Terry Cain's BIB -why does it work and does anyone have those Fostex Craft Handbooks?

[el`Ol]

I have a principal question: is it possible to remove a peak that`s close to Fs, where the impedance curve isn`t flat?

 

[GM]

Greets!

?? Do you mean underdamped peaking, which means either series R is required or Sm needs to be smaller?

GM

 

[el`Ol]

I have a peak slightly above 100Hz in the simulation that could probably not be removed by damping and would like to use a passive notch filter for correction. Drivers with too low Qts peak at very low frequencies and have a deep and wide hole above, what could probably be corrected by a series resistor, I don`t mean that.

 

[GM]

Greets!

You can, though it won't be flat without a zobel, or if it's too near Fs, then a series notch filter to flatten the Fs peak.

GM

 

[fred76]

Greets!

I assume so, based solely on comparing published specs. You need at least this much to get a ~BIB response, so if the amp has more, it will alter the response similar to adding the difference in series R to a driver that doesn't need it.

GM

Hi GM,

So you mean if the amp has high enough output Z to offset the driver's need for a series R filter, it could still have a ~good response for a BIB? So am I right to assume that it's still "build and listen with and without series notch filter" to suit to taste? Thanks.

fred

 

[GM]

Greets!

Correct.

GM

 

[Ray Collins]

Progress Report

I am at the point of finishing the cabinets and thought that an intermediate progress report might be of interest. The cabinets are on my consumable cutting table and are ready for the side to be attached. I stripped out two pairs of CAT5 and bonded them to the inside with silicon.

 

[Ray Collins]

My apologies.....the picture file size is too large and will not transmitt. If anyone has a suggestion please provide it.

 

[Godzilla]

I hope this cat 5 thing works... i wired my BIB with it because i didnt have regular speaker wire..... 8 strands.... 4 to positive.... 4 negative... 24 guage each little strand.

 

[Ray Collins]

Godzilla:
I do too. I used the CAT5 for the same reason.....I was out of speaker wire and zip cord.

Can you help with my picture problem?

 

[blumenco]

it depends...

I just use a single twisted pair of the stuff. one wire to positive (usually color) and one wire to negative.

try to keep the length short and it sounds good. actually it sounds great. that is, at below 15 watts...

thicker gague magnet wire is a little better though..

Clark

 

[el`Ol]

Hello GM!

Thanks for the tip with the series notch filter.

Hello everybody!

I guess it will be an easy task for MJK to modyfy his BLH model so that a TQWT-style closed end instead of a compression chamber can be modelled. Maybe for the lower Fs drivers this is the way to go to avoid silly sizes.

Greets, Oliver

 

[Ray Collins]

Well I used two twisted wires per driver terminal, i.e., four wires per driver...should be twice as good?!

 

[GM]

I hope this cat 5 thing works... i wired my BIB with it because i didnt have regular speaker wire..... 8 strands.... 4 to positive.... 4 negative... 24 guage each little strand.

Greets!

This equates to a little smaller than 18 Ga, so depending on how long the runs are and the amount of current they will need to pass, they will either be fine or act as a series resistor of 'x' value.

GM

 

[GM]

My apologies.....the picture file size is too large and will not transmitt. If anyone has a suggestion please provide it.

Greets!

Davey Jones? turned me on to 'SnagIt' awhile back or you can use the re-sizing feature and link it from an image hosting site such as ImageVenue.

GM

 

[GM]

Hello GM!

Thanks for the tip with the series notch filter.

Hello everybody!

I guess it will be an easy task for MJK to modyfy his BLH model so that a TQWT-style closed end instead of a compression chamber can be modelled. Maybe for the lower Fs drivers this is the way to go to avoid silly sizes.

Greets, Oliver

Greets!

You're welcome!

You can do it the way it is now, but why bother since the ML-TQWT WS works fine?

Oops! I just 'outed' myself! I've been getting Scott to do the sims since I don't have the latest WSs that have the higher SPL plot field. I forgot about being able to do them in the BLH WS. Still, for consistancy's sake, IMO they should all be done with the same WS.

Once the different SPL scaling is accounted for, T.C.'s RS 40-1354 'BLH' sim looks 'close enough' for me:

GM

 

[Godzilla]

... the picture file size is too large and will not transmitt. If anyone has a suggestion please provide it.

Hi Ray... if you double click the icon of your image and it opens in a program called 'Microsoft Office Picture Manager' i can tell you how to modify it so you can upload it to the forum.

Godzilla

PS Thanks GM on the 18 Ga estimate. Usually 16 Ga RS is what i have lying around. Peace.

 

[el`Ol]

You can do it the way it is now, but why bother since the ML-TQWT WS works fine?


GM

Hello GM!

I have come to this thread quite late and I have to admit I have not gone to all this awful lot of pages. According to what I have read at the beginning, wasn`t there the problem that sims did`t work properly?

regards, Oliver

 

[GM]

Greets!

I haven't read all of the thread either, but I assume you're referring to the fact that none of MJK's freeware WSs will show the effects of the room beyond an infinite half space loading, which is all Scott has been publishing even though he has the licensed WS that allows a certain amount of room loading and floor bounce modeling.

Anyway, as you can see, the freeware BLH WS sims more than 'close enough' to his latest shareware ML-TQWT WS by inputting the BIB's design into the BLH coupling chamber fields and listing the horn length as 0.001, with St, Sm = SL, and linear flare rate.

GM

 

[Godzilla]

As per Ray Collins... here's your pic.

Nice job! I butt joined everyting... would have liked to mitre like you but dont have the tools.

Godzilla