hi all
Thinking of trying atc's 3-way active modules with my project.
The amps incorporate active crossovers and should work well as based around their same mid driver, I can also adjust output levels to the high & mid drivers to even off the response.
Now how cheap can I get the modules-anybody got a pair!!
thanks mike

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AV HEAVEN DON'T MESS AROUND /SCANSPEAK/ATC/VOLT FRONT END TWIN HAWTHORNE AUGIE 18'' OB ACTIVE SUBS

Hi,

There are various DIY suppliers of kits for speakers etc., and Elektor Electronics have previously provided designs on solid state and tube amplifiers, which are available as kits also.

Is it worth any publication reviewing these kits, especially if new and innovative designs such as the Elektor PAX amplifier.

Many kits have been stated as high end, so it would be nice to know how Elektor Electronics (solid state/tube) or Wilmslow Audio Speaker kits compare to the commercial equipment.

I think the UK also needs stimulating with regards to engineering - the closing of some science based faculties in some Universities is of a concern, so any hobby based approach or comparison of kits with commercial equipment would help (recall Hafler were regularly reviewed).

Regards,

Richard.

Never a truer word of advice given when self building speakers, I have a mint pair of BC1s an SL700 among a few others kept totally original as a balance reference.

In another analogy, if I altered these it would be like repolishing a reference flat and trying to produce an accurate test report for one of my telescope mirrors

Simon.

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"Quicquid Nitet Notandum"

It seems the best loudspeaker companies make their own drivers or at least heavily modify existing ones.

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Hans

Hi,

To reply to Kengale - i see what you mean for loudspeakers.

For the electronics side of things - most people involved in the DIY area will have PCB's manufactured for their project - i use CAD tools for any theoretical work. In reading Hifi News recently, the ATC pre and power amps are hand built - including the components placed and soldered onto the PCB (March 2010 review).

I would expect that popular brands which will sell more than high end systems, hence popular brands will be automated.

Regards,

Richard.

Hi,

OK, thanks. Will examine Ben Duncans work - i recall his pre-amp work from the late 80's or possible early 90's.

I am currently designing a DAC with sample rate converter - using a <1ps jitter clock generator - but having trouble finding a crystal that will produce the relevant frequency that is a multiple of 176.4kHz (44.1kHz multiple) for use with the clock generator. I am planning to use two clock generators - one for CD (44.1kHz) and the other for the USB input providing the usual 192kHz (48kHz multiple clock).

Regards,

Richard.

I still have one of his preamps from that period built by Audio Synthesis.

hi all

Back to my views on diy loudspeakers,
The only reason why large scale manufacturers produce their own drive units (in my opinion) is cost, if you have the manufacturing facilities then cut out the middle man and build them yourself I'm sure it isn't difficult to 'copy' a proven design.
Take the atc sm75-150 mid unit, or should I say 'volt' mid range unit, or actually mid unit made for volt.....Who actually builds the things bearing in mind baffle mounting looks/dimensions are identical & the dome unit also looks the same. Why no copyright wrangling ??

As for build quality I do go some way to agree that factory is best, but I will say during a fairly loud session with some 'new' kef coda 8's a good few years back the plastic front baffles were left hanging by the wires when the odd dabs of glue simply wasn't enough-lets not forget the one electrolytic cap as crossover.
As for diy it's a fairly broad term, if all the components are factory produced & simply designed & assembled at home should they still be classed as diy, if they were assembled in a factory would they be any different.

Cabinet diy ?, maybe a few years ago you would have been restricted to a heavily braced rectangle cabinet but now there are many companies offering excellent cnc facilities at a very reasonable cost. Not quite the diy of years gone past.
I even mounted my 18'' Hawthorne OB units in a couple of 25mm thick 4ft x 2ft glass panels which I had water jet cut by a local company, it only took a phone call, sketch on some paper & some parting of cash. The outcome is certainly not diy in appearance..

For the diy reviews i fully understand that reviewers would be totally inundated by wannabe projects, so thats why I had a stand at the last whittlebury hall show but I was very disappointed not to receive one single visit from anybody from the trade or press, even if only to give a negative/positive passing comment.

I do think manufacturers have gone too far in stressing the finer points by way of selling their designs, especially regarding crossover phase correction , etc.
i was able to sit in on the active v passive atc demo at heathrow last month. the demo was based on the difference the active version had regarding the phase timing issue over the passive crossover, but while "everybody" in the room agreed the active was better 'cleaner sounding etc' i feel this had no relevance to the crossover as (if you bother to plot a chart over the whole seated floorpan area) you will see the timing only applies to one specific sweet spot and maybe one or two people only, everybody else would have heard a completely different phase relationship & taking wall reflections into account the whole thing soon will become a real mess.

I felt the whole test really brought back the "roots' of active design, independent amps no-intermodulation & short speaker cable runs, no volt drops giving a fast tight response especially in the bass region.
Basics which were never mentioned in the demo !
any comments anybody

mike
On a separate note it will be interesting what the results will be on the back to basic's testing by hi-fi plus, I just hope they are not influenced by the advertising & marketing provided by their patrons.

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AV HEAVEN DON'T MESS AROUND /SCANSPEAK/ATC/VOLT FRONT END TWIN HAWTHORNE AUGIE 18'' OB ACTIVE SUBS

You have got lost here - as long as the distance between the two drive units is much less than a wavelength at the crossover frequency (and the manufacturers do their best to ensure that it is) then the phase relationship between the two will (amongst other things) affect the amplitude response over the crossover region, and this response will then apply over the whole seating area. It also affects the directionality (usually vertical) over the crossover region, sometimes quite drastically.

Well, as an ex-designer of active loudspeakers I am obviously pro, but you really haven't taken up the point of my and Mat's posts: a collection of high grade drivers and bits and pieces and high quality construction results in......... a collection of high grade drivers and bits and pieces. It doesn't result in a high quality design. The only thing that produces high quality design and performance is detailed research and development using suitable facilities, with all components, dimensions, materials chosen for their contribution to the whole and how they interact with the other ingredients - NOT chosen just because they are "high grade" or high cost. This takes a sound technical background, engineering know-how and experience, coupled with good business practice and the ability to implement proper purchasing and manufacturing quality control, followed by skilled correctly-targeted marketing. Plus a fair chunk of capital (development facilities, test equipment, production area, stock build-up, items for demonstration/review-loan, advertising literature, instruction manuals, packaging etc). Without all this you are doomed to commercial failure.

I really haven't got the time to hand-hold you through a complete design process, and you seem to be trying to get other people to donate to you for free skills and experience which has taken years of education and experience for us to to acquire. For example, if you really think that "the job of the crossover had one job & one job only, to deliver a flat response across the audio spectrum" then you've not even begun to graps the complexities of what it has to do, and how the choice of type (Bessel, Butterworth, chebychev..), order (1st, 2nd, 3rd ....) is tied up with the phase, amplitude and transient responses of the speaker units involved INCLUDING THEIR OUT-OF-BAND RESPONSES.
Have a play with http://astro.u-strasbg.fr/~koppen/radio/Activee.html and see if you understand what it is telling you about filter design. Implement a high-pass low-pass combination in a circuit simulation package (there are plenty for free) and and explore the phase and amplitude responses, both individually and in combination. You might then begin to grasp what the crossover has to do, and the effects of different choices.

Better still, get a job, no matter how menial, with a decent loudspeaker manufacturer and see first hand just how much is involved. You might then begin to get to grips with just how hopelessly over-simplified your view of the various concepts is.

Sorry to be so blunt - but I do wish you would read previous posts, both from me and others, IN DETAIL and take them to heart, rather than assume you can break into a highly specialised, technical and skilled market on the back of a few grossly simplified assumptions, hints from forum posters and the ability to pull old VW campers apart and put them back together again.

Regards

Ken

only a few???