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Old 11th September 2012, 10:39 AM   #11
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The geek has good advice. I've been building speakers for years, and still occasionally get nobbled by three ways. Start with a sub or simple two way with cheapish drivers, (you can still get very good results, I'm still using to my active sub/sat system I built years ago that cost about £50 in drivers), a few chip amps to power the system, some basic measurement equipment and Self's book and you'll have years of fun.
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Old 11th September 2012, 10:41 AM   #12
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The Omnitronic 6 Ch amplifier you linked features an electronic crossover , even if it doesn't specify at what frequency ...I guess is just for sub + sat purpose , so around 80 Hz
Dunno the quality of it .
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Old 11th September 2012, 12:43 PM   #13
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Hang on here... that is an *expensive* "kit" speaker.

Seems like on the order of $3,000USD??

So, the question is what is the ultimate goal and what is the budget for the project as a whole?

It would not make much sense to run a signal chain of significantly lower *quality* than the speaker. Price is not equivalent to quality.

I see a few options.

Assuming the OP likes these drivers, the main drivers (the ATC and ScanSpeak) are easy enough to source. For the bass section one can choose from a wide variety and brand, all of whom will likely do as well or better for bass. That leaves a cabinet. The sexy cabinet won't really do that much for the sound, although some cabinet design factors are important. So, some other cabinet could be used or built or found.

In fact the speaker does not need to be built as a single unit. The drivers could all have their own enclosures, or the mid/tweet could be one, and the bass section another (larger is mo' bettah) enclosure.

Given that you want to tri-amp or biamp, the sensitivities of the drivers do NOT need to be matched as they would be in a passive, all-in-one design. Rather you can pick for other factors... or go with the same mid/tweet combo.

You will find that everything is a compromise and a balancing act. Everything.

What you want is Vance Dickason's Loudspeaker Cookbook to start. That has more information than you want, and you will initially drown in it, trying to digest.

Then you will need some FFT type loudspeaker measurement software so you can literally see the results.

After that, make some choices and tweak away!

One way to get rolling is to build something that is cheap, simple and easy. Test and tweak that to get ur feet wet before committing to the high $$ stuff.

There are a number of "kits" that are inexpensive from Madisound and Parts Express. Merely converting a passive little two way to an active two way will give you significant experience in the process, assuming you can measure the results and see what is entailed.

As far as amplification (for a finished high quality build), if you want to "save money" by doing work, you'll need a kit or DIY PCB... there are a great number of really great designs on here, some of which have pcbs being sold (discrete and chipamp) and also consider tubes for the mids and/or highs as a possibility. For a test case/trial, anything will do.

In general you might want to think higher power class AB for the bass, and class A for the mids and highs... although some would argue for certain AB amps there too...

Many folks here have actually built up a variety of different amps of different types.

The variations and possibilities are pretty darn large.

Then too, you can think about a DIY ESL for similar (or less) $$ to the costs of the drivers alone that you are talking about!

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Last edited by bear; 11th September 2012 at 12:45 PM.
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Old 11th September 2012, 06:20 PM   #14
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If you like the idea of active speakers, then you should have a go.

N.B. As someone has already mentioned, the drivers in the PRESTIGE design are fairly high end (and low distortion), so they will likley reveal cheap/bad components upstream.

I have given active threeways much thought, as I want to be in control of my end sound/voicing. But, ultimately I have decided to stick with passive crossovers. This was largely because I did not want to buy 6x mono amps, and also because I wanted a system that was flexible, and not just designed for active three way speaker operation. The active idea sounds easy but once you look into it, more is needed. I may be doing myself a disservice with not going down the active route???

During my decision making process, I have come to a few conclusions that may be useful to you:

Firstly, and most importantly: It would be very unlikley that you would not create an excellent speaker. As a previous poster mentioned, all you have to do is pick three drivers that you like and which are suited to their task (bass, mid, high), put them in cabinets suited to the drivers, and then sort the rest out with active crossover slopes etc.

The Behringer DCX unit is very capable and will be more than you need. It has an excellent DAC, but it is not high end, as the output stages are cheap, and the power supply is rubbish. These units can be upgraded by companies like AUDIOSMILE at a cost. You would still need to use a six channel volume control. This starts to get expensive. Also you end up with lots of uglyish boxes in your rack.

The miniDSP units seem to be the way to go, but they have only average DACs, and you should avoid lots of uneccessary ADC/DAC conversions. Your speaker choice suggests that you seem to be aiming for a high end sound, so these may not be up to scratch. miniDSP have recently released a new unit, the nano DIGI, which takes a digital source and can split it three ways (with active filters), and output 3x digital signals. You would then need 3x decent DACs, and then find a way to control the volume. OR, you could use the Twisted Pear Buffallo III, which will take three stereo digital inputs, and DAC them with a very high degree of quality. It also has a digital volume control built in. You would need three output stages though (like IVY). If you are going down the Twisted Pear Audio route then you may as well add a MUX reciever in front of the nanoDIGI, so that you can switch between multiple digital sources (if you need to).

There are lots of amplifier choices, but I have decided on Hypex UCD180units. Not too expensive, yet will not be a bottleneck in sound quality. I have gone the whole hog and opted for HG hxr versions. Who knows whether the extra spend was required.

Gotta go now. Fee free to ask any questions. I probably have not made much sense.
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Old 12th September 2012, 07:59 AM   #15
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Thanks again for your very useful posts!

Again, I realise this is probably well beyond my capabilities at present, but what is wrong with using an analgue active crossover.

Most studio monitors which by definition have to have very high fidelity, have a simple XLR input, then analogue crossover to the amps, whether 2-way or 3-way.

Or are there no decent analogue crossovers, or is it more to do with the flexibility of a digital crossover? (Again I am think about using my audiolab as the source and minimising conversions and poor DACs/output stages)

To my simple logic, it would seem most obvious to take a well designed passive 3-way kit speaker and make it active (therefore I only need to worry about the crossover and amplification, rather than designing the box and spending ages thinking about driver choice).
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Old 12th September 2012, 08:56 AM   #16
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As has been previously mentioned, to do an analogue crossover AND get the same result as the well designed passive crossover, the transfer functions of the active filters need to match the transfer functions of the passive filters.

If you go with a generic active crossover you apply a certain electrical slope to your speakers and get (once it combines with the drivers natural response) a different slope.

When designing a passive crossover the filter will be designed (if it has been done properly) to get a particular acoustic slope (the slope of the filter may be quite different and there may also be response shaping circuitry in the passive crossover to deal with resonances cone breakup etc).

So if the passive crossover results in a 24db/octave LR acoustic slope you can't just get a 24db / octave active filter and apply it at the same crossover point and expect it to work properly

A DSP based crossover allows much more flexibility in tailoring the crossover, it can be done with analogue as well, but I think that it would be beyond what you are thinking.

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Old 12th September 2012, 09:16 AM   #17
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Ahh. Now, I see the light.
Thank you so much. OK, so studio monitors and actives using analogue active crossovers, must have spent a long time modelling and testing the crossovers to get it just right, and this would likely be beyond my skills/kit ti acheive, whereas, some softwear and a digital crossover greatly simplifies this process.

OK. That's that then!

So, I know people have said that plate amps are not up to the job, but what about something like the digmoda ddc 1055, is this just too poor for the job?

Out of interest - I know everyone does DIY here and that is the whole point, but would I be able to construct the cabinets, install the drivers, buy the amps/DSP and then delivery it to someone with more skill/knowlege/kit than me to set-up?

Doess anyone here offer this kind of service? I guess it would be the same as building a kit car, then getting the engine tuned and sorted by a professional....

Last edited by bushmeister; 12th September 2012 at 09:42 AM.
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Old 12th September 2012, 02:41 PM   #18
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Default Its all in the crossover & measurement tools

Hi Bushmeister,


If you are near Cambridge, pop in for a listen and you can hear how I solved the same set of problems you now face.
Basically I found the best way to ensure real Hi End sound AND protect yourself from huge £ depreciation and losses on "stepping stone" and "learning curve" equipment mistakes is to bite the bullet and find the cash for a DEQX.

Wait a wee while and look out for a used one (£1,200 gets a good spec unit) already in the UK as buying a new one from Australia is a £2,500 to £ 3,000 bill after shipping, import duty and VAT. Ouwch!

The rest is easyÖ!
First select really great drivers, Pro drivers are so much better and well worth the money.My top choices for your system are:
The seductive Beyma TPL AMT tweeter,
http://profesional.beyma.com/ingles/pdf/TPL150.pdf

cross it over at 1,400 Hz to the astonishingly good 10 inch midrange Volt 10 BM2500.4in a sealed box of approx. 30 litres Volt Loudspeakers - About Us

and finish with a sealed box bass volume of 60 Litres to 120 Litres with a Beyma
http://profesional.beyma.com/ingles/pdf/12SW1300Nd.pdf
or Precision Devices PD1550 15 inch basshttp://www.precision-devices.com/showdetails.asp?id=14

depending on size of cabinet you can fit in your room.

Build simple but solid MDF or Birch Ply ( much better) cabinets with some extra bitumen / lead damping pads and fibre glass ( sealed inside 100% cotton sleeves) stuffing. Get local automotive guys to spray paint the MDF or local joiner to stain and varnish the Ply.
MUST build separate boxes for each driver and separate with Sorbothane pads. Buy 1 square foot approx. of 10mm thick Sorbothane and cut 16 squares ( one on each corner) to isolate tweeter from mids and mids from bass. Added benefit of not needing to use DSP to time align drivers as you can do it physically and allow for vertical tilting if required by listening position.
Fit 3 large spikes in a triangular pattern, one at each front corner and one central / rear of the bass cabinets to anchor bass cabinets to floor.

Make up your own simple cables and interconnects using good quality solid core silver, single 0.6mm for interconnects, triple cores for tweeter, 4 cores for mids and eight cores for bass. Use short runs and have one three channel power amp behind each speaker or ( best) 3 mono blocks behind each speaker.
Run digital out from your source (Single ended or balanced) and use the on-board DEQX 6 channel DACís.
You will be blown away by the results!
If you come into even more cash in the future you can simply bypass the DEQX internal DACís and use 6 channels of TP Buffalo e DACís or something else equally wonderful.

Good luck and enjoy the research and reading for a few months, then and only then spend your cash!
Derek.
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Old 12th September 2012, 04:16 PM   #19
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Wow! Now that is an answer!!

Do you have any pics or WIP blogs?

That is a simple, straight-forward and common sense approach, which I think even I would be capable of doing!!
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Old 27th December 2012, 08:54 PM   #20
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Default AWOL- sorry!

Hi Bushmeister,

Sorry just noticed I never replied to your last post.
I am going to upload some pics and descriptive text to a photo hosting site soon.
I will let you know as soon as its ready.
Cheers
Derek.
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