Sansui SP-150 speaker upgrade

[Vikingkong]

Hi there,
This is my first post here, so I apologize if anything I'm asking sounds silly or redundant.

I have a pair of Sansui SP-150 speakers I've inherited from my father and been using for the last 5 years or so. They've been through many moves and have aged a fair bit. There are a couple pots on the back (high and mid controls) that are pretty scratchy, so I've been thinking it's finally time to clean up some of the insides to see if I can improve the sound quality a bit. I figured that while I'm in there, if there are any changes I can make to improve the sound quality, I might as well try.

Here are the specs: Audio Database (SANSUI SP-150 Specifications Sansui)

I know these aren't super high-end, but they have a lot of sentimental value (plus, the wood lattice on front looks quite nice). I'm just trying to make some improvements on a budget. I am happy to replace drivers where appropriate, but some of the guidance I've receive so far has pointed me in the direction of looking at the crossover first. I'm a bit of a newbie for this stuff, but I've rewired my guitars plenty enough to be somewhat confident soldering, and I've got a good multimeter.

Really any advice, guidance, or experience you all might be able to share would be greatly appreciated.

 

[Vikingkong]

For reference, I'm using a Technics SL-D20 turntable into an Akai AA-1135, so nothing too fancy.

 

[tonysrep]

I've been personally researching the upgrade topic on some sp3700s's I suggest you do some research concerning DIY speakers. It will give you the knowledge you need for your quest. I am personally dabbling with Xsim software configuring some crossovers for replacement midranges I wish to replace. Don't know what amp you have driving them but that one item makes a huge difference in sound quality IMHO

 

[gizzyman47]

Deoxit on the controls will solve the scratchiness. Drivers shouldn't need replaced unless there is damage to them. Recapping the crossover can improve things considering their age.

 

[Vikingkong]

The main thing I'm wondering is whether or not a straight 1 to 1 replacement of the caps would be best, or changing up the X-over in some way would get me better results.

If I change from the old caps to something like poly or film foil, do I need to start adding resistors to account for the difference in ESR?

I've noticed some distortion especially in the mids. The lows are nice and full, all things considered.

 

[OldKSF]

This is my first post too. Right now I'm reworking a set myself. I've collected several pair of Sansui speakers, because I'm old and so are they. I'm learning as I go. I'm the newest old guy but I'm figuring it out and this site is a great help. I chose to go with an audio grade cap simply to see about the difference in sound going forward. The old caps were crazy out of value but still low ESR but all tested 'leaky'. I went with the Dayton Audio grade from Parts express and made the rookie mistake of not checking dimensions on the replacements. I assumed they would all be close to the same or smaller. Not so. The 47mf is huge, the 15mf is larger, the 3.3mf and the 2.2mf will both fit fine in the original locations. Sansui used glue like it was free so I used a plexiglass cutting tool to score the edges right next to the old cap and then used a set of auto radiator hose pliers to gently rock the old caps loose after desoldering the leads from the backside. I cut two pieces of nylon for standoffs on the two larger caps to still allow access to the +- input terminals, which you have to desolder to separate the crossover from the plastic surround. I used a Dremel to grind down the remaining glue to give me a level surface to hot glue in the nylon pieces to glue the larger caps to. I also had to micro drill the backside of the pcb because the new leads were larger than the old ($10 set with pin vise, Amazon). I know a lot of people wouldn't go through this for this grade of speaker but I figured its best to learn on a cheap item in case I screw up royally, I paid $25 for the pair. That's where I'm at this morning. With any luck I'll have time to finish in the next couple of days and hear the result. Hope this helps. Good luck.

 

[Vikingkong]

Thanks a lot for your post!
I ordered some poly caps from Solen and they should be arriving today, so this is a great preview into what I've got to deal with soon. I'm going to do one speaker at a time so I can do an A/B comparison and see what sort of difference it makes!

 

[OldKSF]

Thanks a lot for your post!
I ordered some poly caps from Solen and they should be arriving today, so this is a great preview into what I've got to deal with soon. I'm going to do one speaker at a time so I can do an A/B comparison and see what sort of difference it makes!

No problem, glad I could contribute anything at all. I've been reading shared info on here for a long time, I'm basically totally ignorant on all things electronics except loving the vintage gear since it was new. I'm 70, 80% disabled Veteran, basically forced into retirement due to injuries. The last one did me in, so I wanted to keep my mind engaged. So many guys I know quit working and do nothing and they fade pretty quick, so this all is definitely challenging to me. I've heard those are great capacitors. I'll look forward to hearing how it goes for you.

 

[OldKSF]

Nothing like having a new pair of SP-150's in 2026. Terrific sound. Couldn't be more pleased.

 

[OldKSF]

Thanks a lot for your post!
I ordered some poly caps from Solen and they should be arriving today, so this is a great preview into what I've got to deal with soon. I'm going to do one speaker at a time so I can do an A/B comparison and see what sort of difference it makes!

Just curious if you've received your caps yet and had time for the swap.