driver bolted to front or rear of baffle.Critical??

[adrian]

Hi all

If you took a classic Speaker like an MG and took it from its REAR baffle fixing in its original cab,and then set it up on the front,because you much preferred the look of that,..........is it critical, or would it have no effect on the sound or maybe even an improvement?

Or,if you were to diy build a copy of a classic cabinet and did the same thing.

Is it just cosmetic?

REGARDS
Adrian

[Barry]

Hi all

If you took a classic Speaker like an MG and took it from its REAR baffle fixing in its original cab,and then set it up on the front,because you much preferred the look of that,..........is it critical, or would it have no effect on the sound or maybe even an improvement?

Or,if you were to diy build a copy of a classic cabinet and did the same thing.

Is it just cosmetic?

REGARDS
Adrian

It won't necessarily be simply cosmetic, in fact it could have quite a significant effect on the performance.

If the speaker was designed to have the drive unit fitted onto the rear of the baffle, then I wouldn't change it, unless of course you assure yourself that mounting the driver on the front hasn't altered the sound. It all depends on the diffraction at the edge of the drive unit.

[Reid Malenfant]

While I do tend to agree with what Barry has posted loudspeakers have come quite a way since the days of mounting the driver internally. I can't think of any modern speakers that use this method of driver mounting. Not only is there a rather nasty square edge to the 3/4" or whatever thickness of baffle, but the rear of the speaker would need to be removable which will seriously reduce the enclosure stiffness :( Not to mention the possibility of a standing wave developing between one side of the baffle hole & the other...

If you are going to mount it externally make sure you rebate it into the cabinet so it's flush with the baffle, this will give you best performance & minimum diffraction. You may well need to use a thin gasket to seal between the driver frame & the rebate, some thin open cell foam or thin felt is about as good as anything.

[DSJR]

Some Harbeths and possibly Spendor Classic's still mount their drivers from the back, but the whole design thinking is rather different from the "quick-fit" designs of today...

I don't know enough to comment in any depth here, but if the speaker was designed and set up with rear mounting in mind, leave it well alone..

[selfaddict]

On Bastanis Open Baffle speakers drivers are still fixed to the rear of the baffle, well always have been. Maker/designer is specifying that there needs to be 10mm thick straight section on the baffle opening, which then flares 7mm. So the opening is 270mm on the back of the baffle(next to the driver) and opens to 284mm on the front.

[Reid Malenfant]

Some Harbeths and possibly Spendor Classic's still mount their drivers from the back, but the whole design thinking is rather different from the "quick-fit" designs of today...

I don't know enough to comment in any depth here, but if the speaker was designed and set up with rear mounting in mind, leave it well alone..
Ah, I didn't know that Dave, cheers for clearing up that some still do ;)

I don't think it's so much "quick fit" as you put it ;) What you need to remember is that CNC milling machines were simply not made back in the day & rebating a driver would have needed specialised machinery dedicated to each size driver or it being rebated by hand :rolleyes:

Imo the only thing that will change by mounting it on the front is that the enclosure will have a bit more internal volume :eyebrows:

[DSJR]

Anyone interested can look on the HUG, as everything there is to know about these things is there somewhere :)

[Reid Malenfant]

HUG? :scratch:

[DSJR]

Harbeth User Group...

http://www.harbeth.co.uk/usergroup

[Reid Malenfant]

Oh.... I prefer High Performance Loudspeakers 6th edition by Martin Colloms :)

Not quite so compartmentalised :eyebrows:

[DSJR]

Martin Colloms did some great work, but his disasters are long forgotten by most...

[bobbasrah]

Rear mounting on the baffle to deal with weak speaker frames, cone excursion, cosmetics, or deliberately for sonic performance? I thought this methodology was from a bygone age, wrongly it would seem.
Quite iintrigued that this is done on modern speakers, but on these is the port in front of the drive tapered or straight?

[selfaddict]

Only can comment what comes to Bastanis Open Baffle speakers, the port is tapered 45 degrees after 10mm straight section.

http://www.bastanis.de/pdf/Mandala_cutting_plan.pdf

(see page 4)



Quite iintrigued that this is done on modern speakers, but on these is the port in front of the drive tapered or straight?

[bobbasrah]

Thank you Juha,
I can see rear mounting with no cabinet access to consider is entirely practical and leaves a nice flat finish. Simple clear plans on the link, and I presume the tweeter is on a formed mdf or similar horn. The taper on the big drives must consider effects over the 10mm straight to be inconsequential.
Maybe some day I will have a go at OB's, but not practical in my current abode.....

The reason I queried this arose from a comment made earlier on rebating drives flush to the front baffle. At some point when readying to build the last speakers, I read somewhere of the importance of limiting diffraction/resonance from the drive chassis edge to the baffle (particularly tweeters - HF) when rebating. A 45 degree chamfer just clear of the drive was recommended.
However anal in my own case, with a thicker material than design, rebating restored the rear position of the drives relative to the baffle, so that was how I did it instead of face mounting per design. Between noise and dust from the router, it did not best please the neighbousr when I did it though....

I would doubt somehow that these diffractions were considerd on older cabinets.
However unlikely it is that the marginally increased cabinet volume or rear cabinet driver interactions would show dramatic change by front mounting, but it would not be as the original. I guess it is a case of suck it and see if it does no damage.