A very enjoyable Preamp with very annoying hiss sound

jumpindick

So, finally I upgraded the heart of my HT system. I bought Marantz AV7702mkii preamp a couple of weeks back. This weekend I put everything together in the system. It is a 7.2 system with the marantz pre, parasound A23 and SVS PB-2000s being new addition.

After performing the auto calibration, the system sounded great. Those subs are something that was missing out from day one of my HT experience. For the first time (yeah call me dumb..) am noticing what a great quality sub does to overall HT experience. I used to have polk audio PSW111... I love polk speakers, but this sub is something to talk about.

Although the overall experience of "new" set up was really nice, there was a problem. The system generates an annoying amount of "hiss". This is what I have:

1. RTiA9s connected to McCormack DNA-500
2. CSi A6 connected to Sunfire
3. FXi A6s connected to parasound A23 and Rotel.

Except for the rotel amp, which drives two surround back speakers, all other speakers/amps have wireworld XLR cables. Everything is connected to Belkin power conditioner.

The hiss is really annoying. Watching movies at high volume masks the hiss well. But at lower volume, it is noticeable. I have checked the connections and everything is grounded. I have checked speaker cables-- no damage to any cable and they all are meeting their respective terminals (positives and negatives).

I have been reading online. People have reported such issues, but it seems more like hit and miss.. Some talk has been around use of attenuators (10 db). I have no idea what they do. All I have read up is that they will take the gain down without affecting overall sound quality (at least that is what claimed).

I thought to check with you guys.. any help would be really appreciated. So far, I have removed all sources that feed the preamp, and looked at the issue while connecting each source to the preamp at a time (bluray, cable etc.). This did not make any difference. I plugged the preamp directly into wall as well as on the other banks of the conditioner and this also did not do anything. The conditioner shows that the system is grounded.

Is there anything that you guys would recommend? Has anybody seen such issue?

Thank you.

BlueFox

Are you saying the hiss is there with all the sources disconnected? Is the hiss the same level no matter what the pre volume is? Was the pre purchased new or used?

jeremymarcinko

Try turning off audyssey and see if the hiss persists.

tonyb

Does the hiss come from both speakers or just one ? Possible a balanced cable pins got damaged somehow ? Try using RCA cables in the chain pre to amp.

Looks to me like you have a lot of gear grounded to the same spot.

jumpindick

BlueFox wrote: »

Are you saying the hiss is there with all the sources disconnected? Is the hiss the same level no matter what the pre volume is? Was the pre purchased new or used?

I will check on that. I will disconnect all the sources (cable, blu ray, roku etc..) and see if the hiss is still there. I will have to leave the amps connected though (right??) to hear if there is any hiss.

The hiss stays at the same level regardless of volume. Of course, when the volume of a playback (let's say a movie) is high, the hiss is not perceived since the volumes masks it. But if I get closer the speakers, it is still there. At low volume with just flat dialogue coming from center channel, it is clearly noticeable.

jumpindick

tonyb wrote: »

Does the hiss come from both speakers or just one ? Possible a balanced cable pins got damaged somehow ? Try using RCA cables in the chain pre to amp.

Looks to me like you have a lot of gear grounded to the same spot.

The hiss is coming from all seven speakers. The front two towers, center, surround speakers have louder hiss than the surround back speakers. The surround back speakers are hooked up via RCA cables. The rest are connected via XLR cables.

I thought about having too many things attached to one conditioner, but then thought that since there are 10 banks, the unit shall be able to handle.

I will look at connecting the amps to a different conditioner that I have..

tonyb

All seven....then it isn't one particular amp, has to be the pre. Try lifting the ground on the pre. Using a 2 buck cheater plug from any hardware store. Takes a 3 prong plug and converts it to a 2 prong, lifting the ground.

jumpindick

Hello Guys, it seems that I might have found the source of the hissing sound I was getting in my system. I just detached the HDMI cable from cable box end. The other end of this cable was still attached to the preamp. And just by doing so the hissing sound is gone.

What I did not get though is that the cable box was powered down (disconnected) and yet the HDMI cable from cable box was causing this hissing sound.

In my earlier diagnostics, I had detached the HDMI cable end at the pre and left the other end attached to the cable box. In that situation, the hissing sound was still there. But when it was the other way around, (no cable attached to the cable box), the sound was gone. I just did this, so I am going to listen for some longer hrs on the system to be sure that this was IT and no other issues...

I guess, I will be going to get some good quality HDMI cables then. This was the one that came along with the cable box (bright house network).

Thank you all who provided some valuable feedback. I appreciate it.
Dhaval.

BlueFox

Interesting. Generally, cable boxes are a source of hum, not hiss. Is the cable box somehow attached to the system in any other way? It does seem as if the HDMI cable is the culprit. Glad you found it.

tonyb

jumpindick wrote: »

I guess, I will be going to get some good quality HDMI cables then. This was the one that came along with the cable box (bright house network).

Thank you all who provided some valuable feedback. I appreciate it.
Dhaval.

Good man, I usually throw away the cables that come with any device, you know they're going to be the cheapest they can buy in bulk.