Sansui SP-3500's-

super98lsc

Well-Known Member
I found a nice pair of SP-3500s from the original owner for $ 125.00. I pick them up Saturday and will post pictures. Likely I will end up sending them to my dad to go with the 5000x I just rebuilt for him. He presently has a set of all original SP-2000's.

I read on another forum (See below quote) that the SP-3500 was designed and built by JBL for Sansui? Is this a truth or just horse....it??

Submitted by Steve a Audio Enthusiast

Date Reviewed: August 24, 2012

Bottom Line:
Let me first say, I read the reviews here on the SP-3500 Sansui Speakers. I worked for customer service, JBL Sound in 1974 and we would recieve the SP-3500 speakers for repair. The Cabnet design and speakers were all designed by JBL for Sansui. The replacement speakers and network deviders are all manufactured by JBL, thats the reason why the sound is so great.
 
I have a pair of those sp-3500. Grills are a bit beat up and 1 has water damage to the back, but they rock for they most part. Big and heavy.
 
Picked up the SP-3500s today from thier original owner. He is in bad health and selling his home and downsizing. He had 4 of these in a quad setup and now is just keeping one pair for a smaller place.

The grills are perfect, the cabinets can use some cleanup and scratch removal as expected after 50 years.

They sound TERRIBLE.
One woofer the surround has seperated from the cone.
The other cabinet the woofer is really stiff. The surround cloth on these has just aged and dried up over the years becoming rock hard. Oddly I havent seen this problem on the SP-2000 12" drivers. The surrounds on them remains tacky/pliable.

I tested all 5 of the other drivers in each cabinet and they are in good order. Sound fine and the impedances are on target and match.
Even the woofers are fine electrically.

Now to decide what to do with the 14" woofers. Being an odd size my only option may be to do a patchwork (using 2 rings for each with seamed section) refoaming job on them both. The rough opening on these is 12.5" and the outer ring is 14". A small 15" driver with a 13.5/13.75 opening might fit with some carpentry work, however these cabinets are already on the small side for a 12" much less a 14-15" driver.
 

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Driver and interior of cabinet.
 

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the woffer surround is a known problem on the sp 3500. evry single one of them by now..
just get the silicon black gasket maker from any auto part stores. glue them up and you are good to go.
 
I thought about just re-attching the existing surround to the paper cone. The problem is the surround has lost its flexibility completely. Looking at this driver it would appear it tore itself off the surround to break free. The one cabinet that is not torn free but is stiff as board has less bass response than a 2" tweeter. :thumbsdn:

To properly fix these W114's im going to need new surround.
 
I'd use it as an excuse to try a smaller driver in that too small a cab. I'm thinking a backplate and a nice 8-10'' woofer. The bass (if you want to call it that) from the stock 3500's is a joke and it shouldn't be hard to get some improvement.
 
Motostereo you and I must have the same brain. I was also running some quick calculations on the cabinet volume and the 2 mouse holes they call ports, this driver must be tuned for a really high F3. The cabinet is barely adequate for a good 10" driver in a sealed configuration. Typically most drivers require an even LARGER box when in a bass reflex (ported configuration).
 
I know that those 14's mounted in a 4 cubic foot cabinet can actually make some decent bass so it's not the drivers. They also sound surprisingly good as 2 ways crossed over rather high with an Advent tweeter. I never did finish my experiment with the 8-10'' driver in the standard cabs.
 
I must say I had higher hopes for them. I dont want to modify ruin the original cabinets, If I do a test driver in them it will be using a precision cut baffle plate insert to fill the 14" hole using the factory screws then of course that panel holding the test drivers. I wanted to redo these and ship them up to my Dad to go with the Sp-2000's and the 5000x I just built for him. But alas they sound no where close to as good as the Sp-2000s I have here that are recapped and in perfect order.

I cleaned the pots on the one good cabinet with the good woofer in it to give it as fair of a listen as I could. Its like listening to a resonator dropped into a tin bucket. Next I will pull the caps and test them to see if they are anywhere near spec. If not I will replace them and re-test.
 
That's exactly what I was thinking of doing with the precision baffle plate. The beautiful lattice work grille would cover up what had been done and there might even be good sound coming out of them for the first time ever. I found recapping them to be a complete waste of time, money and effort to. In my case they still sounded just as you mentioned. But they did have new caps in them and better yet I had the knowledge that new caps won't polish a turd enough to make it listenable:D.
 
Why is it that people rave about these speakers so much? I know they were engineered with JBL guidance, (says so right on the back panel) and the cabinets are really nice.
I am not convinced the squakers offer anything but 1k screeching perhaps that is the crossovers fault but instincts tell me otherwise.
The tweeters are really invisible, they function but you have to place you ear near them to hear them. Click the crossover back to the soft setting to tame the squakers down and the bulk of the sound is delivered from the center mid-horn. The horn does not sound bad.

Another observation is they are not nearly as well made as my Sp-2000's The SP-2000 have air core inductors on the x-overs and just in general appear better made. Aside from the AlNico magnets on all the drivers. Again I know everyone raves about the AlNico magnets but they lose their charge over time (can be re-magnetized) and they soft clip so to speak near the redline. If I have a driver and clean power to drive a speaker hard and produce a clean say 30hz note why would I want a woofer that "softens" up and de-mags itself when driven with enough power?

Brainstorm:
  • Re-engineer the x-overs completely to provide more balance towards the tweeters.
  • Replace the squakers with a driver that has a warmer tone to blend with the horn midrange.
  • Use a woofer that will produce audio below 100hz accurately in that cabinet sealed or ducted. (my guess would be sealed as the box size is really small for anything using a port)
 
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Why is it that people rave about these speakers so much? I know they were engineered with JBL guidance, (says so right on the back panel) and the cabinets are really nice.



Brainstorm:
  • Re-engineer the x-overs completely to provide more balance towards the tweeters.
  • Replace the squakers with a driver that has a warmer tone to blend with the horn midrange.
  • Use a woofer that will produce audio below 100hz accurately in that cabinet sealed or ducted. (my guess would be sealed as the box size is really small for anything using a port)


I don't know about anyone raving about any Sansui speaker, in fact they seem to be the red headed step child. Sometimes a Sansui speaker can shine and be more musical and warm depending on how they are being fed.

All your brainstorming has been done and contemplated for many many years by many people. In the end those people still don't like the speaker because they are phyo analyzing it instead of listening to the music. Times have changed, how and what people pricive as sounding good might have changed as well. I personaly don't like two way tower systems and woofers smaller than 12" but some will call that very detailed.

There is a huge volume of the 3500s around because people liked the sound and they sold a lot of them. However if one was able to mod and improve them in some way don't you think there would be lots of them done that way already? The point being is the people that end up moding them end up throughing them away if they don't like them as no one else wants them now.

A recap will help the SQ a lot, glue will help the woofer, and new finish will help the aperance. Every thing else is a wast of money that can be spent on speakers one does like.
 
472 appreciate the honesty. I just like the look of the cabinets, it would be a shame to toss them. Same as you I am not a fan of small driver towers that everyone raves about today. Its like a turbo 4 banger... might make good power but I would rather hear my 496 Big Block rattling the walls.

I picked these up cheap to play with, they are nor will ever be my listening room speakers. My mains are monsters designed and built by my father and I about 30 years ago. Flat to 22hz with less than a -1db variance from 22hz-35k. We spent 22 months modeling drivers and testing before we even started building cabinets. The are 4-way 4-drivers 12", 6.5" 4" liquid cooled domed mid, Emit Ribbon Tweeters. It takes 2 people to move them, no sub-woofer required. I spent days typing in box calculation code on a Tandy TRS-80 which we then executed on the mainframes at Tracor Aerospace where dad worked. Funny how far we have come since those days.
 
A while back I picked these up very cheap and havent had time to mess with them until today. Im bored waiting for Fed-Ex to show up with my Sansui CD-10 Xover which requires a signature so im tethered to the house.

Typical Sansui overbearing midrange.
The horn mid sounds like kabuki crapola to me. So I swapped it with a planar transducer.


Lets find some bass now.
The woofer on the SP-3500 doesnt have a low pass filter on it at all, Sansui boasted this desing of using "the woofers natural rolloff" to quell the high end eminating from the 14" woofer. Well it does a horrible job lending the melodious sound of Celestion 12" in a Marshall full stack. Fine if if you want to use these for a guitar amp.


Step 1- Testing a high frequency cutoff for the woofers.

I built up a quick 12db/Octave low-pass filter and ran that inline to the woofer. Now we can enjoy the clean clear detailed mids coming from the planar in the center and the 4" squaker mids are turned down to the soft setting. The planar is on CLEAR which follows the super-tweeters. Since the planar rolls off around 12k the horn tweets do a nice job of providing clear detailed crisp high end.


I softened up the surround stiffness didnt help much. The 14" woofer is a well built driver it is just in WAY too small of an enclosure and its Fs is just way too high for any real low end performance, especially for a bass-reflex box which serves to just add efficiency in the upper bass ranges where I dont want it.

I think I will downsize the driver to a very efficient 10"-12" with TS specs that will work in this cabinet and tune to at least 32Hz F3. Ill determine the tuning etc next.

This is all just for fun not like they will end up becoming my main speakers or something.
 

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