Pioneer 8" fun

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I made an order from Parts express last week and decided to give myself a little gift. I wanted something to play around with that would be fun so I got a pair of Pioneer B20FU20-51FW woofers. I wanted to start breaking them in a little bit and once again found the box that they shipped in very useful.

I think this is going to be a very fun little project. I modeled the driver and I'm gonna build a somewhat massive box that is going to be tuned to around 32hz (I can't remember exact figures right now) but the bass from the 1ft^3 box is not bad. They also seem to go pretty high, but I think I am going to add a helper tweeter. Its really hard to say what they sound like right now, but they seem to sound superizingly good.

For the real box I wanted to try tonge and groove joints all around. I wanted to know if the box will be at all sturdy if it is over 3ft^3 with no screws only tonge and groove and glue.



P.S. Here are some pictures of my 1ft^3 box from PE.
Sorry the pictures were taken with my phone this morning.

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An externally hosted image should be here but it was not working when we last tested it.
I'm doing the same type of thing Nelson, with this and a tiny JBL tweeter I have from one of their SCS series satellites that I got from a friend - for free. I may even try mounting it coaxially (it's that small) by removing the dustcap of the QSL and using the whizzer as a waveguide for the tweeter (10k sounds about right). $9 well spent:D .


How do you guys like them?

I have been hearing lows of things about waveguides recently and AJinFLA I saw your orions and I really like the tweeters your have on them and I was wondering where you got the wave guide for them. I was actually gonna email you and ask you that because I want to try using that tweeter and I wanted to see if it would mate well with these pioneers.

Nelson Pass,
1. Glad to see you away from your home, although I have never talked to you I have heard great things about you.
2. 200 of them? why do you need that many?
3. Which tweeter?

What do you all think about tonge and groove only? Do you think the box will hold up without any screws and being so massive.

I'm at home now and the exact figures are 33hz in a 3.75ft^3 box.

Any recomendations tas to what to try out with this project? I'm gonna try out duct seal along with high fiber wool. Anything else?


That's quite a huge box.
Please also consider the room gain in your modeling. With that much low bottom end. I'm afraid the pioneer might sound a tad boomy.

I also have a pair playing in their test boxes right now and have yet to find the right tuning yet.
Will be pairing up with RS lineaum dipole tweeters.
The one and only
Joined 2001
Paid Member
At $19, the BUFU driver is probably the best deal in
full range speakers. With a high impedance source,
say 8 to 15 ohms, it does quite well. With a voltage
source you definitely need the tweeter and back loading.

Not the same mid and top you would get from the others,
but a smooth inoffensive character typical of less sensitive
motors. It has a decent bottom end and will take a little
abuse. A little bit like a big Jordan.

Hi Josh,

the waveguide used was a Pyle PH65. MCM has what appears to be the exact same thing which is what Zaph used here
The XT-19 was the best 3/4" tweeter I could find. More info here. This site is a must read for anyone who wants to build speakers, along with SL's, JBL,etc.
I'm holding judgement on the QSL until I have time to actually listen to it (too many projects), but hey, it was $9!
Which brings me back to your question. A XT-19 with the Pioneer?
I'm not sure why, unlesss you plan to use it as a "super" tweeter, but then why the waveguide? It certainly wouldn't be needed and thats a rather hi-end driver to be mated to the not so hi-end Pioneer. Lets put it this way. If you subjected the Pioneer to those type of (non-linear) tests above, things would get downright ugly.
The XT19 could be used as a supertweeter , but the better question is should it be used. I think it would be a waste of a fine driver.



My only "fullrange" project so far ;)

An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.
loninappleton said:
What about the lowly Voigt pipe for the Pioneer?

I think I asked this ages ago in another life cycle,
but that Voigt always comes back as a design I want
to build: one driver, tapered enclosure, port
at the bottom,.... done.


I modeled that a while ago, and it looks like it would work fairly well. The main problem is that it's a fairly large enclosure to build for a $20 driver.... though Nelson Pass's comment about how nice they sound with a high impedance source has me thinking a 3 cubic foot enclosure might not be a total waste of effort.

If you have the space, it looks like it could work.
space is pretty much the width of the driver.

The driver to wood expense ratio will most often
fall on the side of the wood.

The Voigts are made with tapered sides by splitting
one board-- poplar is pretty cheap and it has a nice
'ring' to it as I'm told though I have not used it.

What remains is the front and the back from 2 more
shelf width boards. Buying wood is what keeps me
from starting new projects. And tools.

Well I modeled the driver in my room and man would that be boomy. It looks to me like If I tune to 22hz is the right tuning frequency in my room. Does that sound about right?

Any more info on designing the voigt pipe?

I am just interested in those type of tweeters and I want to try one really bad.

What kind of drivers are in your full range?

With room gain 22hz would be very low and less of a reason for me to have to build a sub.

I have been listening to the drivers for a couple of hours a day all week long and they sound pretty good. Right now a little thin sounding and the mids are very prodominant, but the highs seem alright and the bess is good. I want to build a quick set of boxes for these to see how they really sound.

I think this weekend I'm gonna use some scrap wood and build some test boxes, they will only be about 1.5ft^3 and probably using 1/2" MDF since I have quite a bit. I'm gonna try 40litres tuned to 30hz and see what happens. This way I can break them in and get a real feel of how they really sound. I'm interested Voigt Pipe and I really want to try different transmission lines and see which enclosure I prefer.


What kind of drivers are in your full range?

KEF Ci-200QR. $9 Audax woofers x 12. You could do something similar with the Pioneers without breaking the bank. The KEFs are 8" drivers also. My "wood" cost was $12 - total. Only a severe lack of the boom/distortion bass - that many audiophiles like - will result. I've always been of the opinion that the driver producing my midrange/treble should
not be the driver undergoing large excursions (aka large distortion) needed for bass. But thats just me;)



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How are those KEF drivers?

A buddy of mine came to me with two broken KEF drivers, something fell on them in his storage and he says we has plenty of each and wants to get rid of them.

The drivers that he has are the KEF SP1248 this is a coaxial driver with a really nice basket, I have some pictures on my cell phone and can also post them. Also says on there MB 160.

He also has a bunch of the KEF SP1298 also says CR160F. This is the one with the wizzer cone. Build quality of these are not close to as nice as the coaxials.

All drivers come with crossovers still attached.

Are theses drivers good for a fun project or are they not that great?



the KEFs sound very nice, still much work to be done on these, but nice none the less. A bit of roughness in the treble typical to a coax driver, but also terrific imaging - also typical of a "point source" type drive unit.
I think your friend might be slightly confused. Or maybe I am :) . The MB160 is a KEF midbass, not a coax. Maybe it's some coax model that uses the MB160 midbass. I don't know that much about KEF. Also here is the (newer version) CR160F
However its a true fullrange w/ whizzer - so there should be no XO. Perhaps some type of bass blocker or 70V transformer? More confusion. If he's giving then away -TAKE THEM ;) . KEF knows a thing or two about speaker design. That fullrange looks interesting. The specs say 60-16k +/_ 3db! The "power response" says quite different. I realize its not quite the FR, but...Might be another fun driver. I'd say give the ol' Pioneer a shot first. Nelson says they are nice - I'm inclined to believe someone so knowledgable as Mr. Pass.
Try them OB. You may be pleasantly suprised.


Well after a really long week and a weekend full of work tonight after I was able to do a little research on the Voigt Pipes. I found a good website with the equations, couldn't find them on that site.

I was trying to see how big I would have to make it for the tuning frequency I want it. It seems to me that is doesn't really matter how deep the box is, the only think that matters is the length of the front baffle. For my tuning frequency I would have to make mine over 12 feet tall. The ceiling in my room is only 10 feet.

I might see if I can get like some 1/4" wood and build a voight pipe to about 42hz or so, but it looks like right now I don't have the time.

Any other suggestions on enclosures?




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These are supposed to be a quarter-wave device, right? If your enclosure needs to be 12 feet tall, that sounds like your tuning frequency is around 20 hz. You can have a 6 foot length for 40ish hz, or fold it in half for a 3 to 4 foot tall enclosure.

I'm starting to think that a sealed enclosure with the Pioneer drivers would sound good- but a terminated tapered tube might sound better. I'll start running some numbers to see what it would take.
Yea I think I'm gonna try for a tapered pipe I'm just not quite sure where to start designing, but I'm gonna try to design one. These will be for a school project that I am doing. I'm going to compare the TL probably TQWT, a vented, and a sealed box. I'm going to try and run some frequency responce tests to schow the differences. I'd like to put a lot of time and effort into the TLs to make sure they are well designed and I'm gonna design a couple different boxes.

I cannot decided on a tuning frequency because of so much room gain. The only way to come up with a somewhat smooth responce is to tune at 22hz, which is really low with the fs on this speaker. What would you all recomend?

Today I got around to trying some open baffle. This is my first time bending wood and I'm very happy with the way it turned out. I went out and bought a much thinner blade, unfortunately much smaller, bt I can still cut almost 2" deep with it which was plenty on the 3/4 MDF I used. These speakers still need time to break in (I hope) because they don't sound that great. They sound is a little thin. Great bass responce though. Really great bass actually. I just went to Home Depot and bought two 4"x2" sheets of 3/4" MDF to try out. $10 each is not much and the $25 blade is nice too. The cuts I made were great and They bend very easily. I'm not sure of the angle of the wings, I was going for 30degree, but I just decided to step away from making them well designed, I just didn't care since they are temporary. Right now there is no bracing keeping them at this angle, just a little glue.

I had a friend come over and help me with making the slits, because my table saw is not giant and I needed a little help ripping 4" 24 times. He was very excited when I showed him what all of the slits did and then he heard the speakers he had a huge smile on his face. I wa talking to him a little more and I'm hoping he will become a member here and start building some speakers.

Anyway, here are some pictures.



An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.
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