Acceptable nearfield monitor noise level question (LSR25P)

H

HomeRec

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I have a couple of JBL LSR25P studio monitor speakers that are about 2.5 weeks out of the store. With all of the other DAW equipment turned off, I listened to the two speakers at full volume, with nothing coming through them. One of them has an electronic "buzz", and both of them have a faint background "hiss".

The "buzz" seems odd, but I figure it may be due to interference from a power source somewhere (monitor or audio/power cable crossover), and I'm going to see if I can track it down.

However, the hiss also seems odd. What is the acceptable noise level for a nearfield studio monitor speaker at full volume? Should it be absolutely noiseless, or is there a certain allowance for high volume?
 
I imagine the background hiss is the result of using unbalanced cables to your monitor, don't know about the buzz though...

pAp.
 
PapillonIrl said:
I imagine the background hiss is the result of using unbalanced cables to your monitor, don't know about the buzz though...

pAp.
Click to expand...

Actually, the cables running to the monitor speakers are balanced 1/4" to XLR cables.

When testing the speakers, nothing was delivering input to the speakers. The "buzz" could be power noise, but the hiss seems inherent in the speakers themselves.
 
Try disconnecting the input cables from the monitors and see if they are still making noise. Maybe it's a grouning problem?
 
vox said:
Try disconnecting the input cables from the monitors and see if they are still making noise. Maybe it's a grouning problem?
Click to expand...

I did disconnect the input cables, and there was no difference. It could be a grounding problem, as I'm running a 7-plug surge protector off of a 2 --> 3 prong plug adapter and 8' extension cord.

I know, I know. It's not the best way to set things up. However, I don't have any 3-prong plugs in the same room, and the surge protector at least affords the equipment some level of protection.
 
HomeRec,
I suggest you read Appendix A of the user's manual.

JBL LSR25p Manual (pdf)

There's a few suggestions there as to how to reduce hum. But I did not see anywhere that said anything about using without AC grounding.

Can't you take them to a different room/building and test them with a grounded outlet?

I'd imagine your noise is due to the lack of ground. I've never actually turned mine ALL THE WAY up, though.

When I first got mine, one was defective, making a buzzing noise at any volume level. A quick exchange fixed that problem.

Queue
 
Update

I brought both monitor speakers back to the store, and the one with the buzz was exchanged for a new monitor speaker, which is in the same place, same configuration, with no buzzing sound.

I called ahead, and by the time I'd gotten to the store the next day, the salesperson I've been working with for the past few months had verified with two other people that it is not unusual to have a little bit of hissing ("shhhhhh") noise in active monitors due to the proximity of the powered amplifier to the speakers themselves. In fact, he said that even passive monitors sometimes have this problem.

In short, I kept the monitor without the buzz, and the replacement monitor sounds exactly the same. There may still be grounding issues, but at least both monitors seem to be good. Problem solved, at least for now.

Queue: I presently have two shielded 1/4" to XLR cables, one for each monitor. Appendix A of the Owner's Manual is a bit confusing, but from what I can gather, I don't think there is any way to improve the wiring, as my Direct Pro 24/96 only has 1/4" output jacks - no XLR output.

"Can't you take them to a different room/building and test them with a grounded outlet?"

I'm not sure I even have a grounded outlet. But assuming the outlets with three prongs are, in fact, grounded, then I suppose I could test them out there. I know for certain there are no such outlets in the room I have my setup in presently.

"I'd imagine your noise is due to the lack of ground. I've never actually turned mine ALL THE WAY up, though."

The only time I did was to listen for the hiss and buzz, myself. :)

"When I first got mine, one was defective, making a buzzing noise at any volume level. A quick exchange fixed that problem."

Bingo. Same here. As an added precaution, I also made sure to get the closest possible serial number I could to the monitor speaker I was keeping.
 
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I presently have two shielded 1/4" to XLR cables, one for each monitor. Appendix A of the Owner's Manual is a bit confusing, but from what I can gather, I don't think there is any way to improve the wiring, as my Direct Pro 24/96 only has 1/4" output jacks - no XLR output.
Click to expand...

Which outputs are you using on the Aark? Did you install the upgraded drivers that allow you to switch outputs 1,2 and 3,4 to +4dBu?

From Appendix A:
Consumer and semi-professional equipment with unbalanced signals usually have a lower output capability
(-10dBV) than professional devices (+4dBu). In these cases it is recommended to use the LSR25P RCA input. This input has been specifically designed to accommodate the lower output levels typical of consumer and semi-professional equipment. crimson = Queue's editorial additions

What does this mean? If you are using an Aardvark Direct Pro 24/96 (RCA outputs 5,6), which are consumer line level (-10dBV), you should use unbalanced RCA cable, connected to the RCA inputs on the JBL LSR25P (also -10dBV). The sensitivity of the RCA input is approximately 12 dB higher than the XLR input. If you're using 1,2 or 3,4 and you've got it set to +4dBu, and you're using a balanced 1/4" TRS to XLR then you should be good to go. You might want to disconnect the wire going to pin 1 of the XLR input to the LSR25P. This could reduce ground loops.

Queue
 
I'm using outputs 1,2 with a balanced 1/4" - XLR cable out to the LSR25Ps.

I bought the cables with the speakers, and briefly considered returning them for RCA - RCA cables when I noticed the outputs on the 24/96 labelled "monitor" were RCA, not 1/4" jacks. However, the manual itself gave instructions for monitoring through outputs 1,2, so I figured I was good to go. Also, I figured connecting to the XLR input on the LSR25Ps would be better than the RCA.

As far as disconnecting wires, if the hiss was really intrusive, I might consider it, but it doesn't really sound like something I want to get into. Thanks for the advice, though - I'll keep it in mind. :)
 
Homerec,
Are you using the version of the Aark drivers that allows you to set the outputs 1,2 to +4dBu? I'd imagine there'd be a significant loss in output on the JBLs if you were not.

Queue
 
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