Need Some NHT Crossover Assistance, Please

[Pete B]

I was just looking at the pics myself and yes you are correct, I'd worry more about the very small caps that probably have high ESR but with resistors like those in series you should be fine. I have seen small caps like that with 1 even 1.2 ohm ESR so if they sound hot after the change you might want to pad the tweeter a bit more. Perhaps do one and compare it to the other, assuming they're well balanced to start.

 

[Dr. Morbius]

I was just looking at the pics myself and yes you are correct, I'd worry more about the very small caps that probably have high ESR but with resistors like those in series you should be fine. I have seen small caps like that with 1 even 1.2 ohm ESR so if they sound hot after the change you might want to pad the tweeter a bit more. Perhaps do one and compare it to the other, assuming they're well balanced to start.

OK, thank you. Right now they aren't what I would call bright speakers. They have detailed highs, but aren't fatiguing after hours at mid to high volumes.

 

[SoundOfSound]

Here is something that could work. You could use 50V Nichicon ES(Muse) caps.

A 220Uf is in the 10% window for the 200uF. For the 160uF cap you could use a 100uF to put through the board hole. Then solder two 33uF caps opposite each other to the long leads of the 100uF cap on the back side. That would give a total of 166uF and be in the 10% window. The 33uF caps have a 10mm diameter so they should be about the same height as the sand cast resistors.

http://www.nichicon.co.jp/english/products/pdfs/e-es.pdf

 

[Dr. Morbius]

Here is something that could work. You could use 50V Nichicon ES(Muse) caps.

A 220Uf is in the 10% window for the 200uF. For the 160uF cap you could use a 100uF to put through the board hole. Then solder two 33uF caps opposite each other to the long leads of the 100uF cap on the back side. That would give a total of 166uF and be in the 10% window. The 33uF caps have a 10mm diameter so they should be about the same height as the sand cast resistors.

http://www.nichicon.co.jp/english/products/pdfs/e-es.pdf

Thanks for the suggestion. However, I've already purchased 10 caps from Erse to go into the four spots on each crossover. I am going to use two caps (100 & 65) to make up the 165 uF value in one location. Some hot glue, some zip ties, rubber bands and a few paper clips should make it work.

 

[CarnahanBB]

Yup. If they measure the same they should sound the same.

I have to ask then...why would you take the time to replace them then? Lord knows I don't have the time or money to waste on frivolous projects especially ones I think will yield no positive results.

 

[Pete B]

Electrolytic caps are good for 10 years according to Military standards, perhaps 20 until catastrophic failure. I'm PB2 here, see the scorched circuit board:
http://www.diyaudio.com/forums/multi-way/230929-psb-stratus-gold-x-over-help.html#post3393485

http://www.diyaudio.com/forums/multi-way/230929-psb-stratus-gold-x-over-help-2.html#post3394054

 

[Dr. Morbius]

I have to ask then...why would you take the time to replace them then? Lord knows I don't have the time or money to waste on frivolous projects especially ones I think will yield no positive results.

There are a few reasons. As Pete B. stated, electrolytic caps have a limited useful shelf life as their values tend to drift. This can cause problems in the crossover, as seen in the links Pete B. posted. But it can also allow low frequency signals to be sent to the tweeters causing distortion and possibly blowing a tweeter as well.

Another reason is I'm a tinkerer at heart. I enjoy getting my hands dirty and finding out how things work, weather it's speakers, guitars, bicycles, computers or whatever. Hell, I'd probably upgrade my toaster if I had one.

And finally I'm trying to learn more about electronics and speaker building in general. Next year I plan to start one or two DIY speaker projects and with a little bit of luck they should turn out pretty decent. Also, I'd like to eventually learn how to repair amps and preamps as that's a great way to get into some very nice equipment on the cheap.

 

[CarnahanBB]

There are a few reasons. As Pete B. stated, electrolytic caps have a limited useful shelf life as their values tend to drift. This can cause problems in the crossover, as seen in the links Pete B. posted. But it can also allow low frequency signals to be sent to the tweeters causing distortion and possibly blowing a tweeter as well.

Another reason is I'm a tinkerer at heart. I enjoy getting my hands dirty and finding out how things work, weather it's speakers, guitars, bicycles, computers or whatever. Hell, I'd probably upgrade my toaster if I had one.

And finally I'm trying to learn more about electronics and speaker building in general. Next year I plan to start one or two DIY speaker projects and with a little bit of luck they should turn out pretty decent. Also, I'd like to eventually learn how to repair amps and preamps as that's a great way to get into some very nice equipment on the cheap.

Makes sense to me! I wish I knew someone close who was good with those things. I'm kind of a sponge with stuff like that but I'm seldom 'brave' enough to go it solo. Best of luck and I'm curious to hear your feedback from the results.

 

[Dr. Morbius]

Makes sense to me! I wish I knew someone close who was good with those things. I'm kind of a sponge with stuff like that but I'm seldom 'brave' enough to go it solo. Best of luck and I'm curious to hear your feedback from the results.

I wish I knew someone close that could help me build some speaker cabinets for a DIY project I want to do next year.

I'm working on the NHT crossovers a little bit today so I'll post my progress with pics in this thread. I'm only replacing the caps, the internal wiring and I may do some cabinet dampening too. That's about it though.

 

[RayW]

I wish I knew someone close that could help me build some speaker cabinets for a DIY project I want to do next year.

Posting your location (approximate) in your profile might help. There may be AKers living next door who just don't know it.

 

[Dr. Morbius]

Thanks RayW. I'll get to that in a minute, but first I'm going to post some progress made on the Super Two refurb.

I didn't do too much today, but I managed to get the old caps off the board without much damage. I used a razor blade to scrape off as much excess glue as I could. I'm going to have to steal some leads off of some other caps to get these to fit properly. The excess that I will cut from these isn't going to be quite enough.

Here are the old caps on the left and the new ones on the right. The two black replacements are Erse Pulse-X. One is an 11uF 250V and the other is a 5.6uF 400V because they were out of stock for the 250V version. I'm having to use two electrolytics to make a value of 165uF to replace one of the old caps.

Also, I'm replacing the wiring harness as it's 14ish years old. In the past I've used 16 gauge wire in my projects, but on these I'm doubling that from the input terminals to the crossovers and from the crossovers to the sub. The mids and tweeters will get the usual 16 gauge.

The old term to crossover wires are on the outside and the new ones (for both speakers) are between them.

There's the new subwoofer wire for both speakers and an old one in the middle. I made them a little too long.

 

[allsmith]

Looking good! Seems to me i used some 14awg copper house wire to extend some leads for some caps on a tv power supply board. But i can't remember for sure, i might of had some thinner copper wire i used.as long as it fits in the holes of the pcb board. You could also file down some thicker wire so it fits in the hole, i had to do that the other night on some diodes i installed in a receiver.

Nice job twisting the wires! Did you use a drill to twist them?

 

[Dr. Morbius]

Looking good! Seems to me i used some 14awg copper house wire to extend some leads for some caps on a tv power supply board. But i can't remember for sure, i might of had some thinner copper wire i used.as long as it fits in the holes of the pcb board. You could also file down some thicker wire so it fits in the hole, i had to do that the other night on some diodes i installed in a receiver.

Nice job twisting the wires! Did you use a drill to twist them?

Thanks. I may have to use some copper from some old RG-6 lying around as I've used up my left over cap leads. And to think, I've been throwing all that stuff away. I should probably have used wire for the extra flexibility.

No I twist by hand. I've tried using a drill, but it puts undue stress on the wire.

 

[Dr. Morbius]

Got a little more done. Here are the caps soldered onto the PCB. I'm not too thrilled with how this came out. The caps don't feel very snug. I plan to hot glue them in place once I have verified everything works as it should. That should help.

Here's the top view. I used heat shrink on all of the leads for protection and to prevent any shorts due to so much being exposed. You may be able to see where I cut away some of the nylon on the coil inductor (far right) so the 11uF capacitor would fit. Everything should mount back onto the input terminal plate, but I'll have to use 5 screws instead of 6 as the 6th is no longer accessible.

Although these look like the subwoofer wires in a previous post, they are for the mids and tweets. Each speaker gets one 4 wire twist, each wire being 16 AWG. The old mid and tweet wires are coiled up in the center. I don't know what the old wires are, but they are huge compared to the stock internal wires in my DCM speakers. HUGE!

I used green heat shrink to mark which wire pair would go to the tweeters. The mids and tweets share a common ground so I didn't have to mark the negative wires, but I was tired and wasn't thinking at the time.

 

[allsmith]

Looks good to me! Could you zip tie or black tape them to each other? That might tightened up.

 

[Dr. Morbius]

Looks good to me! Could you zip tie or black tape them to each other? That might tightened up.

Thanks. I'll probably use hot glue. The Super Twos are from NHT's Performance line of speakers so this is probably the last time anyone will want to recap these.

 

[Dr. Morbius]

I finished up one Super Two today. On the left is a Peerless 6.5" sub which is crossed over at 120 Hz. On the right is a 6.5" Foster midrange. I used Mortite rope caulk to dampen the frames.

I used a generic Peel & Seal to dampen the inside of the cabinet. I had to fish the wiring through the subwoofer part of the cabinet with an old metal coat hanger. It's nice to see that even on NHT's budget line of speakers that the cabinet is divided for mids/tweets and subs. Once I solder the speaker wire to the drivers I'll put the stock polyfill back insde the cabinet.

By now I'm getting pretty frustrated due to a couple of mistakes I made during the disassembly. Needless to day that won't happen on the other speaker. I tried to remove some wires before my iron was good and hot and it messed up the PCB. I ended up drilling new holes, but made them too big. I finally got the solder to hold though and put the rest of the cabinet back together. I will NOT make that mistake again! I also hot glued the capacitors together for better stability.

And here they are in my office, which has also turned into my speaker workshop. The tower on the right is the one I modded. I'm going to try to get to the next one within a couple of weeks, however, my brother is coming to town and I have a million things to do before he arrives. Once I've finished the 2nd speaker I'll polish the cabinets.

On top of the Super Twos is a pair of Definitive Technology Studio Monitor 350s. They're nice little speakers, but definitely not worth the $500 MSRP. I bought them new on closeout for $150 shipped.

I have less than $200 total in the NHT Super Twos including 5 caps for each crossover, speaker wire, Mortite caulk, generic Peel & Seal, hot glue and some speaker caulk. Not too shabby.

:thmbsp:

 

[89grand]

Your DCM's are going to get pissed about you cheating on them, and giving love to other brands.:nono:

 

[SoundOfSound]

I finished up one Super Two today. On the left is a Peerless 6.5" sub which is crossed over at 120 Hz. On the right is a 6.5" Foster midrange. I used Mortite rope caulk to dampen the frames.

I used a generic Peel & Seal to dampen the inside of the cabinet. I had to fish the wiring through the subwoofer part of the cabinet with an old metal coat hanger. It's nice to see that even on NHT's budget line of speakers that the cabinet is divided for mids/tweets and subs. Once I solder the speaker wire to the drivers I'll put the stock polyfill back insde the cabinet.

By now I'm getting pretty frustrated due to a couple of mistakes I made during the disassembly. Needless to day that won't happen on the other speaker. I tried to remove some wires before my iron was good and hot and it messed up the PCB. I ended up drilling new holes, but made them too big. I finally got the solder to hold though and put the rest of the cabinet back together. I will NOT make that mistake again! I also hot glued the capacitors together for better stability.

And here they are in my office, which has also turned into my speaker workshop. The tower on the right is the one I modded. I'm going to try to get to the next one within a couple of weeks, however, my brother is coming to town and I have a million things to do before he arrives. Once I've finished the 2nd speaker I'll polish the cabinets.

On top of the Super Twos is a pair of Definitive Technology Studio Monitor 350s. They're nice little speakers, but definitely not worth the $500 MSRP. I bought them new on closeout for $150 shipped.

I have less than $200 total in the NHT Super Twos including 5 caps for each crossover, speaker wire, Mortite caulk, generic Peel & Seal, hot glue and some speaker caulk. Not too shabby.

:thmbsp:

You have your speakers plugged into your fax machine? ...How does that sound? :scratch2:

 

[89grand]

I sure hope that's a printer and not a fax machine because it's common knowledge that ink jets offer moar SQ over outdated fax machines, you know with the dial tone interference and all.