Michael8it

Welcome!!

I know this subject can be a can of worms - this is certainly not my intention. But I am having a hard time believing that $600 caps will give me 6 times the audio quality out of these speakers. I was happy with the Erse caps on the last build and for budget reason will probably just stick with them. I may do the sonicaps on the tweeter but that's it. Thanks for the feedback.

I am rebuilding my Polk RTA 12B crossovers and have noticed TONS of "audio grade" caps for crossovers. I rebuilt another set several years ago and used Erse Caps because the values matched what I needed and the total cost was just over $100. I'm looking at doing another pair and there is no shortage of opinions on what caps to use. The most common suggestion on the Polk forum is Sonicaps, but the tab for those is almost $600 for these crossovers. I could also do a blend of components using Sonicaps in the tweeter circuit and Erse (or Jantzen) for the rest. Any opinions on these boutique crossover caps? Is this just hype? Thanks,

This is a perfect example of WHY you need to LISTEN to speakers and pick something you LIKE. I had a pair of Bose 901's - didn't do anything for me. Picked up a nice pair of KEF 103/2's - ok but not quite what I was looking for. Found a pair of Polk RTA 12's - dynamite. Converted them to 12B's, and recapped them, even nicer. \ Belvedere2 likes his Bose, I moved mine down the road as soon as I could. It's really not a matter of "best" but "different". Different designs have different characteristics and produce a different pallet of sound. Your room size, musical taste, front end gear, and own personal taste all influence what speakers you like.

Welcome Jason! I just started my own C-1 BillD Tribute Mod. I'm about half done and already notice the difference. If you follow his plan you will not regret it.

Welcome! Perhaps you'll want to upgrade that to a MKII ? You would not be disappointed!

Welcome. Feel free to ask questions!

I picked up this pair of Bose 901's for $60..... and they were painted black with cheap spray paint. Just lovely. The seller thought they were the first two ever made because they said "ONE" and "TWO" on the label. For you 'old timers' you know that just meant left and right. When I pointed out to him the serial numbers were not sequential, I think I burst his bubble. I also think his wife was getting in his business and wanted them GONE. So I was happy to oblige him...... I stripped them down and refinished them with a matte finish, and was able to pick up a Series I EQ on eBay (that actually worked!). I also picked up some parts from a pair of Polk's (I just wanted one driver but he sold me the tweeters and x-overs for the same price as one driver), and since they were just sitting around, I though I would try an experiment and hook the tweeters up. I threw on a recording from Canadian Brass that have lots of nice loud brass timbre going on. WOW what a difference a tweeter makes. I really do not understand why Amar refused to use one, it made an incredible difference. It still sounds boxy on the low end, but the high's really opened up with the tweeter added. Maybe I'll make a box for them and sell them as an add-on if someone wants them! This is certainly NOT a smooth tweeter when compared to the Peerless 5514 or 3514's in my Polks. But it still made an incredible difference.

Call this one 'in the bag'. I received the Erse Capacitors in the mail yesterday. They were my choice because they had the right values and were quite economic compared to other makers of Audio Caps. Total cost was just over $100. Here is the work area, yes, the dining room table . The first victim is on the left of the photo. Here is the Lower Crossover that mounts in the cabinet. The posts are on the back of this. I pigtailed the wiring and reversed the connections so that I cannot wire it incorrectly if I need to remove the x-over again. Here is the top crossover. I removed the fuse holder. I had jumpered out the fuse before I changed the caps and noticed less distortion in the tweeter so I removed it completely when I did the caps. I had to drill some new holes to make them look good but that was all pretty straight forward. All that is missing now is the tweeter. The markings on the tweeters say 3514. Supposedly Polk only used 5514's from Denmark and the US before switching to the SL1000 and eventually SL2000. I have been told these are the best sounding of all the tweeters. I have a pair of 5514's as well and will do some A/B testing between the two. Impressions. Much more detail. The subtle instruments come through. The bass is tighter, and I can drive them harder without wincing at the sound. Huge sound stage, even without SH. I have the parts on the way for my C-1 Upgrade and M500(t) overhaul. I think when I am done I will be one very happy camper.

Joe, thanks for the input. Due to the way the x-over in this is designed, I am going to stay with a passive x-over. In essence, each driver has it's own x-over, which means I would need three amps to drive these. I am just not that 'hi-fi'. So I placed an order today for Erse caps, which have the right values and a reputation for being quality audio caps. I'll see what a difference it makes. I think doing the BillD upgrade on my C-1 and the MKII upgrade on my M500t will have as much impact as anything else.

Do you think it was the caps or the new tweeter, or both? I ask because there seems to be two prevailing theories in recapping corssovers: A - it works, don't fix it. B: Caps have a shelf life, and yours have long expired. Replace them and your speakers will sound 10X better. I have the Denmark Peerless tweeter in these, and have been told not to change them (they supposedly sound better than the RDO). I am looking at Erse caps because they have the right values, and Clarity, Solen, et al do not, so I would need to do alot of parallel caps to get the value right, and at 7 capacitors per x-over that is a lot of $$$$$ when you start running them in parallel. My inductors look fine, so I think I will leave them alone. I can always do that later.

After researching how these crossovers work, I would need to Tri-amp these to get it to work right, and that's just not in the budget. I can replace all the caps with Erse caps for $50 per speaker. I can replace the entire x-over, including inductors, for $100 per speaker. So....... Is there any point in replacing the Inductors? Do they age, and are inductors made today any higher quality that the original ones? I am sure there will be a performance gain replace 30 year old caps, but I don't know about Inductors. Thoughts anyone?

Welcome!

RodH - let me know how it goes My RTA12's have a very complicated crossover and I am going to just rebuild these. However - I did seriously consider the bi-amp solution.

And the tweeter. No coloration from being in the cabinet, and they have a really open sound. Are these yours?

Mine are an earlier version of this. There was RTA12, 12A, 12B, and 12C. I have the originals, with the entire crossover on the board (pictured to the left). The later model (12B etc) moved two of the caps to a separate board mounted to the terminal post connector, which is what you see here. Polk is amazing in that they still have technical data for these and I was able to get the schematics from them. They even still have drivers! So I am still leaning toward rebuilding these as the best use of the capital at hand. I am still amazed that when I played these next to a pair of KEF 103/3's there was just no comparison at all. It will be exciting to rebuild these and hear what these really have to offer!

A second option - Run the preamp out to my Audio Control C-101 and take outputs from there. I could fabricate an extension to that case fairly easily (it's half the depth of any other components). As long as I can get the voltage I need from it, space is not an issue. So, instead of putting the AC101 on a tape loop, I take the Pre out from the CT-7 to the input of the AC-101, and have two outputs from there. I think to test the system that would be the most productive way.

I agree. THANK YOU for your help. Time to 'pop the hood'.....

Do you know the dimensions of the middle board?

Ok, now you guys got me thinkin' and that is always dangerous, and generally leads to yet another outlay of cash.... I found this at Marchand , and electronic crossover for $46.00, no case. I am thinking.... mount it inside my CT-7 case (assuming there is room, I have not looked), and steal one of the tape loops (I will never use two tape loops again) for the output(s). I don't have to drill any holes I don't need extra cables (except one pair to another amp) I just need space in the CT-7 to mount it I need 15v to power it. Once I dial in the frequency it is very unlikely I will ever change it so not having 'instant control' is not really an issue. I overhaul the M-200t I have right after I over haul the M0.5t, use the M0.5t for the mid-bass and the m200t for the treble. The M200t is actually a WM200t with tone and volume controls - allows me to adjust the volume to the tweeter to match the mid-bass. I only spent $100 (I'll need some mounting hardware and some components to tap the power). I don't have 'yet another' component in my rack which is already full I completely avoid any possibility of WIFC syndrome.... SO...... does anyone know if there is room in a CT-7 to mount an additional board like this?

I am hoping that it will be offset by WIFC - Wife Induced Financial Coma. This is also translated sometimes as Wallet Induced Financial Coma. Unfortunately Government Bureaucracies seem to be completely immune to WIFC of any form

I'm thinking possibly a DIY - one of the links Rich had does have a PCB and schematic for a crossover. I am assuming that the crossover point is simply determined by the component values. If I am right and I pick the right values then I am getting the right cross over frequency. Otherwise I have to mod my CT-SEVEN and I am not ready to get into that now. Later, yes. But I am focusing on the speakers and amp right now. Plus, bi-amp means.... one more amp..... and more cables..... and more $$$..... and more $$$$$$.... and more $$$$$$$$. This hobby is getting as expensive and target shooting, and real fast too! So for $80 I think I will stick with plan A and just rebuild the crossovers, unless I can find a DIY for a resonable price that is, and another amp, and more cables, and more $$$$$$$$$$$.

I read the attached articles, all of which talk about LF crossovers. The Polk RTA12's have 2 mid-bass drivers, and tweeter mounted outside the cabinet (on top) and a 12" passive radiator. So I would only be looking at a crossover between the mid-bass and tweeter - and I cant find one . All the one's I have looked at have 2 way (bass vs mid-high) or three way (bass-mid-treble). Nothing I see has the crossover I am looking for, which means I am going at it from scratch, or I am not looking in the right place...

Zumbini, I picked that up when I re-read your reply. Any suggestions on active crossovers? I have been looking around on the internet and all I find are pro audio systems, plus a DIY which I am open to, but not a complete kit.

Any suggestions on active crossovers ?