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View Full Version : switching vs. linear - on a scope



Music Machine
2005-09-25, 21:40
Wayne of Boulder posted pics of the PS output over on audiocircle. The pics speak for themselves.

http://www.audiocircle.com/circles/viewtopic.php?t=21808&sid=ba4c86cccaa383a636eb041ee106b9f7

Regards,
Music Machine

dean
2005-09-25, 22:05
I'd be interested to know the scale (both time and amplitude) of that
signal and where it was measured.

Also, it might be interesting to know if any measurable difference
was found on either the analog or digital outputs. :)

On Sep 25, 2005, at 9:40 PM, Music Machine wrote:

>
> Wayne of Boulder posted pics of the PS output over on audiocircle.
> The
> pics speak for themselves.
>
> http://www.audiocircle.com/circles/viewtopic.php?
> t=21808&sid=ba4c86cccaa383a636eb041ee106b9f7
>
> Regards,
> Music Machine
>
>
> --
> Music Machine
>

Music Machine
2005-09-25, 22:58
Yes, time and amplitude are missing. Apparently it's "taken from the 5 volt line feeding the DAC."

Would probably be difficult or impossible to see any output variance with a music signal. Since when do audiophiles care about that. ;)

Regards

seanadams
2005-09-25, 23:06
Wayne of Boulder posted pics of the PS output over on audiocircle. The pics speak for themselves.

http://www.audiocircle.com/circles/viewtopic.php?t=21808&sid=ba4c86cccaa383a636eb041ee106b9f7

Regards,
Music Machine

When I post measurements, I usually include photos or at least a description of the test setup, so that others can reproduce my results. Also my x and y axes are usually labelled. Most of all, where was the scope's ground lead, and at what point were these measured?

These pics suggest that some very straightforward measurements, posted here by myself and others, showing no difference between linear/SMPS for the input supply, are wrong. It would be helpful to know something about how these were measured.

Fifer
2005-09-26, 00:25
Without time-base and amplitude-range settings for the scope, this tells us very little. I assume (and hope) that the settings were the same for both pictures.

Dave D
2005-09-26, 04:42
Most of all, where was the scope's ground lead

Absolutely, and how _long_ is the ground lead, how are signal and ground attached to the probe, the type of probe, including loading, etc., the type of scope and front end amp.

Ringing (which you see in the photo) can appear to be very different from one measurement to the next, depending on the test equipment (mainly probes and probing technique.) The digital supply output could be exciting a resonance in the test setup. I'm assuming that the damping ringing pulses are occurring at the switching rate. (Need some scales.)

You might also check to see if this appears on more than one squeezebox. Maybe you got a bad one.

- Dave

Wayne1
2005-09-26, 07:37
I posted the photos on AudioCircle. Most of the folks there are not as technically minded as the people here.

The 'scope is a Tektronics 475. The probe is a TEK P6109

The settings were .5 volts per division and the time base was .5 u sec.

The points measured were across C61. The photos were of the same points and same settings with two different power supplies.

The SB2 under test was stock that arrived last week from Slim Devices and worked just fine.

Robin Bowes
2005-09-26, 07:50
Wayne1 wrote:
> I posted the photos on AudioCircle. Most of the folks there are not as
> technically minded as the people here.

Ah, you mean they're audiophiles? ;)

R.
--
http://robinbowes.com

If a man speaks in a forest,
and his wife's not there,
is he still wrong?

seanadams
2005-09-26, 09:54
I posted the photos on AudioCircle. Most of the folks there are not as technically minded as the people here.

The 'scope is a Tektronics 475. The probe is a TEK P6109

The settings were .5 volts per division and the time base was .5 u sec.

The points measured were across C61. The photos were of the same points and same settings with two different power supplies.

The SB2 under test was stock that arrived last week from Slim Devices and worked just fine.

What you're measuring is noise coupled onto your probe from the digital side (which _will_ be quieter with a linear supply).

If you measure right across C61 with better/shorter leads, you will not see a significant difference.

max.spicer
2005-09-26, 09:59
Please make sure that some of this conversation is mirrored on AudioCircle! I hate to see my favourite toy dissed. ;-)

Max


What you're measuring is noise coupled onto your probe from the digital side (which _will_ be quieter with a linear supply).

If you measure right across C61 with better/shorter leads, you will not see a significant difference.

Wayne1
2005-09-26, 10:15
Max,

I am in NO WAY dissing the SB2.

I am very impressed with what Slim Devices has come up with.

I CAN hear a difference between the stock switcher and a linear supply. I decided to take a look at the power lines with my 'scope yesterday to see if I could see a difference that could explain what I hear.

Please note that I am saying "A" linear supply. This can be a surplus supply that can be purchased for $18.00 or a battery.

Sean,

Thank you for pointing out exactly what the pictures show. I WILL post your comments on AC.

Music Machine
2005-09-26, 11:02
The SB2 is my favorite toy too! I'm completely pleased with my purchase, and would recommend SB2 to anyone that has a network and a stereo. I think the SMPS included with SB2 is a good choice, adds value, works well. A good linear supply would add too much too the price. For those that want to push performance, and are willing to pay for it, the PS is a logical starting point, (an audiophool no-brainer).

Regards,
Music Machine

seanadams
2005-09-26, 11:16
Here are my own measurements. I still disagree with the idea that the DAC's performance can be audibly improved by changing the external supply.

http://www.seanadams.com/smps_vs_linear/

Remember - "ground" is where carrots and potatoes grow. :)

Wayne1
2005-09-26, 11:54
Here are my own measurements. I still disagree with the idea that the DAC's performance can be audibly improved by changing the external supply.

http://www.seanadams.com/smps_vs_linear/

Remember - "ground" is where carrots and potatoes grow. :)

I am hosting a get together next Saturday evening at a local "audiophile's" house. This is in conjunction with the Rocky Mountain Audio Fest. Anyone who will be in the area of Denver is welcome to attend.

I will have a stock SB2 and various modded ones. I will also have the stock switcher and a couple of linear power supplies.

Please let your own ears decide.

The system used for playback will consist of:

Meadowlark Audio Blue Heron 2 speakers http://www.meadowlarkaudio.com/bh2.htm
R. E. Designs LNPA 150 mono block amplifiers http://www.redesignsaudio.com/LNPA150.html
Source will be the SB2 in various forms. There will be wired and wireless versions there.

I will also have a modded Panasonic SA-XR70 to use to try the digital outs of the SB2 and to see if there is any difference with power supplies or digital cables.

Please contact me through PM for details.

topster
2005-09-26, 13:02
Hi,

One thing that hasn't been mentioned (maybe it has and I missed it, but...) is whether the noise generated from the SMPS could be polluting the power lines for OTHER components.

It might be interesting to see if there is still an audible difference in changing power supplies if the SMPS is fully isolated from the other components.

Just a thought.

Wayne1
2005-09-26, 14:10
topster,

The first time I compared the switching PS to a linear, both were plugged into a BPT balanced power conditioner. The BPT 4 has multiple transformers inside to isolate each source component. The amps were plugged into a separate BPT conditioner.

I heard a difference between the switcher and the linear even with this degree of isolation.

YMMV

Music Machine
2005-09-26, 14:20
Hi,

One thing that hasn't been mentioned (maybe it has and I missed it, but...) is whether the noise generated from the SMPS could be polluting the power lines for OTHER components.

It might be interesting to see if there is still an audible difference in changing power supplies if the SMPS is fully isolated from the other components.

Just a thought.

There may not be any way to completely isolate the switcher. The optical connection would help, but some people don't like those.

I plug the SB2 into a power conditioner, the Jon Risch diy design followed by the SQ&D iso trans. With a surplus linear supply I'm using I notice an improvement from top to bottom. I suppose most people wouldn't notice, or care. If you have upgraded cables, ever treated a cd, used vibration isolation devices, etc. and could hear any difference, then you should try a linear.

Regards,
Music Machine

Hiroyuki
2005-09-30, 09:41
Wayne1,

Are you still hosting the gathering? I know somebody who wants to
attend the event but your PM doesn't seem to work. Thank you.

Best,

Hiroyuki
On Sep 26, 2005, at 2:54 PM, Wayne1 wrote:

>
> seanadams Wrote:
>
>> Here are my own measurements. I still disagree with the idea that the
>> DAC's performance can be audibly improved by changing the external
>> supply.
>>
>> http://www.seanadams.com/smps_vs_linear/
>>
>> Remember - "ground" is where carrots and potatoes grow. :)
>>
>
> I am hosting a get together next Saturday evening at a local
> "audiophile's" house. This is in conjunction with the Rocky Mountain
> Audio Fest. Anyone who will be in the area of Denver is welcome to
> attend.
>
> I will have a stock SB2 and various modded ones. I will also have the
> stock switcher and a couple of linear power supplies.
>
> Please let your own ears decide.
>
> The system used for playback will consist of:
>
> Meadowlark Audio Blue Heron 2 speakers
> http://www.meadowlarkaudio.com/bh2.htm
> R. E. Designs LNPA 150 mono block amplifiers
> http://www.redesignsaudio.com/LNPA150.html
> Source will be the SB2 in various forms. There will be wired and
> wireless versions there.
>
> I will also have a modded Panasonic SA-XR70 to use to try the digital
> outs of the SB2 and to see if there is any difference with power
> supplies or digital cables.
>
> Please contact me through PM for details.
>
>
> --
> Wayne1
>

Wayne1
2005-09-30, 10:44
Hiroyuki,

The gathering is still on.

I am not sure about the PM system here.

I can be reached at boldercable (at) comcast (dot) net

It will start about 6 pm tomorrow night.

I will also be at the Great Divide Lounge for the meet and greet this afternoon at RMAF. Just look around for the Audio Circle group.

Hiroyuki
2005-09-30, 10:50
Wayne1,

Thank you Wayne1. I emailed my friend and he should contact you. I
wish I could attend too... Please report us the findings. Good luck!

Best,

Hiroyuki
On Sep 30, 2005, at 1:44 PM, Wayne1 wrote:

> Hiroyuki,
>
> The gathering is still on.
>
> I am not sure about the PM system here.
>
> I can be reached at boldercable (at) comcast (dot) net
>
> It will start about 6 pm tomorrow night.
>
> I will also be at the Great Divide Lounge for the meet and great this
> afternoon at RMAF. Just look around for the Audio Circle group.
>
>
>

Rupert Dacat
2005-10-10, 20:16
Hi Wayne, and others who might have been there. Anything interesting to report from the gathering that was to take place during RMAF, and which is described more fully below?



I am hosting a get together next Saturday evening at a local "audiophile's" house. This is in conjunction with the Rocky Mountain Audio Fest. Anyone who will be in the area of Denver is welcome to attend.

I will have a stock SB2 and various modded ones. I will also have the stock switcher and a couple of linear power supplies.

Please let your own ears decide.

The system used for playback will consist of:

Meadowlark Audio Blue Heron 2 speakers http://www.meadowlarkaudio.com/bh2.htm
R. E. Designs LNPA 150 mono block amplifiers http://www.redesignsaudio.com/LNPA150.html
Source will be the SB2 in various forms. There will be wired and wireless versions there.

I will also have a modded Panasonic SA-XR70 to use to try the digital outs of the SB2 and to see if there is any difference with power supplies or digital cables.

Please contact me through PM for details.

Wayne1
2005-10-11, 10:54
Rupert,

We had a few folks stop by for the listening session. There were some fairly obvious differences between the stock power supply and the one I build. There were also audible differences between the stock and modded SB2 using digital out to a modded Panny SA-XR70.

I felt the best sound was from the analog outs from a modded SB2 direct to the amps. There are some comments about the session on Audio Circle.

There is also a post on Audio Asylum PC- Audio section that I find rewarding. The person was thinking of selling his SB2 because he felt the sound was "too digital"
http://db.audioasylum.com/cgi/m.mpl?forum=pcaudio&n=6743&highlight=SB2&r=&session=

He bought one of the power supplies I make and then posted this:
http://www.audioasylum.com/forums/pcaudio/messages/7098.html

Davey
2005-10-11, 21:18
Max,

I am in NO WAY dissing the SB2.



Well, you could have fooled me. :)

Am I the only one that thinks it's pretty slimy for Wayne to pop into Sean's forum and tout his "upgrades?"

Sean, maybe you and Wayne have talked privately about this and have an understanding....if not I admire your restraint. Or maybe I'm just hyper-sensitive to this kind of thing?

Cheers,

Davey.

mac
2005-10-11, 22:07
Well, you could have fooled me. :)

Am I the only one that thinks it's pretty slimy for Wayne to pop into Sean's forum and tout his "upgrades?"

Sean, maybe you and Wayne have talked privately about this and have an understanding....if not I admire your restraint. Or maybe I'm just hyper-sensitive to this kind of thing?

Cheers,

Davey.I agree. His unsolicited infomercials are growing old.

seanadams
2005-10-11, 22:20
Wayne is a great guy from my experience. He's passionate about audio and loves his Squeezebox.

I am never going to argue with anyone about what they can or can't hear. I've never heard a stereo system that could reproduce the sound of, for example, a tuning fork two inches from my ear. It is 100% obvious to me that we're not there yet, As such I am quite open minded about any improvements that can get us closer to perfect sound reproduction.

However, if you want to step from the realm of "I can hear it" to "I can measure it" then we will fire back with specific demands for scientific rigor.

We're all on the same team here - we want better sound.

Patrick Dixon
2005-10-12, 00:46
It seems to me that anyone bringing SBs to a wider market is only benefiting Slim Devices and their products. Every SB sold and modified is, after all, a SB sold by Slim Devices.

Good though the SB2 is (and it is good), the 'audiophile' market will always demand something better. It's a small and funny market and not one that SD is very well equipped to tackle (or many 'normal' people understand!). Many 'audiophiles' like the SB's features and connectivity, and so having an audiophile version that fits into the main system in place of a CDP, allows them to use 'standard' SB2s in other areas of the home where listening is not so 'serious'.

We are long past the days of Henry Ford's "any colour you like; so long as it's black" - no 'one' SB product will ever cover everybody's wishes, and I personally enjoy seeing and reading about the wacky ways people rehouse and customise their SBs.

CardinalFang
2005-10-12, 05:30
I personally enjoy seeing and reading about the wacky ways people rehouse and customise their SBs.

I'm still waiting for the SB with valve output stages - put it in a case like this http://www.soundlabsgroup.com.au/shanling/shanling_scd_t200c.htm and then we're talking :-)

radish
2005-10-12, 06:54
It seems to me that anyone bringing SBs to a wider market is only benefiting Slim Devices and their products. Every SB sold and modified is, after all, a SB sold by Slim Devices.

Good though the SB2 is (and it is good), the 'audiophile' market will always demand something better. It's a small and funny market and not one that SD is very well equipped to tackle (or many 'normal' people understand!). Many 'audiophiles' like the SB's features and connectivity, and so having an audiophile version that fits into the main system in place of a CDP, allows them to use 'standard' SB2s in other areas of the home where listening is not so 'serious'.

We are long past the days of Henry Ford's "any colour you like; so long as it's black" - no 'one' SB product will ever cover everybody's wishes, and I personally enjoy seeing and reading about the wacky ways people rehouse and customise their SBs.
Agreed 100%. I do however have one small concern - and that is that non-audiophile people coming to the forum may see all the talk about improving this or that and walk away with the impression that there's something wrong with the original unit, and that they have to mod it to make it sound decent. There needs to be a big disclaimer on audiophile talk indicating that the stock SB2 is way better than anything most people have ever heard.

Fifer
2005-10-12, 07:36
There needs to be a big disclaimer on audiophile talk
Like a pop-up stating "Abandon hope, all ye who enter here" when you click on the 'Audiophile' forum?

radish
2005-10-12, 08:07
Like a pop-up stating "Abandon hope, all ye who enter here" when you click on the 'Audiophile' forum?
Nah, that's riovolution :)

Davey
2005-10-12, 08:17
Like a pop-up stating "Abandon hope, all ye who enter here" when you click on the 'Audiophile' forum?

Perfect!

Davey.

Fifer
2005-10-12, 08:22
Nah, that's riovolution :)
Very true ... ;)

Wayne1
2005-10-12, 09:29
I was asked questions and I answered them with MY opinion. I gave links to what a SB2 owner had to say about it.

I am not dissing the SB2. I have said before and I will say again the I feel Sean Adams and company have produced an incredible product for the price. It has changed the way I listen to music.

To MY ears and in MY system, I felt that it could be made to sound better. Others may disagree. That's fine with me.

I put together a listening session and invited folks to come and hear for themselves and make up their own minds.

If you are happy with the way your SB2 sounds then I am very happy for you. I do agree that for most folks the stock SB2 will sound better then what they are used to listening to.

For some folks whose passion is high quality audio reproduction, they always want something "better". The SB2 is also a way to achieve that.