How Treat Passively Peaky Fullrange Drivers

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FredT300B

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Re: How Treat Passively Peaky Fullrange Drivers
« Reply #20 on: 21 Nov 2011, 04:18 pm »
If it's ok to think "outside the box" and still respect the intent of this post, three things that come to mind are placement, toe-in, and speaker cable. 1) Positioning the speakers closer to a corner will emphasize the bass frequencies and subjectively reduce the relative loudness of any treble peaks. This is a compromise because some of the "magic" of a single driver's soundstage may be lost in the process. 2) Spacing the enclosures as far apart as possible without losing the center image, and pointing them straight ahead with no toe-in, will increase the listening angle and reduce the treble intensity at the listening position. 3) SET amps are especially sensitive to speaker impedance, and many single driver enthusiasts use very small gauge speaker cable and internal wiring to increase the total resistance, which also increases the "Q" of the speaker and the bass amplitude at the driver's resonant frequency.

Also, most of the peakiness of low Q, high sensitivity drivers is generated by the cone itself, but some peakiness can also come from the back wave reflected off the back of the enclosure and through the cone, especially in shallow enclosures that don't have dense stuffing. I've found that a piece of Armstrong 420 contractor series fiberglass ceiling panel glued to the rear wall behind the driver will absorb more high frequency reflections than convoluted foam, loosely stuffed pillow stuffing, or even fiberglass ceiling insulation. This material is about 3/4" thick, and the piece needn't be much larger than the driver itself.

FullRangeMan

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Re: How Treat Passively Peaky Fullrange Drivers
« Reply #21 on: 23 Nov 2011, 01:13 am »
If it's ok to think "outside the box" and still respect the intent of this post, three things that come to mind are placement, toe-in, and speaker cable. 1) Positioning the speakers closer to a corner will emphasize the bass frequencies and subjectively reduce the relative loudness of any treble peaks. This is a compromise because some of the "magic" of a single driver's soundstage may be lost in the process. 2) Spacing the enclosures as far apart as possible without losing the center image, and pointing them straight ahead with no toe-in, will increase the listening angle and reduce the treble intensity at the listening position. 3) SET amps are especially sensitive to speaker impedance, and many single driver enthusiasts use very small gauge speaker cable and internal wiring to increase the total resistance, which also increases the "Q" of the speaker and the bass amplitude at the driver's resonant frequency.

Also, most of the peakiness of low Q, high sensitivity drivers is generated by the cone itself, but some peakiness can also come from the back wave reflected off the back of the enclosure and through the cone, especially in shallow enclosures that don't have dense stuffing. I've found that a piece of Armstrong 420 contractor series fiberglass ceiling panel glued to the rear wall behind the driver will absorb more high frequency reflections than convoluted foam, loosely stuffed pillow stuffing, or even fiberglass ceiling insulation. This material is about 3/4" thick, and the piece needn't be much larger than the driver itself.
Thanks for your detailed report.

FullRangeMan

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Re: How Treat Passively Peaky Fullrange Drivers
« Reply #22 on: 24 Nov 2011, 01:32 am »
One more tip for peaky FR drivers: Add 5mm felt layer outside the baffle, of course it will hide the beautiful mahogany vaneer you pay hi for;
http://www.audiocircle.com/index.php?topic=100846.msg1018154#new

FullRangeMan

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Re: How Treat Passively Peaky Fullrange Drivers
« Reply #23 on: 8 Oct 2017, 04:58 pm »
Just adding this imaging to this old thread, this is a blanket used in car hoods and is very useful to up the bass freq, if used in excess it will down the hi freq too, that may be a useful tool to peaky full range drivers.
Use the 10mm version, image show thinner 5mm.

richidoo

Re: How Treat Passively Peaky Fullrange Drivers
« Reply #24 on: 8 Oct 2017, 06:13 pm »
Shoutiness and peakiness are tamed by using a current source amplifier.

More info:
https://www.current-drive.info/
http://www.firstwatt.com/pdf/art_cs_amps.pdf

Bob_Brines

Re: How Treat Passively Peaky Fullrange Drivers
« Reply #25 on: 8 Oct 2017, 08:44 pm »
Pretty much want Fred said (Hi, Fred).


Full-rangers have a rising response on axis. Don't listen on axis! Most full-rangers are pretty much flat 15* off-axis.


Boxiness is almost always due to reflection off of the back wall coming through the cone. Armstrong 420 works. It is actually 5/8" thick, and at least out here in the sticks only available in 12-packs. I am using a Owens-Corning 703 knock-off that can be had in single panels, but is cheaper in a 6-pack(!).


Bottom end with low Q drivers is always a problem. Use a driver with a Qts above 0.3 -- preferably closer to 0.5. Makes cabinet design so much easier. You can still use SE tubes, but you will get real bass.


BSC does not "take the life out of the music". It give a balanced FR. We have been conditioned from birth to like a smiley faced EQ. A flat FR sounds, well, flat! OK. maybe you do want to have your speakers pointing directly at you. That sparkle and "detail" is fake and characteristic of a rising response.


If your drivers have a crappy FR, screwing them onto a two watt SE amp with thin silver wires is not going to give you audio nirvana (that's lower case letters -- don't get me started). You have to get the FR straightened out first. Then go for the audiophile tweaks.


EQ is your friend, and if you go digital rather than passive, you can still have nothing but wire between your amp and the speakers. Win-win.


Bob

FullRangeMan

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Re: How Treat Passively Peaky Fullrange Drivers
« Reply #26 on: 8 Oct 2017, 10:56 pm »
Thanks Bob for your experiencied tips in passive treatment :thumb:

Bemopti123

Re: How Treat Passively Peaky Fullrange Drivers
« Reply #27 on: 8 Oct 2017, 11:37 pm »
Thanks Bob for giving your expert opinion in the matter.  I am glad to hear that you are still active in the forums. 

 :thumb:

JLM

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Re: How Treat Passively Peaky Fullrange Drivers
« Reply #28 on: 23 Oct 2017, 10:28 am »
Bob is one of my audio heroes.  I commissioned him to build my speakers (last called M18-F200) 13 years ago.  They are floor-standing single driver transmission lines using the "mighty" (now discontinued  :cry:) Fostex F200A AlNiCo driver that last retailed for $575 each (rated 30-20,000Hz, 89 dB/w/m, 8 ohms, no stinking whizzer cone).  I had Bud Purvine EnABL the drivers (Bud invented the idea/process).  As Bob mentioned I've run cable directly from my mono-blocks to the drivers for years (does make auditioning speaker cable all but impossible) and replaced BSC with DSP (currently DSPeaker Anti-Mode 2.0 Dual Core).

And thanks to Duke LeJeune added Late Ceiling Splash tweeters (Dayton Audio 1.125 inch soft dome) on the floor behind speaker to alleviate the high frequency beaming (boost treble response a bit and greatly expanding the soundstage).  This pretty much my destination speaker (at age 61 I'd better have arrived  :)).