AMB Laboratories DIY Audio

[reod]

The EMR finally came in yesterday and I was able to replace the SSR last night. I'm happy to report there's no more buzzing after the initial turn on. Thanks for all the help everyone.

[steinh]

I've just tested a random turn on SSR (Crydom UPD2415-10) in my amp. My transformers buzzes just as loud as with the zero cross SSR (Crydom 2440D). Im my case it seems to be more to the problem than just the turn on caracteristics of the relay. I'm using "budget" transformers, they are probably more likely to buzz than the high end Plitron's, SumR's and similar. Anyways; back to the well functioning EMR.

[linux-works]

thanks for the followup. I was going to try a random-crossing one but you saved me some time.

[steinh]

Just to be clear: In my set up, I could not find any difference between the two SSR's. But it might be a difference in other set ups. As mentioned, the transformers might be an important factor. The interraction between the SSR's and my "soft-start" may also be an issue. And there are surely other matters that I haven't discovered yet...... But for now I am happy with using an EMR. Just have to put in a larger transformer for my E24.....

[tvättbjörn]

Yesterday I replaced an EMR with an SSR, and then my poweramp started humming. However it started 2s after switching on the power, so the toroid was only humming when idling!?

I read here: http://home.earthlink.net/~wd7s/updates.htm that a 10K resistor across the primary of my toroid would solve the problem and it works perfectly.

Btw It is a s216s02 relay, and the electricity here is 230V.

[wobblebonk]

That last linked site said "WHEN USING SSRs WITH LARGE PLATE TRANSFORMERS THERE MAY NOT BE ENOUGH CURRENT DEMAND DURING STAND-BY TO KEEP THE SSR LATCHED ON. THIS WILL MAKE THE TRANSFORMER HUM. THIS SSR DROP OUT CAN BE CURED BY ADDING A RESISTOR SHUNT ACROSS THE TRANSFORMER PRIMARY. FOR THE D SERIES CRYDOM RELAYS, A MINIMUM OF 40MA LOAD IS REQUIRED. A 10K 10 WATT RESISTOR ACROSS THE PRIMARY WILL NORMALLY TAKE CARE OF THE HUM. (09-24-03)" The spec does indeed say minimum 40mA so I guess I will try this before replacing my SSRs as my Crydom D1240s are definitely making some sumr transformers hum. Gonna try some 10W resistors across the primaries I guess, will report back with my success or failure.

[wobblebonk]

So... I read some more and I don't really think the bleeder resistor was intended to fix my problem exactly. (http://www.scribd.com/doc/44176872/Ab-S ... tion-Guide). I tried it anyhow because I was kind of desperate, at first I thought it did help but the hum was still too loud for my liking. I decided to try something else, rotating the larger toroid made a much more profound difference. Now when I put the resistor in and out of the circuit I'm not sure if it was really ever doing anything for my problem. Now the hum is still there, but I almost have to stick my head inside the chassis to hear it, with or without the 10k resistor. I was going to try a mechanical relay to see if it removes the last bit of hum but I've been lazy as my mechanical relays don't have screw contacts and setting it up would be mildly irritating. It is really quiet now, I might just leave it like it is... I'm sure my curiosity will get the best of me and I'll wind up trying it at some point. I maybe should try more toroid rotations first, I really just turned the larger ones in a direction I thought was appropriate one time.

[amb]

A small amount of mechanical transformer buzz may be normal, SSR or not.

[wobblebonk]

Yeah I figured it might buzz a small amount, which is partially why I have held off trying the mechanical relays, it really seems to be quiet enough now. I think it would be exceedingly hard to hear with the case fully put together. I would just like to say though if you have potted toroids do not point the part where the wires come out at each other. Originally I did it just to keep the wires of a similar length but I guess that is where the magnetic fields leak out and it was really buzzing loudly when they were pointed that way. Now I just tried to orient them so that they are both pointing away from where the input wires will be as best I could and the buzz is much quieter. I suppose all that is left to do now is to go off the deep end and move my toroids to another separate chassis, that might really be some overkill though... multi chassis mono blocks...

[Pinnocchio]

In my new amp project I was using the same SSR then the one for my b24 and encapsulated transfos from SumR. There was a huge Buz coming from the transfos. At first I thought it was DC hitting the transfo and causing the the buzzing so I wanted to build a DC trap but before doing so I decided to bypass the SSR and voilà! You could now hear a fly passing by after the change. The transfos were dead quiet. When this was done, my amp bias were now completely off and my DC offset was at 140mV... Had to re-adjust everything. So I guess the transfos were badly disrupted by this buzzing...

The SSR is the exact one in the part list of the b24. Seems like not all transfos love an SSR. Must be depending on the size of the tranfos or many other factors... The article shed some light on this. Now I'm using the same mechanical relay as in the b24 (the bleeder relay) and it works great!