I’m using the MJ Cap-Mx with my M2C in dual mono with no problem. I have no hum and have the power is set for 42.5 volts across the +/-. This should give me some headroom, so it is not running full out and not adding noise.
I have Alpha 20 boards reading to be installed. I plan to pull the M2C boards and replace with the Alpha 20. Should I be concerned about using the boards without speak delay? I don’t think there should a any problem with the PS providing the required voltage.
I have Alpha 20 boards reading to be installed. I plan to pull the M2C boards and replace with the Alpha 20. Should I be concerned about using the boards without speak delay? I don’t think there should a any problem with the PS providing the required voltage.
That’s a cost effective approach for sure, Steve!
I may try that out as well if the speaker protect board doesn’t get the job done for some reason. Ultimately I’m hoping for a more automatic solution than having to switch toggles every time I fire up the amp. And I’m bound to forget to switch them off and potentially fry my speakers.BRN, the Alpha 20 does have a large dc offset at switch on. Since I don’t have a CapMx on my build I’m going with the speaker protect board. Curious to know what kind of dc Vunce is seeing at switch on with the CapMx. Also not sure if the MJ CapMx boards function the same in terms of dc at switch on as the MrEvil boards. So a speaker protect might not be a bad idea, at least until you check the offset once you have your boards in.
Only took 8 months, but I finally have a working Alpha 20W! Excuse the messy wiring. I plan to do some cleanup. The soft start and speaker protect boards are working great! I get no excessive dc to the speakers now. Both channels are settling in at about 11mV. They may even drop a bit lower with more warmup time. I haven’t had a chance to listen to both channels at the same time yet. Hopefully I can do that very soon. Thanks again to Hugh, X, and JPS for a phenomenal design and collaboration to bring these boards to the diyAudio community.
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Congratulations Jwjarch!!
It’s great to see another Alpha is born.
What model Antek are you using?
Good eyes X. Yep, that's an AS-4218. I bought it before the conversations about voltage sag happened, and I was excited to be able to use the same transformer to swap in future Pass amp builds as well. But, just in case, I have an AS-4220 on the shelf if voltage becomes an issue. It would be doubly bad since my speaker protect board is powered off of one of the rectifiers. If I dip much below 24v the relays will disengage. Right now I'm at 24.3v with the amp just powered on. I'll keep an eye on it once I start playing music and see how much it dips.
Thanks for the complements and encouragement throughout this build, everyone. I'm excited to have a platform for other amp swaps now. I already have all the parts I need to populate boards for an ALPHA 4R and an M2X. More fun to come!
And I'll be sure to post about my listening impressions very soon.
Thanks for the complements and encouragement throughout this build, everyone. I'm excited to have a platform for other amp swaps now. I already have all the parts I need to populate boards for an ALPHA 4R and an M2X. More fun to come!
And I'll be sure to post about my listening impressions very soon.
Testing active bridge PSU. I have been testing a new “ideal bridge” active full wave rectifier using the LT4320 and a pair of 36A dual N channel Powerpak 8x8-4 MOSFETs. So far the tests are very promising: under 4A continuous load with over 32v delivered into an 8ohm dummy load, the MOSFETs only reached 32C and that’s just mounted on the PCB with no heatsink. The other advantage is you don’t have the 1.2v drop that normally occurs across a silicon full wave rectifier bridge. More headroom. So just 4 simple components (LT4320, 2x dual MOSFETs, and a 1uF bypass cap) adds this high current ideal bridge to any PSU.
I will be working with Jhofland (who did the layout here) to make a new Class A PSU that will have the ideal active bridge, a CRC, and a capacitance multiplier. All you need to do is connect a pair of secondaries from your trafo and you get nice clean low ripple power (up to 5A output) without having to mount the rectifier onto a heatsink. The cap Mx Pass device will still need some sort of heatsink but nothing too big. This should be an ideal PSU for the Alpha’s.
I will be working with Jhofland (who did the layout here) to make a new Class A PSU that will have the ideal active bridge, a CRC, and a capacitance multiplier. All you need to do is connect a pair of secondaries from your trafo and you get nice clean low ripple power (up to 5A output) without having to mount the rectifier onto a heatsink. The cap Mx Pass device will still need some sort of heatsink but nothing too big. This should be an ideal PSU for the Alpha’s.
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Hi X,
Yes my friend solved the problem as my psu was not functional to debug and the culprit was the BC547C which was purchased from eBay
Thanks Xrk971 , aksa and Balaji for solving my issue
Need to listen to the amp, just power up is done
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Regards
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Very nice work, Cl00sed, very good, compact, neat build. Great case too.
I hope you enjoy the sound, it took some time to get it to this point!!
BTW, I have found most of the eBay semis are OK but even one in ten will delay completion of a project for weeks. It is always better to buy from a known source, even if more expensive. Terrific that you quickly found the bad semi quickly.
Hugh
I hope you enjoy the sound, it took some time to get it to this point!!
BTW, I have found most of the eBay semis are OK but even one in ten will delay completion of a project for weeks. It is always better to buy from a known source, even if more expensive. Terrific that you quickly found the bad semi quickly.
Hugh
Xrk is this heat sink ok for alpha 20 (4 ohms) base plate is 15.7 mm thick . all dimensions in the drawing is in millimeter. i am planning for 200mm*215mm *75mm (weight about 4kg for the size mentioned) . i got your pcbs (alpha + melbourne) through vimal from chennai.
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