Wigwam Jones
Caesar non supra grammati
HOW TO RECAP YOUR OWN SPEAKERS LIKE A BOSS
What is recapping?
Speakers generally have more than one driver in them. When they do, they often have what is known as a 'crossover' in them to ensure that the appropriate frequency ranges get sent to the correct driver. Crossovers can be active or passive, and they can be simple or complex. I am just going to deal with a simple passive, 3-way speaker design of the sort commonly found on vintage speakers. In this case, I am going to replace the capacitors on the crossover network of my Realistic Nova-8 speakers. This is known as 'recapping'.
Why recap?
Passive speaker crossovers are generally made of one or more of the following electronic devices: capacitors, inductors, resisters, and variable resisters, commonly known as "L-Pads" for adjusting individual drivers to your own taste (these are the knobs that stick out of the back of your speakers). Generally speaking, the resisters and inductors do not go bad and do not need to be replaced. But the capacitors are different; they are made up of a chemical paste inside, and over the years, the chemistry changes, and the capacitors stop working within the parameters they were designed for. This can harm drivers in the worst cases, but even if it doesn't damage them, it can ruin the sound of an otherwise excellent set of loudspeakers. So it is quite common to 'recap' a set of vintage speakers, and it quite often improves the sound quality very much.
What do I need?
You need your speakers, of course. And you will need have opened them up (some open from the back, some by taking out one or more of the drivers, such as the woofer) and you'll have to identify the values of the capacitors inside. Presuming that you are doing a 1-for-1 replacement of matching values and not fiddling with the values to create a different sound, you'll want to order replacement capacitors of the same value.
Capacitors are available in a variety of types, and from a variety of vendors. With speakers, the capacitors used in the crossover should be non-polarity (also known as NP) and the voltage should be the same or higher than the capacitors you're replacing. Other than that, it is a matter of taste and budget; there are inexpensive capacitors and expensive capacitors. They are made of a variety of materials. Ask questions, look at prices, decide what you want to spend. In the end, it's your decision. As long as the values are correct and they are non-polarity and the same voltage or higher, you're good as far as having them work for you. Some people feel that more expensive capacitors sound better; your call on that.
You will also need a soldering iron. These are available very inexpensively from places like Radio Shack and lots of mail order places. You don't need to spend much on this; it does not have to be fancy at all. You will not be soldering extremely temperature-sensitive materials.
You'll need some solder. Rosin-core solder is common and inexpensive. Some people prefer to use silver solder. It costs more and is harder to use for some people; the choice is yours.
You'll need some common tools like screwdrivers, needle-nose pliers, wire snips, and that sort of thing. Nothing weird or expensive.
You'll need some sealant of some sort for various things. For example, something to stick the crossover network back down again after you've pried it out of the back of the speaker cabinet. Perhaps some kind of sealant to seal the woofer if you have to take it out and the material used to seal it in place is ruined in the process. You can buy that commercially, some people like to use the stuff used to seal doors in houses, it's a type of rope caulk that you can mold with your fingers. Your choice, but if your speakers are 'sealed' and not 'vented' then you do want a nice tight seal when you put them back together.
Some words of warning!
Soldering is done at a high temperature. You can burn yourself badly. You can start a fire. Please use precautions. Have a fire extinguisher handy. Keep the soldering iron on a stand designed for that purpose when it is not in your hand. Do not breathe solder fumes; they're nasty and bad for you. Just use common sense and be careful and go slow.
Let's get started!
Here is what I'm working on today. A vintage Realistic Nova-8 set of speakers. Classic 3-way design with a woofer, two midrange drivers, and a tweeter.
100_3749.JPG by Wigwam Jones, on Flickr
100_3750.JPG by Wigwam Jones, on Flickr
There are two connectors for speakers on the back, plus an RCA jack (common on Radio Shack speakers, you can ignore it) and a pair of L-Pads for adjusting the mid-range and treble to your taste.
100_3751.JPG by Wigwam Jones, on Flickr
Step One: Remove the woofer
First, I laid my speaker down across two chairs so that I could work on it. I used a Phillips screwdriver to remove the four screws holding the woofer in and gently pried the woofer out and turned it over.
100_3753.JPG by Wigwam Jones, on Flickr
The speaker wires are connected by press-on connectors, they pull off. Notice that there is a 'plus' and a 'minus' sign next to the connectors. The black wire is 'minus'. That's important when you put the speakers back together later. If you get them backwards, you won't damage the speakers, but you might end up with them out of phase that was intended by the crossover designers; this can cancel out frequencies that were meant to be heard, resulting in unsatisfactory sound. If two speakers are out of phase with each other, it can cancel out the bass, which never sounds good.
So keeping in mind which wire goes where, pull off the connectors.
Once the woofer is out, you'll notice the cabinet is full of stuffing. This is generally fiberglass, just like the stuff used to insulate homes. I use a plastic bag to pull this out; it doesn't bother some people but it makes me all scratchy. So I pull it out with a plastic bag like I was picking up dog poop, you know what I mean. Set it aside, it goes back in later.
Step Two: Remove the Crossover
You can see the crossover network below inside the speaker cabinet. It is very common for the crossover to be mounted here, since that's where the L-Pad and speaker connectors are located anyway. You won't be able to reach down inside there and solder on things, so it it going to have to come out. Chances are it is both screwed and glued to the inside of the cabinet.
100_3755.JPG by Wigwam Jones, on Flickr
100_3754.JPG by Wigwam Jones, on Flickr
So, I unscrewed it, then I used a very small flat-blade screwdriver to gently pry it out of the speaker cabinet. Some crossovers take more force than others; on some, I've had to get busy with a screwdriver and a hammer to get the things out. Just be careful and don't damage your crossovers or speaker cabinets.
100_3756.JPG by Wigwam Jones, on Flickr
100_3757.JPG by Wigwam Jones, on Flickr
What is recapping?
Speakers generally have more than one driver in them. When they do, they often have what is known as a 'crossover' in them to ensure that the appropriate frequency ranges get sent to the correct driver. Crossovers can be active or passive, and they can be simple or complex. I am just going to deal with a simple passive, 3-way speaker design of the sort commonly found on vintage speakers. In this case, I am going to replace the capacitors on the crossover network of my Realistic Nova-8 speakers. This is known as 'recapping'.
Why recap?
Passive speaker crossovers are generally made of one or more of the following electronic devices: capacitors, inductors, resisters, and variable resisters, commonly known as "L-Pads" for adjusting individual drivers to your own taste (these are the knobs that stick out of the back of your speakers). Generally speaking, the resisters and inductors do not go bad and do not need to be replaced. But the capacitors are different; they are made up of a chemical paste inside, and over the years, the chemistry changes, and the capacitors stop working within the parameters they were designed for. This can harm drivers in the worst cases, but even if it doesn't damage them, it can ruin the sound of an otherwise excellent set of loudspeakers. So it is quite common to 'recap' a set of vintage speakers, and it quite often improves the sound quality very much.
What do I need?
You need your speakers, of course. And you will need have opened them up (some open from the back, some by taking out one or more of the drivers, such as the woofer) and you'll have to identify the values of the capacitors inside. Presuming that you are doing a 1-for-1 replacement of matching values and not fiddling with the values to create a different sound, you'll want to order replacement capacitors of the same value.
Capacitors are available in a variety of types, and from a variety of vendors. With speakers, the capacitors used in the crossover should be non-polarity (also known as NP) and the voltage should be the same or higher than the capacitors you're replacing. Other than that, it is a matter of taste and budget; there are inexpensive capacitors and expensive capacitors. They are made of a variety of materials. Ask questions, look at prices, decide what you want to spend. In the end, it's your decision. As long as the values are correct and they are non-polarity and the same voltage or higher, you're good as far as having them work for you. Some people feel that more expensive capacitors sound better; your call on that.
You will also need a soldering iron. These are available very inexpensively from places like Radio Shack and lots of mail order places. You don't need to spend much on this; it does not have to be fancy at all. You will not be soldering extremely temperature-sensitive materials.
You'll need some solder. Rosin-core solder is common and inexpensive. Some people prefer to use silver solder. It costs more and is harder to use for some people; the choice is yours.
You'll need some common tools like screwdrivers, needle-nose pliers, wire snips, and that sort of thing. Nothing weird or expensive.
You'll need some sealant of some sort for various things. For example, something to stick the crossover network back down again after you've pried it out of the back of the speaker cabinet. Perhaps some kind of sealant to seal the woofer if you have to take it out and the material used to seal it in place is ruined in the process. You can buy that commercially, some people like to use the stuff used to seal doors in houses, it's a type of rope caulk that you can mold with your fingers. Your choice, but if your speakers are 'sealed' and not 'vented' then you do want a nice tight seal when you put them back together.
Some words of warning!
Soldering is done at a high temperature. You can burn yourself badly. You can start a fire. Please use precautions. Have a fire extinguisher handy. Keep the soldering iron on a stand designed for that purpose when it is not in your hand. Do not breathe solder fumes; they're nasty and bad for you. Just use common sense and be careful and go slow.
Let's get started!
Here is what I'm working on today. A vintage Realistic Nova-8 set of speakers. Classic 3-way design with a woofer, two midrange drivers, and a tweeter.
100_3749.JPG by Wigwam Jones, on Flickr
100_3750.JPG by Wigwam Jones, on Flickr
There are two connectors for speakers on the back, plus an RCA jack (common on Radio Shack speakers, you can ignore it) and a pair of L-Pads for adjusting the mid-range and treble to your taste.
100_3751.JPG by Wigwam Jones, on Flickr
Step One: Remove the woofer
First, I laid my speaker down across two chairs so that I could work on it. I used a Phillips screwdriver to remove the four screws holding the woofer in and gently pried the woofer out and turned it over.
100_3753.JPG by Wigwam Jones, on Flickr
The speaker wires are connected by press-on connectors, they pull off. Notice that there is a 'plus' and a 'minus' sign next to the connectors. The black wire is 'minus'. That's important when you put the speakers back together later. If you get them backwards, you won't damage the speakers, but you might end up with them out of phase that was intended by the crossover designers; this can cancel out frequencies that were meant to be heard, resulting in unsatisfactory sound. If two speakers are out of phase with each other, it can cancel out the bass, which never sounds good.
So keeping in mind which wire goes where, pull off the connectors.
Once the woofer is out, you'll notice the cabinet is full of stuffing. This is generally fiberglass, just like the stuff used to insulate homes. I use a plastic bag to pull this out; it doesn't bother some people but it makes me all scratchy. So I pull it out with a plastic bag like I was picking up dog poop, you know what I mean. Set it aside, it goes back in later.
Step Two: Remove the Crossover
You can see the crossover network below inside the speaker cabinet. It is very common for the crossover to be mounted here, since that's where the L-Pad and speaker connectors are located anyway. You won't be able to reach down inside there and solder on things, so it it going to have to come out. Chances are it is both screwed and glued to the inside of the cabinet.
100_3755.JPG by Wigwam Jones, on Flickr
100_3754.JPG by Wigwam Jones, on Flickr
So, I unscrewed it, then I used a very small flat-blade screwdriver to gently pry it out of the speaker cabinet. Some crossovers take more force than others; on some, I've had to get busy with a screwdriver and a hammer to get the things out. Just be careful and don't damage your crossovers or speaker cabinets.
100_3756.JPG by Wigwam Jones, on Flickr
100_3757.JPG by Wigwam Jones, on Flickr