[8thnerve]

What I am wondering is why PCM conversion to PWM seems to sound better in the Panny then analog to PWM?  There is still processing (a change) taking place.

If done right, PCM -> PWM should be a lossless operation.  Both D to A and A to D processes are lossy.  So theoretically, the signal will reach the amplification stage unchanged.  Can anyone confirm that the digital inputs are converted to PWM without an interum analog stage?  There are few pieces I know of that actually do this.  Spectron, some Sony all-in-one stuff....

[_scotty_]

I couldn't tell you and Panasonic and TI are are not informative on this subject either. The Panasonic does sound noticeably better in transient response when the digital inputs are used.  I think part of the problem is that we were never suposed to discover this receiver or wonder about the
the way the TI chipset was implemented in the final product. I'm as curious
as the next guy but I doubt if we will have any answers very soon about this product. It would be interesting to see one of the glossies cover this piece and see what their impression of it was.  A technical editor could
maybe get someone from Panasonic or TI to brag about what they had done for the advertising copy value.
As a comment on the RF radiation that accompanies digital amplification and digital signal handling, the magnitude of the RF radiation emited by a circuit is a function of the current level and voltage present in the wiring or circuit board traces. If the rail voltage in a switch-mode amp is constant then the RF signal emitted will be related to the current drawn by circuit. More power output means more current and higher RF output. On a small signal basis when
voltages are at 5volts or lower the RF emitted is several orders of magnitude lower and easier to deal with. The two sources of high power radiation in a switch-mode amplifier are the high current, high voltage
power supply buss and the output signal carrying wires or traces before the low-pass output filter.

[JoshK]

What I am wondering is why PCM conversion to PWM seems to sound better in the Panny then analog to PWM?  There is still processing (a change) taking place.

If done right, PCM -> PWM should be a lossless operation.  Both D to A and A to D processes are lossy.  So theoretically, the signal will reach the amplification stage unchanged.  Can anyone confirm that the digital inputs are converted to PWM without an interum analog stage?  There are few pieces I know of that actually do this.  Spectron, some Sony all-in-one stuff....

Spectron converts the digital input to analog first.  I confirmed this as I was looking to add the digital input board, but now I'll skip.

[_scotty_]

A sidebar comment on classd.org, the writers technical analysis of the chipset architecture seems well done but there are gaping holes in his analysis of the sound of various chipsets and amplifiers based on them.
When these various approaches to switch-mode amplification were evaluated for their sonic worth no mention of the type of power supply used to power the amp was mentioned. If sufficient attention was not paid to the power supplies impedance at and above the switching frequency the amplifier operates at the conclusion drawn about how the applied technology sounds is most likely erroneous. Take what the writer says on this particular aspect of the approaches to digital amplification he evaluated with a grain of salt.

[someidiot]

What I am wondering is why PCM conversion to PWM seems to sound better in the Panny then analog to PWM?  There is still processing (a change) taking place.

If done right, PCM -> PWM should be a lossless operation.  Both D to A and A to D processes are lossy.  So theoretically, the signal will reach the amplification stage unchanged.  Can anyone confirm that the digital inputs are converted to PWM without an interum analog stage?

On page 10 of the TI tas5062 datasheet (the PWM processor used in the Panny), it say the following about the device inputs:

The TAS5026A has three PCM serial data interfaces to accept six channels of digital data though the SDIN1, SDIN2, SDIN3 inputs. The serial audio data is in MSB first; 2s complement format. The serial data interfaces of the TAS5026A can be configured in right justified, I2S, left-justified, or DSP modes. This interface supports 32-kHz, 44.1-kHz, 48-kHz, 88-kHz, 96-kHz, 176.4-kHz, and 192-kHz data sample rates.

The datasheet links are at the top of page 9 of this thread. Hope this helps!

[someidiot]

As you've perhaps noticed, there's a realm of positive things to say about the XR series discussed here. To be realistic, it does have at least one negative aspect (IMO) which I'll note here:

The digital inputs are not reflected onto the analogue outputs. That is, the "second room" output (and the Tape output) will not transmit an incoming signal connected to the digital inputs. Said outputs only transmit signals connected in the analogue domain. The internal Tuner is fed through those outputs, so one might assert it belongs to the analogue family. There is a digial output ...

My guess is that Panny were trying to limit the A/D D/A components to reduce cost. Perhaps there's some DRM funk going on there also?

Also, a very informal poll indicates that the vast majority of owners have XRs than run cool. I sent one back because it was running rather hot, and the replacement is running much cooler. BTW, I have never noticed the fan switch on; nobody else has mentioned it thus far.

The heat was not generated from the amplifier stage, but from the power-supply. Specifically the ~40v supply providing power to the amplifier stage. This is located rearward of center, and leftward of center when viewing from the front of the unit. Any heat generated by these components spreads radially from that location (note that the amplifiers are aligned in a row from front to back, on the opposite side).

This may be something peculiar to my environment, as it seems I alone have noted said behavior. I only mention it because I had previously noted the original had been returned for replacement.

- Kris

[JoshK]

Kris,

Do I understand you correctly that if you use the Panny XRS to say process digital inputs from, for example a DVD player, that you cannot output analog outputs (front two channels) to an external amp?  I had intended to get one of these and use it as a 2 channel pre/pro.  I guess that would work.

[someidiot]

Kris,

Do I understand you correctly that if you use the Panny XRS to say process digital inputs from, for example a DVD player, that you cannot output analog outputs (front two channels) to an external amp?  I had intended to get one of these and use it as a 2 channel pre/pro.  I guess that would work.

Josh - I had hoped to do this also (using the ZR1000 for front-channels), and was a tad disappointed that I'd have to use the analogue inputs for doing that. On reflection though, I'm personally very happy with the sound quality. And I didn't purchase the ZR1000. BTW, Panny are careful to avoid describing the unit as having a "pre-out".

Of course, I could have made a mistake somewhere.

[someidiot]

I thought it might be useful to construct a summary of various posts made thus far, such that new readers don't have to wade through 15 pages.

While attempting to be objective, this will undoubtably reflect subjectivity on my part. Also note that snipping sound-bytes from various posts fails to maintain original context. Thus, I note the page number for each quote so you can go back and get more detail yourselves. Better than nothing I suppose. Most quotes are from folks who own the Panny, and I certainly hope nobody minds me quoting them in this manner.

Had intended to categorize each post into one of pro, con, other. However,  it seemed more appropriate simply to separate into perceptions, and differences (between the xr25 and xr45).

Finally, I apologize in advance for the long post.

Perceptions:

The bass and midrange on the unit sound pretty good, but the treble was a bit on the 'harsh' side. It was not as smooth as the Sony's digital amps and it was annoying me after 1/2 hour of listening.

The soundstage was not 'smeared' and instruments were separated fairly well. Impressive for an inexpensive unit.

This isn't a giant killer by any means (IMHO), but for a resonably priced unit it does sound pretty good.

Inquiring minds wanted to know, How goes the burn-in, does the XR25S have what it takes to run with the big dogs. In one word YES. The caveat is that you have to use the digital inputs.The analogue inputs are merely very good. The cutting edge of reality is reproduced when the XR25S is fed a digital signal.

At $300.00 this is a steal of a deal

First, since there is only a 5.1 direct input on both the XR25 and XR45, only 5 amplifier channels would be usable with analog inputs. The 6th channel would be active with DD EX and DTS ES digital sources.

Regarding 24/96, I was able to play the Chesky Super Audio sampler (24/96 PCM DVD) using the digital input on my XR25. My DVD player displayed 24/96 output mode and since the TI chip set used in the XR25 supports 24/96 I would assume that all the bits were being processed. It certainly sounded as good as my DVD-Audio discs.

Owner's Manual Link

I've had a chance to break in the XR25 some more and upgrade cables as Scotty suggested. Everything is improved. Analog input is now hard to differentiate from my ICEpower amp. The direct digital input at both 44khz and 96khz sounds significantly better than analog input. This technology is really something special.

I would have to say, after listening to the fully burned in unit, with upgraded PC (per Scotty,) and go with a high quality digital IC, that the Panasonic 45, within its parameters, is pretty much state of the art, I'd say ... the little Panasonic is the one to beat in its power class, let alone its price class.

They have swizzed the power ratings to the desirous, and highly marketable, round number of 100wpc @ 6 Ohms, which I figure might be on the order of around 75-80 @ 8Ohms, which is plenty for most applications.

Volume at -20dB is more than sufficient in this enormous open-plan 14' ceiling "room" for both audio and HT. Playing LOTR last night was an education in both sound placement and dynamics (not to mention the total silence when paused).

Right now I am listening to the Hammond B3 Allstars album, which is very well produced, has alot of punch, with some serious EQ'ing on the bass, drums and organ, with the horns, synths and sisters clearly grooving in the back....brushes can be heard to move in a circular motion from the next room.

I've had an XR25 running for 3 weeks now. My ICEpower amp now powers my VMPS subwoofer (quite an improvement over the old subwoofer amp, BTW).

The power supply on the XR25 puts out quite a lot of heat at idle, around 10 watts I would guess, enough to warm up the top of the case but not trigger the fan. The case really should be ventilated.

I would go so far as to say that my current Value Audio Idea would be to get a Panasonic, --no more need for an outstanding DAC, IC's etc., and sport for the very best speakers you can afford, like some high efficiency full range floors, spending considerably more because of the dough you have just saved with this Rx.

The XR series don't have hi/mid/lo filtering. Instead they use the more simplistic large/small speaker approach, and support one of three cut-off frequencies (100, 150, 200Hz).  The fan is volume-based; not temperature triggered. Other than my feeling the case ought to be vented more effectively this is only negative thing I can say about the overall design

Listening to rhythmic music, has lots of jam, the stop and start of notes is very appealing to me, listening to the Long Beach Dub Allstars is about as jammed out as it gets, and the Panny handles it all extremely well

There is no direct input for the back amplifier channel, so only 5 discrete channels of amplification are possible. The 5.1 subwoofer input is passed through to the subwoofer line output.

What it does not do is state of the art macro-dynamics. And for $300.00 it is unrealistic to expect it to. That being said, it is a musically valid choice and a solid performer. Its control in the low frequencies is astonishing. I have also never heard it sound harsh in my setup. The size of space it can create seems limited only by the associated equipement and source material.

The XR series has most of the latest alphabet soup vis-a-vis processing if that's what you mean

I can tell you that I have tested it on very benign, efficient, 8 Ohm speakers as well as notoriously inefficient 4 Ohm speakers, and while I prefer the sound of the former, the latter seem not to produce any sort of high frequency induced fatigue. I would also say that the weak point of the unit is not response characteristics, or high frequency anomalies, but limitations brought on by the power supply being used.

...comments on success of bi-amping using party mode. I have gone back and forth once or twice between bi-amping and just using front channels, and there definitely seems to be more dynamics and speed when bi-amped.

I haven't heard any problems from my DIY speakers. They are an 8ohm load from 100Hz to 30kHz. They also have a ribbon tweeter which would certainly show up any problem in this area.

BTW, the Panny defaults all speakers to "small". If your 2-channels are full-range, don't forget to adjust the speaker size for them.

The digital inputs are not reflected onto the analogue outputs

Differences between XR25 and XR45:

There is a .4lbs weight difference between the two receivers the XR45 weighs 9.2 lbs and the XR25 is 8.8lbs. It is possible that some of that weight is in the power supply. If the XR45 was available I would get it for this reason alone.

The 45 has an additional optical input, a 'deluxe' remote, 'multi-source remaster processing'. Power ratings are the same on the highly detailed Panny website.

Reasons to upgrade to XR45:

1. better power supply.
2. 2nd zone, which provides pre-out functionality, missing from both XR25 and XR45.
3. on-screen setup, a major convenience.
4. DTS 96/24. When this format is fully deployed, this could largely replace DVD-A, which does not allow direct digital connection.
5. an additional digital input.

John Meyer from Newform Research wrote:
Panasonic has not ignored sound quality in the XR45. I know many listening tests were done during its development. In fact, the XR45 is an upgraded version of the XR25 ...

[Zero]

I only wonder how it compares to the Sony AVD S50ES

[BenF]

BenF, I haven't heard any problems from my DIY speakers. They are an 8ohm load from 100Hz to 30kHz. They also have a ribbon tweeter which would certainly show up any problem in this area. If your speakers tweeter does not have a zobel network on it the increased mid and upper frequency energy that a digital amp can deliver can make a non-zobeled tweeter sound harsh.  Most loudspeakers were not designed with the performance potential of digital amps in mind. The zobel network that should be present on every  ...

Interesting. So, if I'm too cheap to buy new speakers, do I add this network my existing old speakers? Is it hard for an inexperienced DIYfer? I have a pair of Boston A40s bookshelf speakers I was planning to use with these amps. Would it work to add this to them?

For purchasing new speakers, what should I look for? How can I tell if they have this network? I have been intrigued with the time and phase aligned speakers (Vandersteen) and liked what I heard in the 3A's and up. But... since I am looking for budget (and I mean budget) quality audio listening at home, what are some suggested low priced speakers which would work well with the new digital amps? Unfortunately budget is key; the money is going towards the children's musical education, a much better place to spend it, I think.

Thanks again. I find your posts very interesting and informative. Since you have Stan Warren's modded gear, I assume you also subscribe to the approach of budget gear modded=better way to go, so you may know what to do for us cash careful folks.

Ben

[ABEX]

I went and heard Vandies recently and was not to impressed with anything they had. It could have been the Harmon Kardan they were using for a CDP though. Anytime I hear HK in a system it sounds dark to me.

B&W's are well rounded speakers for the low end. I use speakers which not in production ,but I still can get some pairs for around $300.

You would probably want to build an HT array a piece at a time and B&W is a really good co. to do that through. Take a look at Sound and Vision and look for speakers which you can start with as Main speakers then every 6mos. be able to add  to is my sugestion with adding a sub last.

It takes awhile to get a good system together. I have worked on mine off and on for over 20yrs..    

Hunting is fun ,but can be a real chore!

[_scotty_]

BenF, This is really loudspeaker 101. You solder a resistor and a capacitor
together in series. Then solder the resistor to the positive terminal and the
capacitor to the negative terminal and you are done. The values of resistors and caps have to be calculated but if they are in the ball park it will work. I would listen first and solder only if necessary.

[ABEX]

I tried in vain to search for a DIY 2 Prong connector which I could make a better PC with. I also searched my local Ratshack,Tweeters Ect.,BB & CC and came up empty. I guess I will be ordering this one tomarrow. Thanks for the help.ANything has to better the stock piece of junk. A poster over at AA was experiencing the same HF etching problem which was experienced by someone else.

http://cgi.audiogon.com/cgi-bin/cl.pl?cablpowr&1070632047

BTW when in CC tonight I went over to their floor model and noticed it was truely hot to the touch at idle. They probably leave it on 24\7.

[JLM]

BenF:

A good inexpensive speaker to start an audio/HT system with is the Ascend Acoustics CBM-170.  Internet sales only, $160 each.  These are roughly 12 inch x 8 inch x 7 inch with 1 inch recessed soft dome and 6.5 inch aerogel woofer.  Cabinet finished in black pebbled vinyl (the worst news about these speakers, but good for frequent moves or rough environments).  Otherwise well made, comes with 1/4 inch x 20 threaded inserts for wall bracketing.  Quality of construction appears first rate.  Rated 70 - 20,000 Hz, 89 dB/w/m.  (So they will easily be driven by any known receiver, including these Pannys.)

But the sound!  It slams B&W, Dynaudio, or Paradigm at 3 times the cost.  Those sound like hi-fi (trying to be studio monitors and be flat/detailed).  The Ascends add music.  Those provide black and white sketches of the sound, the Ascends add color and display amazing imaging.  I own them and love them.  Perhaps the best retail buy I've made in 35 years.  I have no other affiliation with the company.

They also offer package deals with Hsu subs.  I have separate audio and HT systems, so the CBM-170s are in the HT system (overkill, IMO) with a Hsu VTF-25.  I only run a 2.1 HT system because we don't do HT much and didn't want the expense/look associated with 5.1 and definately didn't want the sound of typical "lifestyle" speakers.

[ABEX]

Here's a review of the Ascends.

http://www.soundstage.com/revequip/ascendacoustics_cbm170.htm

[ABEX]

I orderd the unit through J&R's because it was aprox. $9 cheaper when taking S&H into account. I do not like dealing with them because they have cost me $$ by advertising the wrong product once and another time sent me a defective item. Seems when I deal with them it always cost me more in the long run. My cousin has been doing Biz with them since the mid 70's with no probs so it's just my luck I guess.

The Adaptor I chose is at the following site. They have to send the ordering info before that goes out Friday according to their site. I will be using a Carol Cable PC at first with a Marconi(?) IEC I think it is.

One guy that posted at Madisound is going to do an A/B using a Pass Labs Amp so I guess the word is out and people shall be posting serious impressions shortly along with those already written here.

 Do not have my full array of speakers yet,but they are being worked on as we speak. Another  aspect I am really wanting to findout is weather my external DAC is better for Redbook playback than the internal DAC of the unit. Music playback is alot more important to me than the all digi SS ,but it will be great to have it for movie playback.  

Lastly I have a slew of cables I can test with the unit which I will beable to give observations on along with some others here. I just finished serious evals on cables to market and it looks like another period of evals. I was using a Passive Controller which gave me a good platform to judge what happens in the chain.   It took 3 months of off and on testing and retesting till I was satisfied with the best designs to use. The last 2 weeks I have not really wanted to do any serious listening. Here we go   again!      

Thanks for the help and I shall be giving impressions in a few weeks also.

[Jack Gilvey]

DTS 96/24. When this format is fully deployed, this could largely replace DVD-A, which does not allow direct digital connection.

 Can anyone point me toward a source for these titles available now?


 Someidiot, thanks for that summary...that must have taken a while.

[_scotty_]

Here is a useful link to a side by side listening evaluation of the XR25 and
XR45 by ssangste on the avsforum. http://www.avsforum.com/avs-vb/showthread.php?s=3badef593520d04e7b39af37c60ca236&threadid=304368&perpage=20&pagenumber=14 Scroll down to the comments by ssangste,The Home Theatre Doc. His review is a little below the mid position on the scroll bar.   He actually bought one of each of the receivers and did a comparision.  Much thanks is owed to this guy.
 I popped the top on my XR25 today and spent some time under the hood with better light. There appear to be positions on the power supply board for about 8 more caps and some kind of large inductor. This would account for the weight difference between the XR25 and XR45. The analogue input coupling caps are 47mfd 16v and are probably responsible for much of the difference heard between the analogue and the digital inputs. Changing those little caps out involves a time consuming  procedure which
most people won't wish to pay for. The blackgates would be cheap, and if only three, 2ch analogue inputs were modded the parts cost wouldn't be excessive.  A good case can be made for purchasing the XR 45 for the bigger power supply. The reasons for doing so were probably not stated strongly enough earlier in this thread.  I am not going to sell my XR 25
off and buy a XR 45 for the sonic difference however.

[ABEX]

Thnaks for the Thread Scotty!

Only one crit of the review is that he did not try another Power cord to see if that made a Difference.

As I tried to point out before Digital Switching Amps might react differently than their conterpart. It shall be intresting what I find in my listening and with my speakers.

Having good Copper Cables is a must it sounds\reads like.

Will be waitng on my unit to arrive. Glad I sprang for the 45 after reading that.

Thanks!