Anyone Tweaked the Sound Dynamics RTS-3

[tvr2500m]

I have a pair of Sound Dynamics RTS-3s that I think are a pretty nice speaker for the money - I paid about $150 new for the pair. They are, of course, hardly perfect. The bass needs more control and there's some grain across the upper midrange and high frequencies.

I'm wondering if someone's done some tweaks to improve the sound of the Sound Dynamics RTS-3?

- SJ

[leadbelly]

Hmmm, you are the only person I've known to own a pair of SD speakers other than myself. Mine were SDM2's from the 80's, were a piece of crap, and not worth tweaking in the least. What are yours like?

[tvr2500m]

Originally posted by leadbelly
Hmmm, you are the only person I've known to own a pair of SD speakers other than myself. Mine were SDM2's from the 80's, were a piece of crap, and not worth tweaking in the least. What are yours like?

The RTS-3 I think is a pretty nice speaker. There was a nice bit of hype about them, most notably from the Absolute Sound, so for $150 I gave them a try. Good sound stage, good detail, smooth perhaps to a fault, generally easy to listen to. There're a few reviews on AudioReview. Some positive, some not. I'd agree with just about all of them.

The speaker is hardly perfect but it's suprisingly listenable. I think it's a very nice speaker especially for the money. I was just curious to see if someone had done any easy, quick mods with good result - some cap, resistor or inductor values, some better wire, different cabinet damping, a cabinet brace, etc.

- SJ

[Dyna Saur]

I have a pair of the RTS-3s that I bought from Audio Advisor a couple years ago. Original usage was for TV audio, using a VCR and cheapo 20 year old Pioneer receiver to power them. Results were "just fine" for this purpose. Recently, I tried them on a Dynaclone ST-35 tube amp, feeding that with a Rotel RCD-855 CD player, and then my overall impressions weren't so good, the RTS-3s sounded somewhat thin in the bass and have very "nasally" high frequency response. Just think of clogged sinuses

I've been thinking of playing around with the crossover, or even replacing the drivers woith something (anything) better, after beefing up the cabs' construction.

Or, perhaps just giving them to my sister and her husband, who have a '70s vintage SS receiver and BIC turntable. THey're about perfect for that combination...

/ed B in NH

[Dyna Saur]

I finally got around to looking inside the RTS-3s. The fairly "minimal" crossiver uses a 12 dB / octave for the 4-ohm woofer (15 uF NP electrolytic and .47 uH approx iron core inductor) and 6 dB / octave (3.3 uF NP electrolytic in series with a 4.7 ohm 10W resistor) for the 8 ohm tweeter. Blecchhh...

FWIW, the woofer DCR is about 3.1 ohms, the tweeter's DCR is about 7.2 ohms. Tweeter is small diameter (3/8 to 1/2 inch) mylar dome. Sseaker enclosure internal volume is 0.38 cubic foot,
not including the space that the speakers, crossover and port occupy. The cardboard port tube is 2 inched ID and 3 1/8 inches long. Cabunet has 3/4 in MDF for the front, and 1/2 inch MDF for the sides and back.

When I ran the "numbers", this works out to approx 1900 Hz roll-off for the woofer, and the tweeter doesn't start "kicking in" until 3000 Hz or higher. And, the NP electrolytics really are crappy, especially in the tweeter circuit. This "gap" in coverage probably explains the congested / nasal sound of these speakers.

My current experiment is to replace the crossovers with the Dayton 12 dB/Octave, 3000 Hz crossovers (part number 260-144).

I still have need more time to ake any valid judgements as to the efficacy of this upgrade, so I'll not make any comment at this point, except to say that it did NOT make the sound any worse than original

Keep in mind that these are really 4 ohm speakers, as far as the amplifier is concerned, so putting these on an 8 ohm tube amp's output doesn't really work out too well...

My next experiment, I'm going to try a pair of (no longer available) Optimus / Radio Shack Linaeum Dipole tweeters mounted on top of the cabs, with the internal tweeter and 4.7 ohm resistor disconnected from the circuit. These are 8 ohm, 2500Hz - 20K and 88 dB / W / M SPL.

Stay tuned...

/ed B in NH

[Dyna Saur]

THe "numbers" for the RTS-3s are even worse.... I just checked out the iron core inductor from the LP crosover, it's 1.48 mH,
which works out to an XsubL about 18 ohms at 2KHz. No wonder it's so "congested" sounding

FWIW, the Dayton 3K LP Xover uses 0.42 mH and 6.6 uF (2X 3.3 uF in parallel) set for 4 ohms, the HP uses 3.3 uF and ? mH (value TBD) set for 8 ohms . The 3.3 uF caps are cheap foil/poly which are better than NP electrolytics

No matter, it's bound to sound better already!

/ed B in NH