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robhifi

Not another crossover thread!

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Hi everyone

I just found this thread and thought I could add something to it. I have owned a pair of RF3's for about 10 years and love a lot about the way they sound but I have come to realise over time that on some types of music they can sound harsh and tiring.

 

Aluminium cone woofers, as used in the RF3's, are prone to  breakup resonances which I believe lead to the harshness  I have made a lot of measurements and tested a lot of different crossover variations to try to achieve a less tiring sound but still retain the life and realism of the original design.

 

The attached plots show the frequency response of the RF3 woofers, measured on the axis of the top woofer at 1m. The cone breakup around 4.2kHz is clearly visible on the plot with no crossover. The measurement with the Klipsch crossover shows that the resonance peak is still present and the output at 4.2kHz is only about 5dB down from the output at lower frequencies. The third plot shows the woofer output with a modified crossover which includes a notch filter. The level at 4.2kHz is now about 20dB down and much less audible.(Modifying the woofer filter in this way means the tweeter crossover must also be modified)

 

Regards

Robert

 

 

 

post-54453-0-05180000-1448876007_thumb.j

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Thanks Robert, that's the plot i was referring to!!! I couldn't find the other thread i saw that you had posted it in... this is what made me want to try to do the notch filter. Even Though i just did the simple cap and resistor upgrade, i would still love to try this! I was pleasantly surprised with how easy these boards were to work on... it was definitely nice soldering on a single layer PCB for once! What did you use to build your filter? Also, what would i be looking at for the modification on the tweeter? My only issue is the huge dip between 80-150 Hz in the response plot... why is there such a drastic drop?

 

Thanks again, 

Rob

Edited by robhifi

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Hi Rob

 

What did you use to build your filter?

 

I have designed a new crossover from scratch. Using the frequency and impedance files I measured using REW, I used a program called Passive Crossover Designer to produce designs that I constructed, then measured and listened to. After a lot of trials I came to my final design

The crossover is still a temporary version mounted on a matrix board.

 

If you wanted to try just the notch filter it is a parallel LCR combination in series with the woofers, so you could just put it between the existing crossover and the woofers

 

 

Also, what would i be looking at for the modification on the tweeter?

 

The Klipsch tweeter response through the filter is tilted upwards towards the higher frequencies. I don't know why Klipsch did this but it may be they reduced the level from 2kHz to 5kHz to compensate for the extra output from the woofers cone breakup. When I used the notch filter I felt the tweeter needed more output around 2kHz to 5kHz. The Klipsch xover also has a rising output right up to 20kHz. Again I am not sure why but it might be to increase the off-axis level of the horn. I decided to level out the response.

 

 

My only issue is the huge dip between 80-150 Hz in the response plot... why is there such a drastic drop?

 


The measurements I posted were taken at one meter from the speakers (farfield). This means the room has a drastic effect on the measured low frequency response. I have attached a plot showing the nearfield response taken a few mm from the front baffle midway between the woofers. As you can see the response is much smoother however the measurements around the crossover frequency are not so accurate. The dip around 40Hz is the region where the port fills in the response.

With the notch filter the cone breakup is still there but much reduced

 

I have also attached a plot showing the overall frequency response for the Klipsch xover and my version. Farfield measurement so the low frequencies are all over the place. The only thing I have not sorted is the amount I need to reduce the level of the tweeter. It needs a few dB attenuation.

 

 

post-54453-0-27900000-1449124919_thumb.j

post-54453-0-26540000-1449125454_thumb.j

post-54453-0-04620000-1449125474_thumb.j

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long lost staples of the audiophile on a budget like Allied and Lafayette

 

Don't forget BA!  What was it, Burston Appleby?  Probably wrong, I was just a kid.

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does anybody have a complete modified crossover spec sheet for the RF3?

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Dear diary... jackpot!

Thanks for the clarification, do you have a schematic of your crossover? Are you still working on the tweeter attenuation, or is this going to be the final design? Based on the measurements you'very provided I'd be interested in building a pair of these as well. This seems like it has some serious potential! Wish I had the equipment for these measurements... maybe Santa ;)

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do you have a schematic of your crossover?

 

 

Yes I do. BUT... I am currently away from home and wont be back until 22 December. I have my laptop with all the measurements but I don't have the papers with the final crossover schematic. I would prefer to wait until I am home again rather than try to remember and get it wrong. I am happy to post it then.

 

 

does anybody have a complete modified crossover spec sheet for the RF3?

 

 

Depends what you mean by modified. The crossover I have is a complete new design. See my previous post.

 

Robert

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I think upgrading crossover parts is absolutely worth it. I personally scrapped my original crossover boards and rebuilt them, but with the same value parts, just far higher quality ones from Parts Express. Couldn't possibly be happier. Just bought new air core inductors I will be putting in today. Also added much stronger internal cabinet bracing, as well as damping the horn and woofers. The difference really is unbelievable. They sound like much much more expensive speakers. Screw buying high end speakers, just buy a good old used set of Klipsch speakers and do some mods. :D (did same mods to matching center and surrounds) Only paid $100 for the RF-3 II towers. Yet I get many people saying they are, hands down, the best speakers they have ever heard.  :D (having acoustic room treatments and Audyssey Multi EQ helps, as well)

Edited by ninjai18

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Often a problem: the loudspeakers are worth less than the new parts you want to use to modify them. I usually encourage people to put the money into better loudspeakers. For example: do you think a pair of RF-3s can hang with a pair of RF-7s?

Edited by Deang

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do you think a pair of RF-3s can hang with a pair of RF-7s?

 

 

I have never heard a pair of RF7's but I would guess they are better speakers.

I paid around $400 for my RF3's about ten years ago.  At the moment in Australia I could buy a new pair of RF7's for US$7400 (discounted!!) or a good second hand pair for around US$5000. I can upgrade my speakers with new parts for a fraction of that.

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Often a problem: the loudspeakers are worth less than the new parts you want to use to modify them. I usually encourage people to put the money into better loudspeakers. For example: do you think a pair of RF-3s can hang with a pair of RF-7s?

 

No, they couldn't hang with RF-7s, that is a good point, as the horn and woofers and overall enclosure are better in the RF-7s. But I will say, I have heard stock RF-7s, and while they do sound great, I certainly prefer the sound of my fully modded RF-3 IIs. But that's just me. :P Now, I can't even imagine how incredible some upgraded/modded RF-7s would sound! Okay, I was probably being a bit hasty saying "screw buying high end speakers" - many consider RF-7s to be high end (I know, it's a matter of perspective) and they certainly are worth the cost of entry,

 

My end-all be-all of speakers is an RF-7 II HT system with fully upgraded crossover networks, better bracing in place, and the damping mods. :D

Edited by ninjai18

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does anybody have a complete modified crossover spec sheet for the RF3?

 

 

So, this is the official values Klipsch uses. I used the original values to do mine and they sound great, though I am curious to see what he came up with for values based on his REW measurements. My interest is peaked! :D

 Klipsch_RF3_crossover.jpg

 

msg_4542_0_87860000_1426727214.jpg

Edited by ninjai18
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Yeah, I've done the crossover component upgrade and the dampening mod for the horn as well, and am very happy with them. I still think the complete crossover upgrade is gonna be where its at if it can deliver on removing the higher frequencies from the woofers. A set of RF-7s would be amazing... I'd love to play with a set of those.

Edited by robhifi
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Yeah, I've done the crossover component upgrade and the dampening mod for the horn as well, and am very happy with them. I still think the complete crossover upgrade is gonna be where its at if it can deliver on removing the higher frequencies from the woofers. A set of RF-7s would be amazing... I'd love to play with a set of those.

 

I agree, I cannot wait to see the schematics for it! :D I am probably going to do these upgrades, as they seem well founded. I am wondering though, I would like to do something similar to the crossovers in my matching RC-3 II center and RS-3 II surrounds. How would I go about doing that? Any chance you're going to measure those, as well?

Edited by ninjai18

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Sorry I cant help you with the RC-3 and RS-3 crossovers. I bought my speakers with an RC-3 center but I sold it because I only listen to 2 channel music. I'm not into home theater so the changes I made have been for music not movies.

Robert

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Been away a couple of days.  Thread has wandered a bit, but that's cool. 

 

However, to back up a bit, I don't question Danley's genius, but I didn't get a clear answer to whether he bettered PWK's standard of covering 98% of the available recordings at a lower cost than the K'horn.

 

Dave

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Been away a couple of days.  Thread has wandered a bit, but that's cool.

However, to back up a bit, I don't question Danley's genius, but I didn't get a clear answer to whether he bettered PWK's standard of covering 98% of the available recordings at a lower cost than the K'horn.

Dave

This must be mine--erm,...it's my opinion that they solved different problems in different ways (at vastly different historical times). And I still think the one thing would be a wonderful top for the other thing.

I think it would be poor form to say more than that I love Klipsch, I'm happy to own their stuff, and that I'm grateful that the company provides the resources to support this wonderful community.

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