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Here It Is: The All Singing All Dancing HTMCPS

I assembled this CNC

But I think I remember that you reversed the polarity and burnt out the OPA2134's, I am wondering if this affected the capacitors.

The four 100uf/35v on the supply rails.

I could be worth a try in replacing them.

Also make sure your RCA's are all wired correctly, if there not or have loose joints this can cause hum.

You also must have the 0v/gnd from the PSU connected to the gnd input on the CNC.

I am just trying to think of things that could cause hum.
 
My first CNC I built I used cheap RCA jacks. I would get a bad hum until I twisted the RCA cable and got it to sit "just right." I finally switched out the jacks for some of these (no affiliation, AK site sponsor):

http://www.partsconnexion.com/product7493.html

and the hum completely disappeared. In my case it was a grounding issue and cheap RCA jacks.

Can you try twisting your RCA cables to see if the hum disappears? Could you post pics of your solder points on your RCA jacks and how they attach to your case?
 
I used this kind of jacks (insulating) and had a bum hum. Turns out that I must have over tightened the nuts and BOTH (in & out) of the left channel shields were shorted to the case. The right channel jacks were OK.
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HypnoToad said:
... you reversed the polarity and burnt out the OPA2134's, I am wondering if this affected the capacitors.

The four 100uf/35v on the supply rails.

It could be worth a try in replacing them.
Click to expand...

This. If you fed the pos to the neg leg of the caps, they will likely blow (internally).
 
HypnoToad said:
I assembled this CNC

But I think I remember that you reversed the polarity and burnt out the OPA2134's, I am wondering if this affected the capacitors.

The four 100uf/35v on the supply rails.

I could be worth a try in replacing them.

Also make sure your RCA's are all wired correctly, if there not or have loose joints this can cause hum.

You also must have the 0v/gnd from the PSU connected to the gnd input on the CNC.

I am just trying to think of things that could cause hum.
Click to expand...
Hi Phillip..Yes you are correct in that I inadvertently did a reverse polarity connect and blew the a.r.s.e out of the OPA's... BUT now that I have established it's within the cnc I will just run it on the two x 9V source until I get it right. Ordering the replacement cap's today from o/seas.
Will check all solder points. Thanks man...
 
AK members repeat after me.. OzzieLaurie is an i.d.10.T......
When I rewired the Rega RB300 arm I used Cardas didn't I..indeed this was the 3rd RB300 I had done with Cardas so I was WELL used to stripping the tiny cables of their outer sheath, then with the 7 or so baby-hair strands I carefully would "scrape" the delicate strands with a blade, rotating the wires for effective removal all-around of the lacquer-like coating from the strands...Upshot of this is that I did away with the Rega idea of incorporating turntable ground within one audio channel...fitted an extra Cardas wire for a dedicated Ground wire-beautiful...so WHO bloody forgot to SCRAPE the bloody strands so that Ground signal could pass to the CNC ? When I had tried it with the Phono MM in of the Denon, while I connected the Rega Ground Cardas (stripped) wire to the Ground terminal on Denon body, I found this afternoon that it didn't make any diff whether the Cardas Ground was on or OFF the Denon-no Ground link to the Rega was necessary to the Denon ANYWAY- so no hum was NOT due to the NON-SCRAPED, signal blocking clear lacquer on the wire! Needless to say I will leave the CNC running on the two 9V Duracell Ultras while I now for a few days REVEL in the PRISTINE, NOISELESS CNC performance. I will also do some track recording over next couple of days and turn them into FLAC and WAV and let you hear what I have been missing/chasing/pisst-off about not getting !!...LOL Thanks guys for all your advice and time spent on thinking about this issue and then posting. It has all worked-out fine. The sample audio files will help convert some newcomers, and some will not have to ask whether some members think CNC is better than say a CA640P..once they see what housing I have used for MY CNC... heehee..Cheers all, Laurie.
 
Thanks Sach, haha yeah so am I...But what a silly oversight on my behalf....I did an article on vinylengine about the Rega arm rewire and stressed the need to remove the coating from the Cardas strands, I have politely reminded others about not forgetting that and suggested how to achieve a good strip job (still talking about the wire strands.... haha )then I bloody stupidly forget it myself...
But I am so thrilled with the result, so musical and that is with the OPA2134's...so now that it's "humming along in a good way", I think I will take the plunge and buy 2 of the adaptor packages with LM49990's because the bass response, particularly on pipe organ with the OPA2134's is per your findings too-as you said bass is a bit light-on.
 
I am sure it is here somewhere

But with 21 pages of posts to look through, I haven't really had an answer to this jump out.

Why are folks using batteries ? I gather it needs 12 volts DC current yes? SO does something like THIS cause an issue ? Does it introduce noise or something ? Thanks in advance
 
arcorob said:
But with 21 pages of posts to look through, I haven't really had an answer to this jump out.

Why are folks using batteries ? I gather it needs 12 volts DC current yes? SO does something like THIS cause an issue ? Does it introduce noise or something ? Thanks in advance
Click to expand...

Pretty much a noise issue. Also ground-looping hum and complication, avoid without some sort of serious buffer filtering at least.
 
arcorob said:
But with 21 pages of posts to look through, I haven't really had an answer to this jump out.

Why are folks using batteries ? I gather it needs 12 volts DC current yes? SO does something like THIS cause an issue ? Does it introduce noise or something ? Thanks in advance
Click to expand...

Wallwarts should never be used on on preamps especially with Phono preamps.Batteries provide clen DC sound without introducing any hum.Lantern batteries are cheap.You can run 4 for them for an year.A well filtered power supply can be used.I am using one designed by Ak member Omishra.You can find some pics on Joel's build http://www.audiokarma.org/forums/showthread.php?t=456732

Regards,
Sachin
 
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I had a well filtered Rod Elliot designed PSU and it was powered by a wallwart, I swapped it out with my 12v battery supply. Even my wife could tell, without her knowing which was which that the batteries sounded better. To me for around $10.00 to run one of these for a year it's a no brainer, and also to not have to worry about ground loops and hum like Steve said.

But to be honest I have never tried a PSU using an R-Core transformer.

As a side note Steve has some great advice, thanks to his suggestions on fine tuning the bass roll off on HTMCPS it's sounding better than ever.
 
HypnoToad said:
I had a well filtered Rod Elliot designed PSU and it was powered by a wallwart, I swapped it out with my 12v battery supply. Even my wife could tell, without her knowing which was which that the batteries sounded better. To me for around $10.00 to run one of these for a year it's a no brainer, and also to not have to worry about ground loops and hum like Steve said.

But to be honest I have never tried a PSU using an R-Core transformer.

As a side note Steve has some great advice, thanks to his suggestions on fine tuning the bass roll off on HTMCPS it's sounding better than ever.
Click to expand...

It's an expensive experiment but I think you'd be quite surprised. I had the bad habit of leaving my CNC on and draining batteries or having them run out and not having spares (and it being too late to go to a store). I made one of Omishra's power supplies and haven't looked back. It's dead quiet, no grounding issues or hum and it sounds every bit as sweet as batteries (and no wall-wart to futz up the noise).
 
So guys ..correct me if I am wrong

I take it the TT ground just goes to the HTMCPS..no need to carry it out the amp , correct? I deduce this from a picture I saw as below

attachment.php
 
^^yes you are correct. TT tone arm ground wire ends at phono preamp stage. No need to carry it further till next amp in the chain.
 
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