Model 5s: Lifeless, Dull, and BOOMY

[Guest russwollman]

Just out of the box, this pair of Model 5s is...awful, with boomy, muddy bass and a lack of clarity, almost as though they were waterlogged.

I haven't gone inside them yet, but I know there must be something wrong. All the drivers work, but no one would want to listen to these monsters for very long.

I'm open to ideas. They're too heavy not to be good speakers ;-)

[Guest Droog]

If your power source is good ( I once tested speakers on a bad receiver) and your getting sound from all 4 drivers in each cabinet, and both units sound bad with a lack of clear mid and high frequency response.....my guess would be a problem with the crossover network. The model five's are more complex inside then other KLH models(this site has some photos) . Others may know specific details. Model five's are nice speakers, well worth fixing.

[Guest russwollman]

Hello, Droog. I had a look inside them. The crossover components—and there are lots of them—are soldered to a board. There are 5 coils, several resistors and a few caps. It's a neat arrangement.

One thing I do notice: the woofers seem rather floppy, or loose, on their suspensions, as though the cones are far too free, unlike Advents and ARs.

Perhaps comparing them to a bright pair of Advents isn't right. But the bass is pretty dumpy compared to the Advents' nice, tight, tonal bass deliver.

[mrdb]

It is possible that the surrounds are leaking air. The cloth was treated with some kind of flexible sealer which flakes off over the years. The midrange surrounds have the same problem. I tried some PVA-type glue on my Fives but the system resonance went up to about 65Hz (supposed to be around 44Hz). If I wet the surrounds, the resonance drops back to 44-45Hz. I don't recommend that you try this glue (Aleen's Tacky Glue). I have seen references to an edge sealer supplied by Orange County Speaker in Southern California, but you have to call and ask for it, there is no listing on their web site. Re-treating surrounds is a do-at-your-own-risk proposition, I found out. Measuring system resonance requires an audio oscillator and an AC voltmeter.

The crossover caps are likely to need replacing.

Check out my write-up, picture and schematic in the KLH section.

Bob Van der Veen

mrdb

[Guest russwollman]

Dear Bob, Thanks for your reply. Unfortunately, my iBook won't let me look at your documents, and I don't have the knowledge to figure out how to do it.

I did embark on an interesting little project tonight per post #377 in the Advent section of this board. You might want to have a look just for the sake of knowledge and curiosity.

One of the Model 5s I purchased was slightly damaged in transit, so I'm waiting for a settlement. If it turns out that I keep them, let me know if you're interested in them. I shouldn't admit this, I know, but I have enough speakers.

[Guest russwollman]

I removed the woofers and discovered I could see right through the surrounds. Then I became very brave—or reckless—depending upon your perspective.

I had some sealer left over from an Advent surround project. It's white but dries clear. It contains vinyl acetate and dibutyl phthalate, which sounds suspiciously like some sort of rubber compound to me.

So I poured a line of it into the concave surrounds, spread it nicely, and lo and behold, the Model 5s ARE nice speakers with surprisingly good bass response.