Buzzing Classe Amp with 803D & HTM3?

[beden1]

I hooked up my new 803Ds along with the HTM3S. Impressions & pictures to follow next week.

I had a question and hoped for some advice. I hooked up my Pioneer Elite 82TXS receiver as the pre-pro, a Classe CAV-150 amp (6 channels & bi-amping the front three speakers), along with using the 703s as the surrounds. I have them and the Velodyne SC-1250 sub amp plugged into a Furman - Elite 15 PF Power Conditioner (this model made to plug in amps). I also have a Richard Gray Power Company 600 conditioner plugged into an adjoining outlet on the same wall . . . along with the DVD player, TV, and cable box plugged into it. I have separated the power cords as much as possible from the input cables. I'm using Blue Jeans Cables from pre-outs to the amp with splitters for bi-amping (RCA, not balanced). Transparent cables to each speaker.

The 703s are hooked directly to the receiver and there is no buzz - just clean air out of those speakers.

I had a very noticeable buzz coming out of the three front speakers hooked directly to the Classe amp. I then used paper clips as shorting pins into the 1 and 3 pegs of the balanced inputs. This reduced the buzz by 1/2.

I changed the cables and splitters to the amp with M Series (Monster Cables) that I had, and there was no change.

Do all amps have some buzz, or is there something else I can do? I don't remember a buzz in my systems that I had in the past.

[Gremal]

It's not possible to use a receiver as a preamp because it has built-in amplification. I suspect this is the root of your problems.

[beden1]

It's not possible to use a receiver as a preamp because it has built-in amplification. I suspect this is the root of your problems.

The receiver has pre-outs which enables you to use an outside amp. By doing this, I am by-passing the three front channel amps in the receiver.

[Kal Rubinson]

Simplify by starting with the amps direct to the speakers and no input, no line conditioning. Then, if that's OK, add each additional device and see where/when the hum comes in.

Kal

[beden1]

Simplify by starting with the amps direct to the speakers and no input, no line conditioning. Then, if that's OK, add each additional device and see where/when the hum comes in.

Kal

Thanks Kal. I will go through the steps and let you know how I make out.

[beden1]

Simplify by starting with the amps direct to the speakers and no input, no line conditioning. Then, if that's OK, add each additional device and see where/when the hum comes in.

Kal

Kal,

I started with the amp by disconnecting it from the power conditioner and plugging it into the wall outlet. I then disconnected it from the receiver, and unplugged the other power conditioner and light from the outlets on the same wall. The amp was then by itself directly powering the speakers. The low level buzz is still there. I also checked the speaker connections to see if any were shorting, and did not see any problems.

So, its the amp. Is this a problem with my amp, or do high power amps produce a low level buzz in general?

[Glen B]

Is this a problem with my amp, or do high power amps produce a low level buzz in general?

With my current Classé amp, input open, there is only a very faint hiss with my ears pressed to the grill cloth of my speakers. Over the years I have owned more amps in the 200-300+ watt range than can be counted on both hands. None have produced any audible noise other than what is described above, which is normal. Is the CAV-150 a new [used] amp or have you owned it for a while ?

[beden1]

Glen,

I just bought it used from a dealer in New England through AudioGon. On the exterior at least, it's a very clean like new looking piece.

I am getting just a hiss from the right speaker tweeter, but the mid range has a buzz like humm. The center channel and left front speaker have the same level of audible buzz . . . audible from 5-6 feet if you are trying to hear it with no volume level.

I was trying to listen to a Liz Story Winter Solstice piece (piano solo) last night and had to change CDs as the buzz was bothersome.

[beden1]

As I am currently using the 6 channels of the amp to bi-amp for three channels, do you think it will make any difference if I switch to bridge mode?

[Glen B]

As I am currently using the 6 channels of the amp to bi-amp for three channels, do you think it will make any difference if I switch to bridge mode?

From what you said, the buzz is common to the left, right and center channels. The cause could be anything, including a failing power supply cap. If Classé is employing two separate supplies shared by three each of the amp's six channels (a possibility), that could account for the noise being common to three. You should probably send the amp to the factory for a check-up.

[Kal Rubinson]

Kal,

I started with the amp by disconnecting it from the power conditioner and plugging it into the wall outlet. I then disconnected it from the receiver, and unplugged the other power conditioner and light from the outlets on the same wall. The amp was then by itself directly powering the speakers. The low level buzz is still there. I also checked the speaker connections to see if any were shorting, and did not see any problems.

So, its the amp. Is this a problem with my amp, or do high power amps produce a low level buzz in general?

Seems like it is the amp. The amps I have rarely ever make any sound unless I put my ear to the tweeter.

Kal

[KEF]

"a Classe CAV-150 amp (6 channels & bi-amping the front three speakers)"

"Do all amps have some buzz, or is there something else I can do? I don't remember a buzz in my systems that I had in the past."

Just out of curiousity, have you tried to run the amp straight (not bi-amped) to the speakers to see if anything changes?

FWIW, I do not get a buzz in my system when running in stereo

Cheers,
Keith

[beden1]

Just out of curiousity, have you tried to run the amp straight (not bi-amped) to the speakers to see if anything changes?

FWIW, I do not get a buzz in my system when running in stereo

Cheers,
Keith

Keith,

I'm going to try the bridge mode next to see if that has any effect. I'll play with it tonight (again) to see if anything changes. I'll try straight stereo as the last resort, as I was hoping to use the max power of the amp for the three front speakers.

[KEF]

Keith,

I'm going to try the bridge mode next to see if that has any effect. I'll play with it tonight (again) to see if anything changes. I'll try straight stereo as the last resort, as I was hoping to use the max power of the amp for the three front speakers.

I think it would be at least worth a test to see if anything changes when not bridged - you never know.

Best of Luck,
KEF

[beden1]

Well . . . I am very happy to report that my (in my mind) mission impossible to "virtually" eliminate the noticeable buzz has been successful, and, I'm not really sure why!

I tried to bridge the amp/speakers, and the speakers/system hated it! I then tried to hook up just a stereo connection, and it hated too?

I'm not sure why, but, the B&W speakers seemed to really hate using their jumper wires? In this setup, the buzz was worse, and when powering the amp down, the speakers sounded like a bottle rocket launching? The B&W tweeters are particularly extremely sensitive. It was interesting however, to actually hear the many hundreds/thousands of vibrations per second become focused to my ear as they fluttered down to an eventual hault.

The amps' instructions are very descriptive about various connections including a bridge mode. When I tried this however (with my 803Ds using their jumper cables), the buzz got worse and the aftermath was a disaster. It's interesting that Classe does not give intructions for bi-amping this six channel amp (CAV-150), as it seems to be most comfortable at home with this setup vs. the others.

In my setup, the amp is hard to work on as it is located in a cabinet. I had to pull it out and set it on a box for access to the back panel. I was ready to throw it in the trash after finding the other connections didn't work, but, I decided to try my original bi-amp connections again (as this connection was the least offensive). I was very careful with each connection, making sure all were clean and tight (I even used an open wrench to tighten the spade speaker connections). I also positioned each cable in an organized manner so that each would not be disturbed when I pushed the amp back into position. I held my breath when powering it back on, and walla . . . it worked? The buzz/open circuit noise is now only about 1/10th of what it was originally. And, because this amp sounds so sweet powering the B&Ws, I can live with a faint noise only perceivable by placing my ear right up to each speaker.

Thank you to all including Kal & Keith for your help.

Brooks

[KEF]

Good news Brooks, glad you got that sorted -

Cheers,
Keith