Need to work on evening out the shellac finish but I bet by the weekend I will be listening to some tunes. I joked with a friend that it looks like I found these in the basement of the BBC. The shellac gives it that old time appearance. I used maple plywood and maple for the wings.
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Hi!
Do you think I can use the Celestion TF1525 / TF1525e in a similar project?
Which one of those two could be the best for 0-500hz in an open baffle?
Celestion TF1525 - Pressed Chassis Speaker Driver Unit
or
Celestion TF1525e - Pressed Chassis LF Speaker Driver
Thank you!
Do you think I can use the Celestion TF1525 / TF1525e in a similar project?
Which one of those two could be the best for 0-500hz in an open baffle?
Celestion TF1525 - Pressed Chassis Speaker Driver Unit
or
Celestion TF1525e - Pressed Chassis LF Speaker Driver
Thank you!
Merry Christmas! Of the two choices you have offered, the "e" version is the best bet with it having a higher xmax. But with only a moderate Q and high upper 40's FS, it far from an optimum solution. Can you make a usable OB from the "e" woofer, yes, but with significant sacrifice in balanced performance relative to the Manzanita. Plus, there will be a lot of crossover work to optimize what the woofer can do. Wish either of these drivers were closer to the original Peerless 12 or the current GRS-15. But, honestly, they are not really close.
BTW, thanks to the DIY community for pushing the thread views over the 750,000 mark!!! The most for a set build project that I am aware of. Quite a mile stone! Best...
BTW, thanks to the DIY community for pushing the thread views over the 750,000 mark!!! The most for a set build project that I am aware of. Quite a mile stone! Best...
Happy Holidays!!
So, I got everything slapped together and nuthin' blew up. Ahh, first step completed. My son gave me a hug and thanked me for having music in time for Christmas. Of course, I put on some of his favorite music.
Later I didn't feel something was right and tracked it down (after being very careful the first time) and realized I had the full range speaker wired incorrectly.
I am very happy with the outcome but this is the first time I've ever made my own speakers rather than buy 'off the shelf'. I don't have any equipment to measure speaker performance so are there some clues as to what I should be hearing after swapping resistor values? The highs seem diminished from what I would expect, so my thought was to reduce the resistance of the default resistors in order for the highs to be slightly more pronounced. Is my thinking right? I admit I am very ignorant in this area. But I can say, for under $300, these speakers are crazy good! VERY pleased, as is my family.
So, I got everything slapped together and nuthin' blew up. Ahh, first step completed. My son gave me a hug and thanked me for having music in time for Christmas. Of course, I put on some of his favorite music.
Later I didn't feel something was right and tracked it down (after being very careful the first time) and realized I had the full range speaker wired incorrectly.
I am very happy with the outcome but this is the first time I've ever made my own speakers rather than buy 'off the shelf'. I don't have any equipment to measure speaker performance so are there some clues as to what I should be hearing after swapping resistor values? The highs seem diminished from what I would expect, so my thought was to reduce the resistance of the default resistors in order for the highs to be slightly more pronounced. Is my thinking right? I admit I am very ignorant in this area. But I can say, for under $300, these speakers are crazy good! VERY pleased, as is my family.
Hi John,
Hope this isn't too far from the spirit of this thread. Seems the knowledge may be useful even here...
I plan to build an open baffle system BUT this one will be a reference platform for testing some dipole tweeter designs. That may sound a bit strange but I have found the easy way to get the most neutral bass and mid is this way.
Anyway the plan is large woofer or two with a 5-7 inch mid crossed at around 150-200 Hz and would like to avoid a really wide baffle ( would like to keep it at or below about 25 inches wide)
The question has to do with Qts and sensitivity
In your post above you mention the Qts being too low in the Celestion woofers mentioned. I understand this and for a lower sensitivity system the higher Qts would be to advantage.
However what if we want to end with a sensitivity around say 88 db. Seems to me the only way is to use two parallel higher sensitivity woofers to get enough to work with, then filter down from there??
I see that Jamo has had success with this dual high sensitivity woofers on smallish baffle arraignment ( not sure what Qts their using).
Also Trolls Graveson has an open baffle design that uses a single high sensitivity/ low Qts woofer BUT on a rather large baffle , and woofer close to floor.
Curious what you think about the higher sensitivity/ low Q woofer chopped at around 170 hz approach on a "smallish", vs the lower sensitivity high Qts designs??
also here is a woofer thats both high sensitivity AND high Qts. Seems strange to me. Not sure how thats done. I suspect however I would still need two of these to end at around 88 db sensitivity on a baffle at or below 25 inches wide?
Eminence Alpha-15A 15" Driver
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Yes that's right. If you are building the crossover from posts 1601-1602 that have a tweeter trap included, you can do two things. Lowering the attenuation resistor will make the tweeter overall louder. Changing the trap resistor will have a more subtle effect, working on only part of the tweeter range.
You can short out either resistor with a piece of wire or even another resistor to hear that the full effect is. That's a good way to hear what parts of the spectrum are affected and allow you to judge what changes you need to make.
It can take a bit of back forth.
The Alpha 15 is probably the best known OB woofer of the past decade. That's due in large part to Martin King's OB papers design that use the Alpha. Some folks love 'em, some folks don't.
I'll let John chime in with his thoughts, as he has experience with this driver (I think).
The Alpha 15 is probably the best known OB woofer of the past decade. That's due in large part to Martin King's OB papers design that use the Alpha. Some folks love 'em, some folks don't.
I'll let John chime in with his thoughts, as he has experience with this driver (I think).
Thanks Pano
any remembrance of what specifically the love/ hate was?
Happy New year to all! Lowmass... Starting with the Emi Alpha 15 efficiency VS. QTS. The efficiency spec provided by Eminence is miss leading. Wish they would not do that. If you run the numbers you find that from 50 - 200 Hz where you really use the Alpha as an OB woofer, the net value is about 92.5 db/watt. If you use a reasonable passive crossover with a 200 Hz target, the series parasitic losses will knock about a db of that. So you are around 91.5 net. And the only reason it is that high is because of the relatively high free air FS of 41 and meager Xmax of 3.8 mm peak. No free lunch.
However, running a pair of Alpha's in electrically in parallel, (4 ohms net prox) you theoretically gain 6 db in sensitivity - operating efficiency. And your passive crossover inductor values are cut in half relative to a single 8 ohm driver. So you net out around 97 dbw for the pair at F=. For the 25" baffle you plan, assuming no wings, 1/2 space, F= calculates out to around 150 to 160 Hz. From that starting point, with a series inductor we start trading away your 97 db at 6 db per octave. The result (assuming we trade 12 db away) is a flat OB response into the upper 30's with a net efficiency around 85-86 dbw. BTW, the Alpha on baffle FS will lower to around 38 Hz with the baffle loading and added resistance from the inductor. So it all pencils out.
However, running a pair of Alpha's in electrically in parallel, (4 ohms net prox) you theoretically gain 6 db in sensitivity - operating efficiency. And your passive crossover inductor values are cut in half relative to a single 8 ohm driver. So you net out around 97 dbw for the pair at F=. For the 25" baffle you plan, assuming no wings, 1/2 space, F= calculates out to around 150 to 160 Hz. From that starting point, with a series inductor we start trading away your 97 db at 6 db per octave. The result (assuming we trade 12 db away) is a flat OB response into the upper 30's with a net efficiency around 85-86 dbw. BTW, the Alpha on baffle FS will lower to around 38 Hz with the baffle loading and added resistance from the inductor. So it all pencils out.
As for Alpha short comings.... the large and nasty break up peak at 1,800 needs to be tamed with a good trap. Even crossed over at 200-300 Hz (1st or 2nd order), you can still hear the break up. 1,800 is smack dab at peak ear sensitivity. And the low 3.8 mm Xmax limits clean output, especially from 60 Hz down. Another reason you should run 2 in parallel. And there is the high FS limitation. You can buy a GRS 15 from PE for $25 - $30. It has much less break up, slightly higher Xmax, lower FS plus it is less than half the price. In fairness, the Alpha is a more durable driver.
Hi All - The Vifa/Peerless TC9FD is unavailable to me in my location. I can get the following from Fostex, what might be the most suitable replacement and could I keep the crossover design the same?
FE83EN
FF85WK
FE103EN
FF105WK
FE126EN
FF125WK
FE166EN
FF165WK
Edit, cant get the 20mH inductor either, but 18.0 and 22.0 mH are readily availale; which should I choose?
FE83EN
FF85WK
FE103EN
FF105WK
FE126EN
FF125WK
FE166EN
FF165WK
Edit, cant get the 20mH inductor either, but 18.0 and 22.0 mH are readily availale; which should I choose?
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Prolle.... Sad to hear the TC9 is not available to you locally! Of the Fostex drivers you listed, the closest is the FF105WK. It will require a trap to damp out the peak that appears to be around 7,200 Hz. This driver is also a bit more efficient so it will require a higher value resistor pad. Which will have an effect on the high pass crossover cap value. What these differences mean is the TC9 crossover will not work well.
I think the FF 105 can work pretty well, but it will require some crossover work.
As for the low pass inductor, 18 - 22 work well enough. Not an issue there. If you do try the FF105, The 18 MH is a better bet. Wish I had better news. Best
I think the FF 105 can work pretty well, but it will require some crossover work.
As for the low pass inductor, 18 - 22 work well enough. Not an issue there. If you do try the FF105, The 18 MH is a better bet. Wish I had better news. Best