AVS Forum banner

1 - 5 of 5 Posts

·
Registered
Joined
·
438 Posts
Discussion Starter #1 (Edited)
I see the RC 70s going sale for $250 at Fry’s’ pretty regularly. I think that’s a phenomenal deal considering their build quality and the quality of the components. My gripe with these speakers is their laidback sound, particularly the bloated upper (-mid) bass, and the recessed treble. However, the tweeter/treble itself very refined. So I was wondering if the crossover circuitry/board could be modified or replaced to make them sound more transparent and forward-neutral? I wish I could get folks like Dennis Murphy excited about this idea. Unlike the 2nd gen Pioneers all the drive units of RC-70 are great quality drivers, so it would be a much simpler and cheaper mod considering that one needn't replace the drive units.
 

·
Registered
Joined
·
2,603 Posts
That's a pretty interesting idea. I've thought about it a little myself, but I never bothered to do much more than a couple seconds of that! :)

If you look at their response here (http://www.soundstagenetwork.com/measurements/speakers/energy_rc_70/), you can see the tweeter is flat from 2kHz and up. Their problem is the large mid-to-upper bass hump from 100Hz to 300Hz, and then the smaller hump from 300Hz to 2kHz, relative to the tweeter output.

If the tweeter output is padded down, you could simply remove that and bring the tweeter level up some. Same with the midrange, but to a lesser extent.

But without knowing the crossover circuits, my guess is that the tweeter and mid don't have any padding to reduce. So you'd have to pad down the woofers to their level instead of bringing their levels up.

I think you could do a pretty good job simply by adding padding resistors to the woofers and, to a lesser extent, to the midrange driver, to bring those levels more in line with the tweeter output. If you padded the woofers by 5 or 6 dB and the midrange by 2 or 3 dB, you'd get a pretty flat response overall.

The problem with doing so is that you're now bringing the sensitivity down by a few dB, but the overall response would be much flatter.

With more in-depth measurements of the woofers output, the midrange output, and the tweeter output, some more refinement in the crossovers could be done to really get a nice response (but again, likely at the cost of losing sensitivity). The bass probably also needs some cabinet re-tuning (adding or removing stuffing or padding to the interior walls).
 

·
Registered
Joined
·
438 Posts
Discussion Starter #3 (Edited)
That's a pretty interesting idea.

If you look at their response here (http://www.soundstagenetwork.com/measurements/speakers/energy_rc_70/), you can see the tweeter is flat from 2kHz and up. Their problem is the large mid-to-upper bass hump from 100Hz to 300Hz, and then the smaller hump from 300Hz to 2kHz, relative to the tweeter output.

I think you could do a pretty good job simply by adding padding resistors to the woofers and, to a lesser extent, to the midrange driver, to bring those levels more in line with the tweeter output. If you padded the woofers by 5 or 6 dB and the midrange by 2 or 3 dB, you'd get a pretty flat response overall. The problem with doing so is that you're now bringing the sensitivity down by a few dB, but the overall response would be much flatter.
I am glad you think it’s a worthwhile idea. I am not too concerned about the slight loss in sensitivity as they seem to be efficient speakers (92 db). Yes, since the crossover points are 600 Hz and 2.4 kHz, and since a tapered crossover has been implemented you could get away with padding just one driver, either the top bass or the midrange driver. In the tapered design, supposedly the top woofer also handles the midrange frequencies.

Too bad I don’t have these speakers anymore, perhaps some of the RC-70 owners would be interested in trying this…
 

·
Registered
Joined
·
970 Posts
Is the lower output of the tweeters due to them being less sensitive than the bass drivers or is it due to the crossover design? Before reading this thread, my head had been spinning on picking up a set and swapping the tweeters with either ribbons or AMT types. Or possibly finding a pair of Veritas tweeters to swap in. I have both the RC-70s and the Veritas 2.2i's. The RC-70s are fun. I enjoy being able to really crank them up without fear of blowing a driver. I ran them full range powered by an Earthquake Cinenova Grande amp and the drivers never seem troubled. I don't dare do so with my Veritas. Yet for music, I will take the Veritas any day of the week. Even though I can't push them the same way. The mids/tweets are just silky to my ears. Never get ear fatigue, yet do with the 70s.
Having pulled all the drivers out of both pairs I own, it wouldn't be too tough to retro different tweets in.
 

·
Registered
Joined
·
438 Posts
Discussion Starter #5
Is the lower output of the tweeters due to them being less sensitive than the bass drivers or is it due to the crossover design? Before reading this thread, my head had been spinning on picking up a set and swapping the tweeters with either ribbons or AMT types. Or possibly finding a pair of Veritas tweeters to swap in. I have both the RC-70s and the Veritas 2.2i's. The RC-70s are fun. I enjoy being able to really crank them up without fear of blowing a driver. I ran them full range powered by an Earthquake Cinenova Grande amp and the drivers never seem troubled. I don't dare do so with my Veritas. Yet for music, I will take the Veritas any day of the week. Even though I can't push them the same way. The mids/tweets are just silky to my ears. Never get ear fatigue, yet do with the 70s.
Having pulled all the drivers out of both pairs I own, it wouldn't be too tough to retro different tweets in.
IMHO the tweeter has very good resolution, I wouldn’t go as far as swapping the tweeter. If the mid-bass rise is somewhat attenuated I think the tweeter will seem to come through loud and clear, and the speakers will sound more transparent. I wonder if what I have suggested above would do the trick; it would be nice to get some expert advice.
 
1 - 5 of 5 Posts
Top