KLH Model Five ~ Restoration Part 1 ~ Disassembly & Crossover Rebuild

In this video I take apart a set of ailing KLH Model Five speakers, diagnose an issue with the crossovers and rebuild both crossover boards with new parts.
Parts Used In This Video - PARTS EXPRESS
QTY 2 - 027-220 - 3.0uF 250V
QTY 6 - 027-226 - 4.0uF 250V
QTY 2 - 027-578 - 16uF 400V
QTY 2 - 027-256 - 25uF 250V
QTY 2 - 006-5.1 - 5.1 Ohm 10W (Use 5 Ohm if available)
QTY 2 - 006-6 - 6 Ohm 10W
QTY 2 - 006-10 - 10 Ohm 10W
QTY 4 - 255-955 - 15 Ohm 10W
Some of these board are slightly different. Inspect the actual value on your boards before purchasing parts. See note regarding 5.1 ohm resistor.
Resources:
www.classicspeakerpages.net/li...
00:00 Introduction
00:37 Removing the Grills
02:55 Rear Panel Information
04:13 Initial Testing
06:21 Removing the Woofer
10:12 Removing the Crossover
12:59 Removing and Testing the Tweeter
15:27 Crossover Testing
24:59 Gutting the Crossover Time-lapse
25:28 Parts Choice
26:20 Crossover Rebuild Time-lapse
29:00 First Look at Rebuilt Crossover
30:40 Bode Plot of Rebuilt Crossover
31:15 Capacitor Prep for 2nd Rebuild
38:29 Rebuilding the 2nd Crossover
46:34 Cleaning the Rotary Controls
47:37 Frequency Response Variations w/ Control Settings
OLED Background Credit:
Khai Truong

[@emorykearns2073]

Thank you so much for all your help with my rebuild these speakers are amazing I really appreciate all your help. They sound wonderful. It’s an incredible difference with the news caps your the man 🙏

[@patmeadows4759]

Greetings Ben. Great video as usual. Camera work and audio excellent. I was fortunate to pickup a pair of Model 5's ($300 CDN.) that needed thee top side and bottom exterior sanded and refinished and sides just light sanding and restraining. I flipped the grill cloths and restapled. They turned out great. I have made and addl. front speaker grill on masonite type board and plan to make a second set of grill cloths with a lighter 18 ct. linen cloth. The woofers are the square magnet versions and the crossovers are the printed circuit board variety. By coincidence I used the same make and values of new polypropylene caps as you did in this part 1 video. I retained the original resistors as they were in great shape. After the crossover restoration they sound fantastic (for their vintage and age) . I have also restored along the way may Advent OLA and NLA versions for friends of my same 'Baby Boomer' era!! All powered by fully restored versions on Marantz Receivers and upgraded with some restoration vintage 70's era TT.

[@MrSquekersUPSB]

Thank you so much for these videos! I have a model 20, and the tweeter on my left speaker is out, and I noticed that the balance knob doesn’t properly work. Seeing you go through this process makes it seem approachable!

[@wwz1011]

I loved my KLH Model Six speakers. I let them go at a weaker moment. Right now, I have a pair of Model 23s. The cabinets on the 23s are really nice. Sadly, someone in the past replaced the tweeters...

[@don7680]

Hey Ben, as a retired tech (who worked at a high end audio amplifier mfg) I really enjoy your videos! You have a superb bench setup and great equipment. Most of the other tech's on YT could learn a thing or two about having a great setup and keeping it neat and tidy, other than Mr Carlson - who's bench setup is like the helm of the Starship Enterprise. Thanks

[@NovaluxStereophonic]

Thank you for the kind words. I try to keep things as clean as possible for my own sanity. I know many techs with vastly more experience and knowledge than I that are perfectly comfortable in relatively “untidy” environments but for me I get frustrated and lose tools when things get messy. I am glad others are noticing though, it took me a long while to optimize this bench and it works very well for me.

[@matthewtaylor7355]

MR CARLSON WUD NOTT BOTHER UPGRADING THIS TAT... NOT COST EFFECTIVE AT ALL...

[@poormanselectronicsbench2021]

I am currently tinkering with a pair of Acoustic Research AR11's I picked up at a bargain price, BUT, they had some cheap 8 ohm woofers scabbed into them, probably because of foam surround rot and poor ownership care and speaker repair choices. One thing I did notice on the teardown was, the internal wiring was all marked as being 22 gauge stranded wire. I personally find that small of a diameter wire, especially going to the LF driver / woofer as being totally absurd, as it barely has a rated current carrying capacity for the speaker at rated power. Since the air core choke had a solid wire winding measuring out at 17 gauge, I am planning to rewire any connections going to the woofer with 16 gauge stranded wire. I think it's funny how much emphasis that "audiophiles" place in getting oxygen free battery gauge sized cabling for a connection between an amp and the speakers binding posts, only to find true inadequacies used in mass production inside of the cabinet that they are not aware of. I find it kinda crazy that "wire nuts" were used inside of those speakers for connections, hopefully your corrections will help it perform better.

[@matthewtaylor7355]

Ur right audio files r unaware of the cheap wire used inside speakers.. They miss the obvious.. It takes the genius to c this

[@kampeskaMNSD]

Was wondering if you have ever restored a pair of TEAC LS-350? Just completed part 1 of KLH Model 5 restoration. I've never done this before. Disassembled one speaker before taking pictures of everything. Have any ideas? Sure wish I would have found your channel first.

[@cjay2]

Such beautiful and well-designed speakers. They sounded great back then, and I imagine they still do. And the acoustic suspension is still the way to go. Modern ported designs really work poorly in the bass, no matter the price.

[@mikepxg6406]

They look like a blind man put them together. And those wires wound together with those weird toy town terminals. Very poor construction

[@matthewtaylor7355]

@@mikepxg6406 Wasting new caps on tat lol

[@daviddaydodge8985]

Re building the x overs for a client and I’m finding an extra 4.5mfd cap that has “tweeter protector” printed on it. I imagine this was added sometime long ago. Thinking it should probably be removed…?

[@OliverThayer-cv2kp]

I have a pair of model 5s with a PCB style crossover, I couldn’t find a date stamp anywhere, the serial number is 08341, would you know approximately what year they were made? thanks

[@Tuberhead1000]

How did you setup the O scope to do frequency response? A video on measurement technique might be popular...

[@NovaluxStereophonic]

Certain Siglent scopes and signal gens can be linked with USB or ethernet, the scope then controls the signal gen. I’ll keep this in mind for a future video.

[@participantparticipant506]

What background music did you use for the crossover rebuild time lapse?

[@NovaluxStereophonic]

I put some details in the description of the video. Something I whipped up years ago…

[@emorykearns2073]

Will using the 5.1 ohm resistor versus finding a 5 ohm resistor make a huge difference.

[@NovaluxStereophonic]

No, the original resistor has a tolerance of 10% so the value can range from 4.5 -5.5 ohm. The replacement that I chose has a 1% tolerance so fits within the range with room to spare.

[@jdsalinger73]

If you don't have a function generator, can you input a sine wave from KZbin?

[@NovaluxStereophonic]

Yes, as long as you have control of volume a test tone video can be used for basic checking of the drivers. The main thing is to avoid putting low frequency high powered signals into the tweeters.

[@tomasvalentin6896]

👍🏿

[@jdsalinger73]

It seemed to me that your capacitance measurements were close enough to spec and the freq response curves didn’t show a huge change afterward. So did you mostly rebuild for return on investment and because you were in there anyway? Just curious. Is the paper cap film or lytic? Are the black ones film?

[@NovaluxStereophonic]

Return on investment was not a factor in the decision. My recollection is that all of the original caps are electrolytic. Electrolytics that old need to go. They some may have “worked” but while the board is out it’s better to replace them once with film and never have to worry about going back in there in my lifetime. The replacement capacitors are all PP film types.

[@jdsalinger73]

@@NovaluxStereophonic OK, thanks. Getting ready for a restoration and don't have a capacitance tester. Was pondering whether I should rebuild the XO or not. Now I know it's a must.

[@NovaluxStereophonic]

@@jdsalinger73 Oh yeah, if you are going through the trouble of pulling the crossovers, replacing the caps is the way to go. Resistors are 100% optional. Also consider adding jumpers for all of the common ground connections. If you have the point to point crossover version the rivet joints between the terminal strips and crossover plate can develop resistance over time and cause issues.

[@Moto7357]

if a crossover calls for a 6uf but a 6uf is unavailable, can i use a 6.2? Or is it better to use 2 3uf’s?

[@NovaluxStereophonic]

I would look at the tolerance of the original part. If it’s large like 20% and the new part of 1% or 5% for example the 6.2 would be fine. Depends on the original circuit and capacitor type.

[@Moto7357]

Also I need a new speaker attenuator for an Altec Lansing 887a Capri speaker. How can I find out which one to buy?

[@emorykearns2073]

OK last question I noticed that some of the resistors had a wattage value on them which doesn’t match the new ones for example the 10 ohm original says it’s 5w but the new one says 10w

[@NovaluxStereophonic]

Fine as long as the new ones are equal to or greater than the wattage rating of the original part.

[@emorykearns2073]

@@NovaluxStereophonic does the tweeter have to be redoped I’m sure taking the metal off could very tricky

[@NovaluxStereophonic]

@@emorykearns2073 No, only the woofer should be considered for surround doping. The other driver have paper surround IIRC

[@TheAndrewWScott]

Got any vids on model six restore?

[@NovaluxStereophonic]

I do not. For KLH the Five and Eight are really the only ones that I seek out for restoration.

[@TheAndrewWScott]

Don't blame you. The early sixes have the grill clothe glued to the baffle and the x-over is buried in epoxy. I inherited a set from my grandmother that she purchased in '62. One of the tweeters has gone out, so I'm researching the best way to go at it. Gotta bust out the chisel!

[@emorykearns2073]

Is there any chance you could send me a parts list please of what you used please 🙏

[@NovaluxStereophonic]

I just added the parts list that I used to the video description. Use at your own risk :)

[@emorykearns2073]

@@NovaluxStereophonic you are the man bro thank you 🙏

[@davek8552]

Can you rebuild mine?

[@NovaluxStereophonic]

I am not sure that it’s financially viable but you are welcome to message me on my Facebook business page and we can discuss.

[@mariokolenko4322]

Change capacitors and resistors and leave that nasty iron coils and aluminium plates????? Why??? Point to point wire and air core coils is much better.

[@slackthompson6984]

a pair of these stolen from me east central FL about a year ago ....................

[@matthewtaylor7355]

Is all that wadding necessary.. Does it not muffle the sound.. The crossover is an over complicated jumbled mess... Old tat..And the overloud cow bell new age music

[@mikepxg6406]

I am from UK. Never heard of them. They look dreadful. And original construction is amateurish.

[@matthewtaylor7355]

Buy new from China Hi Fi... Why d they bother with this old crap

[@wayneg296]

👍👍😎✌️🤟