Received a pair of 656S (or rather SB, the label states). Sound nice played as a raw driver, however when exercising them at 20 Hz at +/- 3.5 mm, I can hear that there is a venting problem.
The spider is well vented, but the space underneath the dustcap is not vented at all.
- Venting through pole piece? The screening cup seems to be glued on pretty tightly. I could drill a hole in the back, but I suspect the pole piece is not vented (i.e. has no hole) anyway as most other W4 drivers use phase plugs.
- Venting through VC former (à la Peerless CSX)? There seems plenty of space to put holes in the VC former. I suspect drilling/cutting will easily bend the hole former. Is using a very hot soldering iron to poke hole a good idea? I seem to remember even Kapton melts at something like 300°C?
The spider is well vented, but the space underneath the dustcap is not vented at all.
- Venting through pole piece? The screening cup seems to be glued on pretty tightly. I could drill a hole in the back, but I suspect the pole piece is not vented (i.e. has no hole) anyway as most other W4 drivers use phase plugs.
- Venting through VC former (à la Peerless CSX)? There seems plenty of space to put holes in the VC former. I suspect drilling/cutting will easily bend the hole former. Is using a very hot soldering iron to poke hole a good idea? I seem to remember even Kapton melts at something like 300°C?
First of all, my girlfriend would kick my butt if I took a soldering iron anywhere near her newly finished speakers. (W4-656S and 28-847SA X'ed at 6500Hz with a series XO) Sencond, my 656's aren't going to see much 20Hx material. However, if you are still conserned ... I'd either try to pull the sheilding cup off and see if it's vented, or drill as you previously mentioned. If the W4-656S is built anythiing like its 3" cousin the W3-881S, then the pole may look just like this...
An externally hosted image should be here but it was not working when we last tested it.
Never realized this pic was of an 881, but you are right.
The 881 has a Nd magnet, the 656 has a regular ferrite + most probably a bucking magnet, so the motor design would have to be diffrerent.
Anyway, I have a couple of 881s, and I usually pull of the plastic cap because it inhibits spider venting. Surprise: the pole piece itself is not vented! The exploded view you provided seems to be accurate in every detail except this (at least, I can't imagine why they'd bore a hole on the front side and not let it go through all the way).
Pulling off the shielding is close to impossible. They used an awfully strong glue on the inside...
Can you say anything about the newly completed speakers you made for your girlfriend?
The 881 has a Nd magnet, the 656 has a regular ferrite + most probably a bucking magnet, so the motor design would have to be diffrerent.
Anyway, I have a couple of 881s, and I usually pull of the plastic cap because it inhibits spider venting. Surprise: the pole piece itself is not vented! The exploded view you provided seems to be accurate in every detail except this (at least, I can't imagine why they'd bore a hole on the front side and not let it go through all the way).
Pulling off the shielding is close to impossible. They used an awfully strong glue on the inside...
Can you say anything about the newly completed speakers you made for your girlfriend?
They are 3.3L vented boxes tuned to 76Hz. The are finished in black vinal pleather. I will be posting some pics soon. The 656's look real nice with a black backgrond and the 28-847s tweeter is translucent. You can see a little of the white felt behind the dome. It looks brown and goes well with the copper look of the 656's. As far as sound (the important stuff) They sound nice. All my friends that come over say they sound really good. I dont have a whole lot to compare them with. They are the FL and FR for a custom HT settup. I am starting the rears (just a 656 up facing omni) and dunno what Im gonna do about the center. Maybe a pair of 656's and one 847 built into a TV stand. I may go with a TB sub just for kicks.
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