Home > Electronics, Projects, Vintage > Refurbishing Vintage Sansui SP2500 Speakers (Crossover Repair)

Refurbishing Vintage Sansui SP2500 Speakers (Crossover Repair)

I’m always keeping my eyes out for interesting vintage hi-fi speakers from the ’60s-’70s, and found a nice set of Sansui SP2500s on Craigslist. Produced between 1960 and 1974, these beautiful walnut speakers are solid and very heavy – definitely high quality. I’ll share some photos below, and then dig into reconditioning them!

Here are the vintage ads for the Sansui speakers. Click on the image for the full-size version!  The web site is down apparently, replaced with a placeholder park page redirecting to a spam site. Sorry, no vintage ad anymore! I should’ve hosted it here instead.

Unlike newer speakers (including a pair of Sansui SP7500X that are still waiting to be refurbished), these are very easy to remove. Six screws to remove the crossover panel from the back, disconnect the driver leads from the spade terminals, and pull out of the back. Like all older electronics, speakers also have components that can fail inside. The crossover network, distributing and filtering the amplified audio to the different drivers, contains capacitors which can fail with age just like the capacitors in an antique radio or in your modern electronics. It’s easy to forget speakers have parts that can degrade inside, when they’re almost always treated like a single box unit.

If you’re buying speakers from Craigslist and they have adjustable crossovers, make sure to check them on all settings to help assess their condition.

With the crossover removed, it’s easy to see the components that need replacing. The three blue cylinders are the crossover capacitors, in 2.2uF, 4.7uF and 10uF varieties. These are bipolar electrolytic capacitors, a special type that is slightly more expensive than standard electrolytic models, but they are required because speaker current is AC and must flow both directions across the capacitor. A polarized capacitor would be likely to explode if used in the same application.

Parts Express sold me everything I needed for these speakers, and a few others:

The old capacitors are glued to the board and I didn’t want to damage it, so I snipped the leads as close to the end as possible and bent them into terminals, then attached the new capacitor to the wire and soldered together.

Repeat for the other capacitors, and after trimming the leads, much nicer:

Two speakers means two crossovers:

Reinstalled and ready to rock:

My only complaint now is the diffusers send the high-frequency audio straight into my carpet, when placed on the floor. I suspect these were meant to sit on stands somewhat. I’ll experiment with different positions for the speakers in my living room, but if it ends up not helping, the hole is symmetrical so I can just rotate the top assembly and now the speaker will send its sound up, towards my ears.

I have several more pairs of speakers – Sansui SP7500X, Bose 601 Series 1 and Cerwin-Vega D-5s. I’ll post photos of refurbishing their crossovers when I get to it.

If you’d like to buy the parts to complete this repair for yourself, you can get a great of the same ones I used over at Easy-Kits all in one place!

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  1. Tyler
    May 31, 2011 at 7:26 am | #1

    What were the symptoms the speakers had that you knew to replace capacitors? I just picked up a pair of sp1500′s that sounded ok when I purchased, but when I ran them on my system, the woofer has a “scratchy” sound that I didn’t hear earlier. All the speakers are in good shape save for this noise. Thanks! Tyler

  2. jwk
    May 31, 2011 at 9:24 am | #2

    Hi Tyler, those symptoms match what I was experiencing – some crossover settings would play no audio at all; others would be scratchy, static-filled or otherwise distorted. Sounds like yours are going to need this same treatment. I’d give the controls a good cleaning while you’re at it, too, if the SP1500s have adjustable crossovers.

  3. VANCE HESTER
    June 18, 2011 at 1:00 pm | #3

    Hello, I have a pair of sp-z7 I cannot get any sound out of the midrange or tweeter but horn and wooofer sound fine there is one 50v 2.2 capacitor hooked to the setting adjustment and 1 50v 8.2 connected to the midrange and no visual damage so any experience with anything like this? Thank you for your time! VANCE

  4. October 9, 2012 at 7:54 am | #4

    Thanks you for posting this online. I’m about to recap a different 70s Sansui speaker (SP-X8700), I wouldn’t have thought to leave the original capacitors on like that–very smart. Thanks again.

  5. Kyle
    October 23, 2012 at 8:36 am | #5

    Dude, thanks for the excellent pictures of the crossover repair. I have a pair of Sansui XL-500 speakers. The pots spin all the way around so I assume they are shot. When I pull the crossover from the cabinet, how do I know which other parts to change? Are they usually burnt? Just change them all? Thanks!

  6. jwk
    October 23, 2012 at 8:43 am | #6

    Kyle, your crossover should have a few other components – resistors, capacitors, and inductors. In the photo of the SP2500s, the resistors are the white blocks; the inductors are the metal framed devices.

    With a multimeter, you can measure the resistors and make sure the reading matches the stamped markings. For the inductors, just make sure there’s continuity through them and they haven’t gone open. Capacitors you’d definitely want to replace. I’d be surprised if a resistor or inductor in the crossovers was bad, unless the speakers were literally blown by having far too much power applied.

  7. Jordan Rautiola
    November 6, 2012 at 7:42 pm | #7

    What is your opinion of the Sansui S-1000U speakers? What vintage would they be and how would they sound compared to similar year Advent, KLH, AR, etc?

  8. jwk
    November 6, 2012 at 7:52 pm | #8

    I’d be a bit skeptical of them myself. They’re mid 1980s vintage, not exactly a period known for stereo sound quality the way speakers from the 60s-70s were, and before a lot of the modern measurement and specification techniques came onto the scene in the ’90s. The result being I’m not sure I really believe their frequency response, power rating and sensitivity. Later Sansui stuff such as these doesn’t have a very good reputation in the audio community. Those speakers also lack the iconic wood lattice grills of the ’60s and ’70s models which in my opinion looks far superior to the fabric cover. I’d expect them to sound acceptable, certainly, but not spectacular.

    Unfortunately I can’t really help with the comparison to other ’80s speakers as that’s not a time period I collect much of. Most of my speakers are ’60s-70s, or ’90s+. Brief research shows them selling for $20-60 per pair (Craigslist, Kijiji, Goodwill, others). For that price, if you like the look of them and don’t need the most discerning reproduction, it would probably be worth it.

  9. charles allen
    November 28, 2012 at 4:04 pm | #9

    you mentioned having some sansui sp7500x – i took mine apart to freshen up and have lost the correct order of wiring to each speaker – i,m a dummie ! any help ? this is from the crossover to each spk.

  10. tony
    May 6, 2013 at 6:53 am | #10

    very good info on the capacitor replacement. any suggestions on replacing the actual speakers?

  11. tony
    May 8, 2013 at 6:04 am | #11

    what can you tell me about Sp 100 speakers. Purchased a pair on eBay awhile back. Both need attention,. How can you tell if the capacitors are good / bad and where can I purchase new speakers.

  12. jwk
    May 8, 2013 at 9:33 am | #12

    I’d replace the capacitors outright. You can’t really tell if they’re bad by looking, but they most likely are at this point. You can get new capacitors (and speaker drivers) at http://www.parts-express.com, I buy most of my speaker repair materials from them.

  13. June 5, 2013 at 4:30 am | #13

    Traditional man-made speakers are my passion , I also prepare that for big orchestra guys. Thanks for your report.

  14. Josh
    March 26, 2014 at 10:14 am | #14

    awesome way to easily change the capacitors!! i am wanting to replace the speaker wire receptor clips. you know how to get those off w/o damaging the chip board? they are super snug!

  15. Rick
    March 31, 2014 at 7:44 am | #15

    I am looking for some advice, I have a set of Sansui SP-7500X speakers and the high end frequencies are just to bright. I have them set to soft but the higher frequencies just over ride to mids and bass. Can anybody tell me how to changes the capacitor values to lower the tweeter upper rolloff point and/or reduce the power going to them?

  16. jwk
    March 31, 2014 at 9:17 am | #16

    Rick,

    If you make the crossover capacitors smaller in value going to the tweeters, they’ll roll off earlier. The specific values may be some trial and error as I’m not sure of the crossover circuit used in the 7500X.

    Alternatively, if you know the tweeter’s design impedance (it might be stamped on the back of the driver) you could wire an L-Pad attenuator into the circuit which would let you control the level independently, without requiring changing the crossover configuration.

    I’d recommend the L-Pad more than the crossover capacitor value replacement, personally.

  17. Rick
    April 3, 2014 at 5:54 am | #17

    Sounds like the L-Pad is the way to go since the speaker has to much signal sent to the tweeters. I don’t have any sitting around and would like to have an adjustable one. I think the serial resistor value goes down and the parallel resistor value goes up as the attenuation decreases so i would have to find a ganged pot and wire it reversed on one side. Do you know if I can simplify things by just making one of the resistors (parallel?) adjustable or would this make the imdedence matching to far off?

  18. jwk
    April 3, 2014 at 8:17 am | #18

    Keep in mind the L-Pad will dissipate some power, so standard small pots might not be robust enough for that application. (Not to mention, might be difficult to find a low-ohms replacement.)

    I would recommend a commercial integrated unit such as http://www.parts-express.com/speaker-l-pad-attenuator-100w-mono-1-shaft-8-ohm–260-265?utm_source=google&utm_medium=cpc&utm_campaign=pla or http://www.skycraftsurplus.com/l4controll-pad4ohm4w.aspx?gclid=COHU87TbxL0CFZNqfgodHQUAHg

    I don’t think you would get good impedance matching if you use a discrete+variable, or if you use standard potentiometers.

  1. July 9, 2011 at 5:10 pm | #1

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