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ClaudeJ1

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

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What frequency range will you need them to cover.     There will be very very different suggestions if you need them to cover from 3k, 6k, 12k and up....

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Any idea's for tweeters?

Sent from my D5833 using Tapatalk

2 or 3-way? For 2-way, a 1.5" driver/horn is a good compromise, but some 1" drivers will go that low on the right horn. If you have active Xovers with PEQ, you can bring up the rolloff on the woofer and use sharper filters in a 2-way or 3-way. I recomment, if possible that from 600 to 6 Khz. it comes out of one driver.

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The intention is a 3 way active with mid and treble driven by pass 6w class a modules and the bass horn driven by one of my 40w valve amps. May change later. All controlled by a minidsp. Thinking about crossing the bass horn to the Azura 340 horn at around 400hz, this rolls off at about 10k so looking for something to carry on up from there.

The 340 horn is pretty flat to 10k so why should i cross to the tweeter much lower than that? Is this correct thinking or have i missed something....

Thanks Dave

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Edited by nzlowie

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The 340 horn is pretty flat to 10k so why should i cross to the tweeter much lower than that? Is this correct thinking or have i missed something....

 

.... because it may not be flat when measured from another angle.

 

 

 

It's complicated.   For example, if your 340 is flat measured straight on .... but has rolled off a lot when measured at an angle ..... then you may want to choose a tweeter with a wide coverage pattern  (to fill in where the 340 has started to roll off to the sides).

Edited by davewantsmoore

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The intention is a 3 way active with mid and treble driven by pass 6w class a modules and the bass horn driven by one of my 40w valve amps. May change later. All controlled by a minidsp. Thinking about crossing the bass horn to the Azura 340 horn at around 400hz, this rolls off at about 10k so looking for something to carry on up from there.

The 340 horn is pretty flat to 10k so why should i cross to the tweeter much lower than that? Is this correct thinking or have i missed something....

Thanks Dave

Sent from my D5833 using Tapatalk

Not sure if a 40w amp is going to be enough for the QPies... I originally drove mine with a Pro Yamaha 250wpc amp, and downsized to about 80wpc and it just doesn't appesr to have the UMPH that it did with the Pro amp.

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Not sure if a 40w amp is going to be enough for the QPies... I originally drove mine with a Pro Yamaha 250wpc amp, and downsized to about 80wpc and it just doesn't appesr to have the UMPH that it did with the Pro amp.

 

I ran mine with 10W originally then to 30 Watts. Never came close to more than a watt or so in my room in Indy. 

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Not sure if a 40w amp is going to be enough for the QPies.

 

There is another (or a more detailed) explanation for what you experienced than simply "lack of watts".

 

I've run mine with quite a few amps (the daily-drive being 16 watts) .... but I calculate that there is 4w peak power going into them.   The average level is drastically lower.

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Dave, this is in line with my findings also. When I did peak measurements of my K horns in 77, at very loud levels, I hit 10w PEAKS with 1/4 W average power. The Qpie efficiency is similar to that. Now if there is a 10 db boost which might be necessary in a large absorbent room, then 100 W of peak power should do the job.

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Dave, this is in line with my findings also. When I did peak measurements of my K horns in 77, at very loud levels, I hit 10w PEAKS with 1/4 W average power. The Qpie efficiency is similar to that. Now if there is a 10 db boost which might be necessary in a large absorbent room, then 100 W of peak power should do the job.

Could be due to the room tune then... I know my Yamaha power amp is rated at 80wpch with all 11 channels being driven, but when I had the P2500 250wpc amp driving the QPies it sounded like there was more umph or slam than I currently have (even though the level indicators were flickering for a 1wpch load). Not that it doesn't sound good, just seems to lack a little.

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Could be the ugly word 'synergy'. Some amps just don't match well with certain speakers.

 

Bruce

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In this case it's all about the power supply trying to supply power to too many channels as opposed to dedicated to and 250 was for just two channels

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In this case it's all about the power supply trying to supply power to too many channels as opposed to dedicated to and 250 was for just two channels

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I really like the way the big Crown PS-200 sounds on my bass bins. Is it synergy, quality, or just brawn?  I have tried a variety of amps on these but there is something added with the Crown as far as clarity.   BTW going active on the front three has been a big step forward and lives up to all the positive expectations. Eventually I will go active for the rest of the system but I am sure it will be less impactful than the front. 

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brawn?

 

It could very well be the "opposite"....   even in a large room at loud levels, we are still talking a few hundred milliwatts average power, and a few watts peak power.    Many amplifiers offer much less (distortion and noise) performance than their product sheets tell you about when the output levels drop this low.

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brawn?

 

It could very well be the "opposite"....   even in a large room at loud levels, we are still talking a few hundred milliwatts average power, and a few watts peak power.    Many amplifiers offer much less (distortion and noise) performance than their product sheets tell you about when the output levels drop this low. 

 

 A high damping factor then?

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 A high damping factor then?

 

No.     If you use an amplifier with very very low 'damping factor', then you will have more bass response.

 

Otherwise, it doesn't make any difference at all.

 

 

PS - what most people hear about 'damping factor' is 90% myth.

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 A high damping factor then?

 

No.     If you use an amplifier with very very low 'damping factor', then you will have more bass response.

 

Otherwise, it doesn't make any difference at all.

 

 

PS - what most people hear about 'damping factor' is 90% myth.

 

 

It is my understanding that a higher damping factor will mean that the bass will sound a bit tighter.  Not so?

"The lower the amplifier's output impedance, the higher the damping factor, and the tighter the sound is. A damping factor of 1000 or greater is considered high. High damping factor equals tight bass."  Quote from Crown website (came up first when searching amplifier damping factor).

My initial comments were about the quality of the sound produced by the PS-200 with the QP, not the quantity.  My little $20 Lepai test amp produced plenty of quantity.  The Crown just seems cleaner than the others I have tried thus far.

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It is my understanding that a higher damping factor will mean that the bass will sound a bit tighter.  Not so?

 

Heh.  That's what 'they' say....   The short answer is no (or at least it's not that simple) ....    in reality there are a few important thing going on, to think about.

 

 

At the system resonance (where the mechanical attributes of the moving system no longer dominate), the 'damping factor' of the amplifier does two things.    It sets the amount of steady state output (lower damping factor = more output) .... EQ sets this straight.   ie.  if you have too little or too much output, then you adjust the output to what you want.    

 

The second is that the damping factor controls how the cone moves back to rest when the signal stops.   However we need to understand that "more damping" isn't always better, as the response of an overdamped speaker is distorted just as an underdamped one is.    When we look at most speakers, we find that much lower levels of damping are required, say for example somewhere between 1 and 5 .....   than we typically see people talking about as being "awesome"  (eg. 10, 50, 100, 1000, etc. whatever)

 

In a horn the resonance is already quite damped.   So the effect is quite modest compared to other speaker types.

 

 

The myth of "it will make the bass tighter" comes from the fact that a high damping factor will have reduced output at system resonance .....   and low, will have have more output at system resonance.    If your speaker is designed for the typical high(ish) damping factor amp ..... then using a low damping factor amp, will produce  more bass at the system resonance frequency.   Which subjectively sounds 'boomier', 'muddier' ... ie,  "less tight".      But it isn't a case of high performance vs low performance .....  it's just a case of using the output impedance of the amplifier to provide EQ to the speaker  (increasing the bass around the system resonance frequency).    Misplaced EQ can sound 'bad'.

 

We all got bamboozled about this, when the hifi companies marketed the concept of "control" to us.     Control (over the woofer) is a good thing... and more of it must be better....   but that's not right.

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