Chasing an Elusive Hum

[Rick Cornish]

Thanks, Mike!

Do you think this one compares?
http://www.rotel.com/content/leaflets/2 ... -11-13.pdf

New. Same price (~$1000).

[HCMarkus]

Just in case folks are looking for a cheap solution that I neither recommend nor not recommend. All I know is: it exists:

http://www.sweetwater.com/store/detail/ ... fgod5a4Kdg

[mikehalloran]

Thanks, Mike!

Do you think this one compares?
http://www.rotel.com/content/leaflets/2 ... -11-13.pdf

New. Same price (~$1000).

Besides no published 4 OHM spec? What's up with that?

Otherwise, it's a Class AB amp which is a good thing as most serious hifi amps are. It pulls 400W as it runs. That's a lot less than a Class A amp. Bryston is also a Class AB.

AB is not a fixed standard. The variables in design mean that bias is applied so that the transistors operate somewhere between null point switching (B) and full on when the amp is running (A). Every designer uses his/her secret sauce in the compromise and Bryston is considered among the best as they are glad to tell you:
http://www.audioadvisor.com/prodinfo.as ... r=BY4BSST2

I looked again at the Carvins I linked you to earlier. I see that the more powerful ones are Class G. This is much better than Class D for hifi applications.

Here's the best explanation I've run across lately of the different amplifier types.
https://www.maximintegrated.com/en/app- ... vp/id/5590

The Pioneer we all had in the '70s was Class B.

I am not pushing Bryston, really. It's just that these are well known to me and their reputation is impeccable.

Frankly, I wouldn't have one in my California studio unless it had its own cabinet and air conditioning as many studios do. Large Class AB amps are heat pumps. If I had passive monitors, I'd try a Carvin Class G and would return it if it didn't sound great.

I used the Carvin no-hassle return once a long time ago, BTW. Ordered up a bass and it was fantastic … except for the part where they misunderstood my order and changed a spec on me. They took the return and paid for the shipping – then asked if they could have a second chance to get it right. I still have that one.

[Phil O]

Just in case folks are looking for a cheap solution that I neither recommend nor not recommend. All I know is: it exists:

http://www.sweetwater.com/store/detail/ ... fgod5a4Kdg

I thought Sweetwater had a falling out with Behringer. They must have burried the hatchet.

[Rick Cornish]

Just in case folks are looking for a cheap solution that I neither recommend nor not recommend. All I know is: it exists:

http://www.sweetwater.com/store/detail/ ... fgod5a4Kdg

I thought Sweetwater had a falling out with Behringer. They must have burried the hatchet.

Thanks, Phil. This looks VERY interesting—and the price is certainly right!

[Rick Cornish]

AB is not a fixed standard. The variables in design mean that bias is applied so that the transistors operate somewhere between null point switching (B) and full on when the amp is running (A). Every designer uses his/her secret sauce in the compromise and Bryston is considered among the best as they are glad to tell you:
http://www.audioadvisor.com/prodinfo.as ... r=BY4BSST2

I looked again at the Carvins I linked you to earlier. I see that the more powerful ones are Class G. This is much better than Class D for hifi applications.

Here's the best explanation I've run across lately of the different amplifier types.
https://www.maximintegrated.com/en/app- ... vp/id/5590

The Pioneer we all had in the '70s was Class B.

I am not pushing Bryston, really. It's just that these are well known to me and their reputation is impeccable.

Frankly, I wouldn't have one in my California studio unless it had its own cabinet and air conditioning as many studios do. Large Class AB amps are heat pumps. If I had passive monitors, I'd try a Carvin Class G and would return it if it didn't sound great.

I used the Carvin no-hassle return once a long time ago, BTW. Ordered up a bass and it was fantastic … except for the part where they misunderstood my order and changed a spec on me. They took the return and paid for the shipping – then asked if they could have a second chance to get it right. I still have that one.

Thanks, Mike!

The tutorial on Max Integrated is the best I've seen, too. Thanks for sharing.

Thanks for the recommendation on Carvin. I checked out http://www.carvinaudio.com/products/dcm ... -power-amp
• Great company reputation
• Great specs on the 1000W model—rated all the way to 2 ohms! (class D, BTW)
• But—it's really a PA amp… hence, it has fans, which make noise which is bad in a small studio like mine where I can't rack up the amp in another room

Presently leaning towards the Rotel (new) or a Bryston (used) as you originally suggested.

[Phil O]

Thanks, Phil. This looks VERY interesting—and the price is certainly right!

Just for the record, that was HC's post.

Philippe

[Rick Cornish]

Just for the record, that was HC's post.
Philippe

Understood and noted. Thanks for forwarding on the info.

[HCMarkus]

Just in case folks are looking for a cheap solution that I neither recommend nor not recommend. All I know is: it exists:

http://www.sweetwater.com/store/detail/ ... fgod5a4Kdg

I thought Sweetwater had a falling out with Behringer. They must have burried the hatchet.

Yes, I think that was a number of years back. I believe Sweetwater took Mackie's side long ago, when Behringer was the new kid on the block. In my opinion, it was obvious that Behringer was making look-alike products that were reverse-engineered. Behringer has come a long way since its early days, with its purchase of Midas and very popular products like the x-series mixers.

[monkey man]

Could be. Or maybe you got unlucky. Dunno. But, I make it a point to never drive while I'm drinking. The driving part is too distracting.
Phil

LOL

[Killahurts]

Rick, looks like they talked you into getting a new amp.. which is cool, but I wanted to address the hum problem, just for fun. Did you cut the ground wires (XLR pin 1) on the balanced cables, only on the amp side?

i.e., you leave the grounds connected on the source/mixer/interface side of the cables..

Sorry I'm too late with this old thread, but maybe it will help someone else.

[Rick Cornish]

Rick, looks like they talked you into getting a new amp.. which is cool, but I wanted to address the hum problem, just for fun. Did you cut the ground wires (XLR pin 1) on the balanced cables, only on the amp side?

i.e., you leave the grounds connected on the source/mixer/interface side of the cables..

Sorry I'm too late with this old thread, but maybe it will help someone else.

Good suggestion, Killahurts, I'll add it to my standard hum and buzz checklist.

In this case, the amp had only TRS or RCA inputs, and I did try both. It was a bad amp all along.

[MIDI Life Crisis]

I'm late to the party, but I will add that I occasionally get some interference that is not quite 60 cycle in my left speaker. I discovered that my USB and CAT5 cables were too close to the audio connection. Once I moved those wires a bit further away the hum stopped. Probably not your issues, but most studios have a crapload of wires and it's easy to miss a leak from a data (as opposed to a power) cable. MIDI cables are also good candidates for noise to filter into the system, especially if they are too close to an unshielded USB cable.

That said, I remind the members that it's always good to have a "60 cycle hum" patch ready to drive the the engineers and audio tech guys crazy at gigs.

[Killahurts]

In this case, the amp had only TRS or RCA inputs, and I did try both. It was a bad amp all along.

Cool. The method I wrote only works with balanced cables, whether TRS or XLR. The idea is that the cable is still shielded, but the shield is disconnected from the ground at the receiving end, so a loop can't occur. Only problem would be if you had to have long cable runs, but in the studio we usually don't.

I couldn't use my Adam S3A through my Adam Sub 1 for a long time because it would create a hum in the S3As. I just used a bass management system for crossover. I clipped these wires and it worked perfectly.. nowadays, I run the sub from another output, without crossing over (S3As are full range and the sub is tucked underneath). Of course, I had to solder back the wires I had cut..

[HCMarkus]

That said, I remind the members that it's always good to have a "60 cycle hum" patch ready to drive the the engineers and audio tech guys crazy at gigs.