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Fixing Technics speakers - some questions

coonmanx

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Thanks guys.
I'm not going to buy new ones just yet. I'm in it for the learning experience and the pleasure of "making stuff work". Can anyone point me to good documentation on crossover- what is it and why do I need to worry about it.. I thought I'd be removing 2 wires from current drivers, then resoldering those to the new drivers (no talking about structural modifications to the box itself). Is there another (mandatory) component inside that I haven't seen? Is it something that definitely needs to be replaced?
Apologies for my flood of questions and thank you so much for taking the time to respond and comment!
Ido
LOL that everyone is trying to force you into buying new speakers when you actually want to learn something. If I had listened to the naysayers like that I would never had built three different sets of speakers. Frankly, you can get good results with repurposing. I have definitely found that to be true.

A good place to start might be here. This site is a wealth of knowledge. Basically what you should know about the crossover is that is splits the frequencies so that different parts of the sound spectrum gets handled by different parts of the speaker (wooofer, midrange and tweeter). The woofer handles the low frequencies, the midrange handles the middle frequencies and then the tweeter handles the highs.

You would have to take a look at that crossover to see how it is built. But if you can match the sensitivity of new drivers to the old ones and they cover the same frequency range then there should not be any issues. As for how it will sound... well you have to just try it and see. Unless you are going to invest in a whole lot of equipment. It's a journey of sorts, understanding speakers. Some of it is fairly simple and some more complex.

This would be a good place to start and feel free to ask questions if you don't understand something.

http://www.mh-audio.nl/Loudspeaker.html
 

coonmanx

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I actually think that some crappy old Technics might be a great starting point to dive in and experiment. What does OP have to lose...

About $100. And that $100 can be a fun little project that might just turn out great.
 

hex168

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Here's a cut-and-paste from an older post that gives a starting point for DIY:

A beginner's guide:
http://audio.claub.net/software/DaveDalFarra/Simple Loudspeaker Design ver2.pdf
Unibox is good for sealed and ported box calculations:
http://audio.claub.net/software/kougaard/ubmodel.html
This page has a lot of good, free loudspeaker software:
http://audio.claub.net/software.html

Poking through this thread will give you some background information on speaker design:
https://www.diyaudio.com/forums/multi-way/332688-design-own-speaker-scratch.html

An example woofer that could work in your roughly 1.7 cubic foot box :
https://www.parts-express.com/Peerless-SDS-160F25PR01-08-6-1-2-Paper-Cone-Woofer-Speaker-264-1146

And an example tweeter:
https://www.parts-express.com/Peerless-DA25BG08-06-1-Aluminum-Dome-Tweeter-6-Ohm-264-1460

Among the nice folks at the Parts Express Tech Talk forum, there are people who will often model a crossover for a beginner. If I were you, I'd post there and ask for suggestions.
https://techtalk.parts-express.com/forum/tech-talk-forum
 

Spkrdctr

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If he can do it all for $100 for the pair, then it is a learning experience. But if he gets any cost creep in it at all. He could be near $150 and that is a whisker from $200 brand new. But if the money is not an issue, you can tear into them, just don't expect much in sound quality when finished. Plus they are still ugly as sin. But you will come away with an appreciation of how speakers are made.
 

Laserjock

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Go to Amazon and buy a pair of the DIY Swan HiVi 2 way or 3 ways.
Learn a bunch and if you learned correctly, you’ll thank me for not going down the junk heap route.
 
OP
I

Ido

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I've been reading and learning about crossover networks for about 2 hours now.. I don't know what's in the cab currently but to my understanding I'll need a 3-way passive crossover (correct?). I think I can find the x-over, 2 woofers, 2 mids, 2 tweeters at around 200$. for me- it's worth it. I don't expect it to compete with new, modern speakers, I just know I'll enjoy doing it. any pitfalls I should be wary of? specific types that don't go well together? specific combination that do go well?
I DO like the DIY HiVi 3way though... maybe I should just do that...
Damn we live in a world with too many options!
 

Doodski

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I've been reading and learning about crossover networks for about 2 hours now.. I don't know what's in the cab currently but to my understanding I'll need a 3-way passive crossover (correct?). I think I can find the x-over, 2 woofers, 2 mids, 2 tweeters at around 200$. for me- it's worth it. I don't expect it to compete with new, modern speakers, I just know I'll enjoy doing it. any pitfalls I should be wary of? specific types that don't go well together? specific combination that do go well?
I DO like the DIY HiVi 3way though... maybe I should just do that...
Damn we live in a world with too many options!
If you are stuck on a learning process then buy a modern speaker kit that is properly designed and calibrated for the drivers and crossover. There are many. Invest your money wisely. :D
 
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AnalogSteph

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This. Optimizing the crossover is a major part of passive speaker development. You pick drivers with a sensible combination of sensitivity, level handling, usable frequency ranges and dispersion, tune the enclosure using woofer TSPs or select a woofer that works in what's there, sort out the baffle (including flush mounting and reducing difffraction if need be - here the old trick of placing foam around the tweeter may prove handy), but the crossover is how it's all integrated. While you'll generally have an idea of how steep you want your slopes to be, there is no shortage of simulating, measuring, tweaking values in practice.

In an speaker that old I would also pay attention to the level of bracing in the enclosure, of which there may not be that much. Note that it may also be using a sealed midrange and you may have more promising options if you accept the need for a little sealed enclosure of its own. Just throwing a midrange that's open in the back in a common volume with the woofer is a big no-no in IMD terms.
 
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tomtoo

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@Ido
Its cool that you like to learn. But to learn in speaker building you need measuring equipment.
Sure you can put into this cases some drivers. Use the old or new x-overs and hope it will sound acceptable. The outcome will be nearly random. So what you learned? How to build a speaker where the soundquality is random. Thats not much. So to realy learn, you have to measure. Speaker building is not as easy as many think. At least if the outcome should not be random. Imo its much more easy to start with a diy kit. Than get measuring equipment and learn by changing.
Just read the directiva project on this site. How much knowledge,simulation and measuring is going in.
 
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coonmanx

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@Ido
Its cool that you like to learn. But to learn in speaker building you need measuring equipment.
Sure you can put into this cases some drivers. Use the old or new x-overs and hope it will sound acceptable. The outcome will be nearly random. So what you learned? How to build a speaker where the soundquality is random. Thats not much. So to realy learn, you have to measure. Speaker building is not as easy as many think. At least if the outcome should not be random. Imo its much more easy to start with a diy kit. Than get measuring equipment and learn by changing.
Just read the directiva project on this site. How much knowledge,simulation and measuring is going in.
I have to say that I completely disagree with this...

First off, if someone doing the speaker building gains a lot of knowledge before they start then that will be an advantage. Yes, you aren't going to know exactly how two different drivers will play together but there are driver specifications that can give you a whole lot of information before you even start.

So last year I decided to repurpose some Celestion Ditton 110 cabinets. I had bought the speakers just for the crossovers. I already have a pair that I swapped drivers out for some newer and better drivers. I use them daily in my main system, along with some Speakerlab 1's. But I never did anything with the crossovers. So I figured, why not get another pair and then pull the crossovers out and then recap those to be swapped back into the speakers that have the old and untouched crossover. That way I can still use the speakers while I redo the crossovers and also if I don't like the results then I can always slap the old crossovers back in. I actually have one crossover already refreshed but then I moved and I still need to do the second one.

Anyway, I already had some Dayton Classic 8" woofers and figured why not go for another speaker build. I had some Peerless tweeters that I figured would work fine but then I could not locate them so I got some Monacor tweeters from Germany for a good price. Got some crossovers that cross at 2.5 kHz. Put it all together and the tweeter was too bright and the speaker was not balanced. So I looked up what resistors I needed in order to pad the tweeter down by about 3 dB and it worked great. Gave them to a friend and they sound wonderful at his house. They do not sound "random" at all. I did not use any measuring device besides my ears.

But before I even started I already knew the parameters of the drivers. I probably should have realized that the tweeter was more sensitive and would need to be padded down. But I quickly figured that out.

Frankly I would not recommend that the OP get new crossovers as that is really not needed and would be a waste of money. Better to simply find out what the crossover points are and match some drivers to that. If you know the sensitivity of those speakers it would also help for matching drivers. And drivers need to be crossed in at the proper point. So yeah it is tricky but it is doable. I would recommend that he simply replace the capacitors in the old speakers. That would be sufficient. And then if he has any questions he should ask for some guidance at Parts Express. They can probably also tell him which drivers will "play well together".

I would also suggest to him that he takes his time and thinks it through. That is important. Don't rush it. Go one step at a time. It will be a great learning experience.
 

coonmanx

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Obviously a three way build is more complex than the two way build that I did, but the science is the same. Just a bit more complicated.

I think that the folks at Parts Express might be good for helping you choose some drivers that will work well together. That is their job. I would definitely go for some dome tweeters. They sound so much better and giver you the dispersion that you want, unlike cones. Much better imaging. The other two drivers, the midrange and the woofer just need to sound decent, match to the crossover points and have the proper sensitivity as well.
 

tomtoo

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I have to say that I completely disagree with this...

First off, if someone doing the speaker building gains a lot of knowledge before they start then that will be an advantage. Yes, you aren't going to know exactly how two different drivers will play together but there are driver specifications that can give you a whole lot of information before you even start.

So last year I decided to repurpose some Celestion Ditton 110 cabinets. I had bought the speakers just for the crossovers. I already have a pair that I swapped drivers out for some newer and better drivers. I use them daily in my main system, along with some Speakerlab 1's. But I never did anything with the crossovers. So I figured, why not get another pair and then pull the crossovers out and then recap those to be swapped back into the speakers that have the old and untouched crossover. That way I can still use the speakers while I redo the crossovers and also if I don't like the results then I can always slap the old crossovers back in. I actually have one crossover already refreshed but then I moved and I still need to do the second one.

Anyway, I already had some Dayton Classic 8" woofers and figured why not go for another speaker build. I had some Peerless tweeters that I figured would work fine but then I could not locate them so I got some Monacor tweeters from Germany for a good price. Got some crossovers that cross at 2.5 kHz. Put it all together and the tweeter was too bright and the speaker was not balanced. So I looked up what resistors I needed in order to pad the tweeter down by about 3 dB and it worked great. Gave them to a friend and they sound wonderful at his house. They do not sound "random" at all. I did not use any measuring device besides my ears.

But before I even started I already knew the parameters of the drivers. I probably should have realized that the tweeter was more sensitive and would need to be padded down. But I quickly figured that out.

Frankly I would not recommend that the OP get new crossovers as that is really not needed and would be a waste of money. Better to simply find out what the crossover points are and match some drivers to that. If you know the sensitivity of those speakers it would also help for matching drivers. And drivers need to be crossed in at the proper point. So yeah it is tricky but it is doable. I would recommend that he simply replace the capacitors in the old speakers. That would be sufficient. And then if he has any questions he should ask for some guidance at Parts Express. They can probably also tell him which drivers will "play well together".

I would also suggest to him that he takes his time and thinks it through. That is important. Don't rush it. Go one step at a time. It will be a great learning experience.

I dont see the point where you disagree with what i said. Did you measured your speakers?
 

coonmanx

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I dont see the point where you disagree with what i said. Did you measured your speakers?
Nope. My ears did.

I also recognized that the tweeters were more sensitive so that was the reason for the mismatch. So I employed an L-pad configuration, which I calculated would give me about 3 dB of attenuation. I used this page to plug in values and then I ordered the correct resistors (ceramic).

http://www.mh-audio.nl/Calculators/att.html
 

coonmanx

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I'm not saying that measuring equipment is not useful. I just don't think that it is necessary, especially on a project where there might be some trial and error like this. A cheap project.

I actually did find those Peerless tweeters later, after I had already installed the Monacor tweeters. Anyway, I guess I have some spares in case a new project come along, but frankly I don't need any more speakers. I am overspeakered.
 

tomtoo

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I'm not saying that measuring equipment is not useful. I just don't think that it is necessary, especially on a project where there might be some trial and error like this. A cheap project.

I actually did find those Peerless tweeters later, after I had already installed the Monacor tweeters. Anyway, I guess I have some spares in case a new project come along, but frankly I don't need any more speakers. I am overspeakered.

Isnt trial and error a random outcome?
 

coonmanx

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I guess I also did "measure" in a way by utilizing an EQ and seeing what frequencies were too strong. It became obvious to me quickly that it was indeed the high end that was over represented. So the L-pad configuration came in handy. It might have been better if I had drivers that were perfectly matched but in the end it all worked out.
 

coonmanx

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Isnt trial and error a random outcome?
I have a pretty good record. Those speakers that I gave to a friend along with a cheaper mid 80s Technics amplifier do sound very good. It might be nice to analyze them some time. But I don't get caught up on this sounding "technically correct". I just like things that sound good. So being technically correct is not important to me.

It's the same thing with brewing beer. I usually don't measure for alcohol content. I know what is in there and I know about what it should be. And anyway, the important thing is how it tastes... is it balanced. There is an art to it. It isn't always about the science. Science is good but only takes you so far.

BTW, we are talking about a guy slapping together a cheap $100 set of speakers. So why not just say, "Go have some fun and learn"... Frankly I would love to get in on a cheap project like that because I have never built a set of three ways. I kind of want to and especially would like to see if you can create something better. One of the things that I did see about those SB-K22's is that they are only rated to handle 40W or so. But that could just be the cheap drivers that are in there.
 

coonmanx

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Also I am saying that it is not necessarily random if you do some research before you start and choose your drivers wisely. Read the specs. What is the recommended crossover point? What is the driver sensitivity? What is its resonant frequency (also related to crossover point)? Woofers need to be matched to cabinet size, either ported or sealed. How much power can that driver take? That information is out there ahead of time. If you just go to a page where they sell tweeters of all kinds and you randomly choose... then you will indeed get random results. But if you choose wisely you will get much better results.
 

tomtoo

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I have a pretty good record. Those speakers that I gave to a friend along with a cheaper mid 80s Technics amplifier do sound very good. It might be nice to analyze them some time. But I don't get caught up on this sounding "technically correct". I just like things that sound good. So being technically correct is not important to me.

It's the same thing with brewing beer. I usually don't measure for alcohol content. I know what is in there and I know about what it should be. And anyway, the important thing is how it tastes... is it balanced. There is an art to it. It isn't always about the science. Science is good but only takes you so far.

BTW, we are talking about a guy slapping together a cheap $100 set of speakers. So why not just say, "Go have some fun and learn"... Frankly I would love to get in on a cheap project like that because I have never built a set of three ways. I kind of want to and especially would like to see if you can create something better. One of the things that I did see about those SB-K22's is that they are only rated to handle 40W or so. But that could just be the cheap drivers that are in there.

If you have to replace all the drivers and the x-overs, that 40w are as interesting as the rotten sack of rice in china that was fallen over 500 years ago.

The only thing thats usabel for this project is the case. And thats not much and gives some constrains.
And this is where my logic kicks in.
Dont get me wrong, everybody should have fun with what he is doing. But dont ask me if it makes sense from my point of view if you can stand the answer.
 
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