Digital volume control question....
 

On 2006-05-20, Jim Lesurf wrote:
In article , John Phillips
wrote:
...
I assume that's what good DSP volume controls do.
...
The snag is that the above is all a matter of the details of
implimentation. Whereas a decent analog attenuator simply uses the
properties of the physical materials to do all this for you. No need for
the makers to work out a noise-shaping anf dithering process and ensure
sufficient precision, etc. :-)

True, but once you have worked it out once it's very easy to replicate
and does not have the degradation mechanisms.

--
John Phillips

Digital volume control question....
 

"Jim Lesurf" wrote in message
...
In article , Keith G
wrote:

"Jim Lesurf" wrote in message
...
[big snip]


That's all very interesting but a little way wide of the point - forget
expensive, 'laser cut' options, my curiosity here is that in an amp
costing only 60 quid (and which includes 6 inputs, headphone socket,
phono stage as well as all the necessary ADC/DAC circuitry, power
supply &c.) there is a very useful *digital* (ie cheap) way of
controlling volume/treble/bass/balance/muting/'loudness' with some of
the major functions (not all) available on the (included) remote
control.

Yes, I'd agree. I was just pointing out that some people have an aversion
to anything 'digital',


They *do*....???

(How strange!! ;-)


and that a 'digital attenuator' may have flaws, so
should assessed with due care. But the silicon for one is cheap, and
should
be able to give good results if well done.


Yes, if not done at least reasonably well then best not done at all, like
most things. I don't think these cheap amps would suit the more demanding or
perhaps, more discerning user, but bearing in mind the price, the sound
levels do go up and down much like you'd expect them to when you press the
appropriate buttons (or turn the knob)!!



Note also that applying tonal changes (treble, bass, etc) is slightly more
complex, so again should be fine if well implimented, but...


Yes, I can see that it might be a bit more complicated. Asitappens, I'm not
a great Tone Control user myself (apart from hacking the treble off a bit on
a *really* busy record) but I think it's always good to have the option.



If 'properly implemented' means that any artifacts, digital 'rounding
off' or whatever are *inaudible* there might be the possibility of an
inexpensive digital 'front end' which offers the convenience of remote
control on the main functions as well the additional capability to
adjust tone/balance/loudness/muting &c. (An amusing concept on a valve
amp!!)

Yes. However the above comment should be applied with caution in practice
since it starts by assuming that the imperfections *are* "inaudible". The
snag is that they may not be. For example, a digital volume control will
have a clipping level in a way that an analogue one does not. This may not
matter for some applications, but be vital in others. Hence "inaudible"
will depend both on the volume control and the specific use.


Sure...



I don't have any real objection in principle to 'digital' controls.
Indeed,
I tend to prefer processing signals in digital form when the process needs
flexibility, etc. However the reality is that an ADC-process-DAC-psu-clock
combination is electrically more complex than a pair of resistors. Hence
it
gives the poor designer/maker more options for making errors. :-)


Yes, I can see that it does but, as someone else has said, the cost of
fitting and manually wiring up an analogue pot is likely to be greater than
the cost of the necessary digital components on a PCB.

FWIW, I've had a fair amount of (mild) grief myself from carbon volume and
tone pots - not to mention hard-wired input selector switches!! When these
buggers play up it is a serious inconvenience (especially to non-DIYers) and
the effects on sound quality can be quite severe - silence on one channel or
the volume blasting through flat out on both, for instance!! (Been there,
done all of that!!)

Perhaps I'm naive, but I think the days of truly dodgy electronics are well
past us. It's still possible to buy crap of course, but mostly I think we
are getting more bang for our bucks than ever before and I don't think
manufacturers playing in an international arena are going to risk their grip
on the markets with anything too pooey....??

PCB appliances are generally pretty marvellous for what they cost these days
(ever scruted a computer card or motherboard closely?) and even the latest
hard-wired stuff like the Chinese valve amps seem to be of a very high
standard - I remember the pics of the internals of Fleetie's amp (the first
of the Chinky Cheepies in this group) and the response at the time was
generally one of people being quite impressed with all the gubbins inside
it. Since then, my own 'investigations' have proved that all the Chinese
amps I've seen so far have been built better than I could manage myself!!
(OK, not saying a lot, I know!! ;-)

Digital volume control question....
 

On Sat, 20 May 2006 13:42:14 +0100, "Keith G"
wrote:


"Stewart Pinkerton" wrote in message
.. .
On Fri, 19 May 2006 19:02:31 +0100, "Keith G"
wrote:

Well, I reckon a 30 wpc amp will work out at about 2 to 4 quid per watt,
but
the trouble is you *need* 100+ watts these days (ludicrous) and then I
reckon you are looking at 5 times that sort of money *at least* for
similar
(construction/appearance/appointments) 'assembly line' amps....??

Untrue for subs, Keith. You can buy a 500 watt 'plate' amp with active
crossover and all necessary connections and controls, for less then
three hundred quid. Just the job for getting deep, clean bass down to
20Hz at decent SPLs from an 18" cube. Also one of the last remaining
areas where the home builder can beat the commercial stuff.


The thing with home builders is that just about all of them think they are
beating the commercial stuff or I guess they wouldn't bother??

But it's not all about the money - many DIYers are looking to beat
commercial stuff in terms of ultimate performance/specification and are well
aware they would definitely *not* be beating commercial producers on a cost
basis if their own labour was priced into the equation....!!??

Still true in absolute terms. DIY satisfaction has a lot of clout, but
in the real world, home-built full-range speakers can in no way
compete with good commercial equivalents. All else is wishful
thinking.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

Digital volume control question....
 

On Sat, 20 May 2006 18:45:18 +0100, Adrian C
wrote:

Keith G wrote:
The thing with home builders is that just about all of them think they are
beating the commercial stuff or I guess they wouldn't bother??

But it's not all about the money - many DIYers are looking to beat
commercial stuff in terms of ultimate performance/specification and are well
aware they would definitely *not* be beating commercial producers on a cost
basis if their own labour was priced into the equation....!!??


Some people want to climb a mountain because it is there. The people
that put a wall around that idea don't understand the enjoyment one gets
in making the journey - no matter how ill looking the end looks (or not!)

Sure they do - but they also understand that a home-built car will not
win at Le Mans.............

I take my hat off to this person and many like her.
http://en.wikipedia.org/wiki/Jeri_Ellsworth

DIY electronics rules forever!

Kudos to a fine example of the best of US 'can do' thinking, but note
that she now works as a 'consultant'.............
--

Stewart Pinkerton | Music is Art - Audio is Engineering

Digital volume control question....
 

On Sat, 20 May 2006 19:04:17 +0100, Serge Auckland
wrote:

Adrian C wrote:
Keith G wrote:
The thing with home builders is that just about all of them think they
are beating the commercial stuff or I guess they wouldn't bother??

But it's not all about the money - many DIYers are looking to beat
commercial stuff in terms of ultimate performance/specification and
are well aware they would definitely *not* be beating commercial
producers on a cost basis if their own labour was priced into the
equation....!!??

Some people want to climb a mountain because it is there. The people
that put a wall around that idea don't understand the enjoyment one gets
in making the journey - no matter how ill looking the end looks (or not!)

I take my hat off to this person and many like her.
http://en.wikipedia.org/wiki/Jeri_Ellsworth

DIY electronics rules forever!

Absolutely!

Like many of my generation I got into electronics through the DIY route,
trailing round the component shops in Lisle St in London, falling over
the ladies of the night in our search for some particular component!
Sadly, now, just buying components is a trial in itself. It has to be
mail-order or forget it. One notable exception is the wonderful emporium
of Gee's in Cambridge. A real old-fashioned component shop staffed by a
great guy who's been there since Schottky was a lad.

Sadly building one's own stuff from scratch is a lot more expensive than
buying it built. Stewart mentioned buying plate amplifiers for
sub-woofers, which is fine, but if you want to make your own amplifiers
you end up spending a lot more than buying one. Keith's own experience
with the POS amplifiers shows this up well. There's no way you can even
buy the box for the price of the complete unit from Comet, Argos or whoever.

I hope there will always be a DIY sector interested in building stiff
not because it's cheaper but because it's a lot more satisfying.

Indeed it is - been there done that lotsa times. However, in the 21st
century, it can *not* get you better performance.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

Digital volume control question....
 

In article , Keith G
wrote:

"Jim Lesurf" wrote in message
...


Yes, I'd agree. I was just pointing out that some people have an
aversion to anything 'digital',


They *do*....???

(How strange!! ;-)

Well, you said it... :-)


FWIW, I've had a fair amount of (mild) grief myself from carbon volume
and tone pots - not to mention hard-wired input selector switches!!

So have I, mainly due to a willingness to use quite 'old' equipment at
times. However I'd hope that any decent audio equipment made in recent
decades would be using the newer materials which don't degrade or cause
problems as in days of yore... :-)


When these buggers play up it is a serious inconvenience (especially to
non-DIYers) and the effects on sound quality can be quite severe -
silence on one channel or the volume blasting through flat out on both,
for instance!! (Been there, done all of that!!)

I can recall days when the advice you might get would be to use '3-in-1
oil' to 'mend' a duff carbon pot. :-) However for some time now, unless
you are using very old (or cheap) items nothing like this should arise.

Perhaps I'm naive, but I think the days of truly dodgy electronics are
well past us.

It would be nice to think so. I also hope for peace and the end of poverty,
too... :-)

It's still possible to buy crap of course, but mostly I
think we are getting more bang for our bucks than ever before and I
don't think manufacturers playing in an international arena are going
to risk their grip on the markets with anything too pooey....??

Having a world market actually helps those who wish to flog duff or
counterfeit or out-of-spec goods. They can keep changing brand name or
market, or simply fake/falsify things... If you read IEEE Spectrum you
would be aware that this is now a very serious problem, and one that is
quite hard to deal with.

Yes, there are lots of good quality. cheap, items on sale. But in with it
will be items using second-hand or faked components, and/or made with no
real regard for actual performance beyond the point of sale. Having a well
known brand name on the box may well help. But even that may not in some
cases since they may have bought in faked components without knowing so.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

Digital volume control question....
 

Stewart Pinkerton

But it's not all about the money - many DIYers are looking to beat
commercial stuff in terms of ultimate performance/specification and are well
aware they would definitely *not* be beating commercial producers on a cost
basis if their own labour was priced into the equation....!!??

Still true in absolute terms. DIY satisfaction has a lot of clout, but
in the real world, home-built full-range speakers can in no way
compete with good commercial equivalents. All else is wishful
thinking.

Now you've gone too far. DIYers may not be able to produce an equivalent speaker
as cheaply as a commercial one, but every commercial speaker can be improved.
DIY for economy is mostly dead everywhere, not just in electronics. Unless you
include kits. DIY now is about quality and style.

The designers of "good commercial" speakers are constrained in part by
commercial considerations peculiar to factory production. For every speaker they
make, some ideals will be sacrificed to those constraints.

It follows that those designers could produce better speakers if the constraints
were removed. They could, given sufficient resources, DIY better than their own
commercial products.

Stupid DIYers with insufficient resources have *never* been able to compete with
commercial products.

But what about kits?

Clever DIYers with sufficient resources will *always* be able to compete in
terms of quality and fit-for-purpose. Eventually.

Time is a problem, I have to admit. In the case of Le Mans, by the time I built
the car that would have won in 1970, it was 2002.

cheers, Ian

Digital volume control question....
 

On Mon, 22 May 2006 11:58:24 GMT, "Ian Iveson"
wrote:

Now you've gone too far. DIYers may not be able to produce an equivalent speaker
as cheaply as a commercial one, but every commercial speaker can be improved.
DIY for economy is mostly dead everywhere, not just in electronics. Unless you
include kits. DIY now is about quality and style.

No, commercial speakers *have* been improved. That is the point They
are the product of careful initial design, then redesign and tweaking
both in anechoic chambers and real listening rooms. That is a luxury
most don't have for diy. They build one set, then live with the
result. The chances of a happy result of being better than the
commercial equivalent are vanishingly close to zero.

d

--
Pearce Consulting
http://www.pearce.uk.com

Digital volume control question....
 

"Stewart Pinkerton" wrote in message
...
On Sat, 20 May 2006 18:45:18 +0100, Adrian C
wrote:

Keith G wrote:
The thing with home builders is that just about all of them think they
are
beating the commercial stuff or I guess they wouldn't bother??

But it's not all about the money - many DIYers are looking to beat
commercial stuff in terms of ultimate performance/specification and are
well
aware they would definitely *not* be beating commercial producers on a
cost
basis if their own labour was priced into the equation....!!??


Some people want to climb a mountain because it is there. The people
that put a wall around that idea don't understand the enjoyment one gets
in making the journey - no matter how ill looking the end looks (or not!)

Sure they do - but they also understand that a home-built car will not
win at Le Mans.............



Bit disappointing from an engineer - why ever not, if it was built by
someone with the same (or better) expertise and resources as the
'professionals'....??? (I believe it happens from time to time in the
motorcycle world on possibly lesser events than the WSB, but I can't call up
and specific examples - a bit of Googling might come up with summat??)

Digital volume control question....
 

"Don Pearce" wrote in message
...
On Mon, 22 May 2006 11:58:24 GMT, "Ian Iveson"
wrote:

Now you've gone too far. DIYers may not be able to produce an equivalent
speaker
as cheaply as a commercial one, but every commercial speaker can be
improved.
DIY for economy is mostly dead everywhere, not just in electronics. Unless
you
include kits. DIY now is about quality and style.

No, commercial speakers *have* been improved. That is the point They
are the product of careful initial design, then redesign and tweaking
both in anechoic chambers and real listening rooms. That is a luxury
most don't have for diy. They build one set, then live with the
result. The chances of a happy result of being better than the
commercial equivalent are vanishingly close to zero.


Absolutely not the case.

DIY speaker builders almost invariably build more than one pair of
speakers - I know diddley doo about it all, but even I'm on my fifth pair!
(Two of which are/have been for other people!) Also, I believe many DIYers
will spend quite a bit of time tweaking a a pair of speakers after they have
been built, before they consider them *finished*.

Where DIY speaker builders differ from a commercial enterprise is that they
tend to tweak (different drivers and other components in the case of
speakers with crossovers) in the actual room they are going to use the
speakers in and using kit they already own. My own speakers already sound
better than a number of commercial pairs I have here, which have never
suited the room! I double-checked this only a day or two ago - my Pinkies
are *consummately* better in my room than a pair of very respectable JM-Labs
floorstanders (and a pair of even more respectable Ruarks) I have here.

Until you hit the 'sky's the limit' for price (Wilson &c.?) all speakers are
built to a price and it's common knowledge that 70/80 % of the costs of a
pair of speakers (before marketting and advertising &c. are added in) go
into the cabinet. A DIYer has the option to spend the money on the *sound
quality* - where it counts.

All this proclaiming that DIY can't beat commercial is just so much dogma -
any DIYer with sufficient skill/talent/expertise/resources and *funds* can
match the commercial sector in just about any field if he chooses to. Most
commercial enterprises had small, domestic beginnings from what I can see of
it, anyway!!