possible (directly at the SIT) or you'll be desoldering like I did
- CBL on the left channel is best soldered from underneath to avoid getting close to the 2SK2145 or you'll be in there with a magnifying glass and solder wick and flux like I did
- Home Depot carries #6 and #8 split/lock washers in the tiny bins
P.S. You do need to read this thread (especially post #1) at least 5 times
It was late and the lighting was pretty bad but I will post better pictures as this progresses.
Some things I learned from stuffing these:
- MZM gives you 10 diodes (1N4148) but you only use 6 for M25 (D1, D2, D3) and 6 for Sissysit (D3, D4, D5) so you really only need 6 and the extra 4 are gifts. If this is totally wrong please let me know.
- don't think you can be cute and replace the series resistance at R21 with a single 200R until you've read the post where it says to put 100R as close to the gate as possible (directly at the SIT) or you'll be desoldering like I did
- CBL on the left channel is best soldered from underneath to avoid getting close to the 2SK2145 or you'll be in there with a magnifying glass and solder wick and flux like I did
- Home Depot carries #6 and #8 split/lock washers in the tiny bins
P.S. You do need to read this thread (especially post #1) at least 5 times
hm...... Fantasy
aren't we all here from same that reason
8 to 10W SE SIT/VFET/Sand ...... in a best way count on 30W of heat, per channel
🙂
Yes, my VFETs in hand are the 2sk60 2sj18, so maybe 5 watts SIT single ended at 20W of heat per channel. I have the huge transformer and caps from a defunct TA 8650.
My ambitions are getting pared down, Hah, Hah! I'll look into the various single ended simple SIT threads and try to conceptualize.
I have two 4650 chassis, one with working preamp and one with working amp, so maybe just combine for one updated working model and keep the empty chassis fascia for diabolic purposes.
I won't bother you any more here.
look for Papa's Sony VFet amp V.2 , maybe someone is having pcbs for trade
with these VFets you have , you can make iteration with slightly lower Iq and that's it
with these VFets you have , you can make iteration with slightly lower Iq and that's it
I actually already have a v2 that is pre-built and luv it. I was going for either a small DEF type or single ended SIT to have one of those, too. Too greedy.
Thnx.
Thnx.
The amplifier gods have smiled upon me. Got the amplifier ready to try soldering in the optional resistors in the 1-pin headers and decided to do some DMMing and check all my resistors on the input side of the buffer.
R1 started at 100ohms, but rapidly fell to 50, before jumping back to 100 again. Replaced it and the motorboating is gone.
Hopefully my screw taps hold out for one more re-tightening. I tried so hard not to remove the board, but couldn't suction out the solder for the back pin of R1 and had to get on the back of the board to clean it out.
Thanks for the troubleshooting help. ZM, the pre/post buffer information was essential.
Screws are in and music is on in the big system. Still very very nervous that something will smoke at any moment, but it's looking promising.
Thanks again for all the help. Will certainly post more once either something breaks or I'm confident things are working...
Thanks again for all the help. Will certainly post more once either something breaks or I'm confident things are working...
Didn't get to do any real serious listening, but had the stereo on for a good four hours. Sounded great. Will post more details once I get to play, try out the WB, and do a bit of A&Bing vs the F4.
Thanks to ZM for the advanced troubleshooting, NP for making it all possible, and everyone who logs on to contribute. It's a great community here. Much appreciated...
Thanks to ZM for the advanced troubleshooting, NP for making it all possible, and everyone who logs on to contribute. It's a great community here. Much appreciated...