[mikecole]

I bought two Jerome Industry power supplies since there was a minimum order amount. I sent both to Wayne to get one modded and to get a power cord put on the other one. They just arrived yesterday. I thought he would have marked them on the case so I would know which was which, but they both looked the same. I figured this would be great opportunity to do a blind test. I hooked up the first one and was met with a fairly loud transformer hum. I hoped this was not the one that got modded. The difference in sound between this and the switch mode PS was that this one had more weight to the sound. I then hooked up the second one. This one had almost no hum, but the sound was not quite as good as the first one. It had almost the same amount of weight, but something was missing and I do not know what. I switched them both out one more time and the one with the hum still sounded a bit better. I opened them both and saw an extra cap in the one with the hum, so this was the one that had been modded. At least I felt better now, knowing  that I did not waste my money. I heard a consistent difference without knowing which was which. About that time, I noticed that on the end of the plug there was a label indicating this one had been modded - doh. The difference between the switch mode and linear was that the linear had greater weight. The difference between the modded and unmodded PS was not night and day, but still noticable. I am really not sure what I heard that made it more appealing, but the difference was there. At this time, the only software mod was doing the FLAC to PCM conversion at the SB server and, on the Touch, the single output mod was the only one in effect.

[srb]

So what can be done about the hum?  Is this a physical humming from the transformer itself or a 60Hz line hum through the speakers?
 
Steve

[Wayne1]

As Mike noted, the power supply that had been modded had a BOLDER Cable Company labeled heatshrink covering the DC connector and the stock one had unlabled black heatshrink.

Both power supplies will need a good 400 hours of constant use before the true sound of them will emerge. The main power supply filter caps and the reservoir cap have been changed and an additional bypass cap had been added. The sound of the power supply caps and how they are used will improve depending on exactly what caps are used.

I never noticed any hum from either unit when it was on the bench. However these supplies are surplus and have been sitting around for some time. For $10.00 you should not expect every one to be perfect. It could be that some of the windings might have loosened up in shipping. You might want to contact Herbach to see if they would be willing to send you a replacement. If they do and you test it at home to find no hum, ship it out to me and I will mod that one for you at no charge.

[DARTH AUDIO]

I bought two Jerome Industry power supplies since there was a minimum order amount. I sent both to Wayne to get one modded and to get a power cord put on the other one. They just arrived yesterday. I thought he would have marked them on the case so I would know which was which, but they both looked the same. I figured this would be great opportunity to do a blind test. I hooked up the first one and was met with a fairly loud transformer hum. I hoped this was not the one that got modded. The difference in sound between this and the switch mode PS was that this one had more weight to the sound. I then hooked up the second one. This one had almost no hum, but the sound was not quite as good as the first one. It had almost the same amount of weight, but something was missing and I do not know what. I switched them both out one more time and the one with the hum still sounded a bit better. I opened them both and saw an extra cap in the one with the hum, so this was the one that had been modded. At least I felt better now, knowing  that I did not waste my money. I heard a consistent difference without knowing which was which. About that time, I noticed that on the end of the plug there was a label indicating this one had been modded - doh. The difference between the switch mode and linear was that the linear had greater weight. The difference between the modded and unmodded PS was not night and day, but still noticable. I am really not sure what I heard that made it more appealing, but the difference was there. At this time, the only software mod was doing the FLAC to PCM conversion at the SB server and, on the Touch, the single output mod was the only one in effect.

I heard some hum in mine when I first received it. I think it went a way with time? I'll check it out when I get home tonight. It is way better than the stock power cable!! That's for sure.

[jimdgoulding]

If there is anybody sitting on the fence about replacing their stock power cords, let me recount for you my experience.  Now, I imagine mileage may vary.  I replaced the factory supplied power cords with some 7 gauge and not expensive wires.  The original cords supplied by my speaker manufacturer for my active speakers were made way before the kind of research on and the availabilty in abundance of aftermarket cords.  My speakers go deeper and fuller in the bass.  Cymbals struck hard spray out into the room longer without any sense of compression.  Hard hit bass drums have more of a presence in the mix and are cleaner.  Attack, bloom, and decay seems freer and more fully available.  That's a big deal to me.  My speaker amps (two per side) seem to be able to draw more current thanks to the cords to sound bigger and better.  And, there is no downside.  Money well spent for me.

This thread is about power supplies so I'm a bit out of school.  Hope it has some meaning to somebody.  Mikecole's use the word 'weightier' got me going.

[mikecole]

As Mike noted, the power supply that had been modded had a BOLDER Cable Company labeled heatshrink covering the DC connector and the stock one had unlabled black heatshrink.

Both power supplies will need a good 400 hours of constant use before the true sound of them will emerge. The main power supply filter caps and the reservoir cap have been changed and an additional bypass cap had been added. The sound of the power supply caps and how they are used will improve depending on exactly what caps are used.

I never noticed any hum from either unit when it was on the bench. However these supplies are surplus and have been sitting around for some time. For $10.00 you should not expect every one to be perfect. It could be that some of the windings might have loosened up in shipping. You might want to contact Herbach to see if they would be willing to send you a replacement. If they do and you test it at home to find no hum, ship it out to me and I will mod that one for you at no charge.

Yeah, I did not see the label both times I hooked it up because the cord just happened to place the label underneath. Go figure. So if it takes that long for the "true sound" to emerge, does it matter if I leave it on 24/7? After a couple of hours it was not even warm. As for the hum, the other one does not hum as bad as this one, but so far, it is not really bothersome since it is behind the stereo on the carpet. If that changes, I may take you up on your offer - and thanks for offering!

BTW, Steve, the hum is just mechanical. It was reduced just by holding the PS in my hand.

[Wayne1]

Mike,

Keep the power supply plugged into the Touch and have the Touch keep playing 24/7. Use an internet station or just repeat or random play. No need for amp to be on. Just the Touch.

You will hear changes during the first two weeks. After that it will settle down a bit.

Try putting the PS on some foam pads to see if that will reduce the mechanical noise.

[prpixel]

Mine had a noticeable hum also that went away within the first day of use.  There is a very slight hum if I put my ear against it.  Not a problem because I don't listen to it laying on the floor with my head resting on the power supply.