Full range speaker enclosure volume

[bengineer]

Hi all

I'm building my first speaker, with 2 3" full ranges and 1 6.5" woofer.

I've determined that the woofer needs 1.53 ft^3, however calculations for the full range speakers are proving a bit tricky.

These are the ones I have bought, I plan to put them both in sealed enclosures.
http://www.parts-express.com/peerless-by-tymphany-tc-series-tc8fd00-3-full-range-speaker-4-ohm--264-1145
If anyone could point me in the right direction of a recommended volume/calculations to arrive at one I would be very grateful.
Thanks

 

[TLS Guy]

Hi all

I'm building my first speaker, with 2 3" full ranges and 1 6.5" woofer.

I've determined that the woofer needs 1.53 ft^3, however calculations for the full range speakers are proving a bit tricky.

These are the ones I have bought, I plan to put them both in sealed enclosures.
http://www.parts-express.com/peerless-by-tymphany-tc-series-tc8fd00-3-full-range-speaker-4-ohm--264-1145
If anyone could point me in the right direction of a recommended volume/calculations to arrive at one I would be very grateful.
Thanks

The volume can be quite small, and will not be critical.

A few points. You can pretty much claim any speaker to be full range. Your little Peerless drivers are clearly not full range but have a very decent bandwidth.

First of all they are very high Q drivers (0.9) so they can not be driven down to, or below Fs of 125 Hz. If you do things will be very muddy. Those drivers need to be at least 24 db down at 125 Hz. If you are going to drive a speaker below Fs then you need a Qts of 0.35 or even better a bit less.

On the top end things start going severely adrift above 3 KHz and the driver is totally out of bounds by 7.5 KHz and above due to severe cone break up.

So the actual usable bandwidth of those drivers is 400 Hz to 3 KHz. Not bad.

The next thing if you are using two of them then you will have comb filtering problems.

The best way to deal with that since they need crossing over at around 3 KHz is to use the MTM format and put a tweeter between the two mids.

I don't know what woofer you are using. However making a three way speaker is a significant undertaking. You will almost certainly for your first time out be better off crossing your woofer to a tweeter as a two way, and dispensing with the mids.

Basically you want to try on keep the number of crossovers to the minimum unless you are using large diameter woofers.

 

[bengineer]

Hi

Thanks very much for your reply.

I think I will take your advice and use a MTM configuration, with a woofer too.

The amp I have purchased has L-output, R-output, and a low-passed output for a woofer.
Therefore, my query becomes how to setup the L and R with the MTM for best results.

Essentially I need to implement what you described in your above post - bandpass the mids between 400Hz and 3kHz, and have the tweeter take care of everything above.

Any advice on this implementation much appreciated.

Thanks again

 

[TLS Guy]

Hi

Thanks very much for your reply.

I think I will take your advice and use a MTM configuration, with a woofer too.

The amp I have purchased has L-output, R-output, and a low-passed output for a woofer.
Therefore, my query becomes how to setup the L and R with the MTM for best results.

Essentially I need to implement what you described in your above post - bandpass the mids between 400Hz and 3kHz, and have the tweeter take care of everything above.

Any advice on this implementation much appreciated.

Thanks again

The low pass output is for a subwoofer and not a woofer, there is a big difference. You are going to have to design a complete three way crossover.

 

[bengineer]

Thanks, I'll do that then.

The bit that confuses me is this: if I'm using 1 woofer and 1 tweeter, with 2 "full ranges", obviously I will have one full range for L and R, but what about the woofer and tweeter?

 

[TLS Guy]

Thanks, I'll do that then.

The bit that confuses me is this: if I'm using 1 woofer and 1 tweeter, with 2 "full ranges", obviously I will have one full range for L and R, but what about the woofer and tweeter?

I'm sorry, but you are way out of your depth. You need to design, and then build, a three way crossover, low pass. band pass and high pass. The crossover needs to match the acoustic responses of the drivers and level balance them. This is not easy and requires a computer modelling program.

 

[bengineer]

Thanks for your reply, I appreciate your honesty.

I think I have a plan to make things a little simpler.
If I convert the stereo input to mono at line level pre-amplification (with something like this http://marcusmorris.blogspot.co.uk/2010/04/stereo-to-mono-converter-how-to-do-it.html),
then, clearly, the L and R outputs of the amp will be the same.
I can bandpass the L channel and run the two mids off that, then use the R channel with a two-way crossover to drive the woofer and tweeter.

Do you think this is plausible?

 

[TLS Guy]

Thanks for your reply, I appreciate your honesty.

I think I have a plan to make things a little simpler.
If I convert the stereo input to mono at line level pre-amplification (with something like this http://marcusmorris.blogspot.co.uk/2010/04/stereo-to-mono-converter-how-to-do-it.html),
then, clearly, the L and R outputs of the amp will be the same.
I can bandpass the L channel and run the two mids off that, then use the R channel with a two-way crossover to drive the woofer and tweeter.

Do you think this is plausible?

This is just crazy stuff. You obviously have no concept of what a crossover is never mind a band pass filter.

We just can't help you on a forum like this I'm afraid, as you don't have enough basic knowledge of electronics.

What is your woofer? I don't think you have told us. Your best bet is to forget the mids, and just use woofer and tweeter. You are years away from a three way build.