Hello, I'm new here, and have enjoyed some reading. Such a wealth of knowledge.
I have a pair of speakers that my Dad built in the mid 1970's. They were a proven design of which he followed the blueprints and purchased specific driver according to some stereophile magazine (I think). He has talked before about them being pink-noise tested (but I don't know exactly what that means.) He said that he "hand wrapped the cross-overs" too.
They are a three-way. Transmission-Line. 8" drivers, 4" mids, and a tweeter.
There are two knobs on the back that adjust the crossovers, and 35 year old pots would sound noisy and scratchy if they ever needed to be adjusted.
Sometimes the tweeters sound a little crunchy (on certain songs). I had once unscrewed the speaker line input to see if I could determine which was posative and negative, as the old markings had worn off years ago. The wire inside the cabinet looked green with oxidation.
The thing I love about these speakers is that they have a very full range responce, and things like the human voice come through especially well. Excellent imageing, despite the fact that they are closer than I would like to the rear wall as they are a transmission line.
My thought is to replace all the drivers, cross-overs, etc; to refresh them and make them like new. The cabinets themselves I think are excellent (very heavy) and they also have a lot of sentimental value to me.
Would I lose their "magic" if I were to change anything. I had once owed some 2 way speakers that had a soft-dome tweeter, and I thought they sounded good -is this a more modern thing...possible upgrade?
Getting to the question here: Dad had once said that the 8" driver and the distance of the travel of the speaker cone was all carefully planned to match the volume of the box, and the distances in the transmission line (so I don't want to mess that up)
Could I measure the inside dimention of the top cabinet and choose a more modern mid and tweeter. Find a 8" woofer for the bottom cabinet that would work with the cabinet (having the right distance of cone travel). Have the right cross-over to make it all magic and well balanced again?
Another part of my goal, besides replacing worn out drivers, and oxadized wires inside,... is to at a later date build a matching center channel,.. matching meaning that it would at least use the same tweeter, perhaps even an MTM that I could put on it's side under my TV, using two 4" that match the Mids in the aforementioned speakers. I think I could build a cabinet if I had the proven design. I think at some point I'll need to learn to build a cross-over (am open to book suggestions)
I think one of my goals is to have a fairly high SPL rating (is that a good goal?)
I didn't mean to write a book.... Any other info you may want? I have not yet taken the speakers out to measure the inside of the cabinet. Outside dimentions are roughly 12 x 12 x 12 -housing the tweeter and mid, that sits on top of a 12 x 12 x 36 tall which has 8" and transmission line. Then there's a big cabinet surrounding those two inner cabinets making it one. I hope these word of mouth details from my dad who built them years ago help you to envision what I am working with.
What would you do to salvage these old cabinets, and then to build a matching center in the future. Driver selection and crossover is where I need the most help.
Thanks in advance for any suggestions.
I have a pair of speakers that my Dad built in the mid 1970's. They were a proven design of which he followed the blueprints and purchased specific driver according to some stereophile magazine (I think). He has talked before about them being pink-noise tested (but I don't know exactly what that means.) He said that he "hand wrapped the cross-overs" too.
They are a three-way. Transmission-Line. 8" drivers, 4" mids, and a tweeter.
There are two knobs on the back that adjust the crossovers, and 35 year old pots would sound noisy and scratchy if they ever needed to be adjusted.
Sometimes the tweeters sound a little crunchy (on certain songs). I had once unscrewed the speaker line input to see if I could determine which was posative and negative, as the old markings had worn off years ago. The wire inside the cabinet looked green with oxidation.
The thing I love about these speakers is that they have a very full range responce, and things like the human voice come through especially well. Excellent imageing, despite the fact that they are closer than I would like to the rear wall as they are a transmission line.
My thought is to replace all the drivers, cross-overs, etc; to refresh them and make them like new. The cabinets themselves I think are excellent (very heavy) and they also have a lot of sentimental value to me.
Would I lose their "magic" if I were to change anything. I had once owed some 2 way speakers that had a soft-dome tweeter, and I thought they sounded good -is this a more modern thing...possible upgrade?
Getting to the question here: Dad had once said that the 8" driver and the distance of the travel of the speaker cone was all carefully planned to match the volume of the box, and the distances in the transmission line (so I don't want to mess that up)
Could I measure the inside dimention of the top cabinet and choose a more modern mid and tweeter. Find a 8" woofer for the bottom cabinet that would work with the cabinet (having the right distance of cone travel). Have the right cross-over to make it all magic and well balanced again?
Another part of my goal, besides replacing worn out drivers, and oxadized wires inside,... is to at a later date build a matching center channel,.. matching meaning that it would at least use the same tweeter, perhaps even an MTM that I could put on it's side under my TV, using two 4" that match the Mids in the aforementioned speakers. I think I could build a cabinet if I had the proven design. I think at some point I'll need to learn to build a cross-over (am open to book suggestions)
I think one of my goals is to have a fairly high SPL rating (is that a good goal?)
I didn't mean to write a book.... Any other info you may want? I have not yet taken the speakers out to measure the inside of the cabinet. Outside dimentions are roughly 12 x 12 x 12 -housing the tweeter and mid, that sits on top of a 12 x 12 x 36 tall which has 8" and transmission line. Then there's a big cabinet surrounding those two inner cabinets making it one. I hope these word of mouth details from my dad who built them years ago help you to envision what I am working with.
What would you do to salvage these old cabinets, and then to build a matching center in the future. Driver selection and crossover is where I need the most help.
Thanks in advance for any suggestions.
I made an error in descriptiion above. Outside dimentions are 12 wide by 12 deep by 48 tall, that's all I know for sure about dimentions. The insides are obviously then a little smaller. I am fairly certain that there is an enclosure for the mid and tweet, then a seperate enclosure for the woofer at the top of the transmission line. All enclosed by another cabinet, this additional layer making it heavy and sturdy.
Sounds like you have a lot of work cut out for you, but don't fret. Hopefully a TL guy can help you determine what driver characteristics are necessary to work well in the box, and then once a woofer is chosen, a mid range and tweeter that would complement the woofer well can follow, followed by an x-over.
Post an image, especially one that shows the drivers without a grille cloth if at all possible.
What is wrong with the woofers now? The midrange? You said the tweeters were not sounding right?
The noise on the adjustment pots is probably not important IF they are wirewound with a power rating suitable for this application, probably 10watts or more... easy to tell when you look at it.
High SPL? not likely. The SPL is a function of max power rating and the sensitivity of the speakers. Most 8" LF woofers are not going to be terribly high power AND high sensitivity at the same time, if any.
Change the sound, yes changing the drivers will change the sound.
It may be possible to identify the original drivers.
Change only the capacitors in the xovers (assuming they are correctly done for the
drivers you have).
Using Pink noise is a way of testing the frequency response - your Dad probably used an "RTA" or Real Time Analyzer, which is bargraphs centered on various frequencies. Today you can download much more sophisticated test software that runs on your computer (good idea).
There are threads here on TL and variations. Many websites on that design too...
But start with posting some pix of the speakers and you'll likely get more information back than you can handle...
_-_-bear
What is wrong with the woofers now? The midrange? You said the tweeters were not sounding right?
The noise on the adjustment pots is probably not important IF they are wirewound with a power rating suitable for this application, probably 10watts or more... easy to tell when you look at it.
High SPL? not likely. The SPL is a function of max power rating and the sensitivity of the speakers. Most 8" LF woofers are not going to be terribly high power AND high sensitivity at the same time, if any.
Change the sound, yes changing the drivers will change the sound.
It may be possible to identify the original drivers.
Change only the capacitors in the xovers (assuming they are correctly done for the
drivers you have).
Using Pink noise is a way of testing the frequency response - your Dad probably used an "RTA" or Real Time Analyzer, which is bargraphs centered on various frequencies. Today you can download much more sophisticated test software that runs on your computer (good idea).
There are threads here on TL and variations. Many websites on that design too...
But start with posting some pix of the speakers and you'll likely get more information back than you can handle...
_-_-bear
This has mostly been said, but any changes you make will likely be significant, and not always positive. You mentioned that this was a proven design and that you felt it sounded good.
Pictures will help the experts here decide on the best course of action and I would advise you to take any driver and crossover changes slowly, preferrably one at a time, for example. There is little hope of both solid and fast results if you are unable to take your own measurements.
Pictures will help the experts here decide on the best course of action and I would advise you to take any driver and crossover changes slowly, preferrably one at a time, for example. There is little hope of both solid and fast results if you are unable to take your own measurements.
Help me upload photos
I would love to post some pics for you. They are on the computer desktop, and I can't figure out how to upload them.
Sorry for delayed reply. Work has been very busy this week.
Thank you all for your feedback. Someone asked a very important question, "What is wrong with them now?"
I spent a lot of time listening to them recently. Sometimes piano keys sound a little muddy. Someone told me this could be a limitation of my amp though, which I had never thought about. When I was 16 years, we replaced the tweeters. At that time when I was young, I liked to push the loudness button, turn up the treble and bass, etc. That was 20 years ago, and I wonder if the tweeters should be replaced again. I am sure there are many times these were played very loudly over the last couple decades.
I think my listening habits have changed as I got older. I like to have everything flat, carefully position the speakers to create the sweet spot of the sound stage right at the listening center. I enjoy listening with the volume set at -20dB. Sometimes I will turn it up to -10dB with some real cleanly recorded acoustic instruments. I would think that I should be able to go all the way to 0dB on my volume indicator (this would be with the volume knob turned up to 50% power),.. it isn't as enjoyable that loud, and I am afraid to have it clip. (Amp rated at 65watts into 8 ohms. It's a Harmon Kardon I found on a clearance sale. I know it's not very high-end, but it would be hard to beat for the price.)
I think the rubber-surround on the other speaker one has a small tear in it, but it still sounds fine. Hard to get the grills off, they are nailed on.
I think that if I change anything, I should try to source the original drivers, instead of trying to re-invent this wheel.
I also had been thinking of replacing the old terminals with some bigger gold ones, then put some nice matching gold terminations on the speaker cables. (p.s. I know it looks like lamp cord, but it is actually oxygen-free copper wire. Not super expensive, but decent I think.
Really I want to have a matching center channel for when I watch movies.
I think I will research in that direction, measure the inside dimensions of the mid and tweet enclosure, then see about building a center channel that could use the same tweeter. Am I right that you can have better resolution of the surround stage when they match? I normally just listen to the two TL speakers alone in stereo mode, unless I am watching a movie. Embarrassingly, I have old boom box speakers for a center now.
If you still want to see the photo's, help me to know how. I have made a donation and am a member now.
I would love to post some pics for you. They are on the computer desktop, and I can't figure out how to upload them.
Sorry for delayed reply. Work has been very busy this week.
Thank you all for your feedback. Someone asked a very important question, "What is wrong with them now?"
I spent a lot of time listening to them recently. Sometimes piano keys sound a little muddy. Someone told me this could be a limitation of my amp though, which I had never thought about. When I was 16 years, we replaced the tweeters. At that time when I was young, I liked to push the loudness button, turn up the treble and bass, etc. That was 20 years ago, and I wonder if the tweeters should be replaced again. I am sure there are many times these were played very loudly over the last couple decades.
I think my listening habits have changed as I got older. I like to have everything flat, carefully position the speakers to create the sweet spot of the sound stage right at the listening center. I enjoy listening with the volume set at -20dB. Sometimes I will turn it up to -10dB with some real cleanly recorded acoustic instruments. I would think that I should be able to go all the way to 0dB on my volume indicator (this would be with the volume knob turned up to 50% power),.. it isn't as enjoyable that loud, and I am afraid to have it clip. (Amp rated at 65watts into 8 ohms. It's a Harmon Kardon I found on a clearance sale. I know it's not very high-end, but it would be hard to beat for the price.)
I think the rubber-surround on the other speaker one has a small tear in it, but it still sounds fine. Hard to get the grills off, they are nailed on.
I think that if I change anything, I should try to source the original drivers, instead of trying to re-invent this wheel.
I also had been thinking of replacing the old terminals with some bigger gold ones, then put some nice matching gold terminations on the speaker cables. (p.s. I know it looks like lamp cord, but it is actually oxygen-free copper wire. Not super expensive, but decent I think.
Really I want to have a matching center channel for when I watch movies.
I think I will research in that direction, measure the inside dimensions of the mid and tweet enclosure, then see about building a center channel that could use the same tweeter. Am I right that you can have better resolution of the surround stage when they match? I normally just listen to the two TL speakers alone in stereo mode, unless I am watching a movie. Embarrassingly, I have old boom box speakers for a center now.
If you still want to see the photo's, help me to know how. I have made a donation and am a member now.
How to attach pics (copied from an older thread of mine).
Too add a photo,
First click "go advanced" in the box below the "quick reply" message box. Doesn't matter if you decide half way through a message to do that, it carries it foward.
Then click "Manage attachements"
Click browse in the first box at the top and find your picture. Repeat for any more pictures.
Click upload... a message appears "uploading"
When complete click "close this window"
The pictures should now be attached and when you post will appear. I don't think they show in message preview... they never used to anyway.
Make sure your pics aren't too big, a couple of 100k is plenty, and many object when they are massive and it alters the margins
It tells you in the attachments window what max sizes are allowed.
Too add a photo,
First click "go advanced" in the box below the "quick reply" message box. Doesn't matter if you decide half way through a message to do that, it carries it foward.
Then click "Manage attachements"
Click browse in the first box at the top and find your picture. Repeat for any more pictures.
Click upload... a message appears "uploading"
When complete click "close this window"
The pictures should now be attached and when you post will appear. I don't think they show in message preview... they never used to anyway.
Make sure your pics aren't too big, a couple of 100k is plenty, and many object when they are massive and it alters the margins
It tells you in the attachments window what max sizes are allowed.
Photos
Here's some photo's
The midrange driver has a wizzer thingie on it.
Where do I measure from, just accross the diamiter of the paper cone, or the outside edge of the rubber surround. Measuring from the outside of the mounting flange is about 4.75 inches.
Thanks
Alex
p.s. Thanks to all who put the sticky on the front page of Multi-Way. The writeup about crossovers is educational for a new hobbiest like me to begin learning!
Here's some photo's
The midrange driver has a wizzer thingie on it.
Where do I measure from, just accross the diamiter of the paper cone, or the outside edge of the rubber surround. Measuring from the outside of the mounting flange is about 4.75 inches.
Thanks
Alex
p.s. Thanks to all who put the sticky on the front page of Multi-Way. The writeup about crossovers is educational for a new hobbiest like me to begin learning!
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