Another project, father/son

Jcricket

Jcricket

not someday, but today
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My son and I are going to build a set of speakers for him. The idea is to give him a set of full range speakers(30-20k) that are relatively small. I know we have to sacrifice efficiency but he typically uses only solid state any ways.

We have ordered two Dayton drivers fro each speaker. One is a 6.5" subwoofer, part number 295-198. We are going to put that in a .5ft3 vented cabinet tuned to 42 hz(optimal according to the PE website). The top will be the PE part number 295-378 Dayton Audio RS100-4 4" Reference Full-Range Driver. It will go into a .1ft3 vented cabinet tuned to 59hz(again optimal according to PE).

We also order the parts to make a pair of 1st order butterwerth xovers with a xover point of about 127hz. The FR has a rated spl of 87.5dB, the subwoofer is 87.4dB. We'll see how they match.

Some other specs on the drivers.
FR - 80-20khz response

I have not drawn up the box plans but I am thinking about 10 wide, 16.5 tall, and 11.25 deep.

This will be driven by a 150wpc Kenwood separates system that he has. I hope it turns out well. I'll get the stuff early next week an keep updates coming as we go.

Till later...........
Sub - 36-1.1khz response.
 
Sounds like a nice father/son project, jcricket!

The both of you will have some fun & remember this task always.

Keep us posted!

Rome
 
The drivers and crossover parts arrived today. I hope to have time to knock this out this coming weekend. I will post pics and progress as we go.

These will consist of a subwoofer for the lowest frequencies and a full range to compensate for the rest. The idea being to eliminate crossover anomalies in most of the music, allowing the full range to perform as it should(theoretically). These are to be used in a smallish room, about 10x12 at medium to low volumes. Not likely to exceed 100dB. I also wanted these to be small enough for my son to be able to take with him when he goes to college or into the future should he have his own office. The crossover is a simple 1st order butterworth. It may be tweeked after the cabs are built and the speakers are up and running.

Currently, my sketches are of a 10" wide, 14" tall, 12" deep cabinet. It will be sectioned off for each driver. The FR section will be tuned to 59hz and the sub to 42 hz. Crossover will be at about 125hz.



Pictures below are of the components.
 

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Really curious how this will sound!

I built some "Canzonettas" that use similar woofers but I also used Vifa D19 tweeters instead of the small ones in the plans. They sound fantastic!
 
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Sounds like quite a speaker for the size. What do you figure the +/-3dB response to be when those are up and running (Or better yet, what are you aiming for with them)?
 
Gang-Twanger said:
Sounds like quite a speaker for the size. What do you figure the +/-3dB response to be when those are up and running (Or better yet, what are you aiming for with them)?
Click to expand...

What will they be?? I don't know.

What am I hoping for? About 40-20k +/- 3db with about 87db SPL sensitivity.

What will I get, Probably a mess at the first run. I am currently looking for an active 3 way crossover. Everyone is telling me it is the way to go. I figure I could use it as a tool to easily(hopefully) dial it in and then be able to copy the xover frequencies into a passive crossover. All theoretical obviously.

The two drivers I picked are rated pretty well. They certainly are not top shelf items, but reasonable. What I expect is to get from about 40 to maybe 5k pretty well. The frequency response graph posted below show the 4" full ranges performance. It seems pretty jagged above 4k. One of the reviews talked about that a bit. So, if needed, I'll add a tweeter to the top to smooth it out.

And, since I currently have about 5 speaker projects planned, I am going get some software and microphones to try and actually measure the response of the completed speakers.


till later


Edit, the second attachment is the sub's frequency response.
 

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Jcricket said:
What will they be?? I don't know.

I am currently looking for an active 3 way crossover. Everyone is telling me it is the way to go.
Click to expand...

Looks like an interesting design. But, using an active 3-way crossover, will require 3 amps; one for each driver. That sounds a bit more complicated, than your originally stated design goals.

Also, just for grins, have you thought about running the 4.0" full range open baffle? Just bump up the low pass/high pass point a bit, to eliminate any bass wrap around cancellation, and you're good to go. With your 6.5" woofer, I'd try around 300Hz. Low enough to not interfere with mids, and high enough to still get good lower mids from the full range.

Regardless, good luck, and have fun! :thmbsp:
 
Jcricket said:
The FR section will be tuned to 59hz and the sub to 42 hz. Crossover will be at about 125hz.
Click to expand...

Do you mean that the full-range driver is to be mounted in a reflex cab? Bear in mind that at tuning output is a full 180* phase change, hence two seperate drivers with seperate tuning is not a good configuration (even with the crossover, the FR is likely only 3-6dB down at this frequency too).
 
You folks are starting to talk way over my head. I am very much a beginner here. I appreciate the input though.

The cabinet I am building will have too different sections. Both of them ported. Essentially the FR portion will be contained within the sub cabinet.


I am looking at active crossovers that are capable of either 2 or 3 way configurations.
 
I'd try tuning it differently

Treat it like the woofers are configured, in a 2.5 way speaker (yes, I know you don't have a tweeter- but think of JUST the woofers).

Try a vent frequency of about 35-40 Hz for BOTH chambers- use the exact same tuning frequency in both.

Then, use the "subwoofer" only up to about 50 Hz or so. Let the "sub" act as a "helper woofer" in the bottom end.

This will allow both drivers to "contribute" to the low bass- with the second one coming in, right at the point where they're starting to roll off. The additional energy of the second woofer, will lower the effective f3 point of the system quite a lot. And, since both woofers have the same port frequency, there should be minimal cancellation between the two (they should couple together more effectively than if they're tuned differently in frequency).

You will need to experiment, a bit, with the crossover frequency of the second woofer, and the vent tuning of both chambers- but this SHOULD be able to be made to work well.

Regards,
Gordon.
 
Hey Gordon,
Thanks for chiming in. I'll try your suggestion. I think I follow what you are saying. A couple of questions.

Use the sub up to about 50hz or so - get tis frequency through a crossover or low pass filter?

Experiment with the crossover frequency of the second driver - possible a different xover frequency than the sub? Again, a high pass or xover to get it?
 
I ran some numbers in WinISD - FR in a sealed small-box (nominally 1.2 litres), woofer box is 6.7l and tuned to 40Hz with a 3.5cm diameter tube 24cm long. Overall box dimensions might be something like 8x10x14 with the enclosure within for the mid at 5.5x7x4, all assuming 18mm board.

I've assumed the inductor has a dc resistance of about 0.5 Ohms.

Theoretical response chart is first attachment. I'd choose a crossover frequency of 160Hz 1st-order. For the purposes of component calculation, use 4.6Ohm for the FR and 3.5Ohm for the sub.

Interestingly adding 10g mass to the sub cone looks to provide some benefit at the expense of some power handling at 60Hz, some charts for that attached as well.
 

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JImbo,
Thanks for the charts.
Any FYI, parts express has some charts online with actual measurements. The sub is 3.0 ohm and the FR is 3.8 ohm.
 
Okay.

I am looking at purchasing a software and microphone for my laptop. Any suggestions as to a decent software/system/mic to measure the output of the speakers?

I have found a few free down loads. I am looking at several different USB external soundcards for the audio out and mic input. What type of mic - condenser I think?
 
Jcricket said:
Hey Gordon,
Thanks for chiming in. I'll try your suggestion. I think I follow what you are saying. A couple of questions.

Use the sub up to about 50hz or so - get tis frequency through a crossover or low pass filter?

Experiment with the crossover frequency of the second driver - possible a different xover frequency than the sub? Again, a high pass or xover to get it?
Click to expand...

Yes, some sort of low-pass filter on the second driver. This is probably one of those cases, where a low-slope (like 6 or 12dB/oct.) would be preferable to a higher order filter. You want the integration to be "gradual" rather than abrupt, and lower-slope filters also have less phase shift (which would result in less cancellation issues).

You won't need a high-pass filter on the first driver. Just let it play down as low as it can go, naturally. Unless this thing is going to get hammered on (i.e, concerns about bottoming out), it probably will be a good idea to use as much of the low-end out of the first driver, as possible- and let the second driver help out just enough, to get as much LF extension as possible.

Regards,
Gordon.
 
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