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New gift speakers given to me!
My neighbor just rang my door bell and had a surprise for me... He gave me his pair of Sansui SP-70 speakers! He bought these brand new in 1971 from the PX when he was in the Air Force (flew a fighter jet) during one of his tours in Nam. The cabs look so so. A bit of damage on the bottoms due to moisture. I haven't hooked them up yet or inspected the driver surrounds. He gave me his original owner's manual as well as the original color sales lit that he saved all these years!
Great guy, what should I do with these?
Comments
Pics first and dissection of the speaker cabs for sure!
Agree, we need pics.
If they work, you could bring them to Indy. I personally have never heard a set, and I bet others haven't either. Other than that if they don't work, they could be roof tossed in Grand Rapids or salvaged and redone.
And yes, pics should be had.
InDIYana Event Website
I could never roof toss Don's speakers...
I will take some pics today.
I'd consider remaking them and giving them back.
I inherited my dad's SP 1000's. He bought them from another guy while they were in the army.
If they're anything like those, the woofers have a cloth surround and be in fine shape. They measured surprisingly flat with the Lpads in the neutral setting.
I built new cabinets for a pair of 12" 3-way Sansui speakers, they used the double midrange in a side-by-side orientation. Sounded kind of weird, but measured ok. Good bass from the 12" woofer.
Give them a good listening, of course. Assuming for a moment that they do not best your current speakers, I would clean them up, verify proper operation, and re gift them.
Do they meet the qualifications of this years Indy meet? It seems to me they might be pretty close
They do meet the theme qualifications, they are:
I took 12 pictures, will post them tomorrow morning.
The woofers are 8", paper cones, aluminum dust caps, inverted foam surrounds with some sort of coating. They are in very good shape with no signs of rot or damage.
The enclosures are 3/4" veneered pb. They are 1.08 cuft with a 2.75" dia x 3.5" L port. Generous heavy damping material on top, bottom, sides, and back.
Tweeters look like 1" aluminum domes. Very high Fs around 2K.
All of the above makes me question when they were actually made. They definitely look like early 70's, but dome tweeters?
Crossovers are 2nd order electrical on both drivers. The 3 way attenuation switch appears to switch taps on the tweeter shunt coil, not 3 levels of padding resistance.
So it's more of a "presence-pad", that is interesting.
The only thing barring it from theme entry is that it's a commercial offering. However, we could play it first in exhibition at the start of the theme as the "benchmark" build which by all others will be judged if you are open to that.
InDIYana Event Website
For sure on that Ben. I really don't have any time to work on these so they are what they are.
That said I just finished listening to these for about 45 mins with my standard DIY Event tracks. I have to say that they are pretty impressive for 4 decade old speakers. They were obviously designed for bookshelf or near wall placement. They sound like they have zero BSC (I'm listening to them on 24" tall stands 38" from the front wall). The sales literature says these are crossed over at 6000 Hz. If that is true these woofer sound great considering. Maybe retrofitted with a pair of Beast Modes and a crossover with full BSC...
Some vintage speakers sound really good. I am a big fan of vintage yamaha ns monitors and mitsubishi diatones.
I've noticed that with my vintage Spendors and B&Os. Little to no BSC. I wasn't really paying attention to the more technical details of speakers back in the 70s, but I don't recall hearing about pulling speakers out into the room. Even the hifi shops demoed most speakers right against the wall.
Ok here are the pictures:
Water damage
Funky ornate grills
I think a restoration is the way to go. Preserve the history.
+1 restoration. They are cool old speakers.
+2 on resto. Those things are a legitimate design with nice parts (unlike many similar speakers of that era) Beautiful cabinet. I love that terminal plate and that style of the Sansui logo on the grille. Congrats on the cool speaker acquisition!
So just build new boxes and keep everything else the same?
I'm leaning more towards new boxes and a redesigned crossover with film caps and some amount of BSC.
I would replace the caps and maybe add an extra coil and resistor for bsc, just to leave the original crossover design, but that's just me.
That would be easy enough to try.
The water damage is sad. Definitely reconstruct as it was and use the grills.
Also second the BSC ckt. and leave xover as is.
Just noticed it says "woofer 8" CORN type"😂
I had some time today to listen to these again and finally take some measurements. I replaced the two original NPE caps with some new Audyn film caps. The new caps didn't change the sound at all. I was kinda surprised. So I measured the old non-polarized electrolytic caps. After 52 years both NPE caps were still within 5%. "Eat it" to all the ney sayers about NPE crap'n the bed after xx years.
Anyway, the mic doesn't lie. Besides these having zero BSC there was a 6 dB peak in the FR between 5 and 6 kHz! The contour switch only changes the response above 10 kHz.
So I've worked up an external filter network that adds 4-5 dB of BSC and a notch that brings that treble peak down to flat.
My plan is to build this external filter so I can easily switch in/out the BSC and the same with the notch filter.
Great project and I'll bet you'll make them sound better than the designers ever thought possible. I wonder if the grills pull that peak down? They probably do more that just that - and not in a good way!
Hi Tom. Yeah I was thinking those grills aren't helping anything.
Was just here thinking out loud. I wonder if it's an off axis thing? Not horizontal off axis but a vertical off axis thing. I measured them up on a 24" stand and with the mic on the tweeter's axis. Maybe the designer intended these to be sitting on the floor, right up tight to the wall. Maybe with the listener's ears way higher than the tweeter that peak goes away? Maybe I'll drag out the mic and see... but not today, time to go shoot some baskets with my son.
I had a chance to build those filters and give them a listen. They fix the obvious issues and the speaker sound better. But in all honesty they don't sound nearly as good as anything I hear at our DIY events. I'm sure some of it has to do with the older drivers having motors with higher distortion than what we are use to today. Maybe part of it is the minimalistic crossover design. It might be because they have an 8" woofer crossed over at 6 kHz. And then there are those grills and with the inset baffles too!
Sounds like a lot of old technology all in one package.
Does your mind wander into the "make it better" area yet or are you moving-on at this point?
Moving on. I have way too many other projects in the works that will best these by a bunch.