Questions on Quasar like build (BD-Design)

by BS, Australia, Tuesday, August 23, 2016, 00:23 (337 days ago)

Hi Bert, I'm FINALLY starting a build after buying drivers quite some time ago! :smile:

I have a few quick questions.

In regards to dimensions, are the BD15 driver mounting holes on an exactly 380mm diameter circle?

I'm planning to build something very similar to the Quasar MKII, with a few construction differences. One difference is the base, and I might need adjustable feet (like spikes) so I can accommodate some variations in the slope of my old wooden floor. If the baffle is not exactly airtight to the floor (i.e. spaced 30mm off floor) do you envisage any complications such as much of a loss of the floor being an extension of the baffle? Could chuffing occur(I assume not!)

Your thoughts would be appreciated.

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Questions on Quasar like build

by Bert @, Tuesday, August 23, 2016, 08:29 (337 days ago) @ BS

Hi BS,

In regards to dimensions, are the BD15 driver mounting holes on an exactly 380mm diameter circle?

[image]

If the baffle is not exactly airtight to the floor (i.e. spaced 30mm off floor) do you envisage any complications such as much of a loss of the floor being an extension of the baffle? Could chuffing occur(I assume not!)

Absolutely no problem or loss...

Good luck!

Bert

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BD-Design - Only the Best!

BD15 Cutout

by BS, Australia, Sunday, August 28, 2016, 21:31 (331 days ago) @ Bert
edited by BS, Monday, August 29, 2016, 00:25

Fantastic thanks Bert. In regards to the cut-out for the BD15, the Quasar MKII drawings suggest 350mm Diameter cut-out. Can you please confirm that exactly 350mm is large enough to fit the BD15 driver through, or is the cutout slightly larger?

Many thanks

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BD15 Cutout

by Bert @, Monday, August 29, 2016, 08:43 (331 days ago) @ BS

Can you please confirm that exactly 350mm is large enough to fit the BD15 driver through, or is the cutout slightly larger?

I would always use a slightly wider cutout, the driver frames are not CNC made giving tolerances but more to be able to mount the drivers more easy. A tight fit might give problems putting them in or taking them out. But since you have the drivers laying around then you could check differences or fitting for yourself?

Bert

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BD-Design - Only the Best!

AER MD Cutout

by BS, Australia, Sunday, September 11, 2016, 13:07 (317 days ago) @ Bert
edited by BS, Sunday, September 11, 2016, 14:29

Many thanks Bert, Gasper - yes exactly - I'm having panel CNC machined for me as don't have the required tools.

Bert - do you have similar EXACT dimensions and technical drawing for the AER MD drivers?

I'm not using wood for panel so cant hand recess it, and assume Id need validated(tested by me with my drivers) dimensions to provide for machining.

I downloaded the template PDF from AER website, but it doesn't have frame dimensions. It is also slightly inaccurate for my needs - accurate enough to provide to the CNC engineering company - e.g. the holes don't line up and if I do to best effort the outline certainly doesn't with the frame, nor would it provide the required 1-2mm around it to recess it.

I have also tried to recreate a drawing on my computer, but thinking I had it correct and printed it - I've just noted the frame appears not fully symmetrical.
(i.e., now I realise the holes aren't likely 90 degrees apart even if on the same circumference.)

Kind regards
BS

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AER MD Cutout

by Bert @, Sunday, September 11, 2016, 17:06 (317 days ago) @ BS

Bert - do you have similar EXACT dimensions and technical drawing for the AER MD drivers?

Sorry, I don't. The frames are hand made and their fronts sanded by hand as well making it hard to know 100% sure the external size (not square as well). The holes will be on the exact spot but I do not have a drawing of that... best is to measure them yourself from your own drivers.

I have also tried to recreate a drawing on my computer, but thinking I had it correct and printed it - I've just noted the frame appears not fully symmetrical.

What helps is to place the driver(s) on a scanner, scan the frame and take measurements from that?

Bert

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BD-Design - Only the Best!

Design Finalised - dreams about to turn to reality!

by BS, Australia, Sunday, September 18, 2016, 13:16 (310 days ago) @ Bert

Thanks Bert, understood. The machining company will accept 1:1 photocopies, so thanks for the suggestion.

Exciting times ahead.. slightly modified design finalised and submitted. Manufacturing turn around is about 1 week. I bought the drivers from you in 2013 so I'm so excited to be finally turning dreams and plans into reality :grin: :grin: :grin:

Thanks for your help so far!

BD15 Cutout

by Gasper @, Monday, August 29, 2016, 11:55 (330 days ago) @ BS

Hi,

I always declare 1-2 mm bigger cut out to CNC techinician than stated in technical drawings. It is more commodious to work with.

Regards,
Gasper

BD15 Cutout

by BS, Australia, Tuesday, November 22, 2016, 09:01 (246 days ago) @ Gasper

Many thanks Gasper, good advice. I revised design and added additional clearances - particularly around the AER driver which has an unusual shape. Thanks!

High Pass Filtering for Full Range Driver?

by BS, Australia, Tuesday, November 22, 2016, 07:46 (246 days ago) @ BS

Hi Bert!
The CNC machining I'm getting done is taking MUCH longer than expected - so I best use the opportunity to get other things ready.

I plan to bi-amp, with the BD15's low passed and driven by a Sonance DSP-750 (with cross over , EQ, DSP etc, 500W per channel into 8 ohms) and the full range AER MD3B driven by my valve amp - an EAR Yoshino 859.

The Sonance input will be fed from the EAR859, which requires me to modify it to take the output after the volume control, hence I have the opportunity to consider other changes. One I plan is to upgrade the input coupling caps, and hence I am wondering if there is advantage to drop off the very lowest frequencies by changing the input RC constant.

I've not bi-amped before however reading suggests that there are some potential advantages removing the very low frequencies from the high pass amp including conserving headroom and dynamic range, reducing potential PS modulation by the bass, reducing intermodulation distortion potential etc.

I am curious if youve tried High pass filtering the full range drivers and if you can see any downside? I assume there may some some phase considerations, but I'm talking about 30hz -3dB point or similar, and I assume the phase would be more dominated by the room and placement, and the amps natural BW would also have limits.

I am curious on your thoughts.

Many thanks!

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High Pass Filtering for Full Range Driver?

by Bert @, Tuesday, November 22, 2016, 10:43 (245 days ago) @ BS

Hi BS,

I am curious if youve tried High pass filtering the full range drivers and if you can see any downside? I assume there may some some phase considerations, but I'm talking about 30hz -3dB point or similar, and I assume the phase would be more dominated by the room and placement, and the amps natural BW would also have limits.

I always use a high pass filter on the full-range driver to protect them from unwanted damaging movements when playing too loud at sub frequencies. Less distortion and more headroom too of course...

This can be done in several ways depending on the set-up (best compromise).

1) passive in front of the full-range driver (12dB @ 100-150Hz)
2) active (changing your input caps to a smaller value and perhaps a second one for a second order slope).

The first is most flexible but all energy given by the amp gets lost in the crossover not helping the dynamic range of the amplifier.

The signal for the bass can be tapped from the output of the EAR or any other amplifier you want to use or try without changing the crossover settings/EQ for the bass.

The second one would be best for dynamic range. Amplifier at first but secondly also the full-range driver as less bass is going there. Remember that this will also give a phase shift similar to a standard high-pass crossover.

The signal for the bass this way can't be taken from the output but only from the input of the EAR (after the volume control) or from a second pre-amplifier output.

Advantage is that the noise coming from the EAR will not be audible in the bass compared to the first option. If the amps produce hum then this will only be amplified by the amp used for the bass section.

Bert

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BD-Design - Only the Best!

Progress update.. a teaser

by BS, Australia, Tuesday, November 22, 2016, 07:52 (246 days ago) @ BS

They aren't finished yet... but this might give a few ideas of what I'm up to!

[image][image][image]

:grin:

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Cool!

by Bert @, Tuesday, November 22, 2016, 10:30 (245 days ago) @ BS

:cool:

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BD-Design - Only the Best!

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