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KP-301 crossovers


ArmandCroft

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12 hours ago, ArmandCroft said:

I see what you mean now. I’ll see if I can dig up the original schematic for the KP 3.0B crossover. I plan on using these as PA speakers when my band plays and shop/practice space speakers when not in live use, so I would like the protective circuitry in place. Also, are you saying that once they protect your tweeters once  they become less effective or even useless in terms of protection? Thanks.

 

 

I can’t find the thread, as usual, but I BELIEVE (here-say) it said the polyswitches measure .5 ohms “untripped” and immediately go to 1.5 ohms after their first “save”. 

 

They continue to work and save your tweeters, but the resistance slowly climbs each time. So your tweeter sensitivity is slightly decreased over time, maybe not even enough to notice?

 

When they outright fail (burn out, or blow), the parallel resistor saves your tweeter, same as when they “trip”. 

 

But now you would need to open up your speakers and replace the polyswitch in order to have functional tweeters again.

 

 

 

 

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Hi - I might have the answer for your K-48-K, where long story short on my KP-3001 crossover refurbishments (drama on another thread) - I replaced one K-48-K with a Kappa 15-C. 

 

Thus I have a K-48-K sitting in the Emminence 15C shipping box all by its lonesome self.  To help your journey (I am enjoying as others) - I would be glad to offer you my spare K-48-K gratis if you would pay shipping from ZIP 85248 (Phoenix area).  I have to head out the door right now and can take some pics later today if you are interested. 

 

Aloha,

Rick

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18 minutes ago, rszoke said:

Hi - I might have the answer for your K-48-K, where long story short on my KP-3001 crossover refurbishments (drama on another thread) - I replaced one K-48-K with a Kappa 15-C. 

 

Thus I have a K-48-K sitting in the Emminence 15C shipping box all by its lonesome self.  To help your journey (I am enjoying as others) - I would be glad to offer you my spare K-48-K gratis if you would pay shipping from ZIP 85248 (Phoenix area).  I have to head out the door right now and can take some pics later today if you are interested. 

 

Aloha,

Rick

Cool...

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Wow, the support and kindness of this community is a little overwhelming. Well Rick, I could certainly use that woofer so I feel to keep things in karmic balance, I have a K-43-SK, I believe, let me recheck the last letters that is available for anyone who wants to pay shipping. I think we are all going to be contacting Billybob before : 1.going on trips to Vegas 2.asking girls for their hand in marriage  3. important elections etc.... Thanks so much for all your help with these old musical dreams of mine. I looked and looked and people asked why I was so set on these speakers and the answer is revealing itself in a more beautiful way than even I knew. 

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Seems this project is moving ahead nicely. I really want to thank Rick for his kind contribution of the K-48-k woofer, which is on its way. In regards to the Klip circuit, that Geoff noticed was missing, (the tweeter protection circuit) I found the poly switch, suggested by Dave A in one of Rick’s posts but , since it has been removed , I am unsure on the value and type of resistor that goes with it. Thanks in advance

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5 hours ago, ArmandCroft said:

...I found the poly switch, suggested by Dave A in one of Rick’s posts but , since it has been removed , I am unsure on the value and type of resistor that goes with it. Thanks in advance

 

 

200 ohm, 25 watt I think it says in the schematic on the second page of this thread.

 

You should take a screen shot of that schematic, or otherwise save it, as things seem to randomly disappear on here, lol.

 

 

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I am usually pretty good at wiring diagrams but the schematic is a language I don’t speak very well. My bus strip has 5 sets of wires . The schematic shows only HF and LF on the input strip, but now that I look at it again , I assume the W, M and F on the right side mean Woofer,  mid and tweeter. I’m learning , slowly. I’ll take a picture of it as you suggested, and thanks so much for noticing the missing parts. 
    So to replace the Caps, for each speaker crossover I need:

2. 4 uF 250v caps

1. 68uF 100v cap

and to replace the Klip circuit I need:

1. Erse R60-050-L polyswitch

1. 200 ohm 25 watt resistor 

Does that look right Geoff? Thank you for helping me out. 

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Made a little more progress on the boxes. First base coat and a quick clear coat to seal the wood. It's not perfect but I'll take a look at it tomorrow with new eyes and see if it needs to be block sanded and recleared. Ordered new corners, screws, t nuts, etc. Dave A. mentioned that these corners from Parts Express don't have the little reliefs to overlap the edging. Once I get them, I'll see about cutting a little out because I think the overlap is much tougher than a butt joint if you're hauling them around and setting them up regularly. Polishing up the handles and cups. One of the grills is in pretty decent shape and has an expanded sheet metal grate behind the cloth to guard the woofer. The other grill, some "artist" cut off (continues below).......

 

 

 

 

207433496_KP-301Firstcoatpaint.thumb.jpg.c29b2b12e0ab86e1f197389b2059b991.jpg573328249_KP-301firstcoatpaint2.thumb.jpg.bb6d2843cd757ab0db555666c2577e16.jpgthe bottom about half way into the ports so I'll have to make a new grill board. That one has a plastic screen for the woofer. Looks like the brushed brass name plates are salvageable but I also prefer the professional ones that Rick mentioned. I'll look and see what vintages came with which badges. Cheers!

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17 hours ago, ArmandCroft said:

So to replace the Caps, for each speaker crossover I need:

2. 4 uF 250v caps

1. 68uF 100v cap

and to replace the Klip circuit I need:

1. Erse R60-050-L polyswitch

1. 200 ohm 25 watt resistor 

Does that look right Geoff? Thank you for helping me out. 

 

 

There are different schools of thought on the 68uF cap. I think you are leaning towards an electrolytic(100V), as was originally used.

 

Some suggest a film and foil in that value as well. The ones I see are rated 250V or 400V. I always found it odd that the driver that gets the most power has the lowest rated capacitor.

 

You could parallel two 33uF electrolytics for a higher rating too. Klipsch does that very thing in the Khorns and La Scala crossovers.

 

Something I read recently on here suggested always using the same values (ie. 33 + 33) when paralleling capacitors though. That jibes with my OCD. Another post suggested reversing the orientation of one of the paralleled caps as well.  Something to do with the construction of the capacitor. 

 

Don’t forget the 2 x 2uF caps for the tweeter circuit.

 

And if you have not soldered much, even if you have, leave the leads as long as they come so you don’t “fry” the guts of the capacitors when you are soldering them. Heat is the number one killer of capacitors.

 

 

 

 

 

 

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The KP-301s are moving along. I got the ferrofluid today from PX so I went ahead and put the titanium diaphragms into the K-79ks. They tested 9.2 ohms and O.L before and now they both read 8.7 ohms. Nice! Also got the plastic corners so tomorrow I'll see about figuring out how to overlap the extrusions. I decided I wasn't happy with the so-so paint on the cabinets so I've been sanding and priming, going for that Steinway finish. Silly, probably not necessary but I figure they'll be something I'll be proud of for many years. Got most of the capacitors ordered. Decided to go with better 68uF caps per Geoff and Dave A's advice. I thank this community for helping through the areas I'm not so well versed in. It's funny, after all the reading I've done in the last few weeks, my early questions seem a little ignorant but that's the pleasure of learning new things.  I'll post pictures tomorrow. Cheers to these Sonic Reducers!

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  • 2 weeks later...

After many hours of sanding, I decided to just paint these 301's with Duratex. The glossy coating is just asking for trouble. I stripped the badges and cloth off the grills. One had been cut off about 3" from the bottom, so I planed down some poplar and glued it onto the bottom and it seems to have worked out very well. These speakers are 2 different vintages by a few years and the difference is pretty astounding. Speaker 1 has nice plywood grill with expanded steel grill over the woofer inserted with epoxy and the cloth stapled with literally 200 staples. Speaker 2 has a cheapie pressboard grill frame with plastic grate barely held in with hot glue and the cloth was glued on.It's possible it is a replacement but I doubt it. Cloth and logo are the same. One logo I was able to get the black paint off of, the other is too far gone so I'll make a replacement aluminum plate and have the logo die cut in vinyl as a replacement. I'll post a few pics in a separate post. Cheers.

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As I am getting closer to the realization of this project, I am very thankful to all of the bits of knowledge and even parts that have  been shared by a number of more experienced and very patient and generous members. This is just a thank you to you guys and those who make this site a possibility. My hat goes off to you.

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