No ADC needed if the signal is already digital as is the trend nowadays. Board space and test time I dispute in the case of more complex designs. Testing analog filters is quite time consuming and requires fairly dedicated test equipment (like AP) and multiple test points whereas digital can largely self-test. So its not just a function of time in production, its machine hours where the machine's capital cost is significant. Yield I also dispute - its not just a function of transistor count, its also solder junction count - integrated gets better yields and DSP will always be higher integration. DACs (with reconstruction filters) already come on-board with some DSPs and this trend can only continue further.
I omitted the opamp support circuitry - SMT caps for audio performance (NP0) aren't too small and can be more expensive than the opamps they're connected to for the larger values. Alternatively, to use the smaller values the cost of the opamps goes up for the same performance levels (JFETs being more expensive than bipolars).
Undisputed.
I've been very happy with a tri-amped system using 4th order crossovers from Marchand for many years. I find them far better sounding than 3rd order or less. Anything you can include on making the decision on order and type is certainly useful.
There's an old Burr_Brown book on Opamp Function Circuits that has a nice treatment of filters and offers some numerical solutions to single op-amp 4th order filters that I find useful. Some complain of component sensitivity, but I've never had a big issue with it. They work great. If you don't have the book, I can get you the ISBN number. I know there are a lot of them available used for very little.
Best,
Conrad
There's an old Burr_Brown book on Opamp Function Circuits that has a nice treatment of filters and offers some numerical solutions to single op-amp 4th order filters that I find useful. Some complain of component sensitivity, but I've never had a big issue with it. They work great. If you don't have the book, I can get you the ISBN number. I know there are a lot of them available used for very little.
Best,
Conrad
Imho, something that would be a very good idea to add is to say something about "all" the things that are not covered in the book. Why? Well, the book is likely to be widely read especially by those DIY'ers who are not already EE types. They will tend to take such a book as something of a "bible", a sole or primary reference. To some extent, it would be... but it is still important to illustrate (albeit in relatively shorthand terms) that the book covers a subset of the options and implementations. I'd want to show brief examples of some of those options, and maybe just list others. It's important, I think, that the reader be made aware and have a good sense of the length and breadth of the "playing field", even if the plan is to march right down a wide swath of the middle!
Hope this makes some sense...
_-_-bear
Hope this makes some sense...
_-_-bear
Hi,
as I understand from the TOC the book concentrates on HiFi-Filters.
As such I´d expect to see something more than just the usual OP-amp based filters. If one want to use OP-amps one can google and find myriads of similar designs on the net. But hardly anyone builds filters any more with tubes or discretes,even though such filters can sound much better.
What I like is, that the book seems to take the driver into account. Most filter design handbooks focus on the filter, all to often completely ignoring the speaker. So while the filter performs perfectly the desired electrical transfer function, the output of the speaker doesn´t perform the desired acoustic transfer function. Better crossovers allow for additional equalizing. But while passive filters usually combine filter functionality and equalizer functionality in one circuit, active filters most often divide the functionalities. This leads to an increase in filter stages and parts number count. But an active filter may also be designed like a passive filter. This of course leads to filters which are none of the standard types. The acoustic transfer function may be the same in the end, but the parts number count of the filter is reduced and it sounds better.
Will the book deal with this issue?
jauu
Calvin
as I understand from the TOC the book concentrates on HiFi-Filters.
As such I´d expect to see something more than just the usual OP-amp based filters. If one want to use OP-amps one can google and find myriads of similar designs on the net. But hardly anyone builds filters any more with tubes or discretes,even though such filters can sound much better.
What I like is, that the book seems to take the driver into account. Most filter design handbooks focus on the filter, all to often completely ignoring the speaker. So while the filter performs perfectly the desired electrical transfer function, the output of the speaker doesn´t perform the desired acoustic transfer function. Better crossovers allow for additional equalizing. But while passive filters usually combine filter functionality and equalizer functionality in one circuit, active filters most often divide the functionalities. This leads to an increase in filter stages and parts number count. But an active filter may also be designed like a passive filter. This of course leads to filters which are none of the standard types. The acoustic transfer function may be the same in the end, but the parts number count of the filter is reduced and it sounds better.
Will the book deal with this issue?
jauu
Calvin
Interesting but not really the job of a crossover. I wanted to include motional feedback but there just isn't room
That's all in Chapter 14.
Thanks for your input
Me too, but I've called it diffraction compensation
They are in Chapter 8
No GICs, are not planned for inclusion. Looks like there will just not be space.
If you mean filters with voltage-controlled cutoff frequency, as used in analogue synths, why would you use them in a crossover? I think we are not communicating here.
No LC filters are included. It's a very expensive way of getting a delay. Nonplanar topologies?? What are they?
Many thanks for your input.
Minimising topic overlap
Having quickly scanned the chapter list and compared the contents with your 'Small signal Audio Design' there does look to be considerable overlap - one or two chapters look to be almost identical in both. One way to minimize this and free up a little space for more crossover-centric topics would be to omit the chapter on outputs completely (since that's one that looks like its mostly a duplicate) and change the title to something like 'Crossovers for active speakers' - implying that the crossover and power amps are integrated.
Building a stand-alone active crossover box I don't think is going to appeal to many diyers and it seems a bit of a shame to use up valuable book space on material which you've already published when other interesting topics are being squeezed out (like GICs for example).
Having quickly scanned the chapter list and compared the contents with your 'Small signal Audio Design' there does look to be considerable overlap - one or two chapters look to be almost identical in both. One way to minimize this and free up a little space for more crossover-centric topics would be to omit the chapter on outputs completely (since that's one that looks like its mostly a duplicate) and change the title to something like 'Crossovers for active speakers' - implying that the crossover and power amps are integrated.
Building a stand-alone active crossover box I don't think is going to appeal to many diyers and it seems a bit of a shame to use up valuable book space on material which you've already published when other interesting topics are being squeezed out (like GICs for example).
I assume you mean the line input and line output chapters; since they are finished I can speak confidently about them.
I agree that they may look from the ToC to be not very different from those in SSAD, but this is not actually the case. The sub-headings certainly look similiar but it is hard to see how else they could be phrased with equal clarity.
The line input chapter has had some of the more specialised input configurations pruned and there is now more emphasis on low-noise design. Much of the chapter has been rewritten with additional information added. The line output chapter is much extended compared with the SSAD version, with a lot of important material on reducing output transformer distortion added, and is at least twice the size.
I never have and never will simply cut and paste chapters between books. I always aim to give value for money.
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This is, perhaps unfortunately, going to be a history book. Builders of the analog crossovers for Linkwitz speakers are already finding it difficult to source the necessary capacitors . . . a situation that is only going to get worse, since demand for such items is steadily falling. Meanwhile digital signal processing becomes ever better and less expensive . . . and ubiquitous. If the book is long on crossover theory (which can translate to the digital realm) it may have future use . . . but where is the market for a "new" analog crossover?
Hi Douglas
I miss the chapter about the "blameless crossover".
Fun aside: Are you going to show how to take the driver transfer functions into account within the chapter dealing with the subtractive crossovers ?
These filters are by themselves almost useless if you don't resort to some tricks to include said transfer functions.
Regards
Charles
I miss the chapter about the "blameless crossover".
Fun aside: Are you going to show how to take the driver transfer functions into account within the chapter dealing with the subtractive crossovers ?
These filters are by themselves almost useless if you don't resort to some tricks to include said transfer functions.
Regards
Charles
No ADC needed if the signal is already digital as is the trend nowadays. Board space and test time I dispute in the case of more complex designs. Testing analog filters is quite time consuming and requires fairly dedicated test equipment (like AP) and multiple test points whereas digital can largely self-test. So its not just a function of time in production, its machine hours where the machine's capital cost is significant. Yield I also dispute - its not just a function of transistor count, its also solder junction count - integrated gets better yields and DSP will always be higher integration. DACs (with reconstruction filters) already come on-board with some DSPs and this trend can only continue further.
I omitted the opamp support circuitry - SMT caps for audio performance (NP0) aren't too small and can be more expensive than the opamps they're connected to for the larger values. Alternatively, to use the smaller values the cost of the opamps goes up for the same performance levels (JFETs being more expensive than bipolars).
Undisputed.
MiniDSP $200.00 for 4w stereo+ two cheap PS (I used old phone charges) & away you go, 1hr & you making all of the changes you probably ever need.
David
PS: except some people might prefer it in a case
Attachments
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Yes, I was referring to those chapters. I look forward to the deltas when the book comes out. Is the Amazon date of May this year realistic incidentally?
So I take it you had no clout over how your own contributions to Audio Engineering Know It All were presented? I find it hard to disagree there with the reviewer who gave it one star - a breathtaking hatchet job of a book. One of your chapters (12, p367) on 'Negative Feedback' looks to be an almost direct paste, beginning from the final paragraph of p49 of your earlier book 'Audio Power Amplifier Design Handbook, 5e'. Only the paragraph headings and some otherwise dangling cross-references appear to have changed. As the Amazon reviewer from Australia points out, the context provided by earlier paragraphs in the original chapter is notable by its absence.
Hi Douglas,
No offense meant, but that looks like it about covers the state of my knowledge of the subject in 1980's so and all relevant sections have weighty tomes published on them decades ago (from the filters including allpass filter use for time alignment to line-in/out circuits etc), most of which are now available freely for download.
To be honest, I cannot see why it would desirable to publish such a work as it essentially holds only historical interest.
We live in an age where we have:
1) mature modern digital crossover options (including crossovers that can be directly feed digital signals) and which handle time alignment, equalisation and many other functions rather well, are infinitly and instantly adjustable with a precision that state variable analogue filters can never manage, even allow dynamic filtering (to protect drivers against over excursion)
2) fully digital Amplifiers (as in digital input with no intermediate DA conversion except in the power stage) that could be used in active speaker applications fed directly from a DSP Crossover and which use power supply voltage adjustment for the first 24dB of volume adjustment, so no digital domain resolution is lost until more attenuation is applied
3) essentially exclusively digital media being available for the last almost 30 Years already and most historical material also archived only in digital form
Analogue in audio is rapidly becoming a stagnant and uninteresting backwater.
Now mind you, everything I do remains in the analogue for now (for various reasons), however a reference grade work on active speaker systems in this day and age e.g. the 21st century (and not in the 1980's) should probably limit the whole "analogue" section to 10 - 20 pages tops in the history part and focus on the current technologies and how to maximise the return from them.
Kind regards Thorsten
No offense meant, but that looks like it about covers the state of my knowledge of the subject in 1980's so and all relevant sections have weighty tomes published on them decades ago (from the filters including allpass filter use for time alignment to line-in/out circuits etc), most of which are now available freely for download.
To be honest, I cannot see why it would desirable to publish such a work as it essentially holds only historical interest.
We live in an age where we have:
1) mature modern digital crossover options (including crossovers that can be directly feed digital signals) and which handle time alignment, equalisation and many other functions rather well, are infinitly and instantly adjustable with a precision that state variable analogue filters can never manage, even allow dynamic filtering (to protect drivers against over excursion)
2) fully digital Amplifiers (as in digital input with no intermediate DA conversion except in the power stage) that could be used in active speaker applications fed directly from a DSP Crossover and which use power supply voltage adjustment for the first 24dB of volume adjustment, so no digital domain resolution is lost until more attenuation is applied
3) essentially exclusively digital media being available for the last almost 30 Years already and most historical material also archived only in digital form
Analogue in audio is rapidly becoming a stagnant and uninteresting backwater.
Now mind you, everything I do remains in the analogue for now (for various reasons), however a reference grade work on active speaker systems in this day and age e.g. the 21st century (and not in the 1980's) should probably limit the whole "analogue" section to 10 - 20 pages tops in the history part and focus on the current technologies and how to maximise the return from them.
Kind regards Thorsten
That is "fighting words"..
I have auditioned Hypex class D amps. For a sub , yes. For the rest .. Ha ha
A modern class AB amp with all the "candy" (cap multipliers , TMC) is far more engaging than the best D amp. The Eagles (2009) , with their Class D amp stacks in concert ... the sound quality sucked !! Rush , in 1990 with 100.000 watts of class AB , sounded far better. This absolutely carries over to the living room , I would not trade my 250W "blameless" w/ TMC for any of the Hypex's. Not even subjective , but a analog output stage driving a analog loudspeaker is the ONLY way !!
I agree that digital sources RULE (with analog OPS's)
"UnInteresting" to corporate interests that only want to push garbage on the "sheeple" , who know not what good Hi-Fi sounds like!
OS
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Hi,
Now, I am not talking about slow switching, analogue input, looped feedback design in my post above, am I?
I am talking about open-loop system which use powersupply voltage adjustment for much of the volume control range and switch at much higher frequencies.
Stuff that is switching with analogue inputs does interest me in the least. It is counter productive to even consider. Such amplifiers are essentially low order delta sigma analogue to digital converters with very low sample rate (a few 100KHz at best) and so require first a DAC only to follow it with a poor Delat Sigma system.
On the other hand something like the TAS5518 plus correct power stage gives 8 Channels at 300W/4Ohm each with 110dB dynamic range at -24dB attenuation and includes a fair bit of DSP processing on board. Input is strictly digital data. Add the right DSP to it and you have enough to drive 8 individual drivers (so it becomes trivial to implement active radiation pattern control in the speaker, on top of any time alignment and crossover functions you could desire).
It is a whole other kettle of fish. The potential in this kind of technology is staggering.
I have heard partially active commercial systems (passive 2-Way satellites and active 2-way between sub and sats) that incorporate the TAS5518 modulator and fully digital crossovers, time-alignment and room correction.
It is one of the best commercial audio systems I know. Other very good ones I know use analogue crossovers and amps and others even tubes.
However with the CORRECT USE of current technology it is possible to match the performance of the prior art.
I would go further in saying that once we appreciate this kind of technology and actively push it's boundaries it can offer much that is simply infeasible using traditional analogue approaches.
Ciao T
Now, I am not talking about slow switching, analogue input, looped feedback design in my post above, am I?
I am talking about open-loop system which use powersupply voltage adjustment for much of the volume control range and switch at much higher frequencies.
Stuff that is switching with analogue inputs does interest me in the least. It is counter productive to even consider. Such amplifiers are essentially low order delta sigma analogue to digital converters with very low sample rate (a few 100KHz at best) and so require first a DAC only to follow it with a poor Delat Sigma system.
On the other hand something like the TAS5518 plus correct power stage gives 8 Channels at 300W/4Ohm each with 110dB dynamic range at -24dB attenuation and includes a fair bit of DSP processing on board. Input is strictly digital data. Add the right DSP to it and you have enough to drive 8 individual drivers (so it becomes trivial to implement active radiation pattern control in the speaker, on top of any time alignment and crossover functions you could desire).
It is a whole other kettle of fish. The potential in this kind of technology is staggering.
I have heard partially active commercial systems (passive 2-Way satellites and active 2-way between sub and sats) that incorporate the TAS5518 modulator and fully digital crossovers, time-alignment and room correction.
It is one of the best commercial audio systems I know. Other very good ones I know use analogue crossovers and amps and others even tubes.
However with the CORRECT USE of current technology it is possible to match the performance of the prior art.
I would go further in saying that once we appreciate this kind of technology and actively push it's boundaries it can offer much that is simply infeasible using traditional analogue approaches.
Ciao T
But the "correct use" will never be. profit margin will cater to the masses and give us the most perceived output/ quality, and the "masses" will reference to what they are given. Optimum is not compatible with a "made in china" profit margin.
Also , the "prior art" has been advanced to quite a high level recently. (still at 50% efficiency , can't get rid of that)
OS
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