I finally finished the second one and now playing in stereo. I had some problems with the second one due to some cold solder joints. My thanks go out to Valery and Jeff for helping me diagnose and debug the amp.
Sounds fantastic - super bass, smooth and clear mids and sparkling highs.
I need to build a second PSU, right now running both off the same one until some more 4700uF 50v caps come in.
I am running 80mA bias and offset is now 0mV and stable. The matched input LTP's really helps.
Good troubleshooting job on your side as well
It's a teamwork after all
Nice local heatsinks on the right board 😎
In debugging I had to pull off all the power transistors so when reinstalling, I figured I might as well add heatsinks which requires them to sit taller. I will do the same on the first amp now that it's all working.
I just realized that I have an Abletec 450w 53v dual rail SMPS that would be a good match requirements wise. I wonder if this can work? Would "bus pumping" be a problem? And crosstalk from one channel to the other through the SMPS?
http://www.diyaudio.com/forums/class-d/281698-abletec-53v-dual-rail-450w-supply-20-a.html
I also have a 300va trafo that should make 49v rails.
I just realized that I have an Abletec 450w 53v dual rail SMPS that would be a good match requirements wise. I wonder if this can work? Would "bus pumping" be a problem? And crosstalk from one channel to the other through the SMPS?
http://www.diyaudio.com/forums/class-d/281698-abletec-53v-dual-rail-450w-supply-20-a.html
I also have a 300va trafo that should make 49v rails.
Last edited:
Most of Valery's boards work with the mini Slew but not all with the big BJT version. I think Valery and Thimios found a work-around but I haven't tried that. The mini Slew is more forgiving.
Thank you Terry.
That i will find out next time.
Valery is so generously to sell me a pair of his IPS- Boards.
It needs some time to pick parts together and got on power.
In that point i am not the fastest.
I follow by reading here and also 100W Ultimate Amp to learn and understand.
With successful build up Amp i later point in here, otherwise i have Questions.
Regards Bangla H. 50+
I just confirmed that the $25 Abletec 450w 53v SMPS works well with the VHEX+ amp. About 20mV ripple after going through the Dx PSU cap bank and filter (60mV with 250VA trafo).
Abletec 900 Watt Peak Class D Audio Amplifier Power Supply 53V DC UL Cul | eBay
Details here:
http://www.diyaudio.com/forums/clas...ual-rail-450w-supply-20-a-12.html#post4732609
Abletec 900 Watt Peak Class D Audio Amplifier Power Supply 53V DC UL Cul | eBay
Details here:
http://www.diyaudio.com/forums/clas...ual-rail-450w-supply-20-a-12.html#post4732609
Using the Abletec SMPS, I swapped out the Dx PSU with my custom CRCLC and I now get only 1mV of ripple! That's 20x better than the last one. There is absolutely no sound from the speakers with ear pressed to the tweeter or woofer. Dead silent, no hiss, no hum, no nothing (well maybe barely audible in the lower than room background noise category)... 😎
Attachments
Last edited:
That's interesting. Most SMPS that I have tried balk at charging a bank of capacitors. They see them as a short at start up and usually go into fault.
It may be that the R between the first 2 banks provides enough impedance to prevent it from looking like a short.
Greetings mr xrk sa1831,sc3503 &2n5089 not available in my place any equalent value pls reply sir
I buy those from Aliexpress and they measure well (Hfe) and work fine - sound great in fact.
KSA1381 $5.10 for 30:
KSA1381ESTU TRANSISTOR PNP 300V 100MA TO 126 1381 KSA1381 30pcs-in Integrated Circuits from Electronic Components & Supplies on Aliexpress.com | Alibaba Group
KSC3503 $5.40 for 30 :
Free shipping Ksc3503ds TRANSISTOR npn, 300 V 100mA ke 126 3503 KSC3503 30PCS/LOT-in Integrated Circuits from Electronic Components & Supplies on Aliexpress.com | Alibaba Group
2N5089 $5.06 for 100:
Original free shipping 2N5089 5089 TO92 100PCS/LOT in Stock-in Integrated Circuits from Electronic Components & Supplies on Aliexpress.com | Alibaba Group
You will have to ask vzaichenko for equivalents.
KSA1381 $5.10 for 30:
KSA1381ESTU TRANSISTOR PNP 300V 100MA TO 126 1381 KSA1381 30pcs-in Integrated Circuits from Electronic Components & Supplies on Aliexpress.com | Alibaba Group
KSC3503 $5.40 for 30 :
Free shipping Ksc3503ds TRANSISTOR npn, 300 V 100mA ke 126 3503 KSC3503 30PCS/LOT-in Integrated Circuits from Electronic Components & Supplies on Aliexpress.com | Alibaba Group
2N5089 $5.06 for 100:
Original free shipping 2N5089 5089 TO92 100PCS/LOT in Stock-in Integrated Circuits from Electronic Components & Supplies on Aliexpress.com | Alibaba Group
You will have to ask vzaichenko for equivalents.
Hi Sownel,
You can use MJE350, MJE340 and BC550 accordingly.
Distortion level roughly doubles, but stays good enough.
Cheers,
Valery
Good to know, so if I want a better performing amp that spec's MJE's switching to KSA/KSC is advantageous?
In general - yes, ksa/ksc are faster (higher fT) and higher beta. They are actually designed for video applications - wide bandwidth video amps.
You can also use ksa1380/ksc3502 - same thing, but Vce = 200v (instead of 300v for ksa1381/ksc3503) - sometimes those are easier/cheaper to buy.
Greetings mr.xrk . valery thanks for your quick reply i have many bd139&140.ksa ,bd's what different and sound quality sorry for my bad english
Thak you.
Thak you.
Hi Sownel, BD139/140 will perform very well, however you will have to limit the rails voltage down to roughly +/-35...38V DC for safe operation.
They've got maximum Vce rated at 80V. Assuming the VAS output and the trivers swing almost rail to rail - that's the limitation.
I will publish the corrected values for a few resistors, required for those lowered rails later today.
Cheers,
Valery
OK, attached is the original schematic with 1 output pair - more than enough for 45-50W (8 ohm) output with +/-35...38V DC rails. Well, unless you'd like it to drive some 2 ohm sort of load - then you can go with 2 pairs.
The values you need to change for these lowered rails:
R32, R22, R21, R33 = 2.2k 1W each;
R24 = 24k 1W.
That's it. As I mentioned earlier - you can use BC550, BD139/140 in this configuration.
If you'd like to etch the boards yourself, there is an excellent single-side layout, designed by Albert (abetir) earlier in the thread. Terry (still4given) also made his cool option - built and tested.
Cheers,
Valery
The values you need to change for these lowered rails:
R32, R22, R21, R33 = 2.2k 1W each;
R24 = 24k 1W.
That's it. As I mentioned earlier - you can use BC550, BD139/140 in this configuration.
If you'd like to etch the boards yourself, there is an excellent single-side layout, designed by Albert (abetir) earlier in the thread. Terry (still4given) also made his cool option - built and tested.
Cheers,
Valery
Attachments
More 4700uF caps finally came in so I made up a second CRCLC PSU. Now running dual PSU's true dual monoblock operation but single 300VA transformer with 45v rails. Bass on each channel now has even more headroom and ease of play.
Attachments
Last edited: