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jason str

Type A 4500 question

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36 minutes ago, wvu80 said:

I'm not the expert and I couldn't even hazard a guess.  I would offer that I'm not sure if you add 1db to the mid range you would hear a difference.  It is my impression that it takes a 3db change to be able to hear a difference.

 

The difference is quite substantial in my opinion, the midrange went from in your face to very laid back sounding unbalanced but i think a happy median will be the key.

 

 

Quote

 

I am following what you are doing because I have some Khorns with AA's that will need updated at some point.  Do I build some new ones from scratch?  Do I build A, AA or the A/4500 like you are doing?  These are some of the questions I don't have answers to.  It seems like I change my mind every time I see a post on the subject.


 

 

 

 

I am very happy with the A 4500 version personally.

 

Everybody hears things differently, i suggest finding close forum members with K-horns and letting you're ears be the judge.

 

Components driving them will make a difference as well along with the volume you do most listening.

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20 minutes ago, jason str said:

The difference is quite substantial in my opinion, the midrange went from in your face to very laid back sounding unbalanced but i think a happy median will be the key.

 

I wish I could put my ears against your changes.  It would save me from having to reinvent the wheel.

+++

 

I am very happy with the A 4500 version personally.

I think I would be, too.  It's what I'm leaning towards, but I'm not sure whether to build a new XO like you did or cheap-out and mod my current AA's.

+++

 

Everybody hears things differently, i suggest finding close forum members with K-horns and letting you're ears be the judge.

 

Components driving them will make a difference as well along with the volume you do most listening.

I really couldn't agree with you more.  It's this idiotic notion I have to find the "perfect" solution for a crossover, when everything you just wrote makes more sense.

 

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I'm curious.  I can't tell from the picture, but it appears that you wired the 4 uf tweeter cap directly to the crossover input.  The schematic shows it wired to the output of the squawker cap,  which would create a series circuit to the tweeter...constantly changing the capacitance to the tweeter as you change the squawker cap.

 

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26 minutes ago, mboxler said:

I'm curious.  I can't tell from the picture, but it appears that you wired the 4 uf tweeter cap directly to the crossover input.  The schematic shows it wired to the output of the squawker cap,  which would create a series circuit to the tweeter...constantly changing the capacitance to the tweeter as you change the squawker cap.

 

 

The tweeter is not hooked up directly to the input.

 

I'm still debating what to do and any input is helpful.

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15 minutes ago, tigerwoodKhorns said:

Swamp the transformer and squaker for a 4500 x-over and make it adjustable like an ALK.  It looks like you need to change caps anyway.

 

Please explain.

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I agree with the swamper idea, but very large capacitance (approx. 48 uf per channel) would be needed.  Still curious about the wiring.  Do you have a picture from directly above the crossover?

 

 

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the tweeter is hooked up as shown in the schematic between the midrange capacitor and the autotransformer #5 tap.

 

Crossovers are installed and these are the only pictures i have currently.

 

Happy to do whatever it takes to get it right but will probably need a schematic to follow if possible.

 

 

 

 

canon 002.JPG

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Sorry if you know this already, but...

 

The -3 db point of a first order filter occurs when the Z of the capacitor equals the Z of the driver at a given frequency.

 

Assuming an 8 ohm tweeter, a 4 uf cap's Z is 8 ohms at 4975 hz.  When a 4 uf cap is in series with a 13 uf cap, you will end up with a 3 uf cap to the tweeter.

A 3 uf cap will be down 3 db around 6630 hz.  The 6.8 uf cap in series with a 4 uf cap equals around 2.5 uf, crossing around 8000 hz.

 

My point is, if the caps are in series, as you change the squawker cap you are also changing the -3 db point to the tweeter. 

 

Also, I assume you are using one for Bob's tweeters?

 

Off to do Xmas shopping!

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6 minutes ago, mboxler said:

Sorry if you know this already, but...

 

The -3 db point of a first order filter occurs when the Z of the capacitor equals the Z of the driver at a given frequency.

 

Assuming an 8 ohm tweeter, a 4 uf cap's Z is 8 ohms at 4975 hz.  When a 4 uf cap is in series with a 13 uf cap, you will end up with a 3 uf cap to the tweeter.

A 3 uf cap will be down 3 db around 6630 hz.  The 6.8 uf cap in series with a 4 uf cap equals around 2.5 uf, crossing around 8000 hz.

 

My point is, if the caps are in series, as you change the squawker cap you are also changing the -3 db point to the tweeter. 

 

Also, I assume you are using one for Bob's tweeters?

 

Off to do Xmas shopping!

 

 

No i did not know about that,  I'm no crossover expert by any means but can read a schematic, this modification was just a recommended trial but looks as though it may have been a poor one at that.

 

Yes, using Bob's CT-125 tweeters.

 

Good luck shopping, i had mine done some time ago to avoid the crowded stores.

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Is it possible to drop the squawker to the -4 or -5 taps and keep the 13uF and 4uF caps in place ?

 

Just a thought and the parts are right here.

 

Disregard.

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3 hours ago, jason str said:

 

Please explain.

Middle of my workday so I don;t have much time, but IIRC, a 10 watt 10 ohm resistor equals about 10 ohms if in parallel with the squaker and transformer on the various settings.  Calc the capacitor based on the link that I provided in the previous page using 10 ohms for the mid-range and 4500 for the X over.  I think that teh ALK uses 40 uf.

 

Someone correct me if I am wrong here.  No time to check my notes. 

A4500 Schematic.jpg

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No rush, been going over some old posts myself trying to figure out what to do here.

 

Appreciate the help.

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Move the wire you have on input tap 5, to input tap Y. 

 

Sounds like you already have the K-55 on output tap 3 - which is where you want it. 

 

This combination gives you -5dB of attenuation. 

 

To keep the crossover point the same (@400Hz) , you need to add some capacitance. The math says you need 8.23uF. Just add a 2uF cap to your 6.2 (in parallel) - and you're there. 

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9 minutes ago, Deang said:

Move the wire you have on input tap 5, to input tap Y. 

 

Sounds like you already have the K-55 on output tap 3 - which is where you want it. 

 

This combination gives you -5dB of attenuation. 

 

To keep the crossover point the same (@400Hz) , you need to add some capacitance. The math says you need 8.23uF. Just add a 2uF cap to your 6.2 (in parallel) - and you're there. 

 

Will i need to change the tweeter capacitor value as well ?

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Finished up tonight, i replaced the midrange capacitor out to a Audyn Q4 along with some wiring to make it all tidy like.

 

Put some heavy sound damping sheet stock on the K-400, dampened the inside of the top cabinet and sealed it off with some plywood with a recessed terminal cup.

 

Finally i replaced the old wire with some Knu Konceptz Kord ultra flex wire before sliding them back into place, initial impressions are all positive.

 

 

 

 

 

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That's awesome, Jason! I have my new baffles for the woofer mounting put in place and the K-400 horns installed (rear mounted... tired and just want them done). Since I have the doghouses opened up I need to add the strips to close the backs and put the two ports in (or build the slot port). Put all the parts back in and try them out. I really miss the big sound that La Scalas have.

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41 minutes ago, jason str said:

Finished up tonight, i replaced the midrange capacitor out to a Audyn Q4 along with some wiring to make it all tidy like.

That cap is red in color.  The other caps you had looked white.  What brand did you originally have, and why did you think the Audyn was better?

 

Put some heavy sound damping sheet stock on the K-400, dampened the inside of the top cabinet and sealed it off with some plywood with a recessed terminal cup.

This is interesting.  I see people putting damping material on other models, but rarely on Heritage.  It makes sense to me to add the material, but I read somewhere that damping the horn was not necessary.  Do you have any thoughts on the subject?  Did you see a post where this was done?

 

Finally i replaced the old wire with some Knu Konceptz Kord ultra flex wire before sliding them back into place, initial impressions are all positive.

What AWG did you use?  I'm guessing 16 AWG?

 

I am a big believer that a lot of little changes can pay off big in the overall sound.  That sounds like what you did.

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