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CEBJr
2011-12-07, 10:20
I'm new to the forums and would appreciate some advice about how best to correct a problem with my system. The system consists of a SlimDevices Squeezebox, v.2, a Sony DA4300ES AV Receiver, Vienna Acoustics Haydn Grands (4), and VA Maestro Grand center. I play classical, choral, jazz, and folk. The issue is that when playing choral music at moderate levels via Pandora with the SqueezeBox, very high soprano notes often distort badly. It occasionally happens with solo soprano voices, but this is less of an issue.

I have the SB volume between 40-60 and the Sony typically near 0 Db. At these levels, I also get a quiet hiss with each track.

It happened with my old system and I hoped it would go away when I remade the system two years ago. It hasn't. There are no longer any serious brick-and-mortar stores nearby my home, and so there is no reliable resource to talk with. Does anyone have an idea what's going on here?

Thank you,

Ched

aubuti
2011-12-07, 10:29
Welcome. I can't give you any specific advice, but I do recommend that you set the volume on the SB much closer to 100%, and turn down the volume on your Sony receiver. The SB doesn't have to go all the way to 100%, but get it up at least to 80%. This is a general recommendation for all SBs, as the volume control is digital.

Also note that Pandora is only sending 128kbps tracks, so the fidelity of the source isn't that great to begin with. Even so, it shouldn't distort badly.

w3wilkes
2011-12-07, 10:53
One other thing to be aware of in addition to running your SB volume at or near 100% is you should not plug your SB into the phono jacks on your receiver, but instead Aux, Tape or something other than Phono. The Phono RIAA EQ curve is way different than other inputs and will cause bad listening results if things other than turntables are plugged into Phono.

bhaagensen
2011-12-07, 17:22
One thing to try is resetting the Xilinx. Dona search for the procedure - its something like holding 1 on the remote while plugging the device in. Fixed a similar problem with my SB3 once.

CEBJr
2011-12-07, 20:02
It's plugged into an Aux jack. (Somewhere in the dim past I read to plug only a turntable into the phono jack.) I turned the SB volume up to 95. It sounds much better, but now it goes into "Protect" mode at about minus 10dB. Tomorrow I'll call Crutchfield (where I got the receiver) and ask what that might be about. Before I do, I'll try the Xilinx reset.

Mnyb
2011-12-07, 21:35
Is there any digital input on that reciever you could try ?

Pascal Hibon
2011-12-08, 00:54
Did you try to listen to the same music from your local library?
I don't know Pandora but maybe the music you where listening to was a low quality mp3 file. These files often sound a bit "metallic" in the high end.

CEBJr
2011-12-08, 09:38
Is there any digital input on that reciever you could try ?

I'm using a fiberoptic cable from the receiver to the SB. Logitech tells me that doing it that way bypasses the DAC in the SB so it's using the DAC in the receiver. I haven't any idea about the quality of the receiver's DAC.

Four possibilities:

* Leave it the way it is;

* wire it with the RCA jacks;

* get a SB Touch; or

* get a DACMagic (or DACMagic Plus).

Sigh...

Soulkeeper
2011-12-08, 10:09
Option two is cheap, quick and easy. So I think you should try it and see.

Edit to add:

It just struck me. These two statements:

It's plugged into an Aux jack.
... and ...

I'm using a fiberoptic cable from the receiver to the SB.
... contradict each other. Either you're using an analog (RCA or jack) cable plugged into the aux input, or you're using a digital (fiberoptic) cable. If you have them both connected at once, you probably don't know which of them is in use, which is bad for troubleshooting. (And in a "worst case scenario", the receiver doesn't know either, which may cause it to behave strangely.)

One cable at a time, please. :)

JJZolx
2011-12-08, 10:46
Do you only hear it when listening to Pandora and not when listening to similar music ripped from your own CDs to a lossless format like FLAC?

If so, then it's most likely the lossy encoding of the audio stream. Pandora streamed to the Squeezebox is a poor 128 kbps. High frequencies, in particular, suffer with lossy encoding.

CEBJr
2011-12-08, 12:10
Option two is cheap, quick and easy. So I think you should try it and see.

Edit to add:

It just struck me. These two statements:

... and ...

... contradict each other. Either you're using an analog (RCA or jack) cable plugged into the aux input, or you're using a digital (fiberoptic) cable. If you have them both connected at once, you probably don't know which of them is in use, which is bad for troubleshooting. (And in a "worst case scenario", the receiver doesn't know either, which may cause it to behave strangely.)

One cable at a time, please. :)

Sorry, that was sloppy. It's a digital cable, only.

CEBJr
2011-12-08, 12:17
One thing to try is resetting the Xilinx. Dona search for the procedure - its something like holding 1 on the remote while plugging the device in. Fixed a similar problem with my SB3 once.

I reset the Xilinx. It sounds better, now, but I need to do the comparisons recommended in other posts. It's difficult to do that given that I can't call up a particular song on Pandora, so I have to wait until one overdrives and then see if I have a copy of my own.

CEBJr
2011-12-08, 12:35
Do you only hear it when listening to Pandora and not when listening to similar music ripped from your own CDs to a lossless format like FLAC?

If so, then it's most likely the lossy encoding of the audio stream. Pandora streamed to the Squeezebox is a poor 128 kbps. High frequencies, in particular, suffer with lossy encoding.

I have a Pandora subscription, which raises the bit rate to 192.

JJZolx
2011-12-08, 12:41
I have a Pandora subscription, which raises the bit rate to 192.

Sadly, through the Squeezebox it doesn't. :(

http://forums.slimdevices.com/showthread.php?t=91926

http://forums.slimdevices.com/showthread.php?t=85386

http://forums.slimdevices.com/showthread.php?t=63653

aubuti
2011-12-08, 12:47
I reset the Xilinx. It sounds better, now, but I need to do the comparisons recommended in other posts. It's difficult to do that given that I can't call up a particular song on Pandora, so I have to wait until one overdrives and then see if I have a copy of my own.
You could do that, but a much easier and better way to go would be to make a 128kbps lossy copy of something from your own library. Choose a similar kind of music to the kinds that were exhibiting the distorted treble before. Then put the lossy copy in your library (temporarily), put lossless and lossy in the same playlist and go back and forth to your heart's content.

CEBJr
2011-12-08, 12:51
Sadly, through the Squeezebox it doesn't. :(

http://forums.slimdevices.com/showthread.php?t=91926

http://forums.slimdevices.com/showthread.php?t=85386

http://forums.slimdevices.com/showthread.php?t=63653

See? I told you I don't know anything. You didn't believe me.

JJZolx
2011-12-08, 13:00
I think they may even use a mix of MP3 and AAC. If you google around there's some mention of them using 64kbps(!) AAC.

amcluesent
2011-12-08, 15:40
All the artefacts of 128kpbs stream must be revealed by that setup!

CEBJr
2011-12-14, 15:08
Well, I've done nearly everything except the Pandora/non-Pandora track comparison. I replaced some bad wire, replaced the old SB with a Touch, replaced the Toslink cable with RCA cables, and switched the speaker impedance setting on the receiver to 4 ohms (the VA speakers are 4 ohms). Now I know some people don't like the 4-ohm idea, but the receiver was switching to protection mode at modest volumes. Now it doesn't.

The high frequency performance is improved, but I still get occasional distortion. The issue is likely with Pandora's bit rate, I'm concluding.

Thank you very much for your time, everyone who has helped me. The results are evident.

One more thing - I met a man locally who builds speakers. They are bookshelf speakers, and just beautiful. The sound is clean, transparent, and crystalline (he also powers them with Parasound Halo monoblocks). He told me that he spent over a year on the crossovers, which is why they're $3,500 a pair. My receiver has settings for speaker crossovers and I have no idea what I should do about that. Does anyone?

chenrikson
2011-12-15, 08:03
My Pandora feeds are pretty good, considering. For a while I was using the XM plug-in -- and I was having the HF distortion mentioned above. I upgraded my receiver to a Denon AVR-3808CI with built-in XM. Problem gone.

The OP has really fine speakers but the 4 ohm impedence may be a problem for his Sony -- causing the shutdown problem. Any chance of trying an alternate receiver that is known to be OK with 4 ohm?

CEBJr
2011-12-19, 13:25
When I switched the impedence in the Sony's menu to 4 ohm, the shutdown problem disappeared. The unit sounds very good most of the time, but I still have occasional distortion in the very high vocal registers. When I play my iTunes library through the Touch, I don't hear any distortion so I'm concluding it's a Pandora thing. Maybe I should write/call them.

Mnyb
2011-12-19, 23:43
When I switched the impedence in the Sony's menu to 4 ohm, the shutdown problem disappeared. The unit sounds very good most of the time, but I still have occasional distortion in the very high vocal registers. When I play my iTunes library through the Touch, I don't hear any distortion so I'm concluding it's a Pandora thing. Maybe I should write/call them.

...Thats why you should have your own files if quality is a concern :)
99.9998 % of the user base would not recognize sq if it bit them in thier behind.

Note that 128k will not be artifact free, and you hear it if it is a quality recording.

Lossy compression is even less good on embedded devices with small cpu and no fpu unit, so the decoders has some compromises.

Is it possible to have the server transcode pandora ? Or does the app block this, a worthwhile experiment

Mnyb
2011-12-19, 23:50
Is not the amp a limiting factor if it goes to protection that easy ?

Normally you don't " hear " amps that much when they work properly .

But you sure do when you get close to thier operational limits be it power,voltage,current or whatever.

Some amps dislike the reactive nature of some difficult speakers.

CEBJr
2011-12-21, 11:30
Is not the amp a limiting factor if it goes to protection that easy ?

Normally you don't " hear " amps that much when they work properly .

But you sure do when you get close to thier operational limits be it power,voltage,current or whatever.

Some amps dislike the reactive nature of some difficult speakers.

Again, when I switched the impedence in the Sony's menu to 4 ohm, the shutdown problem disappeared.

CEBJr
2011-12-21, 11:39
...Thats why you should have your own files if quality is a concern :)
99.9998 % of the user base would not recognize sq if it bit them in thier behind.

Lossy compression is even less good on embedded devices with small cpu and no fpu unit, so the decoders has some compromises.

Is it possible to have the server transcode pandora ? Or does the app block this, a worthwhile experiment

This from the Squeezebox Wikipedia entry...

"Logitech Media Server can transcode other audio formats to MP3 on the fly, using the LAME MP3 encoder." This stuff is out of my league, though.

BTW, I've written Pandora and received no reply after two days. It used to be that they would take calls, but no longer. I suppose I could try calling Logitech.