Bottlehead Forum
Other Gear => Speakers => Topic started by: opa1 on December 08, 2022, 07:35:33 AM
-
I've read that some of you have the OB-H-frame set ups. (karl, larpy). I'm wanting to build either the OB over the H-frame or NP SLOB. I have a bunch of FR drivers. FE-103, CHB, Betsy, 873 Zenith, Altec 403a, SP12B EV, Lii Audio MG-F8. I'm leaning towards the OB-H-frame.
I have the Betsy's in a GR type baffle and a sub doing lower duties. This sounds ok crossed around 80Hz. but, I know it can be better.
I've looked at MJK's h-frame article. Seems simple enough. 16" square baffle mounted in the middle. 7.5 deep front and back.
What are y'all using for the H-frame driver? Alpha 15A or some other high QTS driver? I'd also most likely use a plate amp for both drivers.
-
I built H-frames for GR Research subwoofer drivers, which are powered by plate amps. I have stereo subs. The "full range" drivers I use are Lii Audio F-15s. (They're not really "full range," and I eventually added a tweeter to get output above 9K Hz.)
It's more money, but I went the powered sub route. I liked the idea of having the extra flexibility and the extra power (my Lii Audio drivers are powered by a Kaiju). The Rhythmik PEQ370 plate amps I use (one sub and one plate amp per channel) work really well.
I have a small room, so I'm using smaller baffles for the F-15s than I'd like. Because of their small size, I get a –3 dB drop off above 120 Hz (where the F15s cross over to the subs), but I can live with it. The GR Research subs go down with authority to 30 Hz in my little room, and I can even hear output at 20 Hz.
Attached is a photo of my speaker set up.
-
I have the Betsy and a cheap GRS 15" woofer mounted on the same large baffle with partial wings extending up past the woofer. Each woofer has a dedicated 100W sub plate amp, and each Betsy has a large poly cap to keep the lowest frequencies out.
Karl
-
If you have a bigger room than mine, you could build your own version of Caintuck Audio's "bigger barrel" OBs. I originally had my Lii Audio F-15s in such baffles, and they definitely sounded fuller than they do in the tiny baffles I have them in now.
If I had the space in my little room, I'd put my F15s back into the bigger barrel baffles (see photo below) and place them atop H-frames with a sub.
-
Thanks for the quick replies. I had the F15's when they first came out. I sold them without really giving them a chance. Also had the small version of the Caintuck baffles.
Which GRS 15" driver are you using? MJK has a new set up out with a 18" Goldwood in a H-frame. Supposed to play lower than the Alpha15a.
http://www.quarter-wave.com/Project08/Jordan.pdf
-
I've looked at MJK's h-frame article. Seems simple enough. 16" square baffle mounted in the middle. 7.5 deep front and back.
where can I find this? I'm about to hook up my new F-15 Lii big barrel OB speakers I just built, and have no idea what to expect......
Steve T
-
I have a pair of Betsy's on flat baffles. The plan is to combine them with a pair of the Hawthorne 15 inch woofers I forget what they're called driven by a Crown XLS. This is a couple of projects up the line though...John
-
where can I find this? I'm about to hook up my new F-15 Lii big barrel OB speakers I just built, and have no idea what to expect......
Steve T
Not sure if this is what your asking but, here is the MJK U , H set up.
http://www.quarter-wave.com/OBs/U_and_H_Frames.pdf
-
GRS 15PF-8 15" from Parts Express. Claimed Fs 29Hz & Qts 1.39.
Karl
-
I don't have the space for them in my room, but Martin King's OB design using the Eminence Alpha 15A as a sub (http://www.quarter-wave.com/Project09/Project09.html (http://www.quarter-wave.com/Project09/Project09.html)) has always struck me as a good way to go. The baffles in OB design really need to be big (at least 2' by 2', and bigger is better) to get good bass. The smaller baffles with wings such as the one Opa1 copied from GR are, IME, just too small.
Better, I think, to put your Betsy drivers along with sub/woofers in a single larger panel (per Martin King's design above) than to build an H-frame to put under a small baffle with wings. It will certainly be easier: building an H-frame takes a fair amount of time and skill.
-
Here are the drawings of my OBs. The wings are folded back 90 degrees, the widths, curve and height variations present different sound-path lengths for bass cancelation. Built from 3/4" Plyboo, they are too big, but sound good to me.
Karl
-
Here is what I have done with my Betsy: https://zimmer64.wordpress.com/2015/11/08/bg-neo3-betsy-eminence-alpha-15-a-mk-iii/
Built them in 2015. I am still very happy with this one.
Michael
-
I built some baffles for my Zenith 49cz873 12" drivers. They work rather well. I'm thinking of using a pair of GRS 15 PF for the bass with a DSP plate amp. Or a mini dsp and a SS power amp for bass.
-
I bought the GRS 15PF-8 pair. Also the SD100 plate amp. Going the run the pair with one amp at a 4 ohm load. 6V6 tubes on the FR. Have to source the wood. It's a shame the wood costs almost as much as the components. LOL