Yes, this is the version 1.3 PCB populated with parts similar (but not exactly identical) to those in a premium kit that I offer.
I also have parts that will fit on the version 1.2 Twisted pear PCBs from Uriah's GB - I've sent a PM to you with more details and prices.
The 3886 chip must be securely clamped to it's heatsink.
The thermal resistance of that clamping action must be low enough to keep the chip from overheating.
The electrical resistance of that clamping action must be very high, if there is any risk of the heatsink being shorted to any other potential.
No adhesive is needed nor required.
The thermal resistance of that clamping action must be low enough to keep the chip from overheating.
The electrical resistance of that clamping action must be very high, if there is any risk of the heatsink being shorted to any other potential.
No adhesive is needed nor required.
In addition to the insulating spacer (mica or silicone rubber), it won't hurt to dab a thin layer of TIM (thermal-interface material aka white heat-sink goop) on both metal surfaces (heat-sink and metal tab) before assembly. This isn't an adhesive, but merely a filler to improve the contact between the surfaces.
How critical is C10 capacitor?
I been watching this thread with great interest and decided to build my next amp based on the MyRefC circuit. I have done some simulation using SIMetrix-Simplis to help me understand which part is critical in case I try to do a parallel configuration. Using the current circuit and feed with 500Hz input, I notice that there is some resonance in the output waveform. If I change C10 from 22pF to 10pF, it shows a perfect waveform. I double check all my values and all looks right. Comparison of the output is shown below. Anybody here can shed light whats the purpose of C10 in laymans term? BTW, I'm not an EE, just a normal hobbyist.
Thanks,
I been watching this thread with great interest and decided to build my next amp based on the MyRefC circuit. I have done some simulation using SIMetrix-Simplis to help me understand which part is critical in case I try to do a parallel configuration. Using the current circuit and feed with 500Hz input, I notice that there is some resonance in the output waveform. If I change C10 from 22pF to 10pF, it shows a perfect waveform. I double check all my values and all looks right. Comparison of the output is shown below. Anybody here can shed light whats the purpose of C10 in laymans term? BTW, I'm not an EE, just a normal hobbyist.
Thanks,
The last few (~10) Version 1.3 PCBs are in stock, and Version 1.4 PCBs have been delivered but not populated and tested yet - maybe this weekend. The earlier BoMs will fit on Version 1.4 PCBs also - the schematics are functionally identical.
The main differences in Version 1.4 are a few minor placement and layout improvements, support for 15mm pitch MKP10 caps at C4 (as well as 5, 7.5 and 10mm), support for 8 and 10mm caps at C6/C11, 2 additional (optional) bypass box-type caps in parallel with C4 and C7, support for longer resistors (e.g. Holco H4) at several locations (R5-R9, etc.), better shielding in the small-signal area, etc. The audible differences (if any) are likely to be subtle, the main improvement is greater component flexibility. I have also ordered RoHS-compliant Version 1.4 PCBs in Immersion Gold (ENIG) finish, so DIYers in the EU will be able to import them without hassles. Plain old Tin-Lead (HASL) finish PCBs will continue to be available at the same price as before.
The MiniRef version 1.0 PCBs are still about a week or so from Gerber/Excellon tapeout and handover for fabrication. Allow another 3-4 weeks until populated boards are ready for first testing.
The main differences in Version 1.4 are a few minor placement and layout improvements, support for 15mm pitch MKP10 caps at C4 (as well as 5, 7.5 and 10mm), support for 8 and 10mm caps at C6/C11, 2 additional (optional) bypass box-type caps in parallel with C4 and C7, support for longer resistors (e.g. Holco H4) at several locations (R5-R9, etc.), better shielding in the small-signal area, etc. The audible differences (if any) are likely to be subtle, the main improvement is greater component flexibility. I have also ordered RoHS-compliant Version 1.4 PCBs in Immersion Gold (ENIG) finish, so DIYers in the EU will be able to import them without hassles. Plain old Tin-Lead (HASL) finish PCBs will continue to be available at the same price as before.
The MiniRef version 1.0 PCBs are still about a week or so from Gerber/Excellon tapeout and handover for fabrication. Allow another 3-4 weeks until populated boards are ready for first testing.
Last edited:
Noise
Dear All, I finally wired up my my ref rev C from the group build Uriah set up last year. Thanks again Uriah.
I must have done something stupid, I have some noise which goes away if I touch the heat sink for the lightspeed PSU..
I couldn't work out how to get signal ground earthed using the lightspeed?
http://www.zumodrive.com/share/bc3PYjc3YW
Wired as shown in these pictures I get a terrible buzz as soon as I plug a signal in. This goes away if I hot wire from rca input ground to star earth, but the occasional noise from the lightspeed PSU still comes and goes.
I post this here because I know some other people took advantage of Uriah's kind discount to purchase the lightspeed board with the my ref rev c boards.
I PM'd regi regi since the psu design was posted by him though he did not claim it was his design.
Hope some body can spot a silly mistake (or five).
Thanks folks.
Bill. (in japan but south of the disaster zone)
Dear All, I finally wired up my my ref rev C from the group build Uriah set up last year. Thanks again Uriah.
I must have done something stupid, I have some noise which goes away if I touch the heat sink for the lightspeed PSU..
I couldn't work out how to get signal ground earthed using the lightspeed?
http://www.zumodrive.com/share/bc3PYjc3YW
Wired as shown in these pictures I get a terrible buzz as soon as I plug a signal in. This goes away if I hot wire from rca input ground to star earth, but the occasional noise from the lightspeed PSU still comes and goes.
I post this here because I know some other people took advantage of Uriah's kind discount to purchase the lightspeed board with the my ref rev c boards.
I PM'd regi regi since the psu design was posted by him though he did not claim it was his design.
Hope some body can spot a silly mistake (or five).
Thanks folks.
Bill. (in japan but south of the disaster zone)
Oops!
Sorry folks... try this link.
http://www.zumodrive.com/share/bqfyMmUyMm
Thanks for pointing that out Uriah....
I think I must be doing something daft with my grounding regime! Don't think there is any problem with the boards themselves and the lightspeed is responding, both the balance and volume pots are working...
Bill
Sorry folks... try this link.
http://www.zumodrive.com/share/bqfyMmUyMm
Thanks for pointing that out Uriah....
I think I must be doing something daft with my grounding regime! Don't think there is any problem with the boards themselves and the lightspeed is responding, both the balance and volume pots are working...
Bill
Last edited:
Bill I am sorry to say but not much can be gleaned from those photos. No way to zoom them and I cant tell anything except that I like your case quite a lot and its very inventive.
I know for sure its your grounding scheme though. Unplug everything. RCAs and power. Get out the DMM. See if you have conductivity between tabs of LM3886 and the sinks. If you do then check to see if sink and ground can see each other. That would be bad. Probably not your problem but a good safety check anyway. Confirm what Dario asked. Then take an alligator clip and a wire and clip that wire to your input ground. Plug it all back in and turn it on. Touch that wire to your ground points on your board and your star ground as well as your speaker ground. See if it goes away at any point. I had a nasty ground problem and had to take 0V from the transformer to my star ground to solve it. Some will say to do that and others will say not to. Worked for me. YMMV.
The poking around solution usually works for me.
Uriah
I know for sure its your grounding scheme though. Unplug everything. RCAs and power. Get out the DMM. See if you have conductivity between tabs of LM3886 and the sinks. If you do then check to see if sink and ground can see each other. That would be bad. Probably not your problem but a good safety check anyway. Confirm what Dario asked. Then take an alligator clip and a wire and clip that wire to your input ground. Plug it all back in and turn it on. Touch that wire to your ground points on your board and your star ground as well as your speaker ground. See if it goes away at any point. I had a nasty ground problem and had to take 0V from the transformer to my star ground to solve it. Some will say to do that and others will say not to. Worked for me. YMMV.
The poking around solution usually works for me.
Uriah
Thanks Uriah,
I'll poke around as you suggest. (carefully with one hand in my pocket).
I used insulated LM3886 chips but I'll still check there are no shorts from the board to the sink.
0V (pwr ground) at the transformers is connected to star earth through a ground breaker (one per channel which is perhaps pointless).
Input ground on the my ref boards has continuity with pwr ground but the continuity from RCA input grnd to input grnd on the my ref board stops at the lightspeed. I'll run a wire from RCA input grnd to the input grnd on one my ref board as a next try.
I still think I am getting noise from the lightspeed psu (which I made) also.
You can 'download the album' to get high(er) resolution images (1mb) but still pictures are probably not much help.
I am wondering if my ground loop breaker really belongs the other side of star ground, between star ground and the earth from the (fused) IEC socket?
Anyway I will have a play around this weekend and post my findings later.
Thanks to Uriah and Dario for your replies.
Bill
I'll poke around as you suggest. (carefully with one hand in my pocket).
I used insulated LM3886 chips but I'll still check there are no shorts from the board to the sink.
0V (pwr ground) at the transformers is connected to star earth through a ground breaker (one per channel which is perhaps pointless).
Input ground on the my ref boards has continuity with pwr ground but the continuity from RCA input grnd to input grnd on the my ref board stops at the lightspeed. I'll run a wire from RCA input grnd to the input grnd on one my ref board as a next try.
I still think I am getting noise from the lightspeed psu (which I made) also.
You can 'download the album' to get high(er) resolution images (1mb) but still pictures are probably not much help.
I am wondering if my ground loop breaker really belongs the other side of star ground, between star ground and the earth from the (fused) IEC socket?
Anyway I will have a play around this weekend and post my findings later.
Thanks to Uriah and Dario for your replies.
Bill
Found it
I realised I was grounding the RCA input signal ground to the wrong side of the ground loop breaker(s). Once I corrected that I was blissed-out...
The ground loop breaker works!
I had accidentally come to the right conclusion without the aid of knowledge or understanding.
Very impressive sounding amp already! Switched from the dispensable audio source to my favourite shigaclone but still using semi-dispensable speakers till I get the grounding properly wired rather than bodged...
Oooh!!! Sounds goood!
Very happy chap!
Many thanks to all.
Bill
I realised I was grounding the RCA input signal ground to the wrong side of the ground loop breaker(s). Once I corrected that I was blissed-out...
The ground loop breaker works!
I had accidentally come to the right conclusion without the aid of knowledge or understanding.
Very impressive sounding amp already! Switched from the dispensable audio source to my favourite shigaclone but still using semi-dispensable speakers till I get the grounding properly wired rather than bodged...
Oooh!!! Sounds goood!
Very happy chap!
Many thanks to all.
Bill
Thank you Andrew, I had read this article once but I have bookmarked it for re-reading very soon.
Most every domestic appliance in Japan is double insulated, and there is only rarely an earth pin available for AC power sockets. Designated fridge, washing machine, air conditioning, and outdoor AC supply sockets must all have an earth available to satisfy local code... so it is not too hard to set up a reliable earth for our home made stuff.
I don't think the circuit breakers work by detecting earth leakage however...
Appropriate fuse usage is mandatory also!
I appreciate your advice.
Best regards
Bill
Last edited:
If your home does not have Protective Earth (PE) to every mains socket outlet, then you cannot safely connect any mains powered self assembled equipment. END OF STORY !!!
Similarly, earth leakage cannot be detected when the PE is missing, thus RCCB devices are effectively useless.
Locating all your self assembled mains powered equipment in the utility room does not seem feasible.
Similarly, earth leakage cannot be detected when the PE is missing, thus RCCB devices are effectively useless.
Locating all your self assembled mains powered equipment in the utility room does not seem feasible.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.