Rola, made in March 1974. Pretty sure that yours are at least a 2nd gen of drivers in these, i have a feeling that the 1st ones were based on a large batch of surplus drivers (with square magnets)
dave
dave
that was certainly my recollection - I'm sure all the warranty replacement drivers, including tweeters, had square ceramic magnets
Have you compared the EPI microtowers with the microtowers you have designed? What I am saying is can I tweak this M-75 to the same build type that you are doing?
PeterC.
PeterC.
Haven't had a real pair of EPI MT for a long time. I still do have the clones i built in 1974 with what i believe were some of the official drivers.
You don't want to get to to carried away trying to tweak the originals... time & money you'd spend on a new build is not huge, and the latest drivers used in these are miles ahead of the "bose" clones used in the originals. As Chris said these were aimed directly at the bottom end of the market... Chris what was the entry price? <$200 IIRC, so $20-40 for parts including the shipping boxes.
dave
You don't want to get to to carried away trying to tweak the originals... time & money you'd spend on a new build is not huge, and the latest drivers used in these are miles ahead of the "bose" clones used in the originals. As Chris said these were aimed directly at the bottom end of the market... Chris what was the entry price? <$200 IIRC, so $20-40 for parts including the shipping boxes.
dave
Food for thought! I have to think about it because I just picked up the pair of FE207e from kazoo. I think they were enabled by you?
Now to save for the material I need to build the Changs, half or otherwise which will bring me to more questions I will have.
Thanks planet10
PeterC.
Now to save for the material I need to build the Changs, half or otherwise which will bring me to more questions I will have.
Thanks planet10
PeterC.
I just ordered four CHP-70 ready for a build. I have a question - I have some MLTL enclosures, 21 litres, 50 ins high and speaker placement (centre) 15" from top (internal). These were built for Jordan JX92. Can I place the second unit on top when the main forward pointing one is 15" down from the top?
Andy
Andy
Hello Dave,
Wessex and Mercia have two units pointing forward. I always thought it wasn't advisable to put two full range drivers next to each other?
My main point is whether the forward and upward speakers in the mini-towers need to be right next to each other? The other question is how the height of the speaker and the height of the forward unit form part of the MLTL design I have.
andy
Wessex and Mercia have two units pointing forward. I always thought it wasn't advisable to put two full range drivers next to each other?
My main point is whether the forward and upward speakers in the mini-towers need to be right next to each other? The other question is how the height of the speaker and the height of the forward unit form part of the MLTL design I have.
andy
This is something that has persisited as "common knowledge" and a belief i held for a long time (without any experience to support it). That started breaking down when i read in Toole's new book, (to paraphrase), "combing looks bad in a graph, but the ear/brain is expecting it, and it is not the problem people make it out to be". Then i heard a set of Twin front-facing EL70 BR that Bob had down (and the drivers could have been quite a bit closer) and any issues were just not there as long as you were in the farfield.
You will also note that on the 2md page of Wessex that there is a bipole config and one could extend that example to place drivers on adjacent sides. After the experience with Cal's Calhoun BVR with 2 WR125 configured that way, i tend towards this configuration (or if the driver is end-loaded the possibility of an upfiring driver)
The average Zd of the drivers should correspomd to the design Zd. With an end-loaded TL such as microTower (Zd very small) a top mounted 2nd driver is possible. With a much larger Zd as in Wessex then top driver option would mean more ripple, greater driver spacing and other issues like less bass because of increased damping to counter the increased ripple. Not really practical.
dave
Given how long they have been sitting the couple hundred hours i put on these is probably moot. I'd put them in a box, or set them on their magnets and play music FM at low volumes for a couple hundred hours and then start increasing the level. At any time after the initial couple hundred hours they can be put into the system and start playing with a slow ramp up in level.
dave
Hi folks
I started building these for a friend sometime ago and I'm determined to finish them before the year is out! 🙄
I have got to the point where the wadding is glued, two sides and the top of the cabinet. If I have time tomorrow I'll run the internal cable and close the lid. I was going to add a ball of fluffed up wadding behind the drivers, but is it worth adding some in the lower chamber too?
Once glued together I will route out the vents at the base of each speaker and trim the excess MDF along the edges. I might use my 3/4" round over bit down the length of the speakers as I did when finishing off my Brines 1600s
Thanks
I started building these for a friend sometime ago and I'm determined to finish them before the year is out! 🙄
I have got to the point where the wadding is glued, two sides and the top of the cabinet. If I have time tomorrow I'll run the internal cable and close the lid. I was going to add a ball of fluffed up wadding behind the drivers, but is it worth adding some in the lower chamber too?
Once glued together I will route out the vents at the base of each speaker and trim the excess MDF along the edges. I might use my 3/4" round over bit down the length of the speakers as I did when finishing off my Brines 1600s
Thanks
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Tripmaster,
Your bracing looks really neat!
What drivers are you putting in these? The vents look sized for CHR-70.x though.
Your bracing looks really neat!
What drivers are you putting in these? The vents look sized for CHR-70.x though.
The high end response is there, certainly, but it is "rolled off" to a certain extent, giving a warm, laid back feeling by default. As you already know, Dave, this has had me wondering if I need to add a tweeter to my dual-EL70 Castle microTowers (or augment them in some other way), however I have been playing more with EQing and/or my treble control and I have realized that there really isn't anything (that I need) that can't be coaxed out of these drivers.
Perhaps hard to make them sound really "hot" at the high end, but that is not what I desire anyway.
Nice job so far. I would say that generally speaking the stuffing/lining looks inadequate for optimal sound. Are you planning to add the same white lining to the back wall as well? I highly recommend doing so. And yes, by all means add good quality stuffing from behind/below the drivers all the way down to the bottom of the first holey brace (at least).
I used 2" fibreglass insulation for 3 interior walls and stuffed with "Supreme" Polyfil from the rear of the drivers down to the bottom of the second holey brace and these seemed to be optimal for my particulr pair of microTowers. However, I used 18mm baltic birch and I am running EL70 drivers...
Since it appears you are not making any of the panels removable, you would be wise to attach the rear panel with some bluetac and do some testing and stuffing adjustment while the speakers burn in.
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