In this article, I’m going to explain to you why a set of two-way speakers should have a dedicated crossover network. You might be wondering, what exactly is a crossover network. Well, it is simply a board with capacitors, resistors, and coils that limit the frequencies going to specific drivers. They are very popular with three-way speakers. As with three-way speakers, you’re dealing with three drivers. Speaker manufactures however don’t like building an actual network for their two-way speakers. Instead, they use one or in the case of my Electrohome SC 490s, two filter capacitors to limit frequencies going to the tweeter.
Going Back To When I Replaced Them With A Single Cap:
If you read my original review on the Electrohome SC 490s, I had replaced the ancient filter caps with a new set ordered online. While this worked well for a while, it was recent that I started to notice the Electrohomes were loosing their top end slowly. This started back around January 2020, and slowly got worse. My guess was the filter caps I installed were not taking the constant listening. They were more than likely getting fried.
Wait, is this a bad thing?
Well, let’s think about this one for a second. With this kind of setup, you commonly have the woofer directly wired to the input terminals. There is nothing actually limiting what the woofer receives. The woofer is getting it all. This can decrease transient response in the lower treble region going into the upper mid range as the woofer fails to respond fast enough. While there are some woofers that are good at producing these frequencies, they tend to still do a poor job when compared to a quality set of tweeters.
Another thing to think about: So, your tweeters are now in series with a capacitor or two. This will cause them to be quiet compared to the woofers, which are receiving power directly. This imbalance in sensitivity can really throw the sound way out of balance. As now, you have a woofer that overpowers a tweeter that it is supposed to be working with.
You might think throwing an EQ at the system will solve this. It really doesn’t work like that. As now, you are also sending all this extra power to the woofer which will try to produce these frequencies. Your amplifier will also have to work unnecessary hard increasing THD.
Determine What Your Two Way Speakers Use For A Crossover:
While you might be able to find this information online particularly if your speakers are a well documented set, this isn’t always the case. If so, then you’re going to have to go in a little deeper and figure this out yourself. As a precaution especially if you’re working with a very old and/or rare set of speakers, treat everything with extreme care. You really don’t want to ruin a potential great set of speakers by being careless.
Now, determine how your speakers are designed to be serviced. Most speakers made after the 70s tend to have the drivers mounted from the front with removal able grills. Speakers older than that tend to have the drivers mounted from the inside. There are a few exceptions to this so be sure to double check.
For speakers with removable back plates, things are definitely a lot easier as you can literally open the whole cabinet. The only things you have to keep in mind are, the back plate will need to be able to seal on re-assembly ensuring there is no air leaks. These leaks will ruin the entire low-end and potentially the mid range of your speakers. Another thing you need to keep in mind is that your wire leads are more than likely soldered onto the terminals. It is up to you what you want to do here. I found it easier just to leave some wire there and cut them. My crossover networks had their own wiring which worked out.
Now, for speakers that have drivers mounted in front, things get just a little harder. It’s more difficult to see. And running wires is just a little harder. But reassembly is generally easier as getting a good seal is easier with front-mounted drivers.
No matter that type of cabinets your speakers use, determining the crossover type is easy. You should look for either a crossover board or one or two capacitors. If you have a crossover board, your speakers do in fact use a dedicated crossover network. If they are under performing and are more than 30 years old, I highly recommend having someone recap the existing boards. But if you only have one or two capacitors in series with your tweeters, then your speakers do not use a dedicated network. Well we’re going to fix this.
The Solution? Install A Dedicated Crossover Network
While this might sound complicated, it is not. In fact, you can make it as easy or complicated as you want. By this, there are two routes you can take. This is all up to you to decide.
The first route is the hard one. You can buy a crossover specifically for use with home speakers. While this looks like the first route you want to take right off the bat, lets get into why this is the harder route. 7/10 times, you’re going to need to solder. That’s right, these crossover networks are very unforgiving to the DIY install. Here’s an example of one.
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Now the easy route to take, which is going to be the one less taken, is to use a crossover network designed for high end car audio. Now, this might sound strange, using car audio components in a set of home speakers. Believe it or not, they can actually be used in a set of home speakers. This is due to the fact that while car audio does generally run at 4 ohms, a set of car components are at 4 ohms. So a network is designed to maintain this resistance. So, wire the network up to a set of 8 ohm components and you’ll ultimately end up with an 8 ohm load. I have not noticed any negative effects after running a set for three months now. This is the route I took. Not only was it way easier, I had a nice set of JVC crossovers. Here’s a similar set of crossovers as I couldn’t find a set from JVC at the time of this writing.
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The Install + The Condition Of The Old Capacitors.
Upon opening up these speakers, I went ahead and cut the wires going to the terminals on the back panels leaving plenty of extra length. This way, I could easily strip the wiring and leave the original soldering in place. I have to give kudos to whoever soldered these terminals back in the 60s as stripping these wires were not easy. I had to really be careful however the solder held up.
With the back panels removed, I could now easily work on the install. Upon removing the old single capacitors, I found both of them bulging significantly. I found this funny as I really wasn’t giving these Electrohomes much power. Most I’ve seen was around 17 WPC RMS on the receiver’s power indicator.
This opened my eyes on why using a filter capacitor is never a good idea. When you remove a signal, it has to go somewhere. This right here is why a dedicated crossover network is a must on an audiophile application. Take a look at the large coils on the crossovers. They’re huge for one reason. Heat dissipation. The small filter caps I removed, smaller than a penny. I could now see why those filter caps were bulging and more than likely dried out. This was the reason why I noticed a significant degradation in tweeter sensitivity of the Electrohomes.
Moving on, I’m now going to get into the wiring was simple. On the crossover network, you have your amplifier input, woofer output, and tweeter output. All you need to do is wire the woofer to the woofer output, same with your tweeter. Be sure to pay attention to the polarity. Don’t mess this up. When done, place the crossover on the bottom of the speaker and secure it. You can get fancy with glue or just use tape.
Now, you need to wire the crossover network to your terminals, twist the wires together and use wire nuts. Then use electrical tape around the wire nuts. Again, be sure to pay attention to polarity here. Afterwards, test the speaker before re-assembly. Only when everything sounds right, do you re-assemble. Ensure you get a good seal afterwards by turning up the bass and searching for air leaks. Do the same for the other speaker.
If You Have Front Mounted Drivers:
While the process is the same, the order in which you do it is different. The first thing you do is remove the drivers. Install and secure the crossover to the bottom of the speaker. Now wire the input terminals to the amplifier terminals on the crossover. Then wire the tweeter to the tweeter terminals as well as the woofer to the woofer terminals. Pay attention to the polarity to ensure it is correct.
This is almost exclusive to my Electrohome speakers as they had an L Pad. For those unfamiliar, an L Pad is a speaker component that can be used to adjust audio level in a passive manner without affecting resistance. For some reason, my Electrohomes had the L Pads wired to both the woofer and tweeters. High end speakers tend to use them to decrease the volume of more sensitive drivers to allow you to balance the sound. In the case of my Electrohome SC 490s, the woofers tend to overpower the tweeters just a little bit. While the crossover upgrade really helped this out, I wanted to tame the woofers.
But this also wouldn’t have been possible with a filter cap crossover as those are wired in series. As such, I went ahead and cut the tweeter out of the L Pad’s circuit and ran it straight from the crossover network. This way, turning the L Pad would lower the woofer giving me total control over the balance between the two drivers. This was just a bonus touch. I found the tweeters plenty present after the crossover install. This basically gave the L Pads an actual job when sometimes, I just want a REALLY bright sound.
This is how the speakers should’ve been wired from the factory. The drivers. cabinets, and design really are just well layed out. Had Electrohome went with a dedicated crossover, they could’ve had an even better 1960s gem.
In this video, you will find not only a comparison of the filter cap installation but also the L Pad mod in action. Overall, I’m happy I gave these 60 year old speakers the much-needed love. They sound absolutely amazing now. I can’t even look back at this point. What a difference.