Tweaking Voigt Pipes (need advice)

michael_w

As some of you may remember a couple months ago I finished up some mini voigt pipes that sit about three and a half feet tall and use a single three inch full range Audax HT080M0 driver. So far I'm enjoying these speakers with their smooth highs, subtle bass presence and sweet midrange. I would like to do any tweaking (or anything major) before I paint them.

With all the sweet luxuries that come along with a full range speaker I'm still lacking something. These little three inchers lack punch and impact. I have noticed some music sounds amazing on them, while other music just doesn't do it for me. I threw in Michael Bubl

RuSsMaN

The only thing you can do with the nulls is try a zobel (if kicking efficiency down a notch is OK). A rear-firing ambient tweeter is always an option for that spatial touch. Add a powered sub (even a cheapie) to get you down to 40Hz, if you don't get presence, you need a different FR driver.

Full range is cool, what it does, it does well. I've owned a TON of FR designs - but none (even Lowther) can touch a proper 2-way. Sins of omission can be a ****.

Cheers,
Russ

michael_w

Would a zobel network affect the midrange enough or does it just focus on the highs and just slightly change the midrange? I suppose it depends on the impedence curve of the audax driver?

I've thought of the idea of using a tweeter in the back and have the materials to do it but once these broke in I had a change of mind and don't think they need it. At the moment the highs are not something I'm worried about too much.

I've got the diy atlas 15 filling in the lows and if it comes down to it and the pipes branch off to their own system I have a cheapo Athena Sub 8 lying around not doing anything. They're decent enough without a sub, but I hate hearing a well known song and noticing low notes that simply aren't there anymore.

Thanks for the tips Russ. I'll have to try and look into using a zobel network again and see if it'll tickle my fancy. They're not the most efficient speakers at the moment, but it's not like I'm suffering. Even off a t-amp I can push them to decent levels.

RuSsMaN

Sonic T? There is a small 140 pF cap that is shunted across the outputs. Replace it with a Sonicap (slightly larger value I don't recall offhand), makes a TON of difference in that amp.

Bottom line, you have a properly tuned enclosure, and the electronics buttoned up - it simply may or may not be the driver for your application.

Cheers,
Russ

unc2701

I second everything Russman has to say. 3" driver, not much you can do about that. I'd spend a little more time trying to nail down the sub integration- you're not just going to get the 40-80 hz octave without one. One thing you can try before you finish the pipes- I think it was Brines or the quarterwave.com guy found that TL's that go to a point (ie voight pipes) are not an ideal configuration. Try cutting a block to fit in the top of your pipe so that the minimal depth is like 1"- just get it up there good enough that it doesn't rattle and see what it does for your response. I'll look for that page...

michael_w

Alright thanks for all the suggestions. I'll probably just go ahead and paint them sometime in the next little bit. The zobel network can be done afterwards and won't affect the paint

The tops are actually already squared off. From the inside there is about 2" of flat part (2" deep, 4" wide). Sorry for the terrible pictures. The camera hates taking photos indoors.




Little off topic but here are some pics of the half assed stands I made at school. I was bored and threw them together in about 20 minutes. Since the it is 19½" to the center of the drivers I figured it'd be better to have them angled back slightly to aim them at ear level. I lucked out and found the perfect angle. Now I don't have to sit on the floor to listen to them!



I'll have to look into adding new caps to the sonic impact t-amp if it really does make that much of a difference

Thanks again for the tips!

steveinaz

Cool speaks Mike. Single full-range drivers have always drawn my interest.

roystr

im a huge fan of full rangers,mostly because i cant read a schamatic :-)

i can say im more than happy with my FR's.

they simply can not do everything. that said,you say your mids are weak. on mine,the mids are the best part,the tweets are a bit weak as is the lowest bass. nature of the beast. i can say,,id build another pair in a second. but they arent for hard,loud rock. least mine arent. but for classical and acoustic music,,they are some of the best ive ever heard. the clarity/accuracy(to me) is just rite.
blend the sub in and maybe ad the tweet in the rear as mentioned.
good luck,
roy

mhardy6647

They sound awfully small; about half of a typical TQWT (e.g, Abbeys)... are they folded?

Have you fiddled with the stuffing?

You might want to try a BSC (baffle step correction) network, but I don't use one with my TQWT's. You might like it, if you're not using fleapower amplification.

unc2701

mhardy6647 wrote:

They sound awfully small; about half of a typical TQWT (e.g, Abbeys)... are they folded?

Abby's use a Fostex driver with a Fs around 50hz- these are more like 80hz (IIRC), so the quarterwave is a bit shorter.

michael_w

I can't quite remember where I got the forumula but I used this:
(1100/fs)/4

The fs of the driver is 90Hz so it worked out to be 3.056 feet tall so they should be about the right size. If I hadn't used a 3" driver I doubt I'd even have room to put them because they'd be so tall.

I started off with using the little audax's mostly because I was looking for a cheap way to get into the diy side of audio. The drivers were given to me so all I've had to fork out for this project so far is about $15.

I'll have to check out the baffle step correction and see if it's what I'm looking for. I also haven't really played with stuffing too much. Now that I look back on these, I belive I was supposed to mount the driver a little higher. I read it should be about a third the way down from the top? It's a little more centered than that, but I guess with mine being so short it's only a matter of about two or three inches.

The midrange is great but the upper bass lacks some. That's where most of the impact of music comes from and coincidently that's also where the two nulls are in these speakers... I think full range speakers are more suited for those who listen to that certain style of music. Classical, instrumental and maybe soft rock is what they do best. Move to something like Tool and these little things sound pretty crappy (when compared to other speakers).

So far this has been a great way to learn more about building speakers and a perfect opportunity to explore more options in the realm of audio.

Thanks,
Michael

roystr

"I also haven't really played with stuffing too much"

from what i remember reading about those loudspeakers,,you kinda have to putz with the fill untill you get it right.

good luck,
~R~