I've been mucking around with BRs in WINisd recentley, and having previously built a stereo closed cabinet for Monacor's SP-155X, as an external speaker for a television to sit on top of (not too critical an application, hence the choice of a rather cheap driver), I decided to see if it could be used in a BR enclosure.
Plugging the values into WINisd and changing the box volume to 50l, tuning at 48Hz it looks pretty good, with an f3 of about 40Hz, although a little bumpy towards the end but I'm guessing that'll help compensate for baffle step error. It also seems to have some degree of this built into it's response making a baffle width of about 25-28cm ideal, which also fits into the golden ratio dimensions using 18mm MDF.
The sensitivity is also decent, about 93dB making it good for use with an SE pentode amp. However, Qts is high (which means bass will be less controlled? 😕) and the Xmax is limited to about 1mm.
It is a very cheap FR, about £40 for a pair, coupled with some MDF cabinets with some faux grain painting (something I'm very proud of being able to do 😀) could make for a cheap pair of speakers.
I'm sure there's a catch to all of this though, go on, tell me how I'm wrong 😛 !
Plugging the values into WINisd and changing the box volume to 50l, tuning at 48Hz it looks pretty good, with an f3 of about 40Hz, although a little bumpy towards the end but I'm guessing that'll help compensate for baffle step error. It also seems to have some degree of this built into it's response making a baffle width of about 25-28cm ideal, which also fits into the golden ratio dimensions using 18mm MDF.
The sensitivity is also decent, about 93dB making it good for use with an SE pentode amp. However, Qts is high (which means bass will be less controlled? 😕) and the Xmax is limited to about 1mm.
It is a very cheap FR, about £40 for a pair, coupled with some MDF cabinets with some faux grain painting (something I'm very proud of being able to do 😀) could make for a cheap pair of speakers.
I'm sure there's a catch to all of this though, go on, tell me how I'm wrong 😛 !
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Nice to hear about someone doing graining. I did a bit myself a good few years ago. It can be very effective when done well. I recently came across a monumental amount of graining in a large Victiorian House undergoing a complete refurbishment a couple of years back whilst doing some set decorating on a film. All internal doors and frames including a huge set of double folding partition doors dividing a large reception room into two were figure grained in Oak, and done to a very, very high standard. Really impressive work of a master craftsman. A joy to behold.
I find it quite fun, I think it looks amazing on MDF! I think it's not just about using the rubber tool but also using a coarse brush up and down along the faux grain while it's half dry to really get a good close up effect.
I'm not amazing at it, my first few attempts looked rather contrived as I was using the rubber tool in the same position on each stroke.
I'm not amazing at it, my first few attempts looked rather contrived as I was using the rubber tool in the same position on each stroke.
I have good books on the subject if you ever wish to borrow one for improving technique.
Back to the Monacors: there are some drivers by Monacor named SPX200 wp which I am keen to find out about although they are hard to get hold of. I'm waiting to hear when they are in stock. They model really well on WinIsd Pro.
Back to the Monacors: there are some drivers by Monacor named SPX200 wp which I am keen to find out about although they are hard to get hold of. I'm waiting to hear when they are in stock. They model really well on WinIsd Pro.
Very high Qts and a box much larger than VAS is going to result in a muddy sound. Check the group delay curve.
It's worth a build though as a listening and learning exercise.
It's worth a build though as a listening and learning exercise.
Hmm... The group delay is a little high, peaking at 23ms at 40Hz. Objectively speaking, will I hear this?
Here's the group delay graph, the lower trace is for a pair of MA A10P BRs I'm also rebuilding at the moment for comparison
I'd love to borrow your book but the Isle of Man is a long way away 😀 !
Here's the group delay graph, the lower trace is for a pair of MA A10P BRs I'm also rebuilding at the moment for comparison
I'd love to borrow your book but the Isle of Man is a long way away 😀 !
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The catch? It's not that inexpensive. I just think you were lucky. The price is between 40 to 50 pounds where I checked.
At that price I'd much rather get a similar Fostex with lower Qts and better materials overall, at a small extra price increase if any.
At that price I'd much rather get a similar Fostex with lower Qts and better materials overall, at a small extra price increase if any.
Hmm... I can get a pair of these drivers for £40 which is not bad at all. Factoring the cost of the MDF and grill it comes to just under £100.
They will be pretty big though 28x36x68cm!
They will be pretty big though 28x36x68cm!
The extra dough for a pair of FE166 is well spent considering you could be living with them for a long time.
If not the resale value for Fostex is higher.
Alternatively FE126 is about the same, with likely a little less bottom, but more precision there and better dispersion and no wiz cone.
I'd say you get about what you pay for here.
If they had been something south of 30 it would start to look interesting.
If not the resale value for Fostex is higher.
Alternatively FE126 is about the same, with likely a little less bottom, but more precision there and better dispersion and no wiz cone.
I'd say you get about what you pay for here.
If they had been something south of 30 it would start to look interesting.
Oh sorry, 40 for a PAIR! Now it starts to look different.
Where did you get that deal?!
With a 50 liter box you might as well do a horn, volume vise. But of course if the cost difference is real...
Where did you get that deal?!
With a 50 liter box you might as well do a horn, volume vise. But of course if the cost difference is real...
A couple of places are selling them for ~£20 per driver, SJD Supplies and Audiomate here in the UK. I've already built a sealed enclosure for these for a family member who's TV doesn't go loud enough and they sound pretty good, if not a tad 'forward' to use a subjective term 😱 .
Maybe a horn or MLTL? Could it get as small as the BR enclosure and have the same low end response?
I'll fiddle around with it in Leonard Audio's TL design software later today, having finally sorted out my VM.
Maybe a horn or MLTL? Could it get as small as the BR enclosure and have the same low end response?
I'll fiddle around with it in Leonard Audio's TL design software later today, having finally sorted out my VM.
OK, so I've sat down and worked out some box dimensions for 18mm MDF, with an internal horizontal brace.
28cm W
36cm D
68cm H
The reflex port will be a piece of 100mm PVC pipe approximately 115mm long for a tuning frequency of 48Hz.
28cm W
36cm D
68cm H
The reflex port will be a piece of 100mm PVC pipe approximately 115mm long for a tuning frequency of 48Hz.
Hi,
50L is way too high for a 14L Vas driver.
Your tuning will tend to one note bass @ 50Hz.
Especially if the room has a 50Hz major mode.
Simming it, 25L tuned to 50Hz is a better idea.
Sealed and well stuffed in ~ 16L with a BSC
filter and subs is the best way to use them.
rgds, sreten.
That is 1.X dB Chebyshev alignment, known for bad one-note bass, as Sreten said. Use 15-25 L box volume.
I see. After a little further reading I realise this is a bad idea. I still want to use this driver for something as I heard it in a sealed enclosure in a previous build and it sounded excellent. Thanks for all your input 😀, I learn something new every time I visit this forum!
It seems a bass reflex enclosure is inappropriate for this driver as the Qts is far too high. Would it be suited to a MTLT, or horn?
It seems a bass reflex enclosure is inappropriate for this driver as the Qts is far too high. Would it be suited to a MTLT, or horn?
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