[AphileEarlyAdopter]

BenF,
I too think that the XR50 is the successor to XR45. It is not just the weight,  the digital inputs also can recognize 192Khz signals like the XR45. The XR25 did not have this feature.
One interesting and positive development is the THD has gone down.
It is .09% (versus .3%, almost 1/3rd of earlier value) between 20 - 20Khz.  The power envelope is now rated at 4-88Khz at -3db. This rating was not provided with the earlier versions (Xr25/45). This means, that the new versions have a different chipset and the ratings probably came with the new chipsets incorporated in them.
Please note, that -3db at 4Khz is a very impressive figure. Many, even audiophile amps do not come this close. I am expecting the bass to be much tighter/extended).
One thing, I do not understand though is distortion is specified as .9% when the power envelope is specified (and it is same as in previous versions).

Beatles, how does the xr50 compare against the xr45 ? It is quite possible that the xr10 has better parts but probably not better specs/technology. Sometimes, better technology might not necessarily translate to better perceived sound. Still, the newer versions, I expect, would reasonably work well, across a broader range of speakers.

[azryan]

I wouldn't trust Panasonic's 'official' specs in the manual.

These mass market companies are known for fudging the numbers to make things look the way they want them to.

Maybe they just tested the new units a diff. way to get a better dist. rating.
Far from the first time that happened.

I know the new Sony digital Recs had diff. dist. rating in their manuals than posted online at Sony's web page. Then I think J&R.co, had a diff. dist. rating.
Crutchfield I know had a diff. one.

None of it matters compared to actually hearing the units and actually opening them up ad SEEing what's diff. and what's the same.

[Beatles]

I wouldn't trust Panasonic's 'official' specs in the manual.

These mass market companies are known for fudging the numbers to make things look the way they want them to.

Maybe they just tested the new units a diff. way to get a better dist. rating.
Far from the first time that happened.

I know the new Sony digital Recs had diff. dist. rating in their manuals than posted online at Sony's web page. Then I think J&R.co, had a diff. dist. rating.
Crutchfield I know had a diff. one.

None of it mat ...

Leave us not forget that specs don't mean shit in terms of sound quality. WAY too many of you are spec obsessed here. Most people I know grew out of that in the 70s.

[Grayson73]

Beatles,

Can you comment on the SA-XR25, SA-XR45, SA-XR50, and SA-XR70 in terms of sound quality?  How would you rank them?

On another note, Circuit City has the SA-XR25S on clearance for under $140.  I bought an open box for $129.99.

[Beatles]

Beatles,

Can you comment on the SA-XR25, SA-XR45, SA-XR50, and SA-XR70 in terms of sound quality?  How would you rank them?

On another note, Circuit City has the SA-XR25S on clearance for under $140.  I bought an open box for $129.99.

I haven't heard the 70 yet but the 50 is a disappointment. I'd rank them XR10,XR45,XR25,XR50. From finest to worst.

[AphileEarlyAdopter]

Beatles,
Have you accounted for the 'breakin' time on the new xr50 ?
It has much more features than xr25, viz, ability to handle different sampling rates - 44.1, 96Khz, 192Khz, remastering etc
Previously these were available only in xr45.
So I am assuming that its performance should be equivalent to xr45. If that is not the case, then there must have been some cost-cutting with inferior components for a lower MSRP. The xr70 is still $399, hopefully, it does not perform below the the xr45.

[Grayson73]

I haven't heard the 70 yet but the 50 is a disappointment. I'd rank them XR10,XR45,XR25,XR50. From finest to worst.

Hmm,..I compared the XR50 and XR25 last night and thought the XR50 was better.  I haven't compared to the XR45, but would imagine that the XR50 was equal to or better since it supposedly has a newer chip.

Can you ask your engineer at Panasonic to see how he would rank them?

[Grayson73]

From the manual:

Multi-source re-master
This original feature boosts the frequencies of the higher harmonics that
are lost during recording due to compression.
When Re-master is on, the current level appears.
EFFECT 1: For fast tracks (pop and rock)
EFFECT 2: For tracks with a variety of tempos (jazz)
EFFECT 3: For slow tracks (classical)
EFFECT 4: For compressed audio signals
OFF: The re-master processing is off.

Seems to work on pretty much anything.  On older redbook CDs it is very noticeab ...

Have you tried effect 4 yet?  Which effect sounded best for you for TV watching?

I just got mine last night and was trying to see whether 'off' was the best or having the effects on.

Also, have you found a good use for the 'Bass Enhancer'?

[groovetube66]

To be honest I haven't used the bass expander.  This evening I'll try it with a Robert Johnson CD of his recordings from the 20's.  Seems like a good test as those recordings are primitive and trebly.

I seem to like Remaster 2 the best for most things.  I am wondering if Remaster 4 might be good for playing records as it says it is for sources with compressed dynamic range?  I don't have my Thorens hooked up as I need a phono preamp.  I also wonder if Remaster 4 could be tweaked via firmware hack to provide more dynamic range expansion (turned into an LP mode) such that I wouldn't need my DBX 3BX anymore.

[Wayne1]

Yesterday I received a SA-XR50. It was sent to me by a customer to evaluate for mods.

It is similar to the previous generation but there are a few differences.

First off, there is now relay switching in the main speaker signal path. This will add yet another mechanical connection.

The power supply is very close to the one used is the SA-XR25. There are blank spaces on the board for more parts to be added for the SA-XR70. What these parts are for, I do not know as I do not have the service manual. In any case, the PS board does not have as much power supply capacitve filtering as does the SA-XR45.

The SA-XR25 and 45 use 3) TI TAS5182X1 chips in the audio section to supply the switching mosfets. The SA-XR50 only uses 2 of the TI TAS5182 chips. For the front channels there are quite a few small chips and surface mounted components in place of a single TAS5182.  The switching mosfets are the same in all channels as are the output filters.

I have taken pictures of the boards and I will try to find time to post them later on. I have not hooked up the SA-XR50 to any speakers at this time.

[Grayson73]

Yesterday I received a SA-XR50. It was sent to me by a customer to evaluate for mods.

It is similar to the previous generation but there are a few differences.

First off, there is now relay switching in the main speaker signal path. This will add yet another mechanical connection.

The power supply is very close to the one used is the SA-XR25. There are blank spaces on the board for more parts to be added for the SA-XR70. What these parts are for, I do not know as I do not have the service manual. I ...

Thanks for the post, Wayne!  After you have a chance to listen to it and fiddle with it, let us know how this compares to the XR25 and XR45.

Based on what you see on the board, are you able to deduce how the XR50 compares to the XR25 and XR45?

[AphileEarlyAdopter]

"there is now relay switching in the main speaker signal path"

Maybe to make this foolproof, so that if people short the output leads..no damage occurs..tihs is probably a needed feature for a mass-market product. Surely, this can be bypassed ..Business opportunity, Wayne

"In any case, the PS board does not have as much power supply capacitve filtering as does the SA-XR45" Another business opportunity

"For the front channels there are quite a few small chips and surface mounted components in place of a single TAS5182."
This could be a good thing right ? Please let us know after you give it a listen. There are scores of people waiting to buy the SA-XR50 and many would like it to be modded (atleast me). The main thing is , SA-Xr50 has so many features of the xr45 - 96KHz, 192Khz input, remastering etc.  and above all it is now rated for power at -3db at 4Hz. So, we need to see how it fares in the bass compared to its predecessors. BTW, are the chipsets different  TAS5182X1  vs TAS5182 ?

[Grayson73]

The SA-XR25 and 45 use 3) TI TAS5182X1 chips in the audio section to supply the switching mosfets. The SA-XR50 only uses 2 of the TI TAS5182 chips. For the front channels there are quite a few small chips and surface mounted components in place of a single TAS5182. The switching mosfets are the same in all channels as are the output filters.

Since the XR25 and XR45 have the same chip, why does the XR45 sound better?

I found this article on TAS5182

I couldn't find any information on TAS5182X1

[Wayne1]

Since the XR25 and XR45 have the same chip, why does the XR45 sound better?

There is far more to the sound of a reciever than just the controller chips.

The SA-XR45 uses a far more sophisticated power supply for the output section. The volume control is also implemented differently.

The switching relays in the SA-XR50 are to turn on and off the A & B main speakers. The TAS5182 chips already have short circuit and over current protection built into them.

There is no room on the circuit board for any additional PS caps to be added.

[Richard U]

Grayson 73-

Nice article! If I read it correctly, doesn't it mean that for 100 watts for six channels it would need 3 TAS5182s?

Wayne,

Would we be better to try and get a 25 for modding? If not modding, the 50 over the 25?

Thanks

Richard

[Grayson73]

There is far more to the sound of a reciever than just the controller chips.

The SA-XR45 uses a far more sophisticated power supply for the output section. The volume control is also implemented differently.

The switching relays in the SA-XR50 are to turn on and off the A & B main speakers. The TAS5182 chips already have short circuit and over current protection built into them.

There is no room on the circuit board for any additional PS caps to be added.

So theoretically, the XR45 should sound better than the XR50 because it has a better power supply?

I look forward to your real world tests!

[AphileEarlyAdopter]

Wayne,
I still suspect that not using a 5182 for the front channels, is really for reasons of quality.  5182 is a power stage controller, maybe having all the channels in one chip would lead to interference.
BTW, what is the PWM chip in the Xr25 and XR45 ? Looks like the one in XR50 is the TAS5076 which can accept upto 192Khz.
Switching power supplies may not be great, but if implemented well, they are good. They are used even high priced equipment like the Halcro preamps.  Probably some isolation with ERS cloth will help (?) apart from the other mods  you are doing. Also, I think a balanced power conditioner or an isolation transformer will help these switching power supplies. My philips 963sa sounds noticeably different in the dynamics department based on whether it is connected to the wall or the Monster power conditioner.
BTW, how is volume control implemented in the panasonics ? Looks like the PWM chip has volume control. Is it done by controlling the height (voltage) of the PWM output ?

[dwk]

Wayne,
I still suspect that not using a 5182 for the front channels, is really for reasons of quality.  5182 is a power stage controller, maybe having all the channels in one chip would lead to interference.
BTW, what is the PWM chip in the Xr25 and XR45 ? Looks like the one in XR50 is the TAS5076 which can accept upto 192Khz.

Ahhh, are you sure the 5076 is used in the XR50, or just guessing?  The main difference between the 5012 which is used in the 25/45 and the 5076 is that the 5076 has a some level of control over the output bridge timings that can be altered via microcontroller programming - these timing parameters are fixed in the 5012.  This allows optimizing the performance of one or two channels at the expense of the remaining channels.  I suspect that using a different driver arrangement rather than the 5182 is to take better advantage of the programmable timings.

BTW, how is volume control implemented in the panasonics ? Looks like the PWM chip has volume control. Is it done by controlling the height (voltage) of the PWM output ?

It's done differently in different units, and is the main difference between the 25 and 45 (I though this had all been covered before....).   The XR10 and XR45 appear to have variable-output switch-mode supplies, which provide about ~20dB of level control. These units reduce volume by lowering the output voltage of the PS.  Once the PS is at it's lowest output, the units then use digital attenuation on the input word to achieve volume control.  On the 25, there is only a fixed power supply, so all volume control is done in the digital domain.[/code]

[armstrg3]

Interesting !  One "audiophile" thinks the XR10 is best and another ranks the XR45 #1.  Can someone now define or qualify "audiophile"?

[Wayne1]

The SA-XR50 does use the TAS5076.

The SA-XR45 uses the TAS5036A not the 5012. I do not know for certain what the SA-XR25 or 10 uses.