Sansui SP2000 crossover re-cap

[Homey4uk]

Thanks in advance for any help. I have a pair of cherry just purchased from the original owner Sansui SP2000. After doing a lot of reading and research on here I ordered all new capacitors. I didn’t go crazy but I also didn’t order the cheapest. But there are no spades, everything is soldered. Do I need to de-solder all the drivers or should I replace the wiring while I do this? Or merely clip the wires and then solder them or reattach with spades? They sound good now, but I think they can sound better, and the pots are very scratchy and cause the speakers to come and go. I posted another thread tonight about a pair of Marantz HD77 that had crossover issues and went from scratchy and dodgy to 3 of 8 drivers not working after I used some Deoxit on the pots. I asked for help with how to fix them there but I also need to know if I brave the Deoxit again on these Sansui or if I should try something else. Thanks again for your help.

 

[elnaldo]

Hello. I usually cut the capacitor leads, or the wires soldered to the capacitors, and solder the new caps in place.

Inside the speakers the wires are usually long enough to allow to cut 1/2" without causing any problem, and cutting is less invasive than desoldering. I don't see the need to desolder the old capacitors.

If you refer to the wires soldered to the drivers, the same, I prefer to cut at 2" of the driver and solder again when reassembling. I only desolder at the driver terminals if I see it's easy, wire not wrapped on the tab.

 

[tom3]

I just snipped the leads on the caps in mine and soldered the new caps on the stubs. The selector rotary switches on the back do get pretty corroded. See the terminals turn some black. A good cleaning on those is a real good idea. Those old speakers are pretty durable, no foam surrounds, but they trade off some sound quality for power handling I think. And I've noticed some weird wiring on some of the old Sansuis, positive and negative feeds reversed, I guess there's a reason but I don't know why.

 

[elnaldo]

(drivers with reversed polarity are connected that way to compensate phase shifts introduced by the crossover. It's a standard practice in 2nd order crossovers. If you don't connect one driver phase reversed, at the crossover freq both drivers are cancelled by the other one)

 

[Homey4uk]

Hello. I usually cut the capacitor leads, or the wires soldered to the capacitors, and solder the new caps in place.

Inside the speakers the wires are usually long enough to allow to cut 1/2" without causing any problem, and cutting is less invasive than desoldering. I don't see the need to desolder the old capacitors.

If you refer to the wires soldered to the drivers, the same, I prefer to cut at 2" of the driver and solder again when reassembling. I only desolder at the driver terminals if I see it's easy, wire not wrapped on the tab.

Thank you for the help! Sorry I am so slow responding I never received any notifications. I got all the caps replaced and cleaned the crossover switches. They are MUCH smother and faster to respond. However, when I first turn the amp on now there is very distinct and low hum for a few seconds from one of the speakers, then it fades away. Do I need to take them back apart and see if a solder point is loose or what it might be? One of the caps (I think the 22uf), on each speaker, when soldering it I heard that hum. But as soon as I moved the iron away it would stop. Ideas?

 

[Homey4uk]

I just snipped the leads on the caps in mine and soldered the new caps on the stubs. The selector rotary switches on the back do get pretty corroded. See the terminals turn some black. A good cleaning on those is a real good idea. Those old speakers are pretty durable, no foam surrounds, but they trade off some sound quality for power handling I think. And I've noticed some weird wiring on some of the old Sansuis, positive and negative feeds reversed, I guess there's a reason but I don't know why.

Thanks for your reply. I received notifications when I was relied to another thread I started, but not this one. SOrry, I wasn’t being rude. I have played with little RCA and Optimus LX5 for years. Love the linaeum tweeters (have 4 that look brand new but are dead) and they cross wired their tweeters. I have seen some crossover upgrades for them, I have 4 pair right now I am playing with, probably to re-sell eventually, but maybe not, so might try that next. Thanks

 

[elnaldo]

Thank you for the help! Sorry I am so slow responding I never received any notifications. I got all the caps replaced and cleaned the crossover switches. They are MUCH smother and faster to respond. However, when I first turn the amp on now there is very distinct and low hum for a few seconds from one of the speakers, then it fades away. Do I need to take them back apart and see if a solder point is loose or what it might be? One of the caps (I think the 22uf), on each speaker, when soldering it I heard that hum. But as soon as I moved the iron away it would stop. Ideas?

The Hum you hear when soldering is the mains AC Hz, induced by the soldering iron to the woofer. No problem with that, that's normal. It's just the speaker reproducing a frequency you introduced at the wire.

A Hum from the amplifier is probably a capacitor charging. It's normal in many amplifiers, I wouldn't worry too much if it's just a brief second until the capacitor charges. You can try swapping the speakers to check if it's related to the speakers, but I don't think so. BTW, what's the brand and model of the amplifier? Is it too old?

(you can click on the "watch thread" link, at the top-right, to receive notifications on the threads you are interested)

 

[Homey4uk]

The Hum you hear when soldering is the mains AC Hz, induced by the soldering iron to the woofer. No problem with that, that's normal. It's just the speaker reproducing a frequency you introduced at the wire.

A Hum from the amplifier is probably a capacitor charging. It's normal in many amplifiers, I wouldn't worry too much if it's just a brief second until the capacitor charges. You can try swapping the speakers to check if it's related to the speakers, but I don't think so. BTW, what's the brand and model of the amplifier? Is it too old?

(you can click on the "watch thread" link, at the top-right, to receive notifications on the threads you are interested)

It is a Sansui 7900z that just arrived a few days ago. I assume it needs re-capped, but that looks WAY more difficult than doing a few caps on some speakers. It needs some parts, too so I need to figure out where to inquire about that. I guess Barter Town under parts but that will only be seen by members.