RS52 tests and tweaks

[dlr]

I finally finished (unless I find more) my testing of the RS52 2" midrange. This is an interesting driver. I won't go into much here, but I found one characteristic that is, I think, not what the assumptions were about it.

[Dennis H]

Dave's still teasing us! C'mon, Dave spill it.

[ThomasW]

Dave's still teasing us! C'mon, Dave spill it

Here ya go...

http://www.speakerdesign.net/dayton_rs/midrange/rs52/dayton_rs52.html

[dlr]

I forgot the link

Dave's still teasing us! C'mon, Dave spill it.

Sorry, I wasn't trying to tease. I forgot to include the link. Thomas' post has it.

[Rene D]

that great info. I have been eyeing this dome mid since they first posted it. Glad you posted this data before I went out and got a pair though. I was thinking of useing these to replace my P13WH's, But it doesn't look like I can mate them up well enough to my M26WR's. The parents have been pesting for a new set of speakers. Maybe a nice 3-way for them this summer.

One question I did have, Does the metal grill cover on this unit come off with ease? I personly just don't like the look of it.

Rene D

[dlr]

I haven't tried to remove the grill

that great info. I have been eyeing this dome mid since they first posted it. Glad you posted this data before I went out and got a pair though. I was thinking of useing these to replace my P13WH's, But it doesn't look like I can mate them up well enough to my M26WR's. The parents have been pesting for a new set of speakers. Maybe a nice 3-way for them this summer.

One question I did have, Does the metal grill cover on this unit come off with ease? I personly just don't like the look of it.

Rene D

I think that at least one person on the board here has removed it, but I didn't try as I don't have a problem with the look. I think it's better than the bare diaphragm assembly.

[dwk]

One question I did have, Does the metal grill cover on this unit come off with ease? I personly just don't like the look of it.

Yes - pops right off. Just remove the faceplate and push from the back side. I think it looks far better with the grille on than off, but for my waveguide experiments I need to remove it since it's just too big.

Dave - interesting stuff. It'll take some digesting. I'm more inclined than ever to think that buying a sacrificial unit might be in the cards to see what the internals look like.

[dlr]

I'm inclined to do so as well...

Yes - pops right off. Just remove the faceplate and push from the back side. I think it looks far better with the grille on than off, but for my waveguide experiments I need to remove it since it's just too big.

Dave - interesting stuff. It'll take some digesting. I'm more inclined than ever to think that buying a sacrificial unit might be in the cards to see what the internals look like.

but I do want to keep my current working pair, so it will mean buying one. Darren said that he was told that the glue was a heat-based one, so it might even be removed by heating with a blow-dryer. Maybe it could be softened just enough to pop it off.

I'm also interested in comparing measurements of grill/no-grill. It just seems to me that there's got to be some small amount of high frequency reflection going on. That may account for some of the hash above the peak.

[dwk]

but I do want to keep my current working pair, so it will mean buying one.

I agree - I'm not willing to wreck the pair I have, but will probably throw another one in the next PE order I make. I'm gonna need some tweeters to go with these...

Darren said that he was told that the glue was a heat-based one, so it might even be removed by heating with a blow-dryer. Maybe it could be softened just enough to pop it off.

I think many of the adhesives used in drivers are amenable to heat-softening. I doubt you'd be able to put it back together again, but it would at least be a relatively non-destructive way to do it.

For anyone interested, I'm losing hope that the PE waveguides are going to work. Getting any response out of them below about 1.5k isn't happening, even with the 12" version. I had thought that it would be sufficiently close to a conical to be workable lower, but apparently not. It may simply be too shallow. Since you can easily get a normal tweeter to go that low or lower, it seems a futile effort. Too bad, since the exposed black dome looks pretty good in the black waveguide.

I did throw the RS52 on an old conical mid horn that I have - 16"x16" mouth. It was a horrible fit since the throat was originally sized for a 4.5" Seas, but it was sufficient to show that it loaded well down to below 500Hz. Next step is to either make a new waveguide or an adapter to properly size the throat and see how the response looks.

Dave, do you have any guess and/or indication from Darren what the useable xmax is on these things? My waveguide aproach may allow a ~600 Hz xover from the response perspective, but if it doesn't have the xmax to produce any significant output at that level, it's a moot point.

[Dennis H]

Nice article! Thanks Dave. :T

[dlr]

I have no Xmax info

Dave, do you have any guess and/or indication from Darren what the useable xmax is on these things? My waveguide aproach may allow a ~600 Hz xover from the response perspective, but if it doesn't have the xmax to produce any significant output at that level, it's a moot point.

I don't have any info on Xmax. The site shows the power handling and its bandwidth, but with BSC that will be needed, you'll need to take that loss into consideration. Most baffle widths are going to create a step partially in this driver's passband. Though they inidicate a bandwidth of 500-7000, I think that 500 is a stretch, though 7K is doable if you use a steep (read 24db or higher) filter.

I'm considering a 3K first order with the RS28 as I have a mid/tweeter box with 13m8640 and 9300 that can be pressed into service quickly. Then I'll be able to see what the highpass requirements are after diffraction/step are added into the mix.

[Rene D]

I was looking at the dayton wave guides, How exactly are you mounting the dome mid to the back of these? I wouldn't mind trying this method, eve if it's just going to turn out to be cosmetic.

I'll admit it, I'm a shallow bastard. Looks matter :T

[dwk]

I was looking at the dayton wave guides, How exactly are you mounting the dome mid to the back of these? I wouldn't mind trying this method, eve if it's just going to turn out to be cosmetic.

Nothing special - traditional 'POC' engineering. Used a hacksaw to cut off the waveguide so the opening fell just outside the surround, put a thin strip of gasket material on, made a 'baffle' out of 1/2" foam-core art board, and used duct tape to hold the driver on. Wouldn't stand up to 'production' use, but fine for a SWAG; for production you'd probably have to machine a custom mounting faceplate, but it's manageable.

[dwk]

FWIW, I asked Darren on the PE board about xmax for the RS52, and he indicated that it should be around 0.75mm. Using SL's splmax spreadsheet indicates 103dB in free space at 800Hz with a 2.1" diameter. Assuming you can work the baffle so you cross above the baffle step, this gives a max 109dB, which isn't too bad - a bit low for some applications, but should work for most folks.
For my waveguide experiement, this looks good. Since my specific location will be half-space, and I'm getting a few dB from waveguide gain, I may even be able to look at 500 or 600Hz xovers if they're steep (and the distortion behavior holds up). Nice.

[dlr]

You can always count on Darren...

whether it's parts or just info.

[cotdt]

I have heard subjective reports that this RS52 dome midrange has "legendary" clarity and dynamics. Is this true?

[dwk]

Well, I frequent most of the diy-ish forums out there, and I have yet to see much in the way of reports from folks that have these running in systems yet. One guy on diyma, and (I think) djs on mad (BTW - what is it with guys with three-letter-monikers starting with 'd' using these things?) I'd say it's way too early to tell, since even these I'd consider 'preliminary'. There is no doubt in my mind that they're good, but it remains to be seen how good.
Of course, I'm also not sure what 'legendary clarity' would be, particularly in the context of a driver that has been on the streets for a couple weeks...

[joecarrow]

Also- "dynamics" boils down to high SPL capability with low compression, right?

Dwk just said that the max SPL looks to be around 109 db at one meter above baffle step... that's fairly loud, but is it "legendary"?

[dlr]

RS52 will be opened up next week

I agree - I'm not willing to wreck the pair I have, but will probably throw another one in the next PE order I make. I'm gonna need some tweeters to go with these...

I think many of the adhesives used in drivers are amenable to heat-softening. I doubt you'd be able to put it back together again, but it would at least be a relatively non-destructive way to do it.

I have some RS52 stuff on the way, should be here either Saturday or early next week. Then I'll have one to open and investigate.

[silvercans]

Anyone take any distortion measurements on these drivers yet?

[Marzen]

I just listened to some tracks from Gaslight Abbey in a 4way design (mono) using SoundEasy as a digital filter. I tried a 3K and a 5K xo to the RS28AS, not sure yet which I prefer, but the 52 really seemed to compliment the 28 on vocals & guitar. I have a RS180 for mid bass & the RSS315 for the bottom end. Final testing/listening will have to wait until next weekend or whenever I get over this retching flu bug.

[dwk]

WOOOOOOO HOOOOOOOOOO!

After having spent the last 3-4 years putzing around with waveguides, planars, compression drivers and other things in an attempt to realize Tom Danley's Unity arrangement, I can now proudly claim that my first functioning Unity Concept prototype is up and running. Yeeee Haaaa.

I'm using the RS52 as the 'tweeter' in this case, which means it's not really a true Unity, but that's OK for now. I have the RS52 running from about 700 to 5k, which a pair of Stryke SA-071's loading the horn a ways down. This gives me ~200 or so up to 5k in a single unit. I did basic impulse measurements in SE, and then putzed an Xover using Jan/Thuneau's PC code so it looks reasonable in an RTA. Needs some tweaking since it's a bit hot up top, but I'm waiting for my SE V12 upgrade before I get serious. Even so it sounds f'n amazing in certain respects. As Marzen says - guitars and vocals have something special going on.

After all the discussion on AA about how critical the entry holes are, I'm stunned by my initial results - I just drilled 10 3/16" holes in a pattern and slapped the midbass drivers on. Almost literally perfect - nice up to 700 and then they drop like a rock, with a resonance spike up at ~3k.

BTW - quick question. Anyone else use foam-core art board and duct tape extensively in their prototypes? Just curious.

[fsmidt]

Hi, long time lurker and all that. Just read this post and finally i can contribute with something. I got my RS52 pair recently and the first thing i did was cut one open with a stanley knife. Got some shabby pictures from my mobile phone here for those who wanted to see the inside. If anyone needs better quality i'm sure i can get out the real camera, but i'm a bit lazy.

Back
Rear chamber

Cant seem to get the images up in the preview windows, but i think the tag is correct, here goes nothing...

[dlr]

I've got a few shots, thanks to Darren

I have some RS52 stuff on the way, should be here either Saturday or early next week. Then I'll have one to open and investigate.

I received some expendable samples from Darren. One of them had the back end of the chamber cut off already, saving me some work. I hope to be able to do some tests with/without it to see the influence. That will be for later after experiments and a full writeup.

There's a copper cap on one side of the motor. It goes into the gap about 1.5mm or 1/16th inch. I'm really eager to see some distortion measurements. I've yet to take that up. Mark and John do fine work in this area.

The chamber is very well stuffed with fiberglass. I'm going to experiment to see if any improvements can be made at all. I have a couple of ideas, but in any case, opening it up could be irreversible depending on the care taken.

These early versions had less glue holding the chambers on, so they popped off readily, although if first removed the faceplated. Leaving it attached adds weight, so if something goes amiss, the former/coil might be more susceptible to accidental damage.

In short, very impressive as I see it. Now if we could just get Mark of John to make some distortion tests . Here's a link to all the pics (old and new):

RS52 images

One shot:

[Marzen]

...I'm waiting for my SE V12 upgrade...

:huh: I need to visit the Yahoo group more often!
Ward
Edit:
---Ohhhh! I just peaked! Everything on my wishlist & more! Cut/Paste ckt's from the hard drive, independant driver graph colors, built-in RT60, & 4th order notched filters built-in as well....ahh - good times...

[dwk]

Wow - thanks for the photos guys. Interesting construction. At a glance there doesn't look to be an obvious 'oops' that needs correcting.

I've had a chance to play a bit with my Unity experiment mentioned earlier. Stryke SA-071 midbass drivers (which just happen to be exactly the same size as the RS180..), playing up to ~800, RS52 playing playing 800-4k, and the little Dayton neo in a selenium 60x60 horn from 4k up. The 'waveguide' I'm using is a quick knock-off, and in particular the throat needs a bit more filling/smoothing - some of the midrange roughness is due to this I think, although I'm sure there is also some edge diffraction in there as well. Attached are two SE plots - the RS52 with filters in place, and the overall response. I ran out of gain on my tweeter amp which is why it's shelved down - sounds pretty good like this though. The full response plot is a 50ms window smoothed at 1/12th octave - I think this is pretty good for in-room response, and IMHO shows a bit of the advantage of waveguides.
So, a long way to go on this yet, but I'm pretty pleased with where things are. The RS52 sure seems to be a pretty nice driver based on my experience so far.

[Jim Holtz]

Any distortion tests yet?

I'm curious if Jon, Mark or John Krutke have a RS52 for distortion tests. It's coming down to this or a 830882 Exclusive for a mid in my next project so I'm eagerly awaiting results. I've used the MDM-55 in previous projects and really like mid domes. The RS52 has the potential to be a killer driver based on DLR's tests. Now distortion tests to see if it's got it all...

Jim

[jkrutke]

Ooh, nice picture Dave. All that copper is impressive.

The center opening seems huge for being a neo driver. (more of a neo ring than the disc-with-hole) Now I've got to get one of these. I may be testing one soon. Someone offered to send me one about a month ago, but I turned it down because I was busy. I just sent him an email back saying OK I'm ready now. I'm not sure if I'll hear from him though.

I have to say, PE is really coming through with some winners. I just tested a preliminary version of the RS90. I'm guessing at the name, but it is a 3" wide range driver. Before you get too big of a woody, I'll mention it has an efficiency too low to be called a midrange. (83dB) But I've tested a lot of 3" drivers and this one blows them all away in the distortion dept. The motor is loaded with copper, the impedance curve has no rise to speak of. There's venting under the spider too. It vastly outperforms the Hi-Vi B3S, Aura NS3, and actually the RS125 above 300hz too.

[Dennis H]

I just tested a preliminary version of the RS90.

VERY interesting. I see an array of good 3" drivers as being a superior replacement for the big BG ribbons. The BGs run about $10/inch, have problems above 4kHz and have limited LF capability, i.e. they need to be highpassed at 5-600Hz. Seems to me that an array of good 3" cones would be as cost-effective, would be narrower to get close to a line of ribbons (horizontal polar response), could run as high without comb-filtering and could cross lower on the bottom end. You might be able to pull off a superior 3-way line-array (either dipole or box) with some good 8-10", some good 3" and some good ribbons.

[dlr]

Rs90?

I have to say, PE is really coming through with some winners. I just tested a preliminary version of the RS90. I'm guessing at the name, but it is a 3" wide range driver. Before you get too big of a woody, I'll mention it has an efficiency too low to be called a midrange. (83dB) But I've tested a lot of 3" drivers and this one blows them all away in the distortion dept. The motor is loaded with copper, the impedance curve has no rise to speak of. There's venting under the spider too. It vastly outperforms the Hi-Vi B3S, Aura NS3, and actually the RS125 above 300hz too.

I have one "full-range" 3-inch driver (W3-879S) as a replacement in a powered PC speaker set. Also swapped the op-amp in the little built-in with a good one. Surprising how good it sounds on a shelf above my workbench with someone's cast-off AR sub-sat woofer (I hate calling them a sub). They don't al have to have high sensitivity. I don't rock-n-roll while I'm at the bench! It will be interesting to see more info on it.

I was bouncing some emails on the RS52 WRT use of a tapered tube (my minds blanking on the name, no copies here at work) similar to that used by B&W in the Nautilus. This looks like a good candidate for that, given the large and shallow vent opening. I suspect it would help with the slight droop below 4K. I'm going to test this with the drivers sent by Darren to see if any further improvements are possible.

[jkrutke]

I was bouncing some emails on the RS52 WRT use of a tapered tube (my minds blanking on the name, no copies here at work) similar to that used by B&W in the Nautilus. This looks like a good candidate for that, given the large and shallow vent opening. I suspect it would help with the slight droop below 4K. I'm going to test this with the drivers sent by Darren to see if any further improvements are possible.

It looks like the RS52 would be a prime candidate for a tapered closed end enclosure, B&W style. I really believe that type of enclosure works, and I've used it in several ways before. In the image below, a 25TFFC had a small tapered line, and the Seas midrange had a larger one constructed out of PVC and MDF. I've since given up on the project due to a veneer job so poor that I didn't want to look at it. (they still sit in my basement) I sold the mid and woofer to Roman Bednarek, who did a three way and couldn't get good sound out of them. He blamed it on the metal drivers.

I've got tapered closed end midrange enclosures in a 3.5 way long term project I'm working on right now using other Dayton drivers.

[dwk]

Just a teaser, but attached is an 800-4k distortion sweep from SoundEasy. I wanted to go to 5k so the 3rd order product would hit the breakup, but SE V12 seems convinced it MUST terminate a sweep at 1/4 of the displayed window upper limit. This should not be compared to the more 'official' distortion charts since I didn't calibrate and am almost certainly measuring at a lower level than they are. I also had my electronic xovers in place @800 and 4k, although that shouldn't impact the distortion numbers. Test was conducted without a baffle - just put the driver on a stack of acoustic foam tiles. Still, lots to like - at normal levels distortion doesn't look to be a problem.

Looks like I have some work to do on my Unity, though - distortion is significantly higher across the board over this range, and there's a huge jump between 2k and 3k where both 2nd and 3rd order rise up to ~10%. I have no explanation for this - a 'normal' resonance should affect 2nd and 3rd separately.

[cotdt]

that is very low distortion

[joecarrow]

It's hard to say how low, without seeing other drivers tested in the same way. Also, the level is quite important- and dwk didn't say the drivers were being pushed hard. I'm just saying, try not to compare it as apples to apples with the other stuff out there.

That said, thanks for the image. It's really great to see people out there doing independent tests. It's been interesting to read everyone's sites documenting the tests, and I think we all learn a lot from it.

[KJP]

that is very low distortion

Ridiculous low. ;x( RS52

[WillyD]

;x( Please, oh wise DIY gods...bestow upon us a wonderful speaker design using this driver.

;x(

[dwk]

that is very low distortion

Yes, BUT drive level was around 'average listening level' which may be 5-10dB lower than what Zaph and Mark K use, so we shouldn't jump to conclusions just yet. I probably should have tested at a higher level, but I was pressed for time - I just swapped the leads over from the Unity for a sanity check, and was so impressed I thought I'd share. I'll try to make another run if I have time, but no promises. It'd be nice to get 4th and 5th as well.

I did rework my Unity and am still getting inconsistent results, but two distortion sweeps at higher level than the above seem to hold together OK. So, I wouldn't expect anything catastrophic to show up in 'real' tests, but you never know. If Mark K is listening, I probably could send a driver if he doesn't already have one on the way.

I will say subjectively I think the strengths of this driver may not be completely evident with a 3k xover. I'm crossing to the little Dayton Neo so that's undoubtedly part of the problem, but with the RS52 being used up to 5 or 6k the ability to handle 'forte' vocals seems much better than at 3.5 or even 4. For example - KD Lang on '49th Parallel' when she rises to a cresendo it just hangs together and doesn't get harsh. A 4k xover might just be possible with some of the mini neo tweets that are out there now.

[jkrutke]

Looks like I've got a pair on the way, results posted shortly.

John

[AJINFLA]

I just tested a preliminary version of the RS90

Hi John,

a couple questions if you will. Is it an aluminum cone like the other RS drivers? Phase plug or 1pc parabolic like the Aura?
Does it have a neo magnet? Thanks.

cheers,

AJ

[jkrutke]

Hi John,

a couple questions if you will. Is it an aluminum cone like the other RS drivers? Phase plug or 1pc parabolic like the Aura?
Does it have a neo magnet? Thanks.

I'm not sure if Darren minds if I spill the beans on that driver, but it's a 1 piece parabolic, no phase plug. Standard ferrite magnet with a bucking magnet and shield cup, vented through the pole piece and under the spider. While it's black and has a cast frame, it doesn't look like it comes from the RS family.

I've started up a new measurements page for 4" and smaller drivers. It's not posted because there's only a few drivers there, but it uses the same test setup as the 5.5" test. The RS52 results and any other small drivers I do will end up there. I may have another 2" dome to add also.

Note: the RS52's I'm testing will head over to Mark K after I'm done. He has some good experience with a few other 2" domes and I'm looking forward to his insight.

[Jim Holtz]

I'm not sure if Darren minds if I spill the beans on that driver, but it's a 1 piece parabolic, no phase plug. Standard ferrite magnet with a bucking magnet and shield cup, vented through the pole piece and under the spider. While it's black and has a cast frame, it doesn't look like it comes from the RS family.

I've started up a new measurements page for 4" and smaller drivers. It's not posted because there's only a few drivers there, but it uses the same test setup as the 5.5" test. The RS52 results and any other small drivers I do will end up there. I may have another 2" dome to add also.

Note: the RS52's I'm testing will head over to Mark K after I'm done. He has some good experience with a few other 2" domes and I'm looking forward to his insight.

Hi John,

I'm really looking forward to seeing your results on the under 4" class. Any idea when it'll be available for us to take a peek?

;x( Thanks again for your efforts testing drivers. It's a great resource for folks like me.

Best regards,

Jim

[Mark K]

Hi guys,

John's going to send me a pair of the RS52's. I've been and continue to be a bit too busy to be as productive as ;x( krutke but hopefully I can cook up some comparative tests between the Morel 55, which is kind of the standard, and the RS52.

So yea, my site's a little stale. Darren hasn't even emailed me in months. I'm so out of the loop. ?15" RS sub? Full range? News to me...But I'm not dead or anything. Work's been a bit of a --> :conveyer: (Plus, I kinda promised my wife I'd lay pergo in the kitchen before anymore speaker stuff. Now I'm stuck...did I mention the 4 kids under 5...)

Anyway,

hopefully RS52 stuff, and the SS tests, when they show.

[WillyD]

You are all saints. ;x(

Can't wait to hear your thoughts (John and Mark). :T

[AJINFLA]

Thanks Zaph.

I'll assume its aluminum. Sounds like something I'd be interested in.

Mark, just save a couple extra pieces of the pergo for future speaker building.
Dayton really seems to be coming through with some nice drivers. The RS15 looks like the final piece of the puzzle for my next rig. I was holding out to see if AE would come through with any products, but so far, a static website and crickets chirping.
I'll probably wait till July 4th to order a pair. Hopefully they'll do the free shipping thing.
They would be available for testing if anyone was so inclined.

Cheers,

AJ

[cotdt]

there is no such thing as the RS15 on PE's website. why would anyone make a 15mm tweeter? it would be too small to have low distortion.