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KLH Model 5 Rebuild including Recap


baski

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Hi all,

First of all I have to thank carl for running and maintaining wonderful site. I picked up near mint condition KLH 5 for $50 and I connected them to 25 WPC Harmon kardon A500. I felt the sound was too muddled with no High frequency. Doing Google research I stumbled upon this wonderful site. I read way too many of the recapping threads in the site and I decided to recap to make the tweeter work. While Recapping is easily done with some expert advice, I am thinking of restoring the wood too. I would also like to thank Jkent for detailed instructions on how to recap couple of these old speaker. Still I do have couple of questions regarding recap and rebuild. I don't have to touch the grill since they look clean. But I may need to super clean them if possible. Still I have the following questions.


Do I need expensive caps. If not which is cheap and neutral sounding Caps?

When I removed the woofer, I saw a cheesecloth lookalike covering the fiberglass stuffing. Is that normal? As a matter of fact, cloth was in mint condition.

Sealant for woofer from Roy.. He says it will not dry. Will it accumulate dust?

Since I removed the Woofer to access the X-over, What sealant to use as caulking?

Is it blasphemous to change the speaker binding post with banana plugs attached in the picture?

Is it real wood or veneer? If it is veneer, Can I sand it? If I can sand it, how deep I can go.

Jkent mentioned about Vishay cap for bypass. How it is Wired? And what is the advantage?


Thanks

baski


PS: First time posting in this forum. I apologize if the images are too big. I will resize and add them again.


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Hi all,
First of all I have to thank carl for running and maintaining wonderful site. I picked up near mint condition KLH 5 for $50 and I connected them to 25 WPC Harmon kardon A500. I felt the sound was too muddled with no High frequency. Doing Google research I stumbled upon this wonderful site. I read way too many of the recapping threads in the site and I decided to recap to make the tweeter work. While Recapping is easily done with some expert advice, I am thinking of restoring the wood too. I would also like to thank Jkent for detailed instructions on how to recap couple of these old speaker. Still I do have couple of questions regarding recap and rebuild. I don't have to touch the grill since they look clean. But I may need to super clean them if possible. Still I have the following questions.
Do I need expensive caps. If not which is cheap and neutral sounding Caps?
When I removed the woofer, I saw a cheesecloth lookalike covering the fiberglass stuffing. Is that normal? As a matter of fact, cloth was in mint condition.
Sealant for woofer from Roy.. He says it will not dry. Will it accumulate dust?
Since I removed the Woofer to access the X-over, What sealant to use as caulking?
Is it blasphemous to change the speaker binding post with banana plugs attached in the picture?
Is it real wood or veneer? If it is veneer, Can I sand it? If I can sand it, how deep I can go.
Jkent mentioned about Vishay cap for bypass. How it is Wired? And what is the advantage?
Thanks
baski
PS: First time posting in this forum. I apologize if the images are too big. I will resize and add them again.
Welcome to CSP, baski,
Here are my answers to your questions, but I'm fairly certain others may have different opinions:
Do I need expensive caps. If not which is cheap and neutral sounding Caps?
No...Non-polar electrolytics will work fine and are very inexpensive. Parts Express, Madisound, and Erse are all good places to find them.
If you desire to use film caps, steer clear of the high priced variety. The best brands of film caps to use from the above sources are Dayton polypropylene, Carli mylar, and Erse polyester.
When I removed the woofer, I saw a cheesecloth lookalike covering the fiberglass stuffing. Is that normal? As a matter of fact, cloth was in mint condition.
I have never seen a KLH speaker without that cloth behind the woofer. Save it and use it again.
Sealant for woofer from Roy.. He says it will not dry. Will it accumulate dust?
My sealant remains tacky, but dust collection is not an issue.
Since I removed the Woofer to access the X-over, What sealant to use as caulking?
Black sealant caulk or foam gasket tape (my preference) from Parts Express works very well. Duct seal from Lowes or Home Depot also works satisfactorily. Avoid plumbers putty (too soft).
Is it blasphemous to change the speaker binding post with banana plugs attached in the picture?
There is no functional or performance reason to do so... unnecessary work, imo. If you want to re-sell them someday, don't do it.
Is it real wood or veneer? If it is veneer, Can I sand it? If I can sand it, how deep I can go.
It is veneer...It can be sanded. Be careful.
Jkent mentioned about Vishay cap for bypass. How it is Wired? And what is the advantage?
By-pass caps are not necessary....unnecessary work, imo. These speakers were designed, and earned their reputation, with ordinary non-polar electrolytic capacitors. You will not "improve" them with by-pass caps.
Good luck with your project.
Roy
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Agree with Roy's excellent advice on caps.

Sometimes a supplier will select pairs to 1 or 2% tolerance for an extra $ or so. Probably worth doing for a crossover given the modest cost.

I would only comment on the connectors and say use whichever you are most comfortable with.

I like 4mm banana sockets and plugs as this minimises any risk of shorting, something which can happen with wire into binding posts and screw posts.

You can get thin body 4mm sockets so it's feasible to use these while retaining the option of reinstalling the originals should you wish to sell the speakers.

Lovely looking set of loudspeakers.

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  • 2 weeks later...
Roy... Thanks for detailed answers. I ended up buying Clarity Cap from e-speakers and I did splurge on it(Xmas came early for me). I will be completing the crossover in next couple of weeks if my kids/wife permits me to multitask this with another Restoration (small advent) I am doing.

Rob.. I may retain the old sockets for sake of it... I will try to clean and Deoxit the life out of them. As you mentioned the speakers were in really good condition and I was pleasantly surprised that seller let it go for 50 bucks.

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  • 2 weeks later...

Hi baski

I re-capped some Fives (wonderful speakers) with Clarity Caps for one of our members, Redstone7: http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=2557#entry74180

Regarding the binding posts: I agree with Roy but if you want to use banana plugs you could make little "dongles." One of our members posted a nice photo of some he made. Unfortunately I can't find them but the pic below should give you the general idea. Basically you take a short length of speaker wire and crimp a sta-kon ring terminal on one end and a female banana jack on the other. Put the ring terminal on the Five's stud and tighten it down well.

Kent

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  • 2 weeks later...
  • 2 months later...

I am back.. Sorry folks got sidetracked by something called family for couple of months.. Xmas holidays were spent in mexican blue seas during which I was hoping to redo those crossovers. Anyway I recently cleaned up a Vintage Pioneer SX-828 and while doing so I noticed some of the perfectly looking Resistors drifted. Initially I didn't want to touch the resistors since they looked almost new. But when I measured all of them were almost close to the spec except one. 6 ohm resistor was showing 0.5 ohm. DMM is autoranging and i checked other resistors multiple times to confirm what I am doing is right. How difficult it is going to be to check the resistor, eh? Anyway I think i need to replace all of these resistor since I lost confidence in all of them. What would you Gurus suggest I go with. Thanks in advance..

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If I remember correctly, Jkent used Mills wire-wound resistors when he rebuilt the crossovers to my Model 5s. Gosh, that was nearly three years ago. Time flies by! I have owned a Harman Kardon A300 for a week. It drives the Model 5s amazingly well and sounds great doing so.

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On 2/24/2014 at 1:45 PM, baski said:

I recently cleaned up a Vintage Pioneer SX-828 and while doing so I noticed some of the perfectly looking Resistors drifted. Initially I didn't want to touch the resistors since they looked almost new. But when I measured all of them were almost close to the spec except one. 6 ohm resistor was showing 0.5 ohm. DMM is autoranging and i checked other resistors multiple times to confirm what I am doing is right. How difficult it is going to be to check the resistor, eh? Anyway I think i need to replace all of these resistor since I lost confidence in all of them. What would you Gurus suggest I go with. Thanks in advance..

Nice find! You can download the service manual here: http://www.hifiengine.com/library/pioneer/sx-828.shtml

Personally, I would not replace all the resistors. All the caps, yes but resistors don't normally go bad.*

I did use Mills crossover resistors in Jim's Fives but in your receiver you want to use low tolerance flameproof metal oxide resistors and I would go up a step in wattage (replace 1/4 watt resistors with 1/2 watt, replace 1/2 watt with 1 watt). Here is an excellent overview of resistors: http://www.justradios.com/resistors.html and these people are good to deal with. On the off chance that they don't have what you need, Mouser is a good source.

Finding 6 ohms could be tricky. Here is a 1/2 watt 5.9 ohm 1% http://www.mouser.com/ProductDetail/KOA-Speer/MOSX1-2CT52R5R90F/?qs=EI3zrt7d7sP0ZliK5XUlaQ%3d%3d

Here's a 6.2 ohm 1w 5% from PE http://www.parts-express.com/62k-ohm-1w-flameproof-resistor-10-pcs--003-6.2k

Kent

*PS. But I WOULD replace all the resistors in your Model Fives. KLH used 5w sand cast resistors in those and I have seen more than one burned, blackened or cracked resistor in a KLH Five or Twelve. Use 10w resistors for peace of mind.**

**PPS 8 years later(!!) Roy and I have discussed this on and off for a while. I think he found the best answer: Do replace the 5 ohm resistor with a 20 (yes 20) watt resistor. You can also replace the 15 ohm resistor in the Mid circuit with a 10 watt. The other 5 watt resistors should be fine.

Edited by JKent
updated info re resistors
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  • 3 weeks later...

Thanks Kent.. I checked the resistors in Fives Crossover.. What do you know one of the 6 Ohm resister is out of spec totally. I guess I need to buy resistors for Fives too i guess. Since I am going to change all the caps, I am thinking of changing all the resistors too. I need to find a cost effective resistors instead of mills.. How is erse resistors?

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They are fine. No need to get the Mills (guess you blew your budget on those Clarity Caps ;) ). It's just their small size that makes them convenient. Here is a link to a Model Five Crossover I did with Erse caps. It's the later style crossover on a printed circuit board. Also used some Madisound surplus caps and Carlis http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=7890

Replacing all the resistors with Erse cost $3.50. Using Mills would have cost $42.50.

You can see the PCB is kind of crowded, especially with the physically larger Erse resistors, but it certainly can be done.

On the hard-wired xo you have a bit more flexibility. A real cheapskate (like me) could use even more surplus caps:

  • the 25uF could be 2 surplus 10uF + a Carli 4.7
  • the 16uF could be 1 surplus 10uF + 2 surplus 2.7uF
  • the 4uF caps could be 2 surplus 2uF
  • the 3uF could be a surplus 2.7uF

-Kent

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Baski, you asked about changing the binding posts. A word of caution to you and others who may be contemplating such a change; you must ensure that whatever binding posts are used, they must remain insulated (as are the originals) from the aluminum nomenclature plate used as the back panel.

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Regarding the resistors in your Pioneer - as always JKent gives great advice. However, unless the originals are flame proof, and are your typical carbon film type, I would use metal film (not oxide). 5.9 ohms 1% puts you well within the original spec tolerance.

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alkermes,

Thanks for the kind words. Now I have a question (I'm not an electronics expert by any means): Why do you advise against the metal oxide? I know that metal film may be more precise (+/- 1%) than metal oxide (+/- 5%) but is that critical? My recommendation for flame-proof comes from working on tube radios so I guess that's not a major consideration for solid state? Please 'splain.

Carl,

Good point regarding that metal plate. I'll reiterate my point that there is little reason to replace the binding posts--they work just fine. Leaving them preserves the vintage appearance (and value). If you want the convenience of dual banana plugs, Xmas's "dongle" is perfect.

-Kent

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Kent, you have helped so much in your posts here, I hope I can make a small repayment.

When I started getting into audio gear restoration, I did some research on this topic. The consenus is that metal films are preferable because they are less noisy than metal oxides. In the 1/2 watt range you can buy metal films inexpensively, I think the Xicon's from Mouser are 10 for $1. For the fat 1-2 watt resistors metal oxides are fine. You are more likely to find these in the power supply section.

So, it's not so much that metal oxides are bad per se, but that the metal films are better. The cost is insignificant in the common 1/2 watt size, especially compared to going in there and desoldering and replacing. You're likely to only do it once, so my feeling is that the parts cost is insignificant. If you're only replacing one resistor, will you hear a difference? If the resistor was out of spec the unit is likely to sound (or work) better no matter what you replace it with! But if you're going to replace a bunch of them, why not use the best.

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  • 3 weeks later...

Will there be day and night difference between Erse and mills

No.

Virtually all speaker crossovers use standard sand cast resistors like those Erse ones.

Here is a discussion: http://www.diyaudio.com/forums/multi-way/128821-non-inductive-resistors.html

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Ordered resistors from Erse and guess will try to do the crossovers by end of this week. I update if I make any progress this weekend. Thanks for all your inputs. Carl, I am not gonna mess with the binding post. I will make a dongle as Kent suggested...

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  • 7 months later...
  • 1 month later...

Baski,

A word of advice, be careful when you put the crossovers back in the cabinets. I forgot one of the insulating washers when I first put mine back together and I almost blew up the left channel of my power amp. Luckily a couple fuses blew and saved it. Its also a good idea to read the impedance across the terminals to make sure they are in an acceptable range for your amp. I think my XO's with Dayton/Solen caps measured under 4 ohm at rest.

Also, be careful on the dual cap. I assumed I knew which way it went on my first recap and had some issues. Double check the schematic there.

I have attached an image of one of my finished set of boards for reference in case you have not yet started, it may come in handy for cap placement.

Any questions at all on the process let me know. I am just about to start my 4th Model Five Recap.

-Ben

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  • 6 years later...
  • 1 year later...

I just picked-up a free pair of Model 5s, serial numbers in the first 25000, from the first owner.

Cabs are in great shape except for a slightly-dinged top-rear corner on one of them. Grillcloth is mint.

I'm getting ready to recap them and replace the driver seals, but have a coupla questions.

  1. What's the goop people are using to renew the driver surrounds? These appear to be in good shape, but I'd like to make sure they don't deteriorate.
  2. Should I replace the wimpy interior wiring with something like 14awg OFC?
  3. Should I replace the pots?

Thanks, in advance...

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Nice find!

Use ONLY RoyC’s goo on the surrounds. It makes a big difference on the Fives. Get it from eBay seller Vintage-AR or contact Roy. 

No need to replace the wires. But whatever floats your boat. 

Those aren’t pots they’re switches and they’re unobtainium. 

Kent
 

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