B&C Sub designs

Re: B&C Sub designs

Freq ( hz), b+C port, (db) my port ( db ) ( He's also high passing at 40 hz)

33, 126, 123
35, 127, 125
40, 128, 129
45, 129, 130
50, 129, 131
55, 129, 131
60, 129. 131
65, 130, 131
70, 131, 131

So for the few times a night that the box will need to go below 40 hz, ( at this point a few db difference will not even be easy to hear), some of you want to risk, over excursion, increased port velocity, less power handling capability, ( where the box will be 99 % of the time).

Hey thats why this is a DIY forum!! I know what I would do, and some may choose to do something else. Thats up to the individual!!!

Great topic, I had a good time with it Best of luck to you Kip!!!! :)~:-)~:smile:
 
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Re: B&C Sub designs

Just wanted to compare the b+c tbw to the Faital pro 18xl1500 for the heck of it. When I built my subs that was the one I picked, its no longer available, but has been replaced by a new faital model.

After plugging numbers on the NEW B+C tbw100, its almost a mirror image, I mean I've never seen any two speakers so close from 30 to 100 hz in every aspect. long story short, B+C did there home work. Should be a great sounding build for you Kip
 
Re: B&C Sub designs

Exactly Alan,

I think either way he goes he will be significantly better off than his current boxes with that .75" deep "port".

Thanks for giving him a second design option to look at.

Good luck Kip.

Loren

Alan Sledzieski said:
Freq ( hz), b+C port, (db) my port ( db ) ( He's also high passing at 40 hz)

33, 126, 123
35, 127, 125
40, 128, 129
45, 129, 130
50, 129, 131
55, 129, 131
60, 129. 131
65, 130, 131
70, 131, 131

So for the few times a night that the box will need to go below 40 hz, ( at this point a few db difference will not even be easy to hear), some of you want to risk, over excursion, increased port velocity, less power handling capability, ( where the box will be 99 % of the time).

Hey thats why this is a DIY forum!! I know what I would do, and some may choose to do something else. Thats up to the individual!!!

Great topic, I had a good time with it Best of luck to you Kip!!!! :)~:-)~:smile:
Click to expand...
 
Re: B&C Sub designs

Ha! I have a rule ... no 5 string basses... Actually my boss sets the rules and the rule is P-bass or Jazz Bass for the stage, need to go lower? Hipshot or tune. Of course it has nothing to do with the sonic qualities. He just doesn't like they way they look!
 
Re: B&C Sub designs

It's an experiment for me. I don't expect to get it right the first time- there's a lot for me to learn about building cabinets.

I did a show in Berkley tonight and my house engineer was a Meyer Guy (his name is listed on the MSL4 Patent). We talked a little about what I'm trying to do and he said it's going to come down to some personal preferences on tone.

Also- the 40Hz HPF can come or go. It somewhat depends on how the box performs in that area.
 
Re: B&C Sub designs

Kip Conner said:
It's an experiment for me. I don't expect to get it right the first time- there's a lot for me to learn about building cabinets.

I did a show in Berkley tonight and my house engineer was a Meyer Guy (his name is listed on the MSL4 Patent). We talked a little about what I'm trying to do and he said it's going to come down to some personal preferences on tone.

Also- the 40Hz HPF can come or go. It somewhat depends on how the box performs in that area.
Click to expand...



Theres not much going on below for, depending on the room most of the time it sounds better with a 40 hz hpf ingaged, cleans up the mud.
 
Re: B&C Sub designs

Old (Blue Trace) vs New (Green Trace) with 8" Port Wall:

Old VS New.jpg

8" (Green Trace) Port Wall vs 12" (Teal Trace) Port Wall

New 8 vs 12.jpg

If I had a +3dB bump at 54.4Hz with a .60 Q (BBS FDS 336) I can pretty much smooth out the response.

The biggest thing regarding the re-design is the lack of port choking that occurred in the older boxes. We started with the 8" wall version, took measurements and then replaced the 8" wall with the 12" wall. I used no HPF on the measurements and set the LPF to LR24 105Hz. The overall SPL was improved not by amplitude, but by usable amplitude. The old design began to really choke at 50Hz and abruptly cut off at 45Hz. The new design extends to 30Hz with no choking.

My biggest challenge now is the lack of weight... it really wants to dance around as a single cabinet!
 
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Re: B&C Sub designs

So these measurements are just the old OAP boxes with a 2.5" tall port and you added an 8" port wall and a 12" port wall and measured? Interesting that 3db peak at 38 hz on both versions. What freq was the excursion minimum at? I would be a little careful about a boost at 54 hz on that as it may be a frequency rangewhere you are excursion limited. Certainly much better than the original. BTW I would think that what you call port choking at 50hz and then abruptly cutting off at 45 hz would more accurately be just the fact that the output of that design drops abruptly at those frequencies. That is because the "port" in the original OAP design had a resonance around 75 hz that just failed to help the box's output down low. All it did was provide a big hump in the response around 75 hz. The term port choking would refer to the idea that at high output the port airflow becomes turbulent and the port fails to perform as it did at low drive levels. It is likely that your 8" and 12" deep port designs will experience port compression effects at high drive levels using those TBW100 drivers. So if you measured either of those ports with 2.83v and again with 115v (for example) you would find that there would be significant differences between the two with the output in the 35 to 45 hz range being sacrificed at the higher drive level because the port isn't able to perform properly and provide the output in that range that it did with the lower drive level.

With all that said, either one will be much better than what you had.

Loren

Kip Conner said:
Old (Blue Trace) vs New (Green Trace) with 8" Port Wall:

View attachment 4694

8" (Green Trace) Port Wall vs 12" (Teal Trace) Port Wall

View attachment 4695

If I had a +3dB bump at 54.4Hz with a .60 Q (BBS FDS 336) I can pretty much smooth out the response.

The biggest thing regarding the re-design is the lack of port choking that occurred in the older boxes. We started with the 8" wall version, took measurements and then replaced the 8" wall with the 12" wall. I used no HPF on the measurements and set the LPF to LR24 105Hz. The overall SPL was improved not by amplitude, but by usable amplitude. The old design began to really choke at 50Hz and abruptly cut off at 45Hz. The new design extends to 30Hz with no choking.

My biggest challenge now is the lack of weight... it really wants to dance around as a single cabinet!
Click to expand...
 
Re: B&C Sub designs

No. The first comparison is of the OAP box and the new box (with an 8" port wall). Than we pulled out the 8" port wall of the new box and swapped it with a 12" port wall for the second comparison.

The port choking wasn't something that showed up Smaart since I measured at low levels. It was only audible at high volumes in the OAP design around 50Hz -it wasn't audible in the new design.

I think that the OAP box would make a great drum sub with it's natural roll off- if my drummer ever wanted a drum sub. He's been playing long enough that he knows what his right foot is doing, he just needs to know what everyone else is doing.
 
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