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robhifi

Not another crossover thread!

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Just wanted to start off by saying hello to everyone. I am a long time Klipsch fan and (not counting a couple of center channels) a first time owner. For my first pair, I've decided to get my feet wet with a pair of solid second hand RF-3s. I am very happy with the overall sound and am admittedly not over the DIY bug... So I would like to try to eliminate the rather fatiguing sound from them. I was wondering whether anyone has tried adding a notchfilter above the low pass section on a pair of reference towers. Before anyone tells me to leave well enough alone, I just want to say i am doing this as a fun hobby project, and have been an engineering technician for almost 10 years, so I do have boththe skillset and equipment to handle this type of project. Thanks in advance for any insight into the matter.

Ps I have already ordered new Dayton capacitors for the high pass, as well mills resistors, based on recommendations have seen on this site

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I trust you have the schematic from the crossover pinned thread.

 

The unit is bi-wired from what I see.  So you could put an L-pad at the input to the tweeter and see if knocking it down a bit helps.  This might alter the frequency response but is easy to do.

 

If that does not give satisfaction.  I think you have to determine the extent of any peak and you'll have to do that by measuring the frequency response acoustic output.  Not easy unless you have the right equipment.

 

WMcD

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Yeah, ive definitely got a copy of the schematic ;) I think the L-Pad would be handy, but i was thinking more along the lines of doing a filter for the woofer section. During a little searching here on the subject, I found an output graph showing that even though the crossover point was around 2khz, there was still a significant range of higher frequency passing through to the woofer, taking it all the way up over 4khz if I remember correctly. Based on the graph it seems likely that it could be the source of the "fatiguing" quality of the speakers. If so, this seems like it would be fairly easy to fix with a filter... but what would adding a circuit like this do to the overall circuit impedance?

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Welcome, robhifi.  You've no idea how much information and religion you will get here about crossovers.  It will be interesting!

 

Dave

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Thanks Dave! After flipping through the various threads here on the forum, i knew this would definitely be the right place for these types of questions, as there seems to be a lot of very knowledgeable people here. I know the electrical theory behind the basic operation of the circuits and could design one that works... but as we all know, one that works on paper and one that sounds good are two VERY different things! Crossovers are like black magic... so i'd rather pick some brains before i just jump into doing something crazy haha. I know its "just a pair of RF-3s" but it'll be a good learning experiment, and i think the speakers actually have quite a bit of potential for not a lot of money. I also don't think the girlfriend would've been as understanding of me jumping right into a pair of k-horns or la scalas :blink: (neither would my wallet). I figure if i'm going to do experimenting, lets start out on a not several thousand dollar pair  ;) Thanks again in advance to everyone for any insight into this project!

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This is not what you probably want to hear - but leave the original design intact.

I wouldn't mind seeing the plot you found. The electrical model is often quite different than the acoustic response.

By replacing the two oval epoxy coated capacitors with some Dayton Audio capacitors -- you'll hear a smoother sounding loudspeaker. I think the values are 12uF and 5uF. Replace the resistor on the right side of the board with a Mills non-inductive.

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There's nothing wrong with the stock sound of the RF3's so I would suggest enjoying what you have and maybe diving into the mod world down the road. 

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By replacing the two oval epoxy coated capacitors with some Dayton Audio capacitors

 

Dayton Audio has done a great job of replacing those long lost staples of the audiophile on a budget like Allied and Lafayette.  Such fun stuff, and extraordinary performance for the dollar.  Granted, nothing that is likely to temp a Klipschead in the main system, but so many fun choices.  Listening to K'horns driving by some of their 100 dollar or less digital amps says "It's the 21rst century, and we can build amplifiers beyond the dreams of the 50s that weigh almost nothing, cost pennies to build, and provide a level of accuracy few could afford before...and nothing worth a damn has happened to make the K'horn any less the most accurate loudspeaker for the money than it was in 1946."

 

Seriously meaningful, and it's a good time to be alive. 

 

Dave

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I suppose i should just slow down and see how this capacitor and resistor upgrade changes the sound before getting too wrapped up in a second project already. This will be the first time i've used any dayton capacitors, but i'm actually a fan of Dayton Audio, in fact i built my subwoofer around their 15" Ultimax driver... pretty good stuff. I'm having some trouble finding the plot that i had mentioned, but it may very well have been a model rather than the actual response. I'll have to take another gander  ;)

 

I'm pretty excited though, the new crossover components will be here Friday! I should probably upgrade the caps and resistor in the center channel too (RC-3). I can't find a schematic for that model, so i'll just have to open it up to see what i need... not a big deal.

Edited by robhifi

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I used to have those memorized. Oh well -- the values are written right on the caps. Just as before, put your efforts into the two oval capacitors in series with the horn. The resistor matters too, don't cheat.

Take your time, and be very careful when removing the caps. I usually warm the board up a little with a heat gun to soften the adhesive. Don't accidentally run a screwdriver or other tool into the side of one of the coils. Be sure to use heat sinks on the leads when you solder. Also, use an eutectic solder (63/37), not 60/40. Good luck!

Dean

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You can clip the leads on the old caps so you don't have to desolder from the circuit board as well. Then use the stub of the old leads as a solder point for the new caps.

 

Bruce

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You can clip the leads on the old caps so you don't have to desolder from the circuit board as well. Then use the stub of the old leads as a solder point for the new caps.

 

Bruce

 

That is what i have done in the past as well, good advice.

 

Lessening the chance of melting a board is a good thing.

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and nothing worth a damn has happened to make the K'horn any less the most accurate loudspeaker for the money than it was in 1946."   Seriously meaningful, and it's a good time to be alive.    Dave

 

Except for Danley SH-50 and 60 Synergy horns, I'd say you are right. 

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Except for Danley SH-50 and 60 Synergy horns, I'd say you are right.

 

Open to correction as I am not familiar with those.  Do they offer C1 to C10 at 106db/w cleanly at the same price as basic K'horns?

 

Serious question, as I honestly have not heard of "...another major breakthrough." 

 

Dave

Edited by Mallette

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Except for Danley SH-50 and 60 Synergy horns, I'd say you are right.

 

Open to correction as I am not familiar with those.  Do they offer C1 to C10 at 106db/w cleanly at the same price as basic K'horns?

 

Serious question, as I honestly have not heard of "...another major breakthrough." 

 

Dave

 

Got hooked on used TD-1's from the now defunct Sound Physics Labs. 103 db/W but they were designed to be used in pairs, so 4 for stereo. 106 db/W that way and still smaller than a LaScala with 14 drivers per channel (7 per box). Bounced the rest off the walls for greater dispersion in 6.1 setup.

 

Got 10 of those that were used by the Cleveland Symphony, which got me hooked on more phase coherent sound. The patent holder, Tom Danley has since moved on and perfected this "all drivers firing in phase in a single horn" designs called Synergy Horns. He has taken this and scaled them way up to provide "home hi fi sound" to Stadiums all over the world. I recently experienced his 4-15" and 8-12" subs and they can move some serious air at 140 db.

 

So I sold all those boxes for profit and I have now upgraded to 3 flagship Synergy Horn SH-50 that is Constant Directivity with smooth phase response, while being about 1/2 the cubic feet of a LaScala. I retain my Ported Super Heresys with the Cornwall "B" Crossovers for surrounds, with the side channels bounced off a flat wall for greater dispersion.

 

Here are some curves before and after on the SH-50 using

miniDSP Dirac Live

 

So, once you have a great horn speaker, a great PASSIVE CROSSOVER, a digital filter can do the final tweaks to make things ruler flat in the frequency domain as well as tweaking the phase in the time domain.

 

Sounds amazing. This could also be done with a 2-Way Jubilee with TAD driver and Roy's passive network, BUT it would be a much bigger package and would require a corner to get the lower bass, which the Synergy Horns do not.

post-20774-0-02380000-1448730909_thumb.j

Edited by ClaudeJ1

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By replacing the two oval epoxy coated capacitors with some Dayton Audio capacitors

 

Dayton Audio has done a great job of replacing those long lost staples of the audiophile on a budget like Allied and Lafayette.  Such fun stuff, and extraordinary performance for the dollar.  Granted, nothing that is likely to temp a Klipschead in the main system, but so many fun choices.  Listening to K'horns driving by some of their 100 dollar or less digital amps says "It's the 21rst century, and we can build amplifiers beyond the dreams of the 50s that weigh almost nothing, cost pennies to build, and provide a level of accuracy few could afford before...and nothing worth a damn has happened to make the K'horn any less the most accurate loudspeaker for the money than it was in 1946."

 

Seriously meaningful, and it's a good time to be alive. 

 

Dave

 

I have used less expensive Dayton Audio caps. When I measured them, they had much tighter tolerance than the more expensive ones, so I didn't pay the extra. They have low ESR so they allow for very "sharp" transients with any of the Klipsch horns.

 

Used them in Khorns, LaScalas, Cornwalls, K402's with K133's, and my Super Heresy's. Best bang for the buck. Older Klipsch capacitors had a muffled/softer sound which was an immediate contrast once I replaced those in my Khorns first, then all the rest after.

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Except for Danley SH-50 and 60 Synergy horns, I'd say you are right.

 

Open to correction as I am not familiar with those.  Do they offer C1 to C10 at 106db/w cleanly at the same price as basic K'horns?

 

Serious question, as I honestly have not heard of "...another major breakthrough." 

 

Dave

Yeah, Tom Danley is for real (and a great guy). Changed the world and stuff. But I always thought if you had the house/room for khorns, that SH-50's would make really nice tops for them. You wouldn't have to run the basshorn so high and you basically would be "done".

His partners don't approve of offering home hifi products, or at least they haven't historically so their aesthetics remain "road" and flyable.

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