Surface Mount Woofers...

[rogoll]

The Peerless SDS "style" has really gotten me hooked on surface mount woofers, which don't have to be rebutted/recessed/flush-mounted.

I've noticed a few others, such as the Dayton ND105-4, and some of the GRS (but those have other problems that would keep me from using them), also have the thin, surface mount style of frame.

What other popular drivers have this style?

[Pete Schumacher ®]

The Peerless SDS "style" has really gotten me hooked on surface mount woofers, which don't have to be rebutted/recessed/flush-mounted.

I've noticed a few others, such as the Dayton ND105-4, and some of the GRS (but those have other problems that would keep me from using them), also have the thin, surface mount style of frame.

What other popular drivers have this style?

The DA series have very thin flanges and work just fine surface or flush mounted.

[rogoll]

The DA series have very thin flanges and work just fine surface or flush mounted.

Pete, I'm sorry, but when you say "DA", are you referring to Dayton Audio?

[Pete Schumacher ®]

Pete, I'm sorry, but when you say "DA", are you referring to Dayton Audio?

DA135, DA175, DA270 etc.

[Mgboy]

Dayton's silver alu. coned woofers, cheaper than the RS series.

http://www.parts-express.com/pe/show...number=295-335

[RINNAV]

Is there a standard or "rule of thumb" for the a max thickness of the flange allowing for an acceptable surface mount application?

Jason

[Pete Schumacher ®]

Is there a standard or "rule of thumb" for the a max thickness of the flange allowing for an acceptable surface mount application?

Jason

I think it's more a matter of looks than anything else.

There will be an impact on diffraction from the tweeter, but because the surface is curved, the diffraction spectrum spreads, reducing the size of peaks and valleys. Some of the beefier models, have rather thick flanges which will look rather odd being surface mounted, as well as causing more diffraction, and for those, recessed mounting is preferred.

[dlr]

Is there a standard or "rule of thumb" for the a max thickness of the flange allowing for an acceptable surface mount application?

Jason

I've done a lot of testing of drivers and diffraction in measurements. There are few cases where surface mounting is actually significantly detrimental vs. flush mount. It is almost never the case for the driver itself. Midrange units maybe 4" and smaller should be flush mounted. My latest system uses a Scan-Speak 15w/4531 surface mounted. There isn't any significant diffraction of the 15w response to this due to both driver directivity change and the typical lowpass used.

The bigger issue is diffraction of the tweeter's response. Since most drivers have round flanges that varies the distance from tweeter to next driver frame rapidly, the overall impact of surface mounting is also very small. It changes with angle as well, of course.

The more important aspect is changed little with flush mounting and that is the diffraction of the tweeter response caused by the diaphragm of the next nearest driver. It's a large cavity and its impact is orders of magnitude larger the the side edge from the frame of a surface mounted driver, hence my consistent use of felt between tweeter and next driver for diffraction control.

IMO there's too much concern for some of the small factors and not enough for the large ones, this being a case in point. In addition, surface mounting in most cases is a minor aid to reducing relative acoustic offset.

dlr

p.s. Hi Pete, I see that we were typing at the same time.

[blue934]

GR Research woofers are intended to be surface mounted.

david

[Jeff B.]

GR Research woofers are intended to be surface mounted.

david

That may be true, but it doesn't change the fact that it will create some diffraction effects in the tweeter's response it it is nearby.

Now, how audible this diffraction is, is another matter.

[Pete Schumacher ®]

That may be true, but it doesn't change the fact that it will create some diffraction effects in the tweeter's response it it is nearby.

Now, how audible this diffraction is, is another matter.

And as David pointed out, cavity resonance from the nearby cone woofer will dwarf any flange related diffraction effects on the tweeter response.

[arlis_1957@yahoo.com]

i would think the thicker the flange, the greater the defraction. on a mtm i suppose it might be benificial. the da 175 in my avitar ar surface mounted.

[dlr]

That may be true, but it doesn't change the fact that it will create some diffraction effects in the tweeter's response it it is nearby.

Now, how audible this diffraction is, is another matter.

Jeff, the diffraction from the flange, especially on-axis, measures minimally.

dlr

[dlr]

GR Research woofers are intended to be surface mounted.

david

IIRC all Dynaudio woofers and midwoofers were designed to be surface mounted as well. I flush-mounted mine when I started (my first systems used these), but today I would surface mount them.

dlr

[raiderone]

The more important aspect is changed little with flush mounting and that is the diffraction of the tweeter response caused by the diaphragm of the next nearest driver. It's a large cavity and its impact is orders of magnitude larger the the side edge from the frame of a surface mounted driver, hence my consistent use of felt between tweeter and next driver for diffraction control.

So how much felt is needed to control the diffraction in the tweeter response that is caused by the cavity of the next nearest driver(s)? Say in a typical tweeter crossover of around 2kHz next to a 5" midwoofer and in general terms for the felt to be effective, what minimum thickness and space is required to the next nearest driver? Thanks.

[dlr]

So how much felt is needed to control the diffraction in the tweeter response that is caused by the cavity of the next nearest driver(s)? Say in a typical tweeter crossover of around 2kHz next to a 5" midwoofer and in general terms for the felt to be effective, what minimum thickness and space is required to the next nearest driver? Thanks.

1/2" thick x 1/2" wide x 5" long gives good results. Best results are with 1" thick x 1" wide, but you very quickly hit the point of diminishing returns. SAE F-11 is best but F-13 is still very good. I usually cut the length to match the diameter, but this isn't strictly necessary, it just has to be long enough to occlude the woofer from the tweeter's "perspective" so-to-speak.

dlr

[Theresa]

1/2" thick x 1/2" wide x 5" long gives good results. Best results are with 1" thick x 1" wide, but you very quickly hit the point of diminishing returns. SAE F-11 is best but F-13 is still very good. I usually cut the length to match the diameter, but this isn't strictly necessary, it just has to be long enough to occlude the woofer from the tweeter's "perspective" so-to-speak.

dlr

I believe its on the Zaph Audio site where there are tests measuring the effect of diffraction and demonstrates that for tweeters and midwoofers not flush mounting effects the response negatively and significantly. Flush mounting was not developed in order to make speakers look better as almost all non-audiophiles leave the grills on anyway. Also, felt tweeter rings are tested and shown to have negative effects. Now, thicker felt, as discussed here, can be used for positive effect, perhaps preventing diffraction. There is no need to flush mount subs though, mine aren't. I'll keep flush mounting until there's data contradicting that on Zaph Audio. John Krutke is not one to fall for myths, although I don't agree with him about everything.

[benchtester]

I believe its on the Zaph Audio site where there are tests measuring the effect of diffraction and demonstrates that for tweeters and midwoofers not flush mounting effects the response negatively and significantly. Flush mounting was not developed in order to make speakers look better as almost all non-audiophiles leave the grills on anyway. Also, felt tweeter rings are tested and shown to have negative effects. Now, thicker felt, as discussed here, can be used for positive effect, perhaps preventing diffraction. There is no need to flush mount subs though, mine aren't. I'll keep flush mounting until there's data contradicting that on Zaph Audio. John Krutke is not one to fall for myths, although I don't agree with him about everything.

I'm a Zaph fan, too; but dlr (a.k.a. Dave L. Ralph) is a felt guru. His data can be found here (on his web site):

http://www.speakerdesign.net/felt_am...ltssenter.html

(One has to click on the table entries to see the graphs.)

[fbov]

http://www.zaphaudio.com/mtg-surface.html

Always better to review the data before posting...
"Never, ever surface mount a 4" flange tweeter. Other than that, you have a little flexibility and your choice of driver mounting is mostly influenced by looks and acoustic center issues. Even those issues are minor."

[fastbike1]

Ain't that the truth.

I always like to check the source before I quote. That way, when my foot goes in my mouth I can say I did it on purpose.

http://www.zaphaudio.com/mtg-surface.html

Always better to review the data before posting...
"Never, ever surface mount a 4" flange tweeter. Other than that, you have a little flexibility and your choice of driver mounting is mostly influenced by looks and acoustic center issues. Even those issues are minor."