| Mattthew P. |
Hi There,
I'm very new to this DIY speaker thing, but have recently just put together a pair of FR125s in a sealed enclosure based on all the excellent information that I have found on this forum, and I have to say - I have been completely stunned by these things. Its bad because they are overshadowing my main speakers that I spent a lot more on and trumping some speakers that I have recently listened to like fairly expensive Quad bookshelves speakers and they haven't even been broken in yet.
They have got me thinking that I might like to make them my mains with a bit more LF extension and a bit of a bigger sound. As far as HF and mids they are detailed, stunning and very revealing - (insert host of audiophile terms). I was thinking, based on the reviews of the extremis that it would be an ideal mate for the FR125s, and from other posts it seem that the ideal X-over point would be approximately 300 HZ. I suppose it would be similar to the RAW HTFR but the cabinets would be separated and would like to place the extremis in a basic sealed/aperiodic cabinet roughly 9 litres. that the fr125s would sit upon similar to the design posted by planet10, but not necessarily floor standing.
I was wondering if anybody has constructed a X-over for this arrangement yet? This would be my first X-over and was thinking that a simple 1st order butterworth. Using a X-over calculator it seems that a 4.7mH capacitor and a 75 uF would do the trick...but since I am totally ignorant on this stuff, I really have no clue.
Any advice offered would be greatly appreciated...
Best Regards,
Matt |
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| Cal Weldon |
Hi Mattthew,
Does your name really have 3 t's in it?
I would recommend you find out the exact impedance of the drivers at your intended XO. Use that for your calculations, I would consider using a 2nd order LR.
I would cut the bottom off the FR's as well as the top off the Extremis. Try not to have too much overlap between drivers. |
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| Mattthew P. |
Sorry - absolute newbie, but trying to learn...the X-over that I calculated for is at 275 HZ, and its the 4.75 mH inductor, and a 72 uF capacitor. would other components in the X-over be necessary, or would that produce a flat frequency response curve?
Matt |
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| Cal Weldon |
We posted at the same time.
I might even consider lowering it to 200 or 250Hz, the FR is really a nice driver |
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| Mattthew P. |
thanks Cal....
Umm...no, that was a spelling mistake, my name only has two. i haven't figured out how to change it yet...
hmmm...250? the calculator dumped these stats out:
L1 and L2: 10.18..
C1 and C2: 39.8
Will this lower the efficiency terribly having a couple more points of contact and a whole lot of wire to go through? |
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| Cal Weldon |
I'll see if the one of the admin's can look after that for you.
Have you got a readout of the impedances? |
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| Cal Weldon |
| Those figures look about right. Mind you that makes for a lot of metal inside your box and it gets rather pricey as well. I wonder if you wouldn't be better off getting a small plate amp to drive the Extremis separate from the the Fr's and just use a simple cap or cap and coil to cut off the bottom of the Fr's. |
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| Cal Weldon |
| I see the admin's are working hard tonight. Your name seems to have changed already. Thanks SY. |
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| Matthew P. |
| yes - thanks for the name change... |
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| Matthew P. |
Hi Cal,
Thanks again for the advice - I was thinking of doing that to set up a 2.1 system. you're right about the money and metal issue - the second order would make for some serious expenditure for all the caps and coils. a bit too rich for my blood right now, anyways...the 1st order is , well, obviously, half the price, which makes it a bit more attractive. but reading on the 2nd order LR X-over it seems that's what more studio speakers do for a seamless transition. I'm not sure if I want to have a mono LF though, since I would like the Extremis to broaden the sound as well as extend it...although they are sounding great as it is.
hmmm...will need to think more about that. I wonder if RAW would sell their x-over parts for the HTFR a bit cheaper than buying them all separately. What else have people done?
thanks again,
Matt |
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| Cal Weldon |
| It's still in the rough stage but I have a pair of boxes with two of the WR125's and a tweeter and two Extremis' in their own box with a plate amp. Sounds OK. Gives the bottom end lift that the FR's miss. |
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| TerryO |
My 2 bits on this............
If you want a simple 1st order passive crossover, I would try to aim for a crossover point of about ~300Hz or so. I like Cal's idea of a plate amp and would go that way............."if"........you can get one that can be low passed at around 300Hz. The reason that I'd cross over at 300 or so is that I feel that a 1st order Hi-Pass should be at least 2 octaves above the FR125's Fs, and more is better still. This cleans things up substancially for the FR125 in the midrange, the cap is (or should be) cheaper and allows for more powerhandling. The Extremis will certainly give you all the bass you probably need and actually is a pretty nice sounding unit in it's own right. You might as well use as much of it as possible.
IMHO, the FR125 is be a great driver, but actually can have problems on an OB if the damping isn't sufficient, as with many tube amps (especially SETs). SS amps have better control of the bass on these, but you want all that to be done by the Extremis anyway, so why not take full advantage of your driver compliment?
These are just some thought to consider, but you "need" to have a hi-pass crossover on that FR125.
Best Regards,
TerryO |
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| Cal Weldon |
Terry, thanks for piping up.
I have a question for Terry the master. If he uses a regular plate amp and runs it right up, so around 120 hz or so and uses a 2nd order on the Fr's somewhere around there, do you think we are going to be wasting the Extremis? Or making too much use of the Fr's? Will the Fr's run out of steam?
Just wondering. As always, we will bow to the master. Please master speak.
How's the flooding in your area? Oops off topic. |
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| TerryO |
| quote: | Originally posted by Cal Weldon
Terry, thanks for piping up.
I have a question for Terry the master. If he uses a regular plate amp and runs it right up, so around 120 hz or so and uses a 2nd order on the Fr's somewhere around there, do you think we are going to be wasting the Extremis? Or making too much use of the Fr's? Will the Fr's run out of steam?
Just wondering. As always, we will bow to the master. Please master speak.
How's the flooding in your area? Oops off topic. |
Hi Cal,
Well, our community has been cut off from the outside world for a couple of days now, but I should be able to go to work tomorrow as the river's down about 16 feet from what it was. They said it's the worst flood in 45 years.
The "Master" is it? I know you're just trying to trick me! I'm certain that you, as an administrator, know that it's wrong to bait the master in public.
:smash:
Seriously, a 2nd order crossover certainly would allow you to use the FR125 lower. If a sealed cabinet is to be used, it's possible to reduce the volume of the enclosure to effect an acoustic rolloff to aid the crossover, say 2nd order electrical/ 3rd order acoustic. Some of the cabinet design freeware (Boxplot?) will give you a pretty good idea of the internal volume vs. rolloff of the cabinet as well as power handling.
The Extremis will work fine as subwoofer though it's a little spendy. There are, however, several relatively inexpensive sub drivers out there. A couple of Apex Jr. 8 inch (I think they're 8") sub drivers per side (4 total) would cost $140 and you'd still have money left over for an amp or two. If you stick with the Extremis woofers, you could always reuse them in another speaker, say a three-way later on.
I'd be tempted to go the chea...........er, uh....value route first, I think that it should yield a viable solution with outstanding sound.
Waddayasay Cal?
Best Regards,
TerryO |
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| chrisb |
Dave D has a push/push bipole using a pair of these "value-mart" priced drivers which certainly works quite well indeed.
Steve at Apex Jr also has some excellent plate amps for cheap - I particularly like the Audiophile with remote volume & crossover control. |
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| planet10 |
As you know i am pursuing this idea. We have a couple plate amps arriving tomorrow (it was a bit of a struggle to find ones physically small enuff to fit on the back of the box) and the Extremis are sitting waiting. This may have to get swapped a bit as we have 2 sorta similar extremis projects on the go (+ the push-push extremis sub), the FonkenWoof (which also goes under the miniOnken) and the StealthWoofer (no i'm not saying anything about that one).
With active amplification i'm aiming for a 80-100 Hz XO so that the aperiodic roll-off can be aufmented with a single cap on the amp to get 3rd-4th order roll-off. We will also try passive. Because of the size of the components involved this would need to be in the 250-350 Hz range. I'm going to try series 1st order, and choosing a point closest to the bottom of the saddle in the impedance curves makes sense to me.
In the HTFR, Al ended up closer to 400 Hz i believe.
dave |
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| planet10 |
PS. The ApexJr is a really good budget driver. Spec wise it doesn't seem to go all that low, but aperiodically loaded and sitting in the corner it can rattle the windows and doesn't seem to be too hard put to do the really low stuff on the movie DVDs. I'm driving it will a vintage Aurex 2x50W amp which gets its 0.1 feed right ff my Technics processer.
dave |
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| Cal Weldon |
| I like the idea of the Apex Jr woofer. I haven't heard it but I've held one in me greedy little hands and by the way it looks, it must be suitable for such an application. |
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| pblossom |
I have the prototype bipolar Fr125-WR125 gems that Dave or Planet10 built. I, too, required some low end extension. Dave and Chris built me a separate vented box with two Exteremi and a plate amp. After some amount of break-in, I really like the sound.
Paul |
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| planet10 |
| quote: | Originally posted by pblossom
prototype bipolar Fr125-WR125 gems that Dave or Planet10 built. |
Paul,
Did you get the shipping damage on these sorted out?
It is also to be noted that so far all of our extremis designs are based on Paul's woofer.
dave |
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| pblossom |
Dave:
FEDEX denied the claim, so far. Evidently you have to file within 21 days. I filed within the time limit, but the shipper was supposed to. They didn't tell me that when I was on the phone with them...So I'm going to go back after them. Don't expect much. Am not a big fan of FEDEX, currently. |
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| planet10 |
| quote: | Originally posted by pblossom
Am not a big fan of FEDEX, currently. |
I will keep that in mind.
dave |
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| chrisb |
| quote: | Originally posted by planet10
It is also to be noted that so far all of our extremis designs are based on Paul's woofer.
dave |
Like Dave said, frequently with the Extremis driver the 2 main challenges are finding an amp small enough for the enclosure - and if it's a vented box, fitting the ports inside. ...
Once you find a formula that works, you tend to stick with it. |
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| Matthew P. |
those are some great ideas and advice...I do like the idea of setting up two apex JR. subs with amps in each speaker...and the value route for right now might probably be the best way to go until I have learned more.
Sorry its taken me a while to respond. I've been trying to learn more about DIY speaker building, so I don't make hasty and expensive decisions. My FR125S are breaking in very nicely - I've picked up some Belden speaker cable that has also taken some break-in. The highs have become much softer, they're becoming a bit more sensitive, the mids are still spectacular and detailed, and the LF has become less compressed. Over-all very nice sounds coming from these little boxes. At times, and with volume, it feels like these things don't need too much more to fill my apartment. I am happy with the sealed design - I think vented they might become a bit too boomy in my apt.
I am still considering many of the options everybody has offered and am researching different speakers. There doesn't seem to be too many speakers that have the frequency extension that the extremis does. Ideally I'd like to get away with building something that doesn't require extra amplification (reduced cost, the primary consideration right now). Do you think its possible to run the Apex JR's in series with the FRs without extra amplification? What kind of sensitivity do you think is required to get the LF extension proper without a plate amp? Also, with the plate amps - I am guessing that they only have low pass filters without high pass - is that correct?
thanks again for all the advice and comments, I believe I have become hooked on the DIY speaker thing and am considering a couple of projects for family members to get my experience up a bit...primarily - on ebay there's sets of four Vifa logic glass speakers for 60$ and was thinking of pairing them with some Apex JR. tweeters, with basic X-overs - any thoughts?
best,
matt |
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| Cal Weldon |
| quote: | Originally posted by Matthew P.
Also, with the plate amps - I am guessing that they only have low pass filters without high pass - is that correct? |
Most plate amps have two inputs, one line level and one speaker level. It also will have a set of speaker outputs. If you hook the amp up with the line level, there is usually nothing at the speaker out. If you hook up the speaker level inputs, you will have a full range output at the speakers. I believe some of the plates even offer a high pass on the speaker outputs but not sure.
EDIT: In an apartment you might need only one woofer box with two drivers. |
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| planet10 |
Many plate amps have a high pass -- usually 1st order -- for the sats. i'd ignore that and use a high quality cap in front of the sat amps input.
When you are trying to XO really low passively the big XO parts required can easily cost more than a small sub amp....
We got a pair of these ($93) to try out http://www.partsexpress.com/pe/show...tnumber=300-784
dave |
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