Fullranger as mid-tweeter | Power handling?

[soren5]

Full ranger as mid-tweeter | Power handling?

I’ve previously played around with the FAST concept and really liked it. However, I sometimes feel that I’m missing out on mid-bass if I cross at 200-300 Hz. I’ve tested MA Alpair 7.3s and CHR-70.3s supported by TB subwoofers, which sounded best crossed at around 250Hz (LR4 with miniDSP).

My idea is therefore to try woofers that would be able to go higher and then cross at e.g. 600Hz which should be the upper frequency for kick-drums (see attached chart). Currently I’m looking at this 8” woofer, which should go reasonably low in a smallish box and also be able to better handle the higher mid-bass kicks.

SEAS H1252-08 L22RNX/P

Crossing at 600Hz leaves me with new possibilities since many FR drivers would be able to deliver a nice response from this frequency and up. I currently have my eyes on the Fostex FF85WK, which some people seem to really like on this forum.

The Fostex FF85WK has a sensitivity of 85.5 dB and a 15W max power handling (xmax is just 0.35mm ). So here’s my question. If I cross this driver at e.g. 600Hz would that mean I could pump more watts into it without going into distortion? The SEAS H1252-08 specs (88dB / 300W) indicates that this woofer could play quite loud, even in larger rooms. Would the FF85WK be able to “keep up” with the woofer if crossed at 600Hz? Or should I consider the FF105WK or FF125WK, which have higher sensitivity, power handling, and xmax? I’d like to be able to go “party-loud” in a 30 sqm room

Any comments or inputs are welcome. I’d also like to hear if anyone has compared the Alpair 7.3 or CHR-70.3 with the Fostex FF-WK drivers. I really enjoy both of these MA metal drivers, especially for their high frequency capabilities. Do you think the FF-WK drivers would suit my taste?

Thanks!

 

[Jim Shearer]

Having built a modified version of MJK's small, passive OB using FF85k and Alpha 15a w/ XO effectively at 500 Hz, I would say that 'party loud' is not a good idea with the FF85k. Maybe others hear it differently, but I don't think that driver can go to ear bleed levels and still sound good.

I have no experience with the FF105 or FF125, but I would be inclined to try one of them first.

Cheers, Jim

 

[planet10]

It isn't that you can put more power into the driver, but that if you are feeding the system X watts, then the FR gets only a fraction of that. At 300 Hz the estimate is X/2, for 600 Hz maybe X/4.

The FF85wk is very good, crossing that high will let them play louder (but if loud is a goal, go with a larger mid-tweeter) but it means that you are XOing in the middle of the midrange.

A FAST should always use a woofer that goes a couple octaves past the XO. Fortunatly lots of midbasses that hit 2k + easily. One has to be much carefuller with subwoofers.

Do note that midbass is the range from 40-80 Hz so the FR XOed 250-350 (common for the FF85) will have no impact on that range. More likely a quality of reproduction issue with using a sub where a midbass would be more appropriate

dave

 

[soren5]

A FAST should always use a woofer that goes a couple octaves past the XO. Fortunatly lots of midbasses that hit 2k + easily. One has to be much carefuller with subwoofers.

Wouldn't that depend on the XO order though? A higher 4th or 8th order would somewhat eliminate the need for a woofer with high frequency extension, right?

The FF85wk is very good, crossing that high will let them play louder (but if loud is a goal, go with a larger mid-tweeter) but it means that you are XOing in the middle of the midrange.

Is XO in the lower midrange a bad idea? Why is that? You're the expert here so I'm not doubting your statement, just trying to learn something

My concern is perceived lack of kick drum 'snap'. It's not felt in the same way as the deeper tones, especially when playing electronic music. I thought that since some of the kick drum reach 500 Hz (at least according to the chart I showed before), then perhaps having a woofer crossed higher would help to feel more of these kicks

Jim Shearer states that the FF85WK won't play very loud and sound good, even when crossed at 500 Hz. What's your opinion on this, say in a 30 sqm room? And would cleaner high SPL be achievable by going just one size up to the FF105WK?

 

[planet10]

Wouldn't that depend on the XO order though? A higher 4th or 8th order would somewhat eliminate the need for a woofer with high frequency extension, right?

It does, but i'm not a big fan of anything over 3rd order, and given the potential with getting a phase coherent system when the wavelengths are this long when XOing low tend towards 1st order.

Brings up another target goal -- bass drivers cebtres are within a semi-sphere with radius of 1/4 w/l (centre at the centre of the midtweeter)

Is XO in the lower midrange a bad idea? Why is that? You're the expert here so I'm not doubting your statement, just trying to learn something

It is exactly in the lower midrange (160-320 Hz) that i am suggesting.

My concern is perceived lack of kick drum 'snap'. It's not felt in the same way as the deeper tones, especially when playing electronic music. I thought that since some of the kick drum reach 500 Hz (at least according to the chart I showed before), then perhaps having a woofer crossed higher would help to feel more of these kicks

I'd suggest thst the feel part comes in the mid and upper bass (40-160 Hz)

Jim Shearer states that the FF85WK won't play very loud and sound good, even when crossed at 500 Hz. What's your opinion on this, say in a 30 sqm room? And would cleaner high SPL be achievable by going just one size up to the FF105WK?

In an OB with no loading he will be at a disadvantage to the same driver used sealed or in the aperiodic TL i favour.

It is all a matter of trade off between quality & quantity. We have tried FF85, 125, 165 (and 105 are on the break-in bench).... the smaller FF85wk is the most finessed of all we have heard so far. At least until it gets painfully loud.

When Bernie gets the companion WoofTs done for the uFonkenSET we will be playing with XOs up to 500-600 Hz, but the WoofT has 2x4" (subs will be in place for <50-60 Hz)

dave

 

[soren5]

It is exactly in the lower midrange (160-320 Hz) that i am suggesting.

Right, but when I said lower midrange I was referring to my previous suggestion to cross around 600 Hz (that's still lower midrange in my book). I got the impression that you thought this XO point was a bad idea.

Anyway, as you said, this probably comes down to quantity vs. quality, meaning that if I cross higher I can achieve higher SPL but at the cost of loosing some of the sweet mids from the FR driver, correct?

Thanks for the other inputs by the way. Much appreciated

 

[planet10]

Lower midrange is defined as 160-320 hz. Then 2 octaves of midrange (320-640, 640-1250) then upper midrange (1250-2500 Hz)

dave

 

[tuxedocivic]

With a minidsp, just try all the cross overs you want. Pay attention to CTC spacing when your xo frequency increases.

There are far greater concerns than power handling when talking about FAST. Consider that when crossing below 300hz it's about the room and sound power. Above 300hz it's about direct response, although power response still plays a major role.

At VI DIY Fest 2011 Dave had a FAST that got really loud. Louder than his Emkens. That had a 1st order filter on a small Fostex. Dave can remind me of the details. The only thing I'd have to say is that I was more focused on the sub-300hz information at the time of listening. The whole (large) room felt like a pressure vessel.

 

[planet10]

FF85Ken + 2 EL166eN, 1st order series somewhere between 300-350 Hz (1 choke + 1 cap (+ bypass cap)). 166s in Scott's tall ML-TL, FF85 in a 10:1 aperiodically damped midTL.

http://www.diyaudio.com/forums/css/176790-el166-mtm-ml-tl.html

dave

 

[planet10]

The whole (large) room felt like a pressure vessel.

Somewhere on the order of 250m^3

http://www.diyaudio.com/forums/blogs/planet10/493-fall-listening-space.html

dave

 

[chrisb]

At VI DIY Fest 2011 Dave had a FAST that got really loud. Louder than his Emkens. That had a 1st order filter on a small Fostex. Dave can remind me of the details. The only thing I'd have to say is that I was more focused on the sub-300hz information at the time of listening. The whole (large) room felt like a pressure vessel.

yup, they'd SAF be my choice for a "can it go loud" system that still sounds reasonably musical and doesn't consume tons of space or amplifier power

the Eminence certainly has no trouble pressurizing a largish room, but in its current trim leaves me wanting more delicacy and detail, and thank goodness someone else mentioned its imaging shortcomings

but let's be fair - it's a "full range speaker" in the sense that when used for its intended purpose as a PA speaker, you good get away without the use of CD / horn array and still cover the vocal range with adequate intelligibility

 

[soren5]

With a minidsp, just try all the cross overs you want. Pay attention to CTC spacing when your xo frequency increases.

True, the miniDSP certainly makes it easy to experiment with XO frequencies, order/type, and EQ. But since I haven't bought drivers yet I wanted "test my hypotheses” here before buying new drivers.

At VI DIY Fest 2011 Dave had a FAST that got really loud. Louder than his Emkens. That had a 1st order filter on a small Fostex. Dave can remind me of the details. The only thing I'd have to say is that I was more focused on the sub-300hz information at the time of listening. The whole (large) room felt like a pressure vessel.

This is good news for me!

Dave and Chris, I know that you've listened to Mark's metal drivers as well as the new Fostex FF-WK drivers. How would you describe the differences in sound? Of Foxtex drivers I've only tried the FE126En and didn't like the early roll-off. But I guess the FF-WK drivers don't suffer from this in the same way.

 

[tuxedocivic]

Early roll off on the high or low end?

 

[soren5]

Early roll off on the high or low end?

On the high end.

 

[planet10]

FF85 or A7 have quite excellent top end. FF85 can be looked at as a 3/4" tweeter with a huge surround that lets you XO REALLY low, well within the goal of a 1/4 wl hemi-sphere.

dave

 

[mortron]

Sorry to bring up an old thread. In an open baffle speaker, What about utilizing a Visaton B200 as the mid tweeter, and running a pair of 12" drivers mounted face to face per side between the B200s and say a Beta15a on the low end... The 12" has an Fs of 100hz I believe. Would utilizing it from say 200 or so to 2500hz be a ridiculous experiment? Or what would be more adequate xo frequencies?

 

[planet10]

The 12s ar not really needed.

dave