Hi,
I haven't much in diy audio but I have learned a lot. I want to build passive bookshelf speakers( woofer and tweeter) with an amp. However, I was wondering why you would want passive filters inside your speaker cab. Why would you not separate the input into 4 channels one for each speaker, and then amplifier each channel separately.
Theoretically that seems to be the most energy efficient and error proof set-up. Is it easier said than done?
I have seen the miniDSP products but I want to build my own analog system, even though digital crossovers seem far superior to analog filters.
Thanks for the input.
I haven't much in diy audio but I have learned a lot. I want to build passive bookshelf speakers( woofer and tweeter) with an amp. However, I was wondering why you would want passive filters inside your speaker cab. Why would you not separate the input into 4 channels one for each speaker, and then amplifier each channel separately.
Theoretically that seems to be the most energy efficient and error proof set-up. Is it easier said than done?
I have seen the miniDSP products but I want to build my own analog system, even though digital crossovers seem far superior to analog filters.
Thanks for the input.
your confusing three different things.
Passive.
active.
dsp.
on your marks, get set, google..................
Passive.
active.
dsp.
on your marks, get set, google..................
Its reasonable and it's easy enough to do.
In some ways yes, in some ways no. Many prefer analogue filters.
sorry I was not clear,
My intentions are to build bookshelf speakers and an amplifier. But I have options as far as crossover's go.
1) passive crossovers inside speaker cab seem sub par and inefficient to me.
2) I am less familiar with active crossovers( powered crossover circuit with op-amps) , why wouldn't I use passive components to pass certain bands before amplification, is this not feasible? This seems like the best way to not waste power.
3) Or use Digital filtering before or after amplifications (don't know which would be optimal)
Which option is best?
Thank you
With careful selection of drivers and knowledge of amplifiers' input impedence(s), it's very easy and cheap to affect a simple ( 1st or 2nd order) analog passive line level XO's
google PLLXO - oh hell, let me save you the trouble, this is a good summary and even as a link to an excel calculator
TLS.org | Passive Line-Level Crossover
These have the limitation of being fixed XO turnover point and slope, but that's often exactly enough, and the total parts count is low enough that they can often be built in at the input connectors, with a simple shorting bypass to turn the amp back to full range if need be. I did that a few years back with a pair of tube amps.
Not sure how digital filtering after amplification would work 😉
google PLLXO - oh hell, let me save you the trouble, this is a good summary and even as a link to an excel calculator
TLS.org | Passive Line-Level Crossover
These have the limitation of being fixed XO turnover point and slope, but that's often exactly enough, and the total parts count is low enough that they can often be built in at the input connectors, with a simple shorting bypass to turn the amp back to full range if need be. I did that a few years back with a pair of tube amps.
Not sure how digital filtering after amplification would work 😉
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passive low level filters are somewhat limited to first and second order filters (relatively gentle slope). Active (with op-amps) are less limited, and many use 4th order filters.
Digital crossovers have the advantage that you are not limited by parts variability or availability, and can freely change your crossover to improve your speakers.
Digital crossovers have the advantage that you are not limited by parts variability or availability, and can freely change your crossover to improve your speakers.
What do you mean by enough? high order crossover's usually are not necessary?
Thanks for the input this was exactly what I was looking for.
additionally I am using the schitt fulla Headphone amp/ DAC as my source, I don't really know what adverse effects that could have when thinking about using a line level XO?
The only real difference with the PLLXO is the simplicity of the load impedance, along with the buffering that this entails, and the ability to use quality easily obtainable components at low power. Fairly complex filters can be put up on vero-board and simple high-pass sections can be created almost anywhere within the amp.
joe - I think you mis-attributed the earlier quote to AllenB, and I'm not sure he would agree with the sentiment as expressed.
My point was that for a dedicated choice of drivers carefully chosen such that complex orders of filters would not be necessary, that the simplicity of 1st order PLLXO may be all you need - and that sometimes less is just enough, and more is unnecessary. I hear that from my wife of 42yrs all the time.
Since you ask, I believe there is an amount of crossing required to bring two ways together, with the further consideration of the limitations of the drivers.
Where the former cannot be pinned down to a specific function, I'd call the acoustic design into question. I see a crossover design as beginning during the acoustic design.
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