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Multi-Way Conventional loudspeakers with crossovers

The Pencil: inspired by Ohm Micro Walsh Tall
The Pencil: inspired by Ohm Micro Walsh Tall
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Old 13th March 2018, 07:06 PM   #111
boswald is offline boswald  United States
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The Pencil: inspired by Ohm Micro Walsh Tall
Mad has the 5 1/4 poly, PE has it and the 'glass. I have played with most of the 5 1/4s, except the aluminum. These two will do fine. You'll pay 6$ extra each to have a slightly smaller box, less output.
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Old 15th March 2018, 12:28 AM   #112
R. Jamm is offline R. Jamm  United States
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I have more questions about putting this together. I don't have a lot of experience but I can and have put speakers together.
I got a pair of Peerless 83084 mid/bass 6.5 driver (from Madisound-- thanks boswald -- got the last 2 on sale).

I'm planning on using a cabinet size of (internal space) 7 x 8 x 36. Would like to port it from the bottom

You stated :
"Use the 6.5, put it in 14, Mad's port 2"x5.5"(up to 8" in some placements). " What do you mean by the part underline?

I know that the cabinet size affects the bass, but in what way? A cabinet size too big will do . . . ., too small will do...., does it affect the midrange?

The tweeter that I plan on using is the Seas Prestige 27TDF (someone on line used this tweeter with the Peerless driver. I haven't bought it yet--any opinions would be helpful. I'll try to keep the crossover like the one in this article or ... .

I'm planning on starting this project in a few weeks, so any comments or suggestions would be helpful.

Last edited by R. Jamm; 15th March 2018 at 12:31 AM.
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Old 15th March 2018, 12:50 AM   #113
boswald is offline boswald  United States
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The Pencil: inspired by Ohm Micro Walsh Tall
I meant 14 liters, about a half cubic foot. You'll have about a cube after bracing, port, etc.
You're getting in to quarter wave territory with that length, and your drivers will be rather high.
I'd suggest leaving off about 8", your tweeter will end up over 33". If you port on the bottom, you can lose another couple inches. I'll do some calculations later on tunings/ structures.
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Old 15th March 2018, 02:21 AM   #114
boswald is offline boswald  United States
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The Pencil: inspired by Ohm Micro Walsh Tall
You will not be able to use a crossover designed for a conventional arrangement, and you will be want to cross fairly high so you do not need a tweeter that trades high freq dispersion to go lower.

The crossover need not correct for a change from 4pi to 2pi. Just filters and tweeter level.
You might look at the SB19 or other 3/4" tweeters that have great top octave response.
The hardest thing in this project will be dealing with that truncated frame.

How low(long) are you willing to go? My Walsh 2s are 31.5" on little feet. 34" if I use casters.
The box is 24" outside height. The tweeter 2" from the top.
I have nomex and poly/paper on hand in that size hds, so I can do a test mockup if needed.

As for the relationship between box size and bass, more box can mean lower bass, small size can mean more power handling, go too far in either direction and you lose control of the opposing characteristic, too small a box and you've got a loud speaker lacking lows, too large and you can go very low, but only quietly.
Box volume will not affect higher notes unless you get really carried away with small.

Draw up a couple shapes you could live with, try to keep the volume down a bit(18-20liters)
and we'll see how to mitigate(or use) the tubeness of it all.
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Old 15th March 2018, 02:52 AM   #115
R. Jamm is offline R. Jamm  United States
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I can make the length\height to 28" or lower if needed and put the port on the back.

Why is the Walsh 1000 is 38" high and the cabinet is full to the top with some type of acoustic stuff?

Last edited by R. Jamm; 15th March 2018 at 03:01 AM.
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Old 15th March 2018, 03:25 PM   #116
boswald is offline boswald  United States
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The Pencil: inspired by Ohm Micro Walsh Tall
The 38" includes the 'can' and feet/casters, it's probably 30-31" outside, 28-29 inside the box.
It needs to be stuffed more as the proportions get more extreme, to suppress the peaks/dips caused by end loading the tube.
Martin King's TL alignment tables essay gives an explanation with a few examples, without going too deep into the math.
With the larger cross section (that you will have) the proportions are less severe and you can stuff the bottom fourth heavily(or third if you move the port up to the side) and leave the rest open(line the walls if you like).

Because of the enclosure shape what you have will be what we are calling a mass loaded transmission line, where a port and its air mass are together tuning the box, functioning similarly to a longer step-tapered line.
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Old 16th March 2018, 10:29 PM   #117
R. Jamm is offline R. Jamm  United States
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Thanks for all of the information that you provided.
The SB=19 or the Tang Band 28-847SA Dome Tweeter will be used. The Peerless only goes up to 4000, so should a crossover point be 3500 or 4000?

I was thinking of using just a high pass capacitor (metallized polypropylene) to the tweeter. For the Peerless driver, I'm still looking at a simple low-pass filter.

As far as the cabinet size, I'll be using 20-24" or whatever is recommended for this size driver.

Any suggestions would be helpful.
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Old 21st March 2018, 03:07 AM   #118
R. Jamm is offline R. Jamm  United States
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Thanks Critofur and Boswald for answering my questions on this project. I used one of the "building speaker cabinet" web sites to help me determine how big my cabinets should be.
After reading this site with the crossover I'm going to use a simple first order high pass filter (a capicator) to the tweeter. Woofer (full range), no crossover (still learning and got a long way to go--thanks for being patient with all my questions)
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