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.
RETROVOLTAGE 
While refurbishing/updating a (unmolested) pair of SP-2500’s, I noticed the tweeter and midrange pairs are both wired “out of phase”. The terminals on the drivers all have Red dots, which a guy would assume means ‘Positive’. However the Negative from the crossover is wired to the red. Odd. More odd is the woofer appears wired ‘correctly’, with the crossover positive to the red indicated terminal.
I thought this was odd, so I looked at the other speaker, and it was wired the same way. Is this correct?
Recapped (kept the same values), replaced the horns with Peerless domes, added binding posts, made new grills, and refinished the cabinets. Best yet, my wife even thinks they look great!
Cheers. -Brian
No clue about the specifics as applied to the Sansui, but I do know that crossover networks can have a phase change component to them. If the phase change is close to 180 degrees, swapping the phase on the driver would bring it back to zero. Doesn’t sound out of the ordinary.
I didn’t think of the phase flipping, but that does make some sense. Thanks for the reply!
I’m about to tackle the crossovers on a similar set (SP-1700). Already cleaned up the cabinet and grill – which look amazing with the decades of dust and grime removed. Mine looked just like yours in the picture before, but now are a deep, rich, shiny walnut color. Did you do the same, or are you leaving them in original state?
Any thoughts on cleaning up the pots? Mine are pretty corroded. I was just going to get contact cleaner, but seeing some recommendations against that and it doesn’t seem like it will be easy to replace them if I mess them up.
Great thread! I picked up a pair of SP-3500’s at an estate sale last week and I have to say that Im not impressed with the bass response. The mids and tweeters are super bright as well. Does anyone have any suggestions of how to lower the frequency response of the bass driver? Are there any good aftermarket replacements for these?
I need help with this also.
My grandfather recent passed and handed down his sansui sp2500 speakers to me. Im looking to update/upgraded the caps. I just need part numbers 027-324, 027-332, and 027-340 to upgrade them, correct? Please and thank you for you time!
Old thread I know but really you should be replacing the capacitors with Polypropylene capacitors rather then repeating the manufacturers mistake of using cheap electrolytic caps. … Especially with the tweeter and midrange crossover caps…Anything hidden from owners view is always built to a price if possible esp capacitors. I am using a Sansui 2500 midrange in a Leak speaker – replacing the original Leak mid/tweeter and think the Sansui Midrange is one of the nicest mids I have ever heard.( 30 years of HiFi employment in upper end stores) . …It works from 500 hz approx up and leaving alone with no upper cut off. I use then a small supertweeter to supplement the top end starting at about 9 khz just using a single cap and some resistors to get the level right…. Perfect solution. Cheers
I know this is an old post but do you have a pic of that modification?
I had the midrange sitting on top in its own enclosure with the tweeter. I am going to mount the midrange in the leak cabinet bang in the middle above the bass driver with two small tweeters each side of the midrange but am halfway through the work…it’s a bit slow boat to china at the moment…will revisit this comment when I finish. Have two many projects at the moment. Cheers
Need your help, I have three pairs of Sansui S P-2500 Two of them I built my own cabinets, I’ve used you method to change capacitors in all three, however in one pair I used 6.8 caps where the 4.7 were, the pair of original cabinets. I can hear a slight difference. Is it my boxes or the 6.8 cap from parts express, somewhere I read that you could change the value. They sound great however, should I go back and change to the 4.7. I like the sound of my own cabs better. Do you think I would get better sound with 4.7 ? no big deal to change, I’m sure your understanding values is better than mine!
Hi Brad, that will change the crossover point a bit – making it higher frequency – but if you like the revised sound, it’s just fine! You won’t hurt anything. Without knowing the values of the inductors off the top of my head I can’t say specifically what it changes it to, but, I doubt it’s that large of an amount.
Thanks for returning my message, I did change them back to the 4.7, My ears couldn’t tell the difference, maybe slight change in the mid range? They’re a good little speaker, after rebuilding the first pair using your method of piggy backing,and doing a few other things, I put together two more pairs, I really appreciate what you have offered the public in this website. I don’t claim to be a expert at anything, that is when everyone expects your help! Thanks for letting me take advantage of yours.
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.
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?
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?
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.
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!
Traditional man-made speakers are my passion , I also prepare that for big orchestra guys. Thanks for your report.
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.
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.
very good info on the capacitor replacement. any suggestions on replacing the actual speakers?
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.
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?
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.
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.
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!
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.
Pingback: Found: Sansui SP1500 Speakers « jkoebel.net
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
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.
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
Yes, I’m not at home right now, however I will try to remember to take the back with crossovers off and get you a picture, I have six pairs of sansui seekers I’ve done it to, I just piggyback the existing caps using same values, whoever first posted it gave me the idea
I didn’t have any symptoms, I wanted to make sure they were working well, refreshing them. Yours sound like a potentiometers issue, pull your crossover cover off and try some deoxit in your tone pots.