Hi,
I do not see eye-to-eye with him on some points, but there is a lot there
you simply cannot argue with, technical tests whilst not revealing the
complete truth do not lie either, his driver choices are consistent with
his methodology. Its fine by me to not "like" his overall design philosophy,
but a bit pointless IMO to try to pick holes in what he does. e.g. the
SDT3.5 c/o is extremely well designed with some clever subtletly to its
operation. To not like it you still have to be able to understand it.
The reason I like Zaphs stuff is because all the information for the process
is there and beginners could do far worse than studying his site. For his
type of approach its also one of the best sites, whether you like it or not.
If you do not understand his site, then that is a lot of basics unconsidered.
It will still help a lot with other types of designs and philosophical approaches.
😎 / Sreten.
undefinition: Paul Carmody's DIY Audio Projects
Another good site with some very good beginners articles by Paul.
Also has oustandingly comprehensive links to just about everything interesting.
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Auditioning should really be in your own room with your own amplifier. A hifi shop is usually an artifical construct.
Speaker/amplifier/(cables) should be considered a system and one can't be considered with the other.
dave
Hi, low level circuits and active circuits create much lower levels of distortion than those that occur in passive crossovers and the distortion scales with the level.
It is not hard to create low level active circuits that have -100dB or greater THD. It is very diffcult to achive this for the large inductors that are used in a passive crossover. If you use large air cored inductors you can minimise it but the magnetic field escaping from them can easly couple into other inductors in the crossover creating a little transformer and causing crostalk from one part of the circuit to another. As the power level increases these inductors will get hot, something low level ciruits if properly designed should never do. When an inductor gets hot its charcteristics shift so its value will start to change.
But none of this is the main advantage of an active design. The main advantage is that the amplifer is directly coupled to the terminals of the speaker. This means that after a transient occurs and the speaker is returning to it resting position, it is a coil moving in a magnetic field so it will create a electrical signal. In a passive design this signal has to pass back through the crossover before it is damped by the amplifers voltage feedback. In an active design the electrical signal (back emf) is damped directly by the amplifier.
I could go on about this but much more is described on Rod Elliots site:-
http://sound.westhost.com/bi-amp.htm
His rational for using active crossovers is good but I think his design methodology is not. I don't agree with using restance in the output to adjust the roll off of the driver as this reduces the available damping of the back EMF. I would either design the box the right size for the response I wanted in the first place or use a electronic filter to adjust the response.
I notice you are thinking of going with a DSP filter such as the Berhinger. Whilst I am not keen on the behringers sound quality (however there are lots of tweaks available for it) to start to understand how the crossover response will affect the sound of a speaker it is ideal as you can very easly adjust it.
Desining good passive crossovers is very diffciult. There may only be a few components but just about every component intereacts with all the others in poorly predictable ways (this includes the speaker drive units). So none of the variables are independant, this make it difficult to tune. Due to the interaction of the speakers inductance with the crossover changing values somtimes has very different affects to what you are expecting if you think of it as a resistor.
I quite enjoy the challange and had the luxury of it being my job for a number of years. To give you some idea of how difficult it is it took me 18 months full time for me to come up with my first acceptable comercial passive design (a 2.5 way), whilst working for a very patient boss who calmly told me what was wrong with the sound at each point and then left me to find out how to fix it. This included building test boxes and measureing them with an accellerometer to establish their resonances and how to reduce them. As well as hundreds of simulations with LEAP (Loudspeaker enclosure analsys program) which is comercial program that is comprehensive but quite difficult to use. Many driver measurements with MLSSA and a B&K measuremnt system as well as two or three iterations of driver modifications to match the driver to the box. Endless revisions of the crossover and components in the crossover to try to find the right sound. I also had the advantage that as I was an active member of the AES at the time I also got to speak to may of the engineers at KEF who were very active in the AES at the time, whilst I didn't like the way they tuned thier later speakers the depth of understanding of how speakers worked was fantastic. A credit really ought to go to Richard Small and Malcom Jones.
I have drifted a bit of topic here sorry. Back to your design. Whith your room constraints, I would tend to agree that a good sub sat system could be the right approach and this would enable you to start with quite small speakers - the satelites and hence not need to invest too much money in them to start with. If you make them of small book shelf speaker size (like the size of a BBC LS35A) you could make something that is a good satelite and will integrate with the sub well. If you decide to move on and build a more complex design it could be used as a second room speaker full range without the sub. (Or given to friends who are unlikely to want a massive full range speaker)
I quite envy you as you seem to have the time, money and energy to invest in learing about speaker design, I really enjoyed it as it is endlessly facinating all the new aspects that continue to open up as you understand one thing it leads to realising you don't understand another.
Regards,
Andy
In theory all filtering, phase correction done in the digital domain will be superior to any passive XO built. There is only so much you can do in the analog domain. There is simply no comparison when it comes to SQ, the only problem is that the cost of entry into the highest quality Digital XO is fairly high.
Interesting. I'd have thought the opposite because the pre-amp would pipe the sound in analog to the DXO, which would then sample the signal through a DAC which would then fiddle with the waveform and then convert the resulting digital signal through another DAC to go to the receiver. Now, granted, not all DACs are created equally, but I was thinking that maybe the extra sampling of the signal would create more loss than just using ICs/Caps/Resistors. Cool, you learn something new every day. 🙂
Cool!
Wow, I obviously don't know enough about electronics either. 🙁
I don't remember mentioning them by name but yes, they did come up on my list of things to look at. Mostly, I liked their UI and the ability to tune things. My thought was that as long as I can get the speaker to sound 'tight-yet-relaxed' enough for my tastes, I could do the rest in digital.
Something in me just died. Active XO it is.
(yay, my first compromise).Small turns Sparks, small turns. 🙂
The problem is that I've already got a sat/sub setup and I hate it when I compare it to my 3-way speakers. They lack the image and coherence that I want (but then, so do my 3-ways). But I take your point; start small and learn as you go. That's been a pretty consistent message in the thread so far and I see the merit to it.
Nothing is more frustrating than spending a whack load of money on something only to have it sound like ****. That's the stuff that defeat is made of.
I certainly have the energy; time is another thing entirely. I always have many projects on the go; one of which I will need to come off the bench soon for a solid four months. During that time, the HiFi habit will take it's place on the bench to be picked up when it can. C'est la adulthood. 🙁
As for money, that's the easy one. I simply cannot save money so I will never justify spending 6K+ on anything (short of a car or a house) because I can't do it in a single pay cheque. But the diy route allows me to spend my pay cheques slowly and, at the end of it, I've picked up some more useful skills along the way.
Granted, it seems as though most people build enclosures for drivers meaning that my enclosure won't be as 'upgradeable' as I'd hoped, but c'est la vie.
Cheers,
Dave.
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You misunderstand; I was a commissioned sales dude in a former life (first two years of College). I remember all of those time-wasters that used to "gawk and talk" and it used to drive me nuts because I really did have bills to pay.
The fools were all liars; they were either lying to me or they were lying to themselves. I don't want to be "that guy". 🙂
But you're right, auditioning the speakers with the amps is my 'out'.
Hi,
Normally small speakers are easier to make image better as the driver centers are closer together and the frequency at which they change from driving into half space to full space is higher in frequency. (as with all things this is not universally true and some large speakers are exceptional in this respect)
If you have very small sat speakers the sub can end up being to high in frequency and upsetting the image especially if it has a slow roll off filter. Or they could just have a poor crossover and drive units.
Regards,
Andy
Normally small speakers are easier to make image better as the driver centers are closer together and the frequency at which they change from driving into half space to full space is higher in frequency. (as with all things this is not universally true and some large speakers are exceptional in this respect)
If you have very small sat speakers the sub can end up being to high in frequency and upsetting the image especially if it has a slow roll off filter. Or they could just have a poor crossover and drive units.
Regards,
Andy
With the exception of the room, that's what I was thinking. Auditioning AMPs doesn't make any sense unless it's done with all of your other components to use for comparison.
The same goes with speakers; especially after the wakeup call that I had with my last audition where a 6K integrated amp roshambo'd a 17K dedicated amp where the more expensive amp was left twitching on the ground in agony.
You can always keep all music in the digital realm as much as possible. Rip it all to a lossless format, store it on a PC and play it back through digital outputs right into a DSP that accepts digital inputs.
An analog source would go analog through a pre amp, out analog to the DSP. The DSP then does the ADC then does all the great filtering, phase, delay controls, then does the DAC stuff sending individual signals out to each amp for each driver. The only debate in the audiophile world is that ADC - DAC conversions.
If you want HIGH SQ then search for DEQX used on audiogon or similar sites. You can buy it new for over $6K US 😉
Hi,
That depends on where you want to spend your money. IMO the best
compromise for a 3 way is active bass / mid and passive mid / treble,
with similarly rated amplifiers and in particular active baffle step EQ.
Hybrid Design describes the principle for the mid/treble of a 3 way or subs/sats.
Its also possible to build all active EQ and up to 3rd order c/o filters into the feedback
loop and inputs of the power amplifiers, keeping the signal path very simple. Modelling
rather than experimentation is the way to go to achieve this with minimum effort.
😎 /Sreten.
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Yeah, I've got my HTPC setup with all of my movies/music (except the blurays) already. The SC that it has isn't that great though; it needs an upgrade. Although if you go that route, it might be better to buy a HQ sound card and then apply the correction profiles in in the computer itself rather than shelling out 6K for another computer. If software like that doesn't already exist then there's a market for that.
Damnit! Is there nothing in this hobby that is reasonably priced (and still not utter rubbish)? I mean, even interconnects cost three figures.
Note: The above is a rhetorical question. 🙂
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Yes, we've all been there!🙂
Are you thinking that auditioning things is a waste of time unless, your in your own room (rental), with your own front, amps, cables, speakers, blah, blah?!
Am I missing the point altogether?😕 (double Dutch just sprung to mind).
I think things must be done a certain way around, you can't audition something that hasn't been built yet, ie, the entire system!
So based on that, I hardly think its totally pointless, if there is a lesson in there (subjective or otherwise), you will find it. Welcome to DIY!
Mick.😉
Ps. I think this maybe something Geddes woke up to a long time ago.
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IMO, I think its a waste of time to audition amps period. Buy amps based on specs and designs because there is not going to be enough difference with in the same design specs to matter. Bad listening tests will have you making grossly inaccurate conclusions anyways.
Cool stuff, never done the feedback loop stuff.
I still think the entire setup needs overall EQing and phase control and that is where a full digital XO solution excels.
Fair enough too, however, not everyone knows THAT much about amps.
This would be much easier if the specs were a little more, lets say accurate, as some manufacturers do tend to 'carelessly handle' the truth a little.
I must confess here, it does strike me as just a little strange, to say the least that people can readily predict room response from a photo, then not have any idea what is what with an amp or speaker test in the room they're actually in.
Strange days indeed.
This could be put down to subjective differences.😉
Mick.🙂
Hi,
Only in adjustability. EQ and phase control can also be built into the
amplifiers easily. What they cannot do, but digital can is constant delay.
This thread is going where I expected, lots of waffle about very different
viewpoints as to how to best approach an as yet undefined problem.
😎 /Sreten.
df :
Are you going to re-arrange your room ? Are your sketches still valid ?
Considered : Humble Homemade Hifi ? any other good designs ?
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