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Ultimate RF-5 Upgrade


jjptkd

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I'm in the middle of another RF-5 mod so figured I'd start a thread and detail my steps move by move in case someone else wanted to do something similar, I've done something like this in the past with great results but ended up passing those speakers on to @vasubandu for his theater system. With those RF-5's I simply swapped out the complete horn / drivers and crossovers from a pair of RC-7's and installed them into the RF-5's, worked like a charm and was a nice step up from stock for both speakers depending on how you look at it. For the RF-5's it gave them a larger, slightly deeper tone that is very clean sounding, for the RC-7's it extended to lower end a bit and gave them a little more open sound. The difference between the modded RF-5's and running dual RC-7's was actually a smaller incremental change than the other way around.

 

For my next project I'm still installing the RC-7 horn driver combo into the RF-5's but this time I'm building completely new, custom crossovers for this set blending the schematics from three different crossover networks. Basically what I'm doing is building the top end crossover for the horn for the RC-7, nothing is being changed there expect the quality of parts. For the bottom end I'm going build the RF-5 woofer section except with the inductor rating for the RF-3 for a lower crossover point.

 

The stock RF-5 has a crossover point at 2500hz, the RC-7 horn (2.5 way crossover) crosses over at 1950hz and the RF-3 crosses over at 1975hz so basically my plan is to have the crossover point somewhere around 2000hz, which is 200hz lower than the RF-7. Right now I've already installed the horn driver into the RF-5's and I just bolted the top end of a stock RC-7 crossover to my stock RF-5 crossovers so there is a 500hz overlap but it sounds just fine to me, don't think anyone would be able to tell anything was wrong listening to them as there are right now. The RF-5 crossover while bi-ampable is on a single board where the RC-7 is on two stacked boards. I just stacked the top end over the single board and wired it appropriately. 

 

Right now I'm in a holding pattern waiting for parts to arrive in the mail I went with Dayton and Solen caps, mills resistors and ESRE inductors. I'll post additional pictures as soon as parts arrive. As always I'm open to questions, comments or suggestions, this is my first crossover build from scratch, going to run with the parts I have ordered for now but may swap parts in the future or build a second set for comparison purposes. 

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27 minutes ago, wuzzzer said:

And here I was expecting you to say that you sold them and bought RF-7s instead! ☺

Honestly I've been keeping an eye out for a pair of 7's to pop up locally but the 5's have plenty of low end, too much actually most of the time i have to have them dialed back so not sure if the extra cost and dealing with the additional size / weight would be worth it for me.

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38 minutes ago, Deang said:

So much summing error. Do you care - apparently not. 

 

I don't believe you. The woofers are the same in RF-3, RF-5 and the RC-7 cabinet size difference really between all three is negligible and almost non existent between the RF-3 & RF-5.

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1 hour ago, Deang said:

You’re jamming the low pass of the RF-5 with the high pass of the RC-7. You don’t know what you’re doing. 

So what happens if I pull the jumpers and bi-amp? Does that change everything?

 

 Every crossover calculator I've played with online does not change the value of the low end parts regardless of the impedance of the high end?

 

I admit I'm not an expert but I have researched this quite a bit and my ears tell me I'm not too far off here. I ran one speaker they way they are now side by side with a stock one and they sounded very close to the same only real difference being the larger sound from the bigger driver.

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12 minutes ago, jjptkd said:

So what happens if I pull the jumpers and bi-amp? Does that change everything?

 

 Every crossover calculator I've played with online does not change the value of the low end parts regardless of the impedance of the high end?

 

I admit I'm not an expert but I have researched this quite a bit and my ears tell me I'm not too far off here. I ran one speaker they way they are now side by side with a stock one and they sounded very close to the same only real difference being the larger sound from the bigger driver.

Please excuse but, you have not mentioned the bi-amping capability that I can recall, on this or the previous RF-5 project. Of course, still an option one may suppose. Stick with what sounds best to you, of course as, it no doubt was to your recent buyer, and enjoy your build. Have heard from crossover builders here that the bass remains the same regardless of the higher end with a crossover rebuild unless, you take steps to enhance the bass.

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7 hours ago, billybob said:

Please excuse but, you have not mentioned the bi-amping capability that I can recall, on this or the previous RF-5 project.

 

All three of the Reference line I mentioned; RF-3, RF-5 and the RC-7 come from the factory ready to be bi-amped / bi-wired with dual binding posts connected by jumpers, I'm not changing or adding anything new in this regard, just keeping it the same.

 

The reason I mention it is because Dean is insinuating that my low end / woofer crossover calculations are wrong because I'm using a higher impedance horn driver with different crossover values than what was in there stock and that I should have recalculated the woofer section based on the new high end section if I understood him correctly. 

 

Just thinking about it logically, since both speakers were designed to run bi-amped high end and low end separately how could the values be correct and not correct at the same time? Seems to me that these are two separate circuits independent from one another otherwise how would you account for any change going from single post to dual post hook up and have both be right? 

 

As I've said previously there are a few online crossover calculators that allow you to plug in different low and high end impedances to find out inductor and capacitor values, I've played around with them and noted one does not seem to change based on the other but this could be wrong I suppose. 

 

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7 hours ago, billybob said:

Ehancing autoformers/coils(exotic) can produce low end results? Yet, have not we decided that even the RF-3 with very similar cabinet size has good and responsive bass response...


One of the main reasons for the new crossovers was because in order to get the lower crossover point on the woofers I needed to change the inductor size from the stock .50mh in the RF-5 to the .75mh in the RF-3, otherwise I could have just left things the way they are now.The low end parts really didn't add that much to the total cost; inductors were $15.50 each, caps were $4.50 and the resistors were a couple of bucks? It was under $50 for the pair total for the woofer section.  I decided to go ahead and build two completely brand new crossovers because I have a very nice cherry RC-7 sitting in my storage now with half a crossover in it plus another extra RC-7 crossover and cup that is only half there I plan on selling both to recoup some of my costs on this project as soon as I can put them back together again.

 

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4 minutes ago, kevinmi said:

I have a pair of RF-5's that I bought brand new around 2004, and I've never thought of them as having adequate bass. 

I'm sure the room has much to do with it I know in my old house the rf3s didn't have enough bass but in my current room the 5s will knock stuff down in the kitchen across the way not even trying the wife gets upset I have the loudness off and bass on minus 2 but certain movie scenes it still gets ridiculous 

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On ‎1‎/‎13‎/‎2019 at 10:45 PM, jjptkd said:

Every crossover calculator I've played with online does not change the value of the low end parts regardless of the impedance of the high end?

Those calculators don't account for a multitude of things.

 

You need the impedance at the crossover point, not the nominal impedance of the driver.

 

The listed crossovers points from those loudspeakers are acoustic, not electrical, so the calculators aren't much help in this regard. They're good for building from scratch as a starting point, and that's about it.

 

Don't mess with the small coils on the high pass boards. The DCR is high, and there is some mutual inductance. Coil values were massaged while on the board.

 

Same with the low pass coil, the DCR is part of the cabinet volume, port, driver alignment.

 

 

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I think Zilch would approve.

 

Besides, if you can and its fun, why not? You might just learn something along the way...

 

If you buy a measurement mic and post you're results you'll get better insights and help on what's actually changing.

 

Thanks for sharing 😁

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  • 1 year later...

So its been awhile but I updated the speakers once again. @mustang_flht mentioned a Faital Pro HF103 driver in one of his threads and I did a quick search and the spec's seemed to line up with what I needed for a straight swap replacement. I had been previously looking at the B&C DE250 as that seems popular but the input sensitivity is too high and would require either an active crosser or crossover changes so I was hesitant to try them out. 

 

These RF-5's are what I listen to the most as they are my TV speakers so 90% of their use is TV / movies but I'll play some tunes at times, mainly YouTube videos. The speakers with the RC-7 drivers sound really, really good to me so I really wasn't sure what to expect with the new drivers.

 

The best way I can describe these as compared to the stock RF-7 / RC-7 drivers is higher resolution with what seems like an extended top end. Now going with higher resolution anything in my experience is a double edged sword as sub par recordings sound quite a bit worse and distortion or artifacts seem amplified but the flip side is quality recordings sound equally better. 

 

When I first compared the RC-64 II to my RC-7 some years back I remember thinking the 64 II seemed clearer, slightly higher resolution than the 7 but the 7 had noticeably deeper tone and significantly more bass, both were somewhat of a compromise in my mind. These new Faital Pro drivers seem combine the best of both in my RF-5's. 

 

In the future it would be interesting to put one of these drivers in an RC-7 and do another comparison against the 64 II, maybe some day. 

 

 

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Thanks for the feedback and your feeling of listening 👍

 
You know that you can very easily lower the sensitivity of your HF103 without changing the impedance, by 8 ohms in your case, so that the parameters of your filter / network do not change. If you do not want to place new resistors on your filter, you can place the terminals at the terminals of the HF103.

For example, to decrease 3 dB, you can put about 2.3 ohms in series and 20 ohms in parallel. If you just want a drop of 1 or 2 dB, you need to put other resistors in the Lpad.

 

If you lack a bit of brightness above 6 kHz, you can put a capacitor of around 1µF or 1.5µF in parallel with the 2.3 ohms resistor.

 

No need to modify your speaker and wiring for this you can put male and female lugs on your new Lpad to insert it between the wires and the HF103

 

 

As @Deang says, pay attention to the impedance at the network crossing point!

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  • 9 months later...

Hi!

 

I see that this post is not exactly new. But it is extremely interesting to me. I have a set of heavily modified RF5 but with the original HF driver.

I would love to upgrade the HF driver. By looking in this post the Faital Pro HF103 would fit the original RF5 horn?

Or do one have to replace the horn to a RC7 horn? As they seems hard to find that would complicate things a lot.

Really thankful for some advice! :)

 

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