Quasar progress... (BD-Design)

by GC, Friday, February 25, 2005, 18:12 (4715 days ago)

Hi All,

I did spend the whole week with the new Quasar system (double BD15, BD30 and AERmkI for the mid-high frequencies).

[img]images/uploaded/image25.jpg[/img]

It is starting to work out extremely well (at least in my room) and placed free in the room. During the tuning process I've learned a lot about the system's character and knowing where to change things with the passive line filter to my liking.

Next is to test it with other drivers (Fostex for people with a lower budget and the more expensive AER's to see what I can gain in overall quality). I also have to play the system in other rooms to see how the system will perform there but things are progressing positively and soon the system will be ready for reproduction! ;-)

Ciao,

Bert

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Quasar progress...

by GC, Monday, February 28, 2005, 01:02 (4713 days ago) @ GC

Hi Bert
These speakers have a high WAF factor and should do well if they sound as good as they look, which I'm sure they will.:-)

Most people that build OB speakers start with thin panels and shy away from 'thick' panels.
Yours are a little different in that the panels are substantial, with large cut outs to accomodate the sound from the rear of the drivers. Do these cut outs act similar to putting wings on a flat panel to push cancellation of the front and rear outputs to lower frequencies, or is there some other 'magic' at play? ;-) ;-)

Cheers Chris

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Quasar progress...

by GC, Monday, February 28, 2005, 09:27 (4713 days ago) @ GC

Hi Chris,

These speakers have a high WAF factor and should do well if they sound as
good as they look, which I'm sure they will.:-)

They do even better than expected... :-D

Yours are a little different in that the panels are substantial, with
large cut outs to accomodate the sound from the rear of the drivers. Do
these cut outs act similar to putting wings on a flat panel to push
cancellation of the front and rear outputs to lower frequencies, or is
there some other 'magic' at play? ;-) ;-)

The deep cut outs work the same as adding wings but thinking in terms of deep bass then the path length is still very short. The frequency shifts down about 10%...

The magic is to have the full-range driver in a little chamber loaded with a variovent to reduce disturbing back waves in the higher frequencies and providing a more even impedance curve (tube amps like to see that...) and the active approach gives more freedom in the tuning plus the fact that the full-range driver used doesn't need a filter or without reduced sensitivity

Just the way I like it... ;-)

Ciao,

Bert

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Quasar progress...

by GC @, USA, Tuesday, March 08, 2005, 21:36 (4704 days ago) @ GC

The Quasars do look great!

Is that solid wood or sand filled cabinets?

Have you mapped the frequency response?

To what frequency are they flat to at either end of the frequency range? Would the Quasars still benefit from a tweeter and subwoofer to capture the last octave at either end of the frequency range?

What cost are we looking at if they were to be made available in a kit (presumably that you will do so)? (I have a pair of Lowther DX4s so I would need four 15 inch drivers and whatever crossover components that would be needed). Presumably, I would find the wood locally to save on shipping.

Retsel

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Quasar progress...

by GC, Tuesday, March 08, 2005, 23:39 (4704 days ago) @ GC

Hi Retsel,

The Quasars do look great!

Yes, they do look better in real live... :-)

Is that solid wood or sand filled cabinets?

Solid (the system weights about 40kg)

Have you mapped the frequency response?

Nope

To what frequency are they flat to at either end of the frequency range?

They are not flat without EQ, the baffle is too small for that.

Would the Quasars still benefit from a tweeter and subwoofer to capture
the last octave at either end of the frequency range?

It plays 30Hz very well, no need for a subwoofer in my opinion and a tweeter might give better dispersion as main advantage. The AER's do not need the tweeter and according to people the Lowther DX4 doesn't need one either.

In my experience (and my ears, preference) tweeters have more disadvantages than advantages in combination with real full-range drivers...

What cost are we looking at if they were to be made available in a kit
(presumably that you will do so)? (I have a pair of Lowther DX4s so I
would need four 15 inch drivers and whatever crossover components that
would be needed). Presumably, I would find the wood locally to save on
shipping.

The Quasar is an active system, the ones shown on the picture have a BD30 amp built into the bottom.

[image]

Total costs would be about 4 BD15 woofers, 2 BD30 amps and some relative cheap components for the filter making it about 1.820 Euro in total plus shipping. With added mid-high drivers you'll probably pass the border of 2.000 Euro to receive 10% discount over the total if ordered through the on-line shop.

Ciao,

Bert

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Quasar progress...

by GC @, utrecht, Friday, September 02, 2005, 15:42 (4527 days ago) @ GC

Hi Bert,

I now and then check your quasar progress since I know the open baffle idea can give fantastic results.

Your efferts are considerable I must say, and the design has changed quite a bit over the last 2-3 years. The first design was quite similar to the supravox model, but now a more WAFfy thing has come up. I do not want to interfere with your design strategy, but I wonder if you took into consideration the old bipole bass-driver thought from Thiele or Small. A kind of Z~formed baffle to increase run-time from rear to front. Also an interesting method of increasing bass (without possibly increasing electronics and complexity).

In some years I will defenitely build a quasar like system, but first I need to finish the DAC/Clock/RIAA machine and I do not have a lot of time.

Keep up your ground-breaking work!

Hubert

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