Or "Why should the fullrange gang not also post those pretty colourful graphs" 😉
I was measuring the response of drivers for a multi-way project and though I'd give my FR drivers a spin, quite literally!
These are all drivers I've had for many years:
I measured 0deg to 90deg in 5deg steps, which is mirrored on the polar maps. The SPL should reflect sensitivity accurately enough; I set the amplifier for 2.8V and placed the mic at 50cm, then reduced REW's output by 6dB.
First off, all three drivers on-axis, for comparison's sake:
W4-1320SIF 0-45deg response and polar map:
FF85WK 0-45deg response and polar map:
FF125K 0-45deg response and polar map:
I was measuring the response of drivers for a multi-way project and though I'd give my FR drivers a spin, quite literally!
These are all drivers I've had for many years:
- Tang Band W4-1320SIF, mounted in a 9 liters DCR
- Fostex FF85WK, mounted in a 3.25 liters reflex
- Fostex FF125WK, mounted in a 8 liters reflex
I measured 0deg to 90deg in 5deg steps, which is mirrored on the polar maps. The SPL should reflect sensitivity accurately enough; I set the amplifier for 2.8V and placed the mic at 50cm, then reduced REW's output by 6dB.
First off, all three drivers on-axis, for comparison's sake:
W4-1320SIF 0-45deg response and polar map:
FF85WK 0-45deg response and polar map:
FF125K 0-45deg response and polar map:
The FF85WK is quite well behaved, smoothly narrowing at 5kHz and remaining even to 20kHz. I hardly count the light "pinch" around 17kHz.
The W4-1320SIF displays what I've always heard; quite a beaming top-end. It narrows at 3khz and keeps steady to 10kHz, it quickly narrows to a laser. It likely does not matter a whole lot that it broadens again past 16kHz.
The old FF125K is the most uneven, both in frequency and polar responses. It actually looks slightly broader than the W4-1320SIF in certain areas that must matter; afterall I've never had the same impression of overly tight sweet-spot from the FF125K, unless it's just the 10kHz hot-spot messing with my perception.
The W4-1320SIF displays what I've always heard; quite a beaming top-end. It narrows at 3khz and keeps steady to 10kHz, it quickly narrows to a laser. It likely does not matter a whole lot that it broadens again past 16kHz.
The old FF125K is the most uneven, both in frequency and polar responses. It actually looks slightly broader than the W4-1320SIF in certain areas that must matter; afterall I've never had the same impression of overly tight sweet-spot from the FF125K, unless it's just the 10kHz hot-spot messing with my perception.
You mean the 10kHz hot-spot? Yes, definitely audible, but I don't find it that bothersome.
The FF85WK has a small hump around 10kHz as well, though far milder than the FF125K. Do your cone treatments address this or you've found it unnecessary?
And as "painting cones" goes, what would you suggest to simply beautify my 10yo FF85WK's faded cones? One also has what is presumably a tea or coffee stain, so I'd likely have to go in the lower end of the spectrum to cover this up. How about acrylic paint? I've used some undiluted on a paper horn with no visible ill effect to the paper and it seems to paint-on thin enough to add negligible mass.
The FF85WK has a small hump around 10kHz as well, though far milder than the FF125K. Do your cone treatments address this or you've found it unnecessary?
And as "painting cones" goes, what would you suggest to simply beautify my 10yo FF85WK's faded cones? One also has what is presumably a tea or coffee stain, so I'd likely have to go in the lower end of the spectrum to cover this up. How about acrylic paint? I've used some undiluted on a paper horn with no visible ill effect to the paper and it seems to paint-on thin enough to add negligible mass.
The FF125 has the pinch at just under 7 and 10KHz and then a train of harmonics.
All of the FFxxxwk suffer from this to a greater or lesser extent. It is least objectionable in the FF85, a bit more in FF105 and FF165, a lot worse in FF125. The FF225k haven’t been listened to enuff to evaluate, but with a supposed 5k top end they will either be lower in frequency or MIA.
The treatments i do almost completely remove the issues from the FF85 — in a shootout with A5.2eN over a number of hours no clear winner was choosen, sounding VERY similar.
Easy to do things that help are puzzlekoat/modpodge on the cone, the ZIG 2-way glue on the back at the surround interface. There is a dustcap resonance where 20 spots on the dustcap and then a coat of acriylic gloss seems to sort that. EnABL takes things further, you will not an extra half-ring (3 rows, instead of 2) at the surround to help deal with the issue at the surround/cone. If you want to pursue this email and i will gibve more exact instructions.
dave
All of the FFxxxwk suffer from this to a greater or lesser extent. It is least objectionable in the FF85, a bit more in FF105 and FF165, a lot worse in FF125. The FF225k haven’t been listened to enuff to evaluate, but with a supposed 5k top end they will either be lower in frequency or MIA.
The treatments i do almost completely remove the issues from the FF85 — in a shootout with A5.2eN over a number of hours no clear winner was choosen, sounding VERY similar.
Easy to do things that help are puzzlekoat/modpodge on the cone, the ZIG 2-way glue on the back at the surround interface. There is a dustcap resonance where 20 spots on the dustcap and then a coat of acriylic gloss seems to sort that. EnABL takes things further, you will not an extra half-ring (3 rows, instead of 2) at the surround to help deal with the issue at the surround/cone. If you want to pursue this email and i will gibve more exact instructions.
dave
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