[Nuance]

Bryan -

I understand modding the analog outputs as they are probably not very good.  But what is gained modding the digital outs?  Does the mod involve replacing the internal digital clock? 

Further, when using digital outs and feeding an outboard DAC, I do not understand how a power supply change could possibly improve the sound. 

Two years ago at RMAF, a guy selling "high-end" power supplies for the Squeezebox gave me one to try out. I was using the digital out to feed an AVA DAC.  I couldn't hear any difference at all - nothing.  Then again, admittedly, that is the result I was expecting.

On that topic at least, a blind test is in order.

- Jim

Based on Wayne from Boulder Cables recommendation I picked up a better power supply for my Squeezebox duet.  At the time I was using its analog connections, and there was certainly an improvement with the new power supply (linear).  However, when I switched to digital those differences went away, at least to my ears.  And now that I am running through a DAC, its probably not necessary; I'll still use it, though.

So yeah, I guess my experience matches yours.

When I added $30 linear power supply to my SB Duet, I heard an incredible sonic improvement, was one of the best tweaks ever for my setup-FWIW

Was it the black and red one from parts express?  That's the one I am talking about; great improvement if using analog connections, but not so much when I used the digital output to my DAC. 

[Nuance]

I think its safe to say werd is just trolling.  Lets just ignore him, as we're just feeding his silly agenda.

[eclein]

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=120-536%20%20%20%20%20%20%20%20&FTR=120-536&CFID=24256478&CFTOKEN=42329450
 This little baby^

[bpape]

The power supply improvements are there whether using the modded analog outs or the digital out to an external DAC.

Bryan

[jsalk]

OK, I'll have to give it a try.

- Jim

[Mudslide]

Bryan -

I understand modding the analog outputs as they are probably not very good.  But what is gained modding the digital outs?  Does the mod involve replacing the internal digital clock? 

Further, when using digital outs and feeding an outboard DAC, I do not understand how a power supply change could possibly improve the sound. 

Two years ago at RMAF, a guy selling "high-end" power supplies for the Squeezebox gave me one to try out. I was using the digital out to feed an AVA DAC.  I couldn't hear any difference at all - nothing.  Then again, admittedly, that is the result I was expecting.

On that topic at least, a blind test is in order.

- Jim

In the for-what-it's-worth category....

My audio pal and I ran a blind A/B test on a $5 Sears yard sale cdp against an expensive, highly modded and well respected JVC XLZ1050.  We don't have the "golden ears" that many claim to possess, but except for a small amplitude increase in favor of the JVC (and once level matched), a difference could not be determined.  We even swapped speakers, just for the fun of it...no change in results.  YMMV.

[cacophony777]

Thanks, this has been an informative thread!

I'm still a bit unclear on the reason for quality differences in preamp/amp assuming the goal is accuracy? Do the better amps just have a slightly flatter frequency response? Or is there something else going on?

[jsalk]

Thanks, this has been an informative thread!

I'm still a bit unclear on the reason for quality differences in preamp/amp assuming the goal is accuracy? Do the better amps just have a slightly flatter frequency response? Or is there something else going on?

Flat frequency response is not normally the difference.  Almost all amps and receiver amplifier sections exhibit decent frequency response. 

There are quite a few other variables involved, probably the most important of which is the power supply.  A quality dedicated amp will almost always have a very robust power supply compared to that in a moderately-priced receiver.  (This is the main reason they are so heavy.)

A given amplifier circuit is capable of delivering a given number of watts of power to its output.  But it can only do so if the power supply can provide the requisite power.  The larger transformers and capacitors normally found in a good amp will provide plenty of power in reserve to meet the needs of the amplifier circuit. In addition, these power supplies are generally better filtered to reduce ripple.

This is one reason good amps are generally more expensive.  High quality, high capacity parts are not cheap.

Another factor is headroom.  There was a test done at RMAF a few years ago by Peter Smith that showed an "average" speaker being driven by an average of 8 watts of power (which is quite normal).  At the same time, a peak-reading meter showed that transient peaks (drum strikes and the like) in the program material were drawing as much as 250 watts or more.

In this case, to keep things pristine, you would need an amp capable of putting out 250 watts with a power supply that was capable of delivering that power when needed.  Any amp under 250 watts would clip during those transients producing distortion.  In this case, a 100 watt amp would clip more than a 150 watt amp and, thus, exhibit higher distortion levels.

If you have ever listened to a low power amp at a moderate volume and felt compelled to turn it down because it seemed too loud, it was probably not all that loud.  It was more likely that the amplifier was clipping and distortion levels were too high.  People often associate clipping-related distortion with excessive volume. 

If you are not used to having clean power and speakers that can handle high SPL's with minimal distortion, you will end up playing the system far louder than you think you are because you will not be getting the distortion cues that would normally result in having to turn the system down.  You will likely be listening at levels much higher than you think you are.

So, factors that separate a great amp from a moderate receiver amplifier section include (but are not limited to) 1) a cleaner power supply; 2) a power supply with plenty of power in reserve to handle transients; and, 3) enough output to provide the required power for the system with minimal or no clipping.

This is somewhat simplified, but hopefully it will help.

- Jim

[billmcc]

Another factor is headroom.  There was a test done at RMAF a few years ago by Peter Smith that showed an "average" speaker being driven by an average of 8 watts of power (which is quite normal).  At the same time, a peak-reading meter showed that transient peaks (drum strikes and the like) in the program material were drawing as much as 250 watts or more.

Jim,

Was the test done at RMAF in a large room at higher volumes? I ask as I will be using a Boston Acoustics A7200 amp (Sherwood Newcastle A-965 clone) to drive my SongTowers. My room is fairly small at 14' deep and 17' wide with an opening to another room on one side. The A7200 is rated at 100x7 @ 8 ohms which from what I have read is a conservative rating. I do like to listen to music at fairly high volumes (nothing crazy though ) and I am wondering if that is enough power for driving the STs?

http://www.sherwoodusa.com/prod_a965.html

Thanks for the very informative post on amp power. It was very helpful and was well explained for the non technical (that would be me ).

Bill

[newzooreview]

Jim,

Was the test done at RMAF in a large room at higher volumes? I ask as I will be using a Boston Acoustics A7200 amp (Sherwood Newcastle A-965 clone) to drive my SongTowers. My room is fairly small at 14' deep and 17' wide with an opening to another room on one side. The A7200 is rated at 100x7 @ 8 ohms which from what I have read is a conservative rating. I do like to listen to music at fairly high volumes (nothing crazy though ) and I am wondering if that is enough power for driving the STs?

http://www.sherwoodusa.com/prod_a965.html

Thanks for the very informative post on amp power. It was very helpful and was well explained for the non technical (that would be me ).

Bill

Good lord, yes. That amp should have no problem with the SongTowers (unless Sherwood is playing games with their power ratings). The SongTowers sound glorious with a 35 watt tube amp (a well designed one, at least).

For more good background on amplifier power ratings read through the Frank Van Alstine newsletter article on amplifer wattage measurements: http://avahifi.com/index.php?option=com_content&view=article&id=191&Itemid=181

He writes in more detail about the topic in the back issues of his newsletters as well. Very enlightening. 

[Nuance]

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=120-536%20%20%20%20%20%20%20%20&FTR=120-536&CFID=24256478&CFTOKEN=42329450
 This little baby^

Yup, that's the one.  It made a noticeable difference when using the analogs, but I struggled to hear any using the coax digital.  I'll give it another try, as I have upgraded other gear since then.  I am not expecting much, though.

[Elizabeth]

1) the room is nearly always  the only room you got. period. Fiddling with the room is cool if your into that stuff. My preference is to use the other stuff  already in the room as the modifying influence. (the junk they sell as room stuff looks like canned ca ca IMO)
2) the argument about DAC and cheap or expensive transports should be in another thread, NOT this one)
3) IMO: the percentage of cost allocation changes at different price points. (An idea not mentioned prior,  in this set of posts)
IMO: at LOW ($500 total to $5000 total price point MOST of the money should be spent on speakers, that is more than one-half of all money just for speakers.
At a higher value total spent the speaker portion should start dropping, and the electronics should be more of the total.
As for the folks who are in this 'for real', they spend differently than newbies, because they KNOW WHAT THEY WANT.
Thses percentages are for newbies. Everyone else does whatever the hell they want based on personal equipment biases.
Many of the arguements are from folks who have personal preferences and have had a LONG time to develop them.
I used to have $3000 speakers with $1,500  total amp.preamp then about the same $1,500 for all sources. So the 50/50 of speaker to all else was what I owned. this was back in 1985. (It was about the same 50/50 for me back in 1965 when I bought my FIRST hi end stereo, with JBL speakers, and a Fischer amp)
Today I have $5,000 speakers, and a $4,500 amp, a $4,000 preamp, and $10,000 LP sources, and about $7,000 CD source playback, with another $5K in power conditioning.
So you can see my speaker portion has plummeted!
=================================================
BUT any other combination is possible for a wise and well educated audiophile.
=================================================
So ARGUING about what is the right amount to spend, for a well educated audiophile who has been in audio for a long time and knows what the want.. is hogwash all around. IMO.
Some folks spend a fortune on one area, some other in another, and they both have good systems, just different, with different priorities.
For newbies, it makes sense to try and allocate the funds.
The one thing I would avoid as a newbie: no money in budget for any afteermarket cables. , no aftermarket powercords. Buy only cheap cables if any. Mogami, or Kimber PBJ, ir BlueJeans, or other cheap cables. Save your money for the electronics and speakers.

[jsalk]

Bill -

You should have no problem with that amp driving SongTowers.  Their impedance is lower than 8 ohms (averages about 6 ohms), so they will draw more than 100 watts per channel.  You will probably be listening at an average of about 5 - 8 watts of power.  You may have occassional transients that exceed 100 watts, but it will normally be with respect to  percusive events (drum hits for example) that will mask most clipping.  You should have no problem.

- Jim

[cacophony777]

Thanks for the explanation Jim, it was very helpful!

[werd]

I think its safe to say werd is just trolling.  Lets just ignore him, as we're just feeding his silly agenda.

http://www.ihasaids.com/upload/data/1276610097.gif

[Napalm]

There is enough error correction built into any CD transport to almost eliminate data errors.  If this were not the case, computers would not be able to run properly as software is often distributed on CD's and bit-for-bit accuracy is mandatory (computer transports are not normally high-end either). 

Not really. A CD sector is 2,352 bytes.

For data CDs, this is split in 12 bytes sync, 4 bytes sector id, 2,048 bytes real data, 4 bytes error detection, 8 bytes zero and 276 bytes of error correcting code.

For audio CDs, all the 2,352 bytes are used for real (audio) data with no ECC. If there are errors there's no level 3 ECC to help correct them.

Nap.

[Napalm]

I think its safe to say werd is just trolling.

Yes.

Nap. 

[jsalk]

Not really. A CD sector is 2,352 bytes.

For data CDs, this is split in 12 bytes sync, 4 bytes sector id, 2,048 bytes real data, 4 bytes error detection, 8 bytes zero and 276 bytes of error correcting code.

For audio CDs, all the 2,352 bytes are used for real (audio) data with no ECC. If there are errors there's no level 3 ECC to help correct them.

Nap.

CIRC error detection and correction is an integral part of the Redbook audio CD standard.  But your point is well taken.  The error detection and correction is not the same.

- Jim

[jsalk]

OK.  Some posters seem to feel that a high quality power supply on a squeezebox can improve the resulting sound quality of the digital output when fed to an outboard DAC.

I have been thinking about conducting a blind test to determine if this is the case.  (I would imagine that it could have a postive impact on the analog outputs and we can test that too.)

Here is a possible setup for the test:

Frank's AVA Vision DAC has a pair of coax digital inputs and you can switch between them.  If we set up two identical SB units, one with the supplied power supply and one with an "improved" power supply (or even a battery power supply), we can sync the SB's and run each to a separate input on the Vision DAC.

Someone who would not be involved in the listening test could flip a coin to determine which of the SB's would be connected to which input.  Then a cloth of some sort could be placed over the wiring so no one would be able to see which SB was connected to which input.  That way, no one participating in the listening test would know which was which.

Switching back and forth between the inputs while listening to various musical selections would allow listeners to judge whether they were able to hear any difference between the two and which, if either, was superior.

Does this sound like a reasonable approach?  If so, what upgraded power supply should be used to maximize any potential difference?

We could do a similar test with the analog outputs by simply running the SB outputs to two inputs on the preamp.

- Jim

[Big Red Machine]

OK.  Some posters seem to feel that a high quality power supply on a squeezebox can improve the resulting sound quality of the digital output when fed to an outboard DAC.

I have been thinking about conducting a blind test to determine if this is the case.  (I would imagine that it could have a postive impact on the analog outputs and we can test that too.)

Here is a possible setup for the test:

Frank's AVA Vision DAC has a pair of coax digital inputs and you can switch between them.  If we set up two identical SB units, one with the supplied power supply and one with an "improved" power supply (or even a battery power supply), we can sync the SB's and run each to a separate input on the Vision DAC.

Someone who would not be involved in the listening test could flip a coin to determine which of the SB's would be connected to which input.  Then a cloth of some sort could be placed over the wiring so no one would be able to see which SB was connected to which input.  That way, no one participating in the listening test would know which was which.

Switching back and forth between the inputs while listening to various musical selections would allow listeners to judge whether they were able to hear any difference between the two and which, if either, was superior.

Does this sound like a reasonable approach?  If so, what upgraded power supply should be used to maximize any potential difference?

We could do a similar test with the analog outputs by simply running the SB outputs to two inputs on the preamp.

- Jim

Use my Elpac WM220.