Seas Woofer replacement for KLH Model 17?

[TroutBear]

I just picked up a pair of KLH Model 20's from an estate sale - so $45 for the pair plus a Fukuyo Audio Coral single that was in the bundle [center channel use by PO maybe? - will investigate this one later] that appear to be in nice condition. Ordering some binding posts to replace the rca inputs. It looks like the 20's are identical to the model 17 in tweeter and crossover with a 4 ohm woofer versus an 8 ohm one in 17's. If they fire up and check out as is, I'll build the crossovers and would like to replace the woofer with an 8 ohm one.


I'm considering a Seas Prestige A26RE4 https://www.madisoundspeakerstore.com/approx-10-woofers/seas-prestige-a26re4-h1411-10-paper-cone/ as an option. Anyone used this driver in a 17 or have inputs on threads for Model 17 updates - including any suggestions on the crossover - as long as it stays within the complexity level of no greater than 2nd order. Thanks

 

[RTally]

I have a pair of Model 20 with the 4 ohm woofers. That woofer performs above expectations, particularly considering the limitations due to the cabinet volume. I have a 4 ohm capable amp powering the speakers. I am listening to them now, powered by a NAD 7040PE.

If you are going to keep the KLH tweeter, just recap the crossover. I used metallized poly caps for mine. Redesigning the crossover makes no sense since you are unlikely to better the original design which has passed the test of time and been found to be exemplary.

The Model 20 woofer runs wide open and the speaker relies on the natural rolloff of the woofer to mate with the tweeter FR. Any non-KLH woofer will need to have the specs matched to the cabinet and the tweeter. The KLH specs have the crossover frequency at 1500 Hz and the SEAS woofer is rated as having a natural 2000 Hz rolloff. This may result in a hump between 1500 to 2000. An appropriate woofer crossover will need to be used to match that of the tweeter. About the only way to make such a crossover is to measure the woofer in the speaker speaker cabinet and tweak the crossover for a smooth FR with the tweeter.

 

[TroutBear]

I appreciate the good inputs from someone who has refurbished a pair of 20s - I've seen your other posts on various KLHs also, 17s included. I'm ordering caps and resistors plus binding posts today. Mills has the 3 and 7.5 ohms in wire wound but the caps are proving a more difficult exact match. An 8.2 cap is certainly close enough to the original's tolerance band that I don't have concerns on ordering these; the 2s only seem to be out there in 1.8 and 2.2 as a single item without going to a pair of parallel 1.0s. Any comment on the selection there - up or down? Yes, I'm being lazy as I could go read crossover design papers. Cabinets will get a light refurbishment while I wait on parts.

This will let me get them going to review and it may stop there. The 2nd system Hafler DH-200 that these are slated for will drive 4 ohm speakers, as will the primary system MA5100 integrated amp - the desire to change to an 8 ohm woofer is probably more a just because thing...

No luck on a search for the suggested surround dope through vintageAR eBay yet though - suggestions on sources?

 

[RTally]

I try to get as close as possible to the original capacitance value when recapping. A 5% deviation is the most I will use when the exact value is not readily available. Speakers are not precision devices manufactured with tight tolerances. But that does not mean I like to purposely deviate from the specs too much.

Replacing a tweeter filter cap with a higher value will result in a higher crossover frequency. For the KLH 17, the 2 uF caps are part of a contour shaping network. Deviations in these capacitance values will have no impact on the primary crossover frequency but will only impact the shaping of the FR above the crossover frequency.

I often wire caps in parallel to obtain the exact value. Many believe it is best to use caps having about the same value when wiring in parallel, for example, two 1 uF caps instead of a 1.8 uF with a 0.2 uF.

Dayton and Solen metalized poly 2.0 uF and 4.0 uF caps are readily available from Parts Express. There are other vendors for other brands of caps, but I have not dealt with them.