Off the shelf 3 way speaker crossovers

Recently there came into my possession a pair of speakers. Doubtful that many if any would know the brand as they were made and sold locally 30 to 40 years ago. The maker's main "claim to fame" was the cabinets. They offered a number of different size/types of enclosures and would custom veneer them if desired. Internally, they contained what I later learned were CTS drivers but would install upgraded components for a price. Or so I was told once when I went there to browse in the early 1970's. I never bought speakers there as they seemed awfully expensive.

Many years since then I acquired, restored and re-finished two pairs of their speakers. Keeping one and selling the other. This most recently acquired pair is a mini acoustic suspension version of the pair I sold which were a large, bass reflex floor standing 3 way with 5 drivers. Once I refinished the cabinets, those were among the nicest looking speakers I've ever seen.

What I have here is a 3 speaker air suspension box with an 8" and 10" wired as full ranges and a phenolic tweeter wired through a capacitor. So basically a two way system but I would like to convert it to an actual three way.

I am 99% sure the 10" woofer is not original and I suspect it was intended for automotive use - a car sub. Woofers that were in the enclosures I've previously worked on had pleated paper surrounds and this one has stiff foam so I am going to look for a more compliant 10" that will fit the hole.

I don't know if the driver compliment will lend itself to this project but I'm willing to try because they way they are, they sound god awful. I am not looking for ultimate audiophilia but I'm fairly certain they can sound better than they do now.

The only parameters I know are a 1.5 cubic foot cabinet volume, 8 ohm drivers and no enclosed area for the 8" "midrange". There are relatively inexpensive 3 way crossovers available from Parts Express for example so if I were to go that route, can anyone suggest what the optimal crossover points would be?

FWIW, I noticed Parts Express also offer a 10" woofer that will physically fit the opening and operate in the sealed internal cabinet volume I have to work with.

I look forward to any posts from those who care to reply.

 

There is no easy answer. You might want to register and post at:

Multi-Way - diyAudio »

Ideally you'd want drivers that are designed to work together with a crossover that is designed for those specific drivers. Another alternative is to to go with a 2 way system with a passive radiator in the 10" hole. Again, it should be a system that is designed to work together. Good luck!

 

I think you hit on something and that got me to thinking. There is virtually no online info for the company that built these speakers so looking up a particular model is impossible. But be that as it may, I now believe these were originally a two way with a 10" passive. That would be corroborated by the speakers model designation P10 - passive 10". It would also explain the single capacitor crossover to the tweeter and the "modern" clear jacketed speaker wire going from 8" driver terminals to 10" driver terminals so they operated in tandem.

The previous owner did say the woofer got upgraded and made a point of stating magnet size which was extremely over estimated. Whether or not it was he who performed this "upgrade" I do not know. Could be he wanted louder loudspeakers. He was a bit of a yahoo and may equate louder with better.

With this new conclusion, I am going to investigate 10" passive radiators and leave all else as it is. The two previous models I restored were far from sophisticated designs but overall did not sound outrageously bad. Could be that re-furbishing these to a more or less original operating state, they may be likewise.

I have never had to contend with a passive radiator before but have had past experience selling them during the time I was in that business. Some were purposely weighted like certain Polk Monitor Series models and some were not. I guess that may be a topic unto itself but any suggestions regarding "how to pick a passive radiator" would be welcome.

 

http://www.parts-express.com/pedocs/specs/295-494-dayton-audio-sd270-pr-specifications-46184.pdf

"Dayton Audio SD270-PR 10" Passive Radiator" from www.parts-express.com! »

 

Konut's suggestion is exactly what I had in mind. An easy way to do this is by the simple and good sounding two ways of EPI and Genesis. (actually 2 1/2 way) If you can find a pair of 8 inch Genesis woofers on eBay, and a passive radiator from Part Express or Madisound, you have a mid-woofer which does not require a crossover. An alternate would be perhaps a Seas woofer, or Scan-Speak or Dayton... a woofer designed to operate up to about 2.5 kHz and then roll off naturally.

All you need is a dome tweeter (or should you choose a Genesis inverted dome) just a simple 3uf crossover capacitor is all it needs. The passive radiator can be mass loaded to tune it to the woofer.

BTW, the car audio sub-woofer is incompatible with an air suspension cabinet. For a mid driver, you'd need to construct a dedicated midrange sub-enclosure.

 

If I am in the area today, I am going to stop by a local speaker repair/restore business. They have been around for decades and I did see examples of speakers "in the shop" from this same manufacturer during past visits. Out of curiosity I called and the owner knew of the model I have. He said he can make a passive radiator using a CTS driver, which is what were used and thinks he has four 10" on hand. I shall see.

I also came across an old AK thread I read several years ago that to my surprise, concerned these very same speakers. At least I now have a photo of what the original passive looked like. Those I have are walnut veneer and has the "standard equipment" phenolic tweeter not a dome as is in these photos which may be an aftermarket upgrade. Or perhaps not. At time of sale, speakers could be ordered with upscale drivers. I don't remember a dome but do remember being told Trusonic (a la JBL) "bullet tweeters" as being an option. My visits to the factory store pre-dated these speakers so maybe domes were offered later.

 

My visit to the "speaker repairman" yielded what should be the most cost effective solution. It was proposed that the 10" active drivers already in the enclosure be converted to passive's. This will be accomplished by removing the magnet, fitting a more compliant surround and spider and installing a hard disc with a front facing bolt onto which additional mass can be conveniently added in the form of washers.

I've managed to find a simple online "mass finding" calculator and arrived at the figure of 130 grams. I presume this to be total mass so must estimate the weight of the 10" pulp cone, hard disc and attached hardware then subtract that from 130 grams. Theoretically, the difference should be the weight of washers I'll need.