Why rebate speaker cut-outs?

[AndrewT]

Ceroc is a style of Modern Jive that I took up last year.

Probably the easiest of the arranged routines to learn. But there's hundreds of them once you're beyond beginners.

Brilliant, if you can tolerate the whole range of music from 1940s to 2006 including the Crooners to POP.

 

[chatziva]

Reviving an old thread.

I am wondering whether rebating a baffle actually does have a noticeable effect on the sound.

If it does have a negative effect, is it very bad? noticeably bad? or hardly any difference?

If it's hardly any difference then, would one recommend that first time builders/budget speaker builder don't have to bother rebating?

Does anybody have any experimental observations on the topic?

My experience is I didn't hear any difference at all when building my Cygnet MK2 speakers.

Evan

 

[chatziva]

The other issue that to cut an O/D as a outer skin to the baffle, still requires a router. Whereas without rebating one can use a simple jig saw.

 

[Cal Weldon]

For answers to your questions, please read this thread.

 

[PeteMcK]

Zaph|Audio

 

[MechanicalAnimal]

Brothers....

by "rebating" doe you perhaps mean "chamfering"? to allow for easier airflow behind the woofer?

If yes...then the following is a "must-read".

chamfering driver holes

 

[Cal Weldon]

By rebating we assume he means flush mounting. Back chamfering is a good thing to learn about also.

 

[chatziva]

I mean flush mounting.

Don't be quick to dismiss me -you assume I've not done my research.

I am not asking for theoretical analysis or measurements, all I am asking for is listening impressions - whether can one HEAR any difference. Maybe I didn't make that clear enough.

Thanks for your response PeteMcK. The +/-5db spikes around 200Hz in the 2nd graph worry me but the rest don't look too bad.

 

[doug20]

I mean flush mounting.

Don't be quick to dismiss me -you assume I've not done my research.

I am not asking for theoretical analysis or measurements, all I am asking for is listening impressions - whether can one HEAR any difference. Maybe I didn't make that clear enough.

Thanks for your response PeteMcK. The +/-5db spikes around 200Hz in the 2nd graph worry but the rest don't look too bad.

Yes, the measurements say that some people will here a differences.

Back chamfering is a good thing to learn about also.

Yes, its another thing to worry about Im less sure about its audibility though but that link shows there is a change in the FR plot. What I find amazing is that if you rip apart some popular consumer brands you will not find Chamfering on the back of the baffle but it still sounds very good.
Wit that in mind, I pretty sure we can hear a difference but the bigger question would simply be "does the difference matter and can it be EQed if it mattered" (Well, thats two questions)

 

[Andersonix]

I cringe a bit when I see a relief on the rear of the baffle done to improve airflow because to my eyes it looks like it's weakening the baffle. I also have similar feelings about the front counterbore (flush mounting), but I do it anyways -- everything in moderation I suppose?

 

[Brett]

Brothers....

by "rebating" doe you perhaps mean "chamfering"? to allow for easier airflow behind the woofer?

If yes...then the following is a "must-read".

chamfering driver holes

Whilst that is an interesting read, and a useful datapoint, it is hardly applicable to all drivers that have larger router hole (95mm) vs magnet (72mm) width rations like that SEAS has.
The thickness of the baffle against the depth of the driver before the magnet is also making this example more extreme.

An externally hosted image should be here but it was not working when we last tested it.

A larger driver, such as a 2225 or a modern unit with a small neo magnet or a baffle with less depth, such chamfering will have much less effect, so the conclusions cannot be taken as universal.

 

[rabbitz]

I cringe a bit when I see a relief on the rear of the baffle done to improve airflow because to my eyes it looks like it's weakening the baffle.

You are right as it has the potential to decrease the strength but that happens as soon as you put in a hole. A well made cast basket tends to make up for this and bracing can be added if desired so the baffle is actually stronger.

It's important to have good airflow behind the driver and a large percentage of drivers do have motors that tend to get in the way, especially the smaller drivers where airflow is severely restricted. Have a look at the good old Vifa P13 and even the newer SEAS Nextel W15LY001. Some of the newer drivers such as the Vifa NE, Scan Speak Illuminator do address this issue in their design but are a minority.

 

[MechanicalAnimal]

I mean flush mounting.

Don't be quick to dismiss me -you assume I've not done my research.

I am not asking for theoretical analysis or measurements, all I am asking for is listening impressions - whether can one HEAR any difference. Maybe I didn't make that clear enough.

only trying to help here....only trying to help.....

and mistaking "flush mounting" for rebating is due to the fact i'm Dutch.

 

[MechanicalAnimal]

Whilst that is an interesting read, and a useful datapoint, it is hardly applicable to all drivers that have larger router hole (95mm) vs magnet (72mm) width rations like that SEAS has.
The thickness of the baffle against the depth of the driver before the magnet is also making this example more extreme.



A larger driver, such as a 2225 or a modern unit with a small neo magnet or a baffle with less depth, such chamfering will have much less effect, so the conclusions cannot be taken as universal.

this is very, very true