[pekar]

I, too, have the Panasonic whine in my XR50, similar to the above descriptions.  
I've been able to make it disappear by using a car battery and a 400 W inverter.  I've been unable to test if a ferrite on the line will kill it, but I'd suspect not.
So, it looks like a line conditioner would be the answer here.

I'm seriously considering a return and try either the JVC, or the SAXR70, which is supposedly available now at onecall.
cheers!

[dave_c]

Looks like you're right about the XR70.

http://ww1.onecall.com/PID_22427.htm

[ionyou2002]

That's odd that so many have noise issues. I've had my XR50 for a few months now and I have no noise problems at all.

So what kind of setups are you all running? What kind of speakers and such.

I've been thinking of switching to 4 ohm speakers, does anyone here run the XR50 on 4 ohm loudspeakers? Can the panny run 4ohm ok? I know 6 ohm is recommended but does anyone here run 4 ohm without any problems?

[pekar]

I'm using my old Polk monitor 5's which are 4 ohm.  They work fine(at least the amp doesn't seem to have any problems), but I'm not happy with the sound for music.  Midrange is lacking, as is presence.  
I know what these speakers are capable of and it's a lot more than this amp makes happen.
I am very happy with the sound for home theater.
Music is more important to me overall, I'm leaning towards giving the JVC a try.

I blame a cheap power supply, and dirty power for the noise.  It's possible a shielded power cord or a ferrite might help, but I'm just going to return mine.  Some have said the xr70 might have a better power supply, so that might be a solution as well.

[Red Dragon Audio]

I'm using my old Polk monitor 5's which are 4 ohm.  They work fine(at least the amp doesn't seem to have any problems), but I'm not happy with the sound for music.  Midrange is lacking, as is presence.  
I know what these speakers are capable of and it's a lot more than this amp makes happen.
I am very happy with the sound for home theater.
Music is more important to me overall, I'm leaning towards giving the JVC a try.

I blame a cheap power supply, and dirty power for the noise.  It's possible a shie ...

I think I have read a bunch of posts now where folks are having a hard time with parts, not all, of the "digital amp sound".  I know my latest speakers sound great with my XR45...but not all the time...source music is a problem but there is a bit more glare now then when I had De Capos.  They're both 6ohm speakers, but my new ones drop down to 3.2ohms at 200Hz.  I think it's straining the amp too much and therefore causing it to sound strained overall.  This is just a hunch but read what another fellow posted here.

http://www.audiocircle.com/index.php?topic=8189

I am working with a custom transformer company to build a set of autoformers that will double the impedance seen by the amp.  This should relieve our amps of the current delivery problems and provide us with smoother sound.  Obviously, this isn't going to solve the problem for folks looking to power behemoth speakers..but for most of us, it will be a welcome upgrade.  Even guys with 8ohm nominal speakers might find it beneficial as your speakers might have impedance dips, affecting the sound...and it might just sound better anyway.  Sooo....

I'm going to have one prototype made to test out in my setup.  Then I will ship it to whoever else is interested.  They try it for a week,  see if they like it and then send it to whomever is next in line.  If we get a good size group together, we can get more of a discount.  Right now I'm trying to get the cost to around $150-$185/pair.  I might be a bit high on that quote, but it will depend quite a bit on how many of us will end up wanting one.  also, I don't want to say they're going to be $100/pair and then they end up being $200.  You'll be happier if I am overquoting now, then discount them later.

Anyway, I wanted to post this here to the group to see if we can get something together.  I'm also going to call other custom transformer companies to make sure we're getting the best deal possible.

12AWG copper magnet wire, torroidal transformers with wide bandwidth.

Let me ask everyone interested a few questions too:

Do you want them with long 5' leads so you can directly hook them up to your amp and speakers?  If you don't need them that long, you can always cut them down.

Do you want connectors on these leads so they are a "Plug & Play" type device?

What other things would you be looking for in something like this?

[ionyou2002]

Sounds like a good idea heavystarch. Is it possible to have the amp see 1.5x the impedance instead of 2 though? This would have the amp see 4 ohm speakers as 6 ohm for example, which I would think might be the "sweet spot" for this amp seeing as the recommendation in the owners manual is for 6-8ohm speakrs.

I'm always turning my volume up to about -15 db when I want it loud. Not that I have any problems with it, it doesn't get distorted or anything but if it saw a lower impedance I might not have to turn it up so high (all else being equal).

Oh i forgot to mention I have 8 ohm speakers now I'd like to replace with a set of 4 ohms but I was worried it might strain at 4 ohms.

[Red Dragon Audio]

Sounds like a good idea heavystarch. Is it possible to have the amp see 1.5x the impedance instead of 2 though? This would have the amp see 4 ohm speakers as 6 ohm for example, which I would think might be the "sweet spot" for this amp seeing as the recommendation in the owners manual is for 6-8ohm speakrs.

I'm always turning my volume up to about -15 db when I want it loud. Not that I have any problems with it, it doesn't get distorted or anything but if it saw a lower impedance I might not have to turn ...

First off, I have to ask what are the 4ohm speakers you are planning on getting?  That will help me make better recommendations.  Another thing to remember, is that doubling the load seen by the amp, won't change the inherent speaker sensitivity.  If you have 84db/1watt/1meter point sources speakers, you are just going to need more power to get them juiced up in the same sized room.  If you had speakers of 91dB sensitivity, then they would need less power to acheive the same volume levels in that same room.  See where I'm going with this.  Many factors here to consider; even the music played has a big role in volume dial.  My classical music demands I turn it up to -30 in my room with my speakers but most other music, I can have it at around -40 for good levels.

It is possible to get them made at 1.5x but this isn't the goal of this project.   I'll tell you why...  The "sweet spot" we're seeking here is in terms of sound quality not quantity.

I have to refer you back to this post by Paul Speltz:

Yes, I see the Panasonic SA-XR45 is only rated down to 6 ohms. Even amplifiers that are rated down to 4 ohms or less sound better driving a higher impedance speaker load. With the 45, (and its minimum rating of 6 ohms), I bet the sweet spot (where it gives best sound) might even be as high as 12 ohms.

I have sold hundreds of pairs of my ZERO-Autoformers to guys that have put them behind everything from 3 watt SET tube amps to 350 watt Solid state amps. Bottom line... whatever abnormalities an amplifier produces when it is stressed (because of driving lots of current into a low impedance load) goes away when the ZERO-Autoformers are added to increase the speakers impedance. Higher impedance = less current demands = easier job for the amplifier = better sound.

You can read the whole thread http://www.audiocircle.com/index.php?topic=8189">here.

I completely understand your concern for keeping the amp in the "zone" in terms of power output.  However, going from an 8ohm load to a 6ohm load won't gain you any real power in these amps.  You have to remember the power supply in there isn't going to be able to drive any more current to your speakers as the impedance drops.  This is why they can sound strained when pushing lower impedance loads.  hence this little project.

These amps will never produce gobs of power.  I think I have read somewhere that real world "audiophile" power output from these amps is probably more on the order of 75-85watts.  Panasonic rates them at 100watts x 6 at .15% THD for the mass market crowd of consumers who just WANT RAW POWER regardless of distortion specs.


So to calm your concerns over power output losses, don't worry.  You won't be losing any significant power output.  Maybe you have to turn it up to -13 instead of -15 to get it as loud as you want.  But you still have to -00 still so plenty volume to go.  I hope.

[ionyou2002]

Yeah you're probably right, 6 ohms may not be the sweet spot. I've never heard it running on anything other than my 8ohm speakers so i wouldn;t know how changing the impedance affects the sound quality.

I was erroneously thinking that if the amplifier saw a 6ohm load instead of an 8 ohm, it would cause the amp to drive the speakers with more current, thereby not necessitating such a high setting of the volume knob.

Then i thought well if the volume is at -25db rather than -15db but the amp pushing more current, maybe it would sound better while still outputting about the same sound pressure levels.

Oh to answer your question the speakers I was considering were Axiom M80s.

But I don't want to run the amp out of its recommended spec range so i will forgoe the m60s for some other higher impedance model such as 6 or 8.

Though after listening to some new material today i'm kind of liking my speakers again, it all just sounds so good maybe I shouldn't give up a good thing for the possiblility of better. Like they say you don't know what you got till it's gone.

[Red Dragon Audio]

Yeah you're probably right, 6 ohms may not be the sweet spot. I've never heard it running on anything other than my 8ohm speakers so i wouldn;t know how changing the impedance affects the sound quality.

Well I will tell you this; I am not trying to turn this into a business or anything here.  What I am going to do is, get one set made up and try them out in my setup.  If Paul's assumption that 12ohms might be the sweet spot for sound quality, I think I will hear it.  My speakers are 6ohms nominal and drop to 3.2ohms.  If raising the impedance does improve sound quality, I'm going to be telling everyone with digital amps so they can join in as well.  No need to hoarde the sound improvements all to myself.  This is an easy transformer to make I think and should be relatively inexpensive for all of us (more so if we get a group buy).

I was erroneously thinking that if the amplifier saw a 6ohm load instead of an 8 ohm, it would cause the amp to drive the speakers with more current, thereby not necessitating such a high setting of the volume knob.

Actually your thinking is spot on really (except the part about the setting of the volume).  The point I think you are missing though is, we're NOT trying to force our amps to push more current.  That is what is making them strain so hard and thus making them sound edgy, strident or harsh at times.  They're just not designed to deliver gobs of current.  Hence the solution I'm proposing; stop forcing the amps to deliver current levels they can't fulfill, and get them working on a load they CAN handle.

Your speakers will still get the power; just in the form of voltage, not current.  In fact, raising the impedeance I think gives the amp more damping power.  Not sure how much and all but that also means a bit more control down low I think.  Some engineer please jump in here and help me out cuz now I'm just spouting off.

Then i thought well if the volume is at -25db rather than -15db but the amp pushing more current, maybe it would sound better while still outputting about the same sound pressure levels.

That is good thinking(sort of) but again we're running into the problem of forcing our amps to do something they weren't inherently designed for; large current delivery.  Your speakers sensitivity is not going to change so the slight increase in current delivery isn't going to allow you to drop the volume level so much as you think.  The change in current delivery from 8ohms to 6ohms won't get you from -15 on the volume dial to -25.  

Oh to answer your question the speakers I was considering were Axiom M80s.

But I don't want to run the amp out of its recommended spec range so i will forgoe the m60s for some other higher impedance model such as 6 or 8.

Actually, that model is a very good candidate for this amp.  The rating that should get your attention more than the 4ohm impedance (which is what we're talking about fixing here) is the sensitivity; 91dB (they say 95dB in room).  That's pretty damn good!  That just means you won't need as much power as you think.  

-1 watt, you will get 91dB at one meter from the speaker (but remember with every doubling of distance from the speaker you will lose 6dB...room gain will boost that back up too so it's not a total loss of 6dB entirely).
-2 watts, you will get 94dB levels at 1 meter
-4 watts will get you 97dB at 1 meter
-8watts will be 100dB
-16watts will be 103dB
-32watts will be 106dB
-64watts will be 109dB (at 4meters that will be 97dB which is LOUD).

If you sit between 2-4meters, you are in great shape with these two combined.  I would just get the transformer to make sure you aren't overdriving the amp by forcing it to deliver more current than it can handle.

Since the amp is rated for a bit over 64 watts you will still have some head room to play with there.

Though after listening to some new material today i'm kind of liking my speakers again, it all just sounds so good maybe I shouldn't give up a good thing for the possiblility of better. Like they say you don't know what you got till it's gone.

Well if you like what you have now, then you should be fine...but, you can always do this:
Get the M80's and I'll plan to get you the transformers at the same time.  This way you can listen to the combination and see if it is better than your current speaker setup.  If not, then you are out $15 for shipping the Transformers to the next fellow in line, and whatever shipping costs are for returning the M80's. If you buy them used, then you can always turn around and sell them here, eBay or Audiogon.

just some ideas.

By the way, what are your current speakers?

[ionyou2002]

Those are some good ideas. I'm not in the market ofr the Axiom M80s right now but sometime a couple of months down the line maybe. Going to wait to find them on the used market.

I currently have JBL S310s. Specs:

3-way, 10-inch floor-standing speaker
(10" polyplas woofer, 4" midrange, 1" titanium tweeter)
40 to 20,000 Hz frequency response
8 ohms nominal impedance
91 dB sensitivity
200-watt power handling

I was eyeing the Axiom M80s because the go down to 28hz not to mention maybe the aluminum drivers sound better? I guess I'd have to hear them to know how the sound compared to the JBLs I have now. Hopefuly someone who has heard them can post their experiences

I paid only 300 for both jbls shipped off an auction on ebay So it looks like I got a good deal. Tha axioms retail for about $1200, are they worth 4 times the price? Going to sound that much better?

Also since I was seeking sub 40hz I can just get a subwoofer for that although i'm not exactly displeased with the bass output from the s310s i don't really know what I'm missing at 28hz till i hear it (or in that case feel it i guess)

But i guess what i really need is speakers that can go louder than my current ones without straining. i don't get distortion but it seems like the JBLs just don't sound as good when the volume knob is at -15 as they do at -30 for example.

but i'm not sure if that's because of an underpowered amplifier or just characteristics of the speakers themselves or something.

or maybe i should get 2 more speakers and hook them up to the surround channels and run it in party mode to get more sound out of the -30 setting which sounds great.

well i must sound confused and not know what to do without spending a fortune and i hate to bug you with all these questions but you seem very knowledgable on the subject so thanks for answering my questions

[Red Dragon Audio]

Hi ionyou2002,

Don't feel like you are bothering anyone here with questions.  That is what this forum is for; asking questions...and lots of them.

I think you should stick with your JBL speakers and maybe think about upgrading the gutz of your amp or trying the JVC RX-F10.  $250 shipped directly from J&R.com and they have a 30-day return policy.

Or maybe one of the Sony digital amps might sound better to you.  You could try all three at once, and return the ones you don't want.

If you want deep bass, just get a good pair of subs.  Connect them using the speaker level inputs straight off your amp or speakers.  This keeps them in phase with the speakers/amp.