I have 8" center at 63cm ,is low to me .....with some ° inclination tooHere is an example of doing OB's the supposed "wrong way" and yet it still sounds good to me.
A lovely midrange and overall sound even though the small baffles are NOT on the floor.
The Lii Fast-8 drivers may be the reason why? Btw, this is a 1960's mono recording
I can't tell what electronics he's using with that turntable:
That said I think it might be improved by adding a good/fast sub and a pair of super-tweeters.
the Perceval suggestion 300/500hz is good , but you can test 80>300 too all depend room and power you will put in ....
tipical ob http://www.quarter-wave.com/OBs/OB_Theory.html
http://www.quarter-wave.com/Projects.html
Ps remember the single ended amp(hight impdedence out ) can rise the Qts 30%...by Qes
Nelson made F1/F2 Current Source Amplifiers and Full Range Drivers https://www.firstwatt.com/pdf/art_cs_amps.pdf
It would be a mistake thinking that bigger is always better for overall music reproduction quality with OB's. Sure bigger can sound better ... if... it's done right.
Lots of people who experimented a lot with OB construction (including Randy who makes the Caintucks) ended up reducing the size of the baffle and found the soundstage/image, frequency balance and various aspects improved. Size and shape of OB for any given driver(s) choice is kinda an art, not unlike other types of speaker cabinets. Here's a good example of a guy experimenting with different baffle size/shape and like it better reducing the size.
And here's a video/audio demo of the Caintuck-Betsy-OBs with a low powered tube amp.
Last edited:
@nandappe are you familiar with this TQWT design? It looks interesting with the floor firing exit.
I wonder if this design might help some things? You might get better bass response due to better floor/room effects and bass expansion like from a down-firing subwoofer - especially when placed in the corners of the room.
And you can experiment/tune the sound of the cabinet by changing the how high it is off the floor which changes the size/area of the exit opening. For example you could place it on the floor without any feet (no space) to see how it sounds as a completely sealed cabinet then test it at various heights above the floor until you get the sound you like.
Attachments
sorry but you cannot put 8" that low in the floor ....is the BASIC in all speaker system
Narrowing the exit, whether bass reflex or TQWT, will aid the ducting effect.
Floor-standed bottom openings are difficult to adjust.
Attachments
Yikes that is a complicated cabinet to build. Reminds me of folded back horns I've made in the past.
Sorry, but I don't agree. And I've known the guys over on the Decware forum and Steve the owner (who made the recordings and review) for many years, they don't lie about their reviews or make fake recordings. Did you even listen to those recorded videos (with a headset) I posted above?
You can hear it sounds very good!
I think it's possible you're making assumptions based on the knowledge you have about 8" speakers in cabinets.
Well, Open Baffles interact with the floor/room much different than a boxed speaker.
Read about "boundary effects" here >> https://www.enjoythemusic.com/diy/0709/open_baffle.htm
Last edited:
OK I have narrowed down my use of this driver to two options:
Option 1 an Omega-inspired speaker as a combination of their Junior 8XRS and the Super Alnico High Output XRS floorstander. This would use the SB SB20FRPC30-8 inch full range without any filter in a sealed box at the top part of the speaker. The lower woofer would be an SB Acoustics SW26SFC38-8 10 inch ’subwoofer’ in a sealed lower portion of the cabinet. This woofer would be powered by its own plate amplifier - Dayton Audio now do Class D amplifiers that are now available in Europe (correct voltage) and LPF up to 200hz, which is what the passive lower woofer does in the Omega Super Alnico High Output XRS does apparently. I am still on with calculating the cabinet volumes but my experience of the 10 inch subwoofer is that it works well in a 15 litre sealed box - a fairly ‘dry’ accurate if not particularly deep bass response.
Option 2 is a Spatial Audio Europe inspired design combining elements of the Pure 12/15 with the No. 5. My design would involve the SB20FRPC30 at the top in an OB set-up. I would then use an SB Audience Bianco 12OB150-01 running as a mid-bass driver using a passive crossover mounted midway up and finally an SB Audience BIANCO-15OB350 mounted lower in the front baffle and this time running actively from a plate amplifier. Whilst this will be an easier project woodworking-wise I am a bit out of my depth with the crossover between the 12 inch Bianco and the full range driver so any suggestions would be greatly appreciated. They are both 8ohm drivers with 92 db sensitivity for the FR and 96 db sensitivity for the 12 inch if that helps? I would like to keep it an 8ohm speaker. I am wondering about a crossover point between 400 - 500 hz but this is a guess based on previous posts - as for the slope?
If I get a chance I will draw and upload some ‘concept’ sketches for each one.
Option 1 an Omega-inspired speaker as a combination of their Junior 8XRS and the Super Alnico High Output XRS floorstander. This would use the SB SB20FRPC30-8 inch full range without any filter in a sealed box at the top part of the speaker. The lower woofer would be an SB Acoustics SW26SFC38-8 10 inch ’subwoofer’ in a sealed lower portion of the cabinet. This woofer would be powered by its own plate amplifier - Dayton Audio now do Class D amplifiers that are now available in Europe (correct voltage) and LPF up to 200hz, which is what the passive lower woofer does in the Omega Super Alnico High Output XRS does apparently. I am still on with calculating the cabinet volumes but my experience of the 10 inch subwoofer is that it works well in a 15 litre sealed box - a fairly ‘dry’ accurate if not particularly deep bass response.
Option 2 is a Spatial Audio Europe inspired design combining elements of the Pure 12/15 with the No. 5. My design would involve the SB20FRPC30 at the top in an OB set-up. I would then use an SB Audience Bianco 12OB150-01 running as a mid-bass driver using a passive crossover mounted midway up and finally an SB Audience BIANCO-15OB350 mounted lower in the front baffle and this time running actively from a plate amplifier. Whilst this will be an easier project woodworking-wise I am a bit out of my depth with the crossover between the 12 inch Bianco and the full range driver so any suggestions would be greatly appreciated. They are both 8ohm drivers with 92 db sensitivity for the FR and 96 db sensitivity for the 12 inch if that helps? I would like to keep it an 8ohm speaker. I am wondering about a crossover point between 400 - 500 hz but this is a guess based on previous posts - as for the slope?
If I get a chance I will draw and upload some ‘concept’ sketches for each one.
Hi Nandappe,
Beautiful work! I'm tempted to try these SBs in my Viech cabinets http://www.jogis-roehrenbude.de/LS-Box/Berndt_Burghards-Viecher/Viech.htm
Why do you doubt that these drivers would work in BLH cabinets? I.e. what spec do you refer to with 'powerful'?
Just curious - TIA
Simon
I ask you why all the world put the tweeter at ear height ??
you know reflect sound vs direct ??
I build speaker from 1985 and start open baffle 14year ago , avoid who make business
I have decided that my D55 is not powerful enough because of the loose low end.
I think a small to medium sized BH would work.
Attachments
that Beyma 8AG/N seems like a strange driver choice to use for a BH with such a high Qts.
plus the Fs is much higher than the SBs.
I think you may find these SBs will sound better in your cabinet, esp the bass response.
And this guy posted above that he likes the SB in his Coral BH here.
Attachments
Last edited:
I don't understand what you mean here.
You are saying you think the BH cabinet in your pic is too big for the SB?