Pass DIY Addict
Joined 2000
Paid Member
You can give them a try - you'll need to keep a close eye on the temp of the case vs the temp of the adjacent sink. I would try them with something else in a TO-3 can before using them with the rare Sony vFets.
The best insulators that I've found so far is the ceramic aluminum oxide wafers. They are about 1-2mm thick and need to have thermal paste on both sides. An example of Aavid part for TO-247 is the 4180G. The are also available on ebay from a variety of sellers.
These measure the same or better than any sil-pad I've used and cost less than many of them. Because they are thick, you'll never pierce one like you can with a sil-pad.
Looks like we're in the same boat! Thank you jotom750!
My kit does not have the 5 kOhm trimmers. It came with 4 x 470 Ohm trimmers instead. Is this a bug or a feature?
I am in the process of finding some Toshiba drivers (313/2013) instead of the FQP parts in the kit, and I believe the 470 Ohm trimmers are alright to set the bias of the Toshibas -- correct?
The bias for the output stage seems to use 5 kOhm trimmers. Should I replace the ones from my kit with 5 kOhm parts?
Last edited:
I'll get these, you might consider them if you need to buy some 5k anyway (pls note those are 1k to substitute the 500R I got with the kit and the fairchild) , unless I am going for the Toshibas...
3339P-1-102LF Bourns | Mouser France
3339P-1-102LF Bourns | Mouser France
========================================================The boards from my 1st kit are populated with the resistors, caps & pots, but have been languishing in the cellar for months.
Seeing this post got me to check the pots. Seems the store sent 500 Ohm pots with Fairchilds.
The second kit has Fairchilds with four 500 Ohm pots, no 5k Ohm pots!
This from 24th April 2018, 08:26 PM #522
Sorry for the noob question
Hi
Took a wild chance in a auction and got the winning bid in for a Sony TA5650.
I know that the historically right thing to do is to fix the short falls and save it for the future, but let's say for argue sake that you freed it from the vfets, what would be the most rewarding that could be built with 4 pair of 2SJ18 and 2SK60?
Chris
Hi
Took a wild chance in a auction and got the winning bid in for a Sony TA5650.
I know that the historically right thing to do is to fix the short falls and save it for the future, but let's say for argue sake that you freed it from the vfets, what would be the most rewarding that could be built with 4 pair of 2SJ18 and 2SK60?
Chris
That has been the major inspiration the whole time, but since I was one undeserving but happy winner in the lottery I thought I would check up the possibility to go for some more powerful mono design to enable other speakers being power by pass designs.
Currently do my main listening room accommodate 1 pair of DQWT speakers and one TL sub- this give me 95dB sensitivity and Quad II, Jean Hiraga och Aleph to switch between.
For the vfet build have I scetched up a QWT speaker that should land around 97-98dB sensitivity wise, but I also have more traditional speakers where I would like to play around with pass designs for at least the mid-high part but I would need something north of 30W of output to be a viable solution.
I know it sounds like a luxury problem and really greedy, but dont loose all faith.
Should I not manage to find a smart way of making use of it, a will make myself a dual mono pair and release the surplus back to the community in exchange for donations to the original cause.
Currently do my main listening room accommodate 1 pair of DQWT speakers and one TL sub- this give me 95dB sensitivity and Quad II, Jean Hiraga och Aleph to switch between.
For the vfet build have I scetched up a QWT speaker that should land around 97-98dB sensitivity wise, but I also have more traditional speakers where I would like to play around with pass designs for at least the mid-high part but I would need something north of 30W of output to be a viable solution.
I know it sounds like a luxury problem and really greedy, but dont loose all faith.
Should I not manage to find a smart way of making use of it, a will make myself a dual mono pair and release the surplus back to the community in exchange for donations to the original cause.
I am not exactly sure, but does it make sense to match Q5 and Q6 in any way (I have some Toshiba 313/2013 parts to choose from)? Looking at the Q5/Q6 biasing scheme it seems like the circuit symmetry would benefit from P3 and P4 adjusted to the same value, so... any hints would be welcome.
The first channel is up and running! No real issues so far. The only hickup was that I messed up the front-end adjustement when I tried to adjust the output stage because I mixed up the pots.
Note to myself (I am sure I'll mess up again with the second channel): to fix this, I lifted R3 to break the feedback loop (red resistor in attached photo). Since the scope was already up and running, I adjusted the front end (P3, P4) for symmetrical clipping at test point T18 instead of tweaking T18 to 0 V. Then I put some stickers over P3 and P4 to make it harder to mess them up again, and reconnected R3. Then adjust output stage again using P1 and P2.
Note to myself (I am sure I'll mess up again with the second channel): to fix this, I lifted R3 to break the feedback loop (red resistor in attached photo). Since the scope was already up and running, I adjusted the front end (P3, P4) for symmetrical clipping at test point T18 instead of tweaking T18 to 0 V. Then I put some stickers over P3 and P4 to make it harder to mess them up again, and reconnected R3. Then adjust output stage again using P1 and P2.
Attachments
Aleph J power supply for Sony Vfet (2017) amp
Hi All.
I have a DIY Aleph J project that has very large heat sinks that will accommodate both the Aleph J PCBs and the Sony Vfet PCBs attached to their L brackets.
I would like to install both amps into the same chassis, and have a switch so that I can use one or the other. This entails sharing a power supply that has a common Antek AN-5218 18V-18V 500 VA transformer.
The Sony Vfet amp calls for a 22V-22V transformer such as the AN-5222. My AN-5218 has 4 less volts, so it's likely to put out around 4 less volts than the AN-5222. I recall that an 18V-18V transformer puts out about 24 Volts DC using the DIY Audio universal power supply PCB.
Having read the Vfet build thread and other materials, I know that the Vfet amp will work with 20-32 volt supplies. What is the impact on sound quality with a lower supply voltage? What changes are there to output power with a 24 Volt instead of 28 Volt supply? Thanks in advance for your responses!
Hi All.
I have a DIY Aleph J project that has very large heat sinks that will accommodate both the Aleph J PCBs and the Sony Vfet PCBs attached to their L brackets.
I would like to install both amps into the same chassis, and have a switch so that I can use one or the other. This entails sharing a power supply that has a common Antek AN-5218 18V-18V 500 VA transformer.
The Sony Vfet amp calls for a 22V-22V transformer such as the AN-5222. My AN-5218 has 4 less volts, so it's likely to put out around 4 less volts than the AN-5222. I recall that an 18V-18V transformer puts out about 24 Volts DC using the DIY Audio universal power supply PCB.
Having read the Vfet build thread and other materials, I know that the Vfet amp will work with 20-32 volt supplies. What is the impact on sound quality with a lower supply voltage? What changes are there to output power with a 24 Volt instead of 28 Volt supply? Thanks in advance for your responses!