dc270
Now Off the Reservation
Project Freebie
A good friend of mine is always on he look out for projects for me. He found a good one the other day while I was out of town. On our local Craig’s List a person had listed some speakers he and some buddies had built in their college days. He had them listed for some time to sell with no results so he (or his wife) finally got desperate and offered them for FREE!
Most people would probably think more than twice about buying or even accepting custom built speakers, especially those from an old college project. These were diamonds in the rough however! A lot of thought and build quality went into them. Here is what I know about them thus far:
HEAVY, 116 lbs per cab (5.5 cu ft net volume)
15” CTS driver, pleated surrounds
Dual 4” CTS mid drivers
Dual Phenolic CTS tweeters
Custom built/ wound networks
Not mirror imaged
36 Threaded ¼” bolts holding backs on
The networks had these components:
3.5mh & 32uF = woofer circuit
106uf, 1.75mh,10.4uF= mid circuit
.167mh, 10.3uF, & .170mh= tweeter circuit
Polarized caps were used and wired in parallel to acquire their respective values.
The sound of these proved to be deceptively quite good! The bass was tight & well controlled. The woofers were well broke in. The dual mids were accurate and well blended into the woofer/ tweeters. The offset firing tweeters sounded very good with great dispersion from the angled platforms. These were quite efficient needing only ½ watt to get them to room filling capability! The networks, while hand built, were apparently well thought out and applied. The overall balance was good with equal competition between drivers. The construction was first rate with dozens of T-nuts used, wood screws with large cleats and quality MDF with thick Formica wood veneer.
On the other hand the 4” mids seemed a bit beaming due to their recessed placement behind the thick baffle. The Phenolic tweeters are pretty reliable and usually sound good. In their twisted array here they were best used. They can be somewhat directional when used in singles and can sound harsh at high power levels. The woofers look to be of the better made stamped steel frame types with a large square magnet for control. I had seen this woofer type used in Klipsch, Speakerlab and other places. It is a well made CTS woofer
My plan for these is to first mirror image them. The will give them better imaging & symmetry for starters. My second thought is to replace the Phenolics with soft dome types for improved dispersion, using the same offset firing scheme. My next improvement is to measure the hand wound inductors and replace with Erse low loss inductors and then replace the caps with polys on the high end and new electrolytics on the lower end. The cabs need nothing to improve them but perhaps some matting/ padding on the baffle for diffusion purposes. The grill covers will get new material as well. These have simple screw terminal that need a desperate binding post upgrade too.
The cab size reminds me a lot of Klipsch Cornwalls, as does the bass output. With some work I expect the mid & high end to sound quite good but the networks will need rebuilding and some testing done. Perhaps mounting the mids drivers on the baffle fave might help as well
Any thoughts, comments, suggestion on my upcoming project? A special thanks to "Gus JR" for picking up the speaker and bringing them over to me.
Thanks folks- llok forward to some input here.
DC
A good friend of mine is always on he look out for projects for me. He found a good one the other day while I was out of town. On our local Craig’s List a person had listed some speakers he and some buddies had built in their college days. He had them listed for some time to sell with no results so he (or his wife) finally got desperate and offered them for FREE!
Most people would probably think more than twice about buying or even accepting custom built speakers, especially those from an old college project. These were diamonds in the rough however! A lot of thought and build quality went into them. Here is what I know about them thus far:
HEAVY, 116 lbs per cab (5.5 cu ft net volume)
15” CTS driver, pleated surrounds
Dual 4” CTS mid drivers
Dual Phenolic CTS tweeters
Custom built/ wound networks
Not mirror imaged
36 Threaded ¼” bolts holding backs on
The networks had these components:
3.5mh & 32uF = woofer circuit
106uf, 1.75mh,10.4uF= mid circuit
.167mh, 10.3uF, & .170mh= tweeter circuit
Polarized caps were used and wired in parallel to acquire their respective values.
The sound of these proved to be deceptively quite good! The bass was tight & well controlled. The woofers were well broke in. The dual mids were accurate and well blended into the woofer/ tweeters. The offset firing tweeters sounded very good with great dispersion from the angled platforms. These were quite efficient needing only ½ watt to get them to room filling capability! The networks, while hand built, were apparently well thought out and applied. The overall balance was good with equal competition between drivers. The construction was first rate with dozens of T-nuts used, wood screws with large cleats and quality MDF with thick Formica wood veneer.
On the other hand the 4” mids seemed a bit beaming due to their recessed placement behind the thick baffle. The Phenolic tweeters are pretty reliable and usually sound good. In their twisted array here they were best used. They can be somewhat directional when used in singles and can sound harsh at high power levels. The woofers look to be of the better made stamped steel frame types with a large square magnet for control. I had seen this woofer type used in Klipsch, Speakerlab and other places. It is a well made CTS woofer
My plan for these is to first mirror image them. The will give them better imaging & symmetry for starters. My second thought is to replace the Phenolics with soft dome types for improved dispersion, using the same offset firing scheme. My next improvement is to measure the hand wound inductors and replace with Erse low loss inductors and then replace the caps with polys on the high end and new electrolytics on the lower end. The cabs need nothing to improve them but perhaps some matting/ padding on the baffle for diffusion purposes. The grill covers will get new material as well. These have simple screw terminal that need a desperate binding post upgrade too.
The cab size reminds me a lot of Klipsch Cornwalls, as does the bass output. With some work I expect the mid & high end to sound quite good but the networks will need rebuilding and some testing done. Perhaps mounting the mids drivers on the baffle fave might help as well
Any thoughts, comments, suggestion on my upcoming project? A special thanks to "Gus JR" for picking up the speaker and bringing them over to me.
Thanks folks- llok forward to some input here.
DC
