Hybrid H-Frame, OB and nude driver

[Pano]

Yeah, I was afraid that might be a problem.

[iamvalheru]

Would Dayton UM18-22 in a H-frame and powered by a 250W NCore amp be good for decent SPL flat down to 30Hz?

[jjasniew]

Originally Posted by iamvalheru

2500 Hz seems to be the sweet spot between most ribbon tweeters and mid range woofers.

I don't know of any 6-8" woofers that you can crossover at 8K+ other than full range drivers, and at that frequency what happens to constant directivity?

OK, a design trade-off. Let's be glad the physics works out that we can at least choose!

[iamvalheru]

Some minor change of plans, for the low end I will be using a single Goldwood GW-1858 in a H-frame per side since I just found a local Canadian dealer that can get them for less than the Alpha-15A.

Since this is my first OB, and to keep it simple, I've decided to start with a Tang Band W8-2145 in the nude from 600 - 800 to 20K Hz with the option to add a ribbon tweeter above 6K - 7K Hz or where the constant directivity of the W8-2145 stops.

If the W8-2145 don't work to my liking I'll just recycle them into the TV sound bar project I've been wanting to do, and use either SB Acoustics SB17MFC35-4 or SB17CAC35-4 instead.

Now all that I need, and I assume, is a 12 - 15" woofer to place in a no wider than 18 - 22" wide flat baffle to cover between the GW-1858 H-frame and the nude W8-2145.



Any recommendations on good low midrange woofer that would match well to the W8-2145 for use between 150 - 800 Hz, and preferably with a well vented cast basket?



Denis

[Pano]

The GW-1858 is a good choice. You don't really need anything between it and you fullrange if you put the fullrange on a decent baffle. The Goldwood and the WB-2145 will mate up just fine.

[CharlieLaub]

Originally Posted by iamvalheru

Some minor change of plans, for the low end I will be using a single Goldwood GW-1858 in a H-frame per side since I just found a local Canadian dealer that can get them for less than the Alpha-15A.

Since this is my first OB, and to keep it simple, I've decided to start with a Tang Band W8-2145 in the nude from 600 - 800 to 20K Hz with the option to add a ribbon tweeter above 6K - 7K Hz or where the constant directivity of the W8-2145 stops.

If the W8-2145 don't work to my liking I'll just recycle them into the TV sound bar project I've been wanting to do, and use either SB Acoustics SB17MFC35-4 or SB17CAC35-4 instead.

Now all that I need, and I assume, is a 12 - 15" woofer to place in a no wider than 18 - 22" wide flat baffle to cover between the GW-1858 H-frame and the nude W8-2145.



Any recommendations on good low midrange woofer that would match well to the W8-2145 for use between 150 - 800 Hz, and preferably with a well vented cast basket?

Denis

Please keep in mind that the TB fullranger will have no rear output above 2kHz. Since you hear both the direct sound, and reflected sounds and the reflected sounds are especially important for a dipole/OB system, this might leave the high end a bit diminished. Give it a try, and maybe you will like that tonal balance. But if you find some "detail" is lacking that might be the root cause.

[iamvalheru]

@CharlieLaub,

I was hoping for the TB full range to have better rear output, at least in the 4K Hz...

This being said, is the following a viable alternative; crossover the H-framed Goldwood GW-1858 at 250 Hz at which point switch over to nude SB Acoustic SB17CAC35-4 in a MTM configuration with dipole ribbon tweeter or is this too much to ask of those 6" woofers?


Thank you

D

[hop.sing]

Originally Posted by iamvalheru

@CharlieLaub,

I was hoping for the TB full range to have better rear output, at least in the 4K Hz...

This being said, is the following a viable alternative; crossover the H-framed Goldwood GW-1858 at 250 Hz at which point switch over to nude SB Acoustic SB17CAC35-4 in a MTM configuration with dipole ribbon tweeter or is this too much to ask of those 6" woofers?


Thank you

D

I measured a naked satori mw16, which is comparable in size to the sb17, and I would not cross that low. Measurement was taken with the driver in my Hand and roughly 1 Meter in front of the mic ca, 0 -90 degrees.
I just wanted to get the idea how this driver behaves.
I will use it from ca. 800 Hz upwards to around 2500Hz naked and try the new GRS Planar tweeter up there.

[CharlieLaub]

Originally Posted by iamvalheru

@CharlieLaub,

I was hoping for the TB full range to have better rear output, at least in the 4K Hz...

This being said, is the following a viable alternative; crossover the H-framed Goldwood GW-1858 at 250 Hz at which point switch over to nude SB Acoustic SB17CAC35-4 in a MTM configuration with dipole ribbon tweeter or is this too much to ask of those 6" woofers?


Thank you

D

Although 250 Hz would be a little low for a single SB18CAC is you use it nude (there would be a bit too much sensitivity loss) 500Hz can work well, or like you mentioned you could use two of them so that you can cross to the 18" driver at 250Hz.

The SB17CAC has a very clean midrange but usable Xmax is only around 2.5mm. This is still plenty for use to 250Hz. See this review of the driver:
SB Acoustics SB17CAC35-4 6 Inch Ceramic Midwoofer Review
You can skip to the "Bottom Line" section at the end for a summary.

[iamvalheru]

Yesterday I drafted on my CAD a quick 18" H-frame - nude 15" - nude 6" - nude Ribbon and it the 15" over the 18" pushes the tweeter way to high to be useful.

Therefore, and to try and keep the speaker assembly as small as possible, using nude drivers, and with the tweeter around 40" off the ground, how would one of these two other configurations fair at providing good sound quality, directivity and SPL output?

1. MMTMM all nude divers using SB17CAC35-4;

2. MMTMM all nude drivers, using a suitable 10" (e.g. Peerless 830668) and SB17CAC35-4.


Thank you