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ClaudeJ1

Quarter Pie Bass Horn: Measured FR, How2Build, and Hornresp

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Can the Quarter Pie be used in upright position instead of having it flat on the floor?

Yes it can.
This is good to know and what the differences are is what I thought they would be. It would certainly take up less floor space. It comes down to a few more hz or more floor space. It is certainly good to know that they can be used in the upright position.

My side channel QPs are oriented that way with the drivers firing down. Works just fine for that purpose.

Adding a pic. I had to shoehorn this one in between my weight bench and the furnace. Side placement was a must. Please ignore the mess.

post-26564-0-07320000-1450968931_thumb.j

Edited by tromprof
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My side channel QPs are oriented that way with the drivers firing down. Works just fine for that purpose.

 

 

When I measured frequency response along mouth of QP I found out that 300-400Hz is louder at the end opposite to the woofer. So when QP is vertical with the drivers firing down one should get more top frequencies. If opposite I am afraid that high end of QPs will aim the ceiling not the listener level.

Edited by Mariusz_

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Dear Mariusz,

May I know if you are using Faital HF204 in a two-way configuration? Can you tell me more about your impression of them and how you use them?

Thanks in advance!

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I use big round horns (Jabo KH72) at the top of Quarter Pies.

 

I tried Faital HF200, Beyma CP750Ti, B&C DE85TN and Faital HF204 in 2-way configuration. For me HF204 wins.

HF200 rolls off highs too early and needs shelving. 

Beyma sounds harsh and lacks low end a bit (if you need to cross at 400Hz).

B&C plays like HF200, maybe slightly better at high end.

 

And HF204 at last: it seems to be less linear than the rest but sounds best for me.

Can be crossed at 350-375 Hz (in a right horn) and THD are low even at 200Hz.

Highs are clear (the driver has smaller diaphragma and made of polymer - the others have 3-inch titan diaphragmas). It does not reach 20000Hz at full SPL, but 15-16kHz seems enough for most adult ears. I tried adding 3rd way and differences were subtle. Often what we perceive as high tones in music is no more than 8000Hz :-). 

 

If you needed more linear response you could use HF206 which basically is the same driver as HF204 but more flat at 2kHz region. 

 

And speaking of music listening I like live performance character even when using low and moderate volumes. HF204 and QP gives me that type of presentation. It is not mild home hi-fi type sound. HF204/QP dynamics is high and transients are played so faithfully, that you feel punch of drums and drilling sounds of strings. 

Edited by Mariusz_

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I use big round horns (Jabo KH72) at the top of Quarter Pies.

I tried Faital HF200, Beyma CP750Ti, B&C DE85TN and Faital HF204 in 2-way configuration. For me HF204 wins.

HF200 rolls off highs too early and needs shelving.

Beyma sounds harsh and lacks low end a bit (if you need to cross at 400Hz).

B&C plays like HF200, maybe slightly better at high end.

And HF204 at last: it seems to be less linear than the rest but sounds best for me.

Can be crossed at 350-375 Hz (in a right horn) and THD are low even at 200Hz.

Highs are clear (the driver has smaller diaphragma and made of polymer - the others have 3-inch titan diaphragmas). It does not reach 20000Hz at full SPL, but 15-16kHz seems enough for most adult ears. I tried adding 3rd way and differences were subtle. Often what we perceive as high tones in music is no more than 8000Hz :-).

If you needed more linear response you could use HF206 which basically is the same driver as HF204 but more flat at 2kHz region.

And speaking of music listening I like live performance character even when using low and moderate volumes. HF204 and QP gives me that type of presentation. It is not mild home hi-fi type sound. HF204/QP dynamics is high and transients are played so faithfully, that you feel punch of drums and drilling sounds of strings.

Thanks Marius, I myself use an Azura Le Cleac'h 350hz fibre glass horn which I read are very similar to Jabo's offering. I plan to use a 2" driver for a 6db slope crossover such as Type A or ALK universal.

Do you use 16ohm version? What crossover schematics are you using in your Jabo/QP?

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And have you read/heard about another Faital hf20at? This one seems to have an even flatter response and extended higher on top end.

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When I measured frequency response along mouth of QP I found out that 300-400Hz is louder at the end opposite to the woofer. 

 

Yes.   This is why I only use my horn with a -6dB point at 275Hz, and a steep slope   (approximately 48dB/octave).     It takes a lot more work to get such a steep slope right, but is worth it IMO.

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Faital hf20at

 

 

When I measured frequency response along mouth of QP I found out that 300-400Hz is louder at the end opposite to the woofer. 

 

Yes.   This is why I only use my horn with a -6dB point at 275Hz, and a steep slope   (approximately 48dB/octave).     It takes a lot more work to get such a steep slope right, but is worth it IMO.

 

 

 I was crossing my original design at 320 with a 4th order slope. Those who want a higher frequency output might be wise to use a larger reflector than what the plans call for. This would even thing a bit more.

 

Currently working on a symmetrical "L" version of the Qpie, so stay tuned.

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Can the Quarter Pie be used in upright position instead of having it flat on the floor?

Yes it can.
This is good to know and what the differences are is what I thought they would be. It would certainly take up less floor space. It comes down to a few more hz or more floor space. It is certainly good to know that they can be used in the upright position.

My side channel QPs are oriented that way with the drivers firing down. Works just fine for that purpose.

Adding a pic. I had to shoehorn this one in between my weight bench and the furnace. Side placement was a must. Please ignore the mess.

 

This was going to be my first experiment for orienting the QP's.  Don't know when I will finally get them complete at this point... got most of the wood cut over a year ago but surgery and life has gotten in the way.  It would be interesting to see the dispersion patterns of these in both the horizontal and vertical orientation.  Even more interesting will be to HEAR the difference.  I'll be in almost a near field position but can vary depending on where I find the peaks and nulls in my seating position... might be around 10 feet.  I only care about the sweet spot which doesn't have to be very big since only my skull has to fit there.  :)

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might be around 10 feet.  I only care about the sweet spot which doesn't have to be very big since only my skull has to fit there

 

Never had any problems, as long as you can SEE the corner reflector from where you sit, it's all good. The horn is so flat and the variance is small compared to the overall response. 

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Currently working on a symmetrical "L" version of the Qpie, so stay tuned.

 

 

Maybe you could try placing back chamber outside expansion line? Then it would be longer and we could fit back chamber volume to any woofer for reactance annulling.

post-60882-0-86920000-1451372706_thumb.j

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Hi Marius,

I have posted this question above but I guess it got too long and was overlooked, so please forgive me for asking it here again.

What crossover network are you using with the Faital hf204?

Cheers

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Very simple. Because HF204 rolls of quickly from 300hz down I only protect it from the lowest frequencies with single capacitor and attenuate it with autotransformer.

It looks like Klipsch AA network for squawker but value of capacitor is set for impedance of Faital.

Edited by Mariusz_

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Very simple. Because HF204 rolls of quickly from 300hz down I only protect it from the lowest frequencies with single capacitor and attenuate it with autotransformer.

It looks like Klipsch AA network for squawker but value of capacitor is set for impedance of Faital.

I did the same thing with a K402 horn and K1133 driver. wjhich is 8 ohms. However, instead of attenuating the top end with an autoformer, I used a Behringer DCX2496 with a 50-320 Hz. band LR-24 filter and another amplifier to boost up the bass to match the top end.

Edited by ClaudeJ1

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Currently working on a symmetrical "L" version of the Qpie, so stay tuned.

 

 

Maybe you could try placing back chamber outside expansion line? Then it would be longer and we could fit back chamber volume to any woofer for reactance annulling.

 

I plan on doing something along those lines, yes.

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Yes 8ohm. And as far as I remember it shows about 15ohm at 350Hz at my horn.

I am using K55v (16ohm solder lug version) with Type A crossover with a 13uf high pass cap. The efficiency is almost the same as Faital HF204. I suppose I can just swap one out and put the other in.

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post-26564-0-89560000-1451432496_thumb.jFinally got the first one hung today. Decided to hang before finishing, will paint them later. Ignore the mess.

 

The more civilized front end of the theater.

 

 

 

post-26564-0-65760000-1451432596_thumb.j

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