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Another KLH Five recap


JKent

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Right now there are 2 pair of Model Five crossovers on my bench and a third on its way. 

This one is a very basic recap and resistor swap. I know some respected members have said the 5W resistors are enough but I've seen burned resistors in a Five and in the similar Twelves so at 50 cents each I figure 10W resistors are cheap insurance.

This job used parts from Madisound. For each xo:

  • one 3.0uF mylar (from my stash of surplus caps),
  • three 3.9uF Carli mylar (to replace the 4.0uF NPEs)
  • one 15uF Carli mylar (replaces 16uF NPE)
  • two 12uF Bennic NPEs paralleled (to replace 25uF NPE)
  • one Madisound 10 ohm 15W resistors
  • one Erse 6 Ohm 10W resistors (from my parts box)
  • one Madisound 5 Ohm 15W resistors (10W not available)
  • two Eagle 16 Ohm 10W resistors (to replace 15 Ohm)

Several of the values are just a tad off but within the spec tolerance. I discussed adding 0.1uF and 1.0uF caps to make the cap values exact with the owner but we agreed it would not make an audible difference. The Eagle resistors are on sale for 0.50 each and happened to be the closest value available. The Madisound 15W resistors are more than is needed, and a little large, but one consideration was to order everything from one supplier to save shipping costs (and they are also just 0.50 each). And Madisound is great! I goofed on my order on Saturday. Just phoned Monday morning and Adam took care of it!

Total cost of parts for two speakers ~$50. Not bad.

The next set will be essentially the same but the owner of those xo's opted for film caps for the 25uF value. More to follow......

-Kent

 

 

 

 

TK xo 1 before.JPG

TK xo 1 after.JPG

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Nice post. I've been looking for a set of 5's to go with my Sixes, 17's and 32's. They just aren't coming up in my market. I'd settle for a set of 23's. There was a cheap set of 23's in the area recently but the poster wouldn't respond to any contacts.

That cross-over is rather involved. It has an interesting mix of inductor types. Do I count 5 inductors there?

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Tim

Funny--in my experience the 23s are the ones that are hard to find. Fives are fairly common and under=priced. IMHO they compete favorably with the AR-3a and will blow OLAs away. Nice Fives seem to go for 200-300.

Yes. 5 inductors. And six capacitors and five resistors. And a partridge in a pear tree. Not as complex as a Cizek but pretty involved.

-Kent

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3 hours ago, JKent said:

Funny--in my experience the 23s are the ones that are hard to find. Fives are fairly common and under=priced.

 

Not on the West Coast, at least Northern California. I had a pair a couple years back that I foolishly sold. Have not seen another pair come up locally in that time, and check often. They guy that bought them from me had been looking for a pair for a couple years before he found mine. 

Even though I own a pair of AR 3's and 3a's, if a pair of 5's came around locally, I'd probably be all over them. 

 

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Agreed, the fives are maybe the best vintage value out there at about $250 or less typically.  The six's are overpriced in comparison at similar prices.  Some of teh prices for 17's are also crazy low for how good they are.

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Here's one from the other pair. Just slightly different. On these I went with all mylar, so the 25uF cap is made up of a Carli 15uF and a Madisound surplus 10uF. Also added small parallel caps to the 15uF and the 3.9uF caps to bring them up to exactly 16uF and 4uF. Probably not audible but only added about $4 to the total cost, so why not? Speaking of cost, this recap/reresist (?) only cost about $50 for the parts for 2 speakers.

The capacitors were fastened to the aluminum plate using automotive trim tape. Resistors were attached with hot melt glue.

Interestingly (to KLH geeks) the other pair , SN 00481 and 00483, had 2 different style rotary switches; phenolic on one xo and ceramic on the other as shown in the photo in the first post while the second pair had the ceramic ones. The crossovers below were from the pair SN 010436 & 010520. That pair had a date stamp on the back of the xo: May 3, 1968.

 

M5 xo FF.jpg

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Cleanly done.

So you are using the automotive trim tape to avoid hitting the caps with the hot glue? I've always been concerned about heat damaging the dielectric in the caps. I use heat sink clamps when I can while soldering caps and try to do solder quickly to avoid transmitting any unnecessary heat into the cap.

- not sure that is a real fear or just a phobia on my part

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Tim,

I don't know either. Some experienced guys here say not to worry about hot glue and capacitors. OTOH, John O'Hanlon, a bona fide scientist, says not to use it (see page 16 of "Restoring the AR-3a"). I'd like to err on the side of caution.

-Kent

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Thanks Kent.

I'll do a little research on the topic of soldering heat and damage to caps. I find these kind of topics interesting and relaxing. For me this all started with knowing that the dielectric is often made of materials that on the surface don't seem to be very heat resistant. I.e. Paper, (various) plastics, etc. Knowing that we're always replacing caps that fail makes me wonder how this could be improved. While I don't make caps, maybe I can do better when I install them. Just thinking out loud.

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Thanks Kent.

Here is an article on heat stress in capacitors. It talks about the various kinds of caps and the affect of heat. Title is: 

Thermal stress on capacitors: failure prevention

http://www.ee.co.za/article/thermal-stress-capacitors-failure-prevention.html

There's lot of info on the topic scattered around, but most of it is suppositions instead of actual science. 

 

 

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Informative thread here and great x-o pics from JKent. I have no personal experience with this speaker, but it looks to me like maybe there is a color coding going on with the wiring? Also, I think I like those 10W Eagle resistors due to their compact size - gonna have to look closer at these.  

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  • 8 months later...

Finally picked up a set of fives. The grills and badges are good. They need some cabinet work , have one non-functional tweeter, and are missing two of the knobs from the back. Luckily someone on fleabay named "geekyshrink" sold me two knobs. If I figure out who he is I'll thank him.  :P

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1 hour ago, Tim D said:

someone on fleabay named "geekyshrink" sold me two knobs

Guilty. Stupid name, isn't it? ;)

btw--if you ever need anything else contact me through the forum and I'll do better than the "fleabay" price.

Kent (aka geekyshrink)

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That was fun Kent. Not as fun as restoring these fives though.....

I hope the non-working tweeter is just a bad cap. I'll try to take some pics and upload them. Maybe I'll open them up and check it out this weekend.

BTW, the price on fleabay was more than fair, but I'll take you up on your offer next time.

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  • 1 month later...

Opened my Fives up today and the good news is that the tweeters aren't blown. On to ordering Dayton caps and 12w mills resistors. Thanks for all the help.

BTW,  my Fives have woofers with big round magnets and are dated 1968. Does that sound right? I thought Five woofers had square magnets.

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  • 2 weeks later...

I remarked on the topic in another thread just the other day

Securing caps (film types and electrolytics) with a hobby type hot glue gun WILL NOT HARM CAPACITORS IN ANY WAY, FUNCTIONALLY/ELECTRICALLY

Just look at the spec sheets for any cap you choose that uses through leads (caps you solder into a circuit or onto a PC board) if you still have doubts or don't believe me

Or remember the fact that many of the film types we use in our speakers also see duty in and on tube amp circuits

The heat a cap endures from the simple act of soldering far exceeds anything it's ever going to feel from a hot glue gun glob

Subjecting electrolyics to extremely high ambient or contact temperatures over a period of months or years (cooking them) is another story - that can eventually lead to knocking your values out of whack

Just look at the spec sheets for any modern type - they'll provide you a temperature and a time value

There is one (possible) exception and that's an extremely small value polystyrene types (tiny) but you're not using those in crossovers and the solderabilty on those is pretty decent as well for up to 3 seconds (unless you're heavy handed/don't know how to solder/not using some sort of heat sink)

You can melt/ruin them with a soldering iron, but even polystyrenes can easily handle the heat from hot glue 

Film, film and foil and electrolytics?  If hot glue is how you want to go then have at it

Back in the the day, JBL, Stephens, Altec and more than a few others potted their networks and that black asphalt type stuff was a hell of a lot hotter when poured than hot glue will ever be and stayed hotter longer as well

And a lot of those were wax types 

 

 

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  • 2 months later...

Martin and Analogman,

I'm not looking for a fight (could be banished to the Kitchen!). Use hot glue if you want, but the article linked above mentions the harm excessive heat can do. 

I got the advice about not using hot melt years ago from our ol' CSP pal John O'Hanlon, whom most of us know as the editor of the AR-3a Restoration Guide. In real life he has a PhD in physics, is an alum of IBM research and design teams and is professor emeritus of computer and electrical engineering at the University of Arizona. His bio is impressive: https://www.avs.org/Awards-Recognition/Awardee-Interviews/Interviews/John-O-Hanlon/Bio

So if John says hot melt glue can damage capacitors (and he does, on page 16 of the Restoration Guide), you can take that to the bank.

There are good alternatives: GOOP, ny-ties, heavy duty double-sided tape, caulk, bubble gum.... But if you want to use hot melt glue on your speakers, it's a free country.

-Kent

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Yet ANOTHER Model Five re-cap

A CSP member sent me a pair of Model Five crossovers. I was able to use parts I had in my "inventory" (saving additional shipping costs), so here's the parts list for the pair and a shot of the first xo

  • 2) 3.0uF 200V mylar capacitor
  • 6) Panasonic 3.9uF 450V mylar capacitor
  • 2) Erse PeX 15uF 150V mylar capacitor
  • 2) 1uF Paper in Oil cap
  • 4) 10uF mylar surplus cap
  • 2) 5.0uF GE mylar cap
  • 2) 10 Ohm 10W Xicon wirewound Resistor
  • 4) 15 Ohm 10W Xicon wirewound Resistor
  • 2) 5 Ohm 10W Xicon wirewound Resistor
  • 2) 6 Ohm Vishay 12.5W 1% wirewound aluminum finned Resistor

The 25uF caps were built up using two 10uF and one 5uF. They're in the upper right-hand corner--2 yellow 10uF atop one white 5uF.

To the left of that bundle is the 16uF: a green Russian 1uF PIO atop a yellow ERSE 15uF.

I used 3.9uF mylar for the 4.0uF. Those are the 3 brownish "chiclets" in the lower left. Under the middle 3.9uF is a single yellow 3uF mylar.

For some reason 6 Ohm resistors are not that common. I had the aluminum finned Vishays in my parts box. The other resistors are inexpensive Xicon sand cast 10w.

There are those who say the original 5w resistors are fine but I've seen scorched, burned and cracked resistors in KLH Fives and Twelves. I consider the upgrade to 10w cheap insurance.

For those who are interested, that's less than $40 worth of new capacitors and resistors for somewhat complex PAIR of crossovers for some excellent speakers. Could have been less if I had standard wirewound resistors for the 6 ohm (aluminum finned ones were $3.25 each). Also could have used Madisound 2uF surplus caps at 0.35 each to build up the 4uF but the leads are maddeningly short and space is somewhat restricted.

All in all a bargain price for high quality IMHO :D

-Kent

 

KLH 5 xo copy.jpg

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Here's the other one. Layout is slightly different (the 2nd one is always better ;)).

I checked the old caps. Some were spot on while others were way off:

Value          Measured       Measured

25uF            38uF               36uF
16uF            18uF               17uF
2x4uF           2,9, 2.8uF      1.3, 1.4uF
2x2uF           2, 2uF             2, 2uF
3uF                3.3uF              3.4uF

JM KLH5 xo 4_edited-1.jpg

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