Hi,
Why do you think a fully passive system is not described ?
It is, all the passive x/o details are given / referenced.
rgds, sreten.
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I apologize for posting in such way as to be interpreted as a reply to the most recent... I should have made myself more clear by quoting something like #154:
... I have read nothing in this thread discussing the cost of c/o components as a factor into reaching a "beer budget" and only suggest that it be considered, passive or active. And while the above quote does have the words "2-way passive" contained with in it the author seems to favor active c/o (dbx?) and multiple amps only three posts later. Certainly some driver combinations will practically dictate actively crossing over, multiple amps and possibly EQ correction as well...
The range of available drivers, at least for the woofers, is a fairly well established pool of just a few viable candidates, at least with relatively simple passive c/o. The mid/high frequency components have probably a much broader selection available, at a given price point ("beer budget", what ever that means) but like in most other OB with "helper woofer" threads very little discussion/comparison is ever made on selection of crossover components (outside of MJK's Erse selections) and I think beer budget would dictate it be considered.
Cheers
Hi,
MJK is fairly clear about x/o components for the the bass/mid c/o point,
values need adapting for the 4 ohm bass, and the mid/treble c/o is
thoroughly detailed by Zaph for cost effectiveness.
"Beer budget" means something you could afford by not going out to
the pub so often, cheap, and so good enough the sacrifice is worth it.
It also implies you spend the least money possible for a good result.
rgds, sreten.
MJK is fairly clear about x/o components for the the bass/mid c/o point,
values need adapting for the 4 ohm bass, and the mid/treble c/o is
thoroughly detailed by Zaph for cost effectiveness.
"Beer budget" means something you could afford by not going out to
the pub so often, cheap, and so good enough the sacrifice is worth it.
It also implies you spend the least money possible for a good result.
rgds, sreten.
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Hi,
I think I've been over this thread a couple of times... today, even, but have read several others too and maybe missed the relative link or post. Components for a pair of Alphas adjusted for 4 Ohm? How about for the GRS duals? I'm not good with Mathcad (yet) so have been really combing the forums for tested crossovers with established parts list?
Cheers
I think I've been over this thread a couple of times... today, even, but have read several others too and maybe missed the relative link or post. Components for a pair of Alphas adjusted for 4 Ohm? How about for the GRS duals? I'm not good with Mathcad (yet) so have been really combing the forums for tested crossovers with established parts list?
Cheers
Hi,
IMO it is fairly clearly laid out at the start of this thread. Dual GRS units
and the Zaph mid/tweeter combo (with in wall c/o) makes most sense.
The Alpha's don't come into it (in this thread).
For 4 ohms you double capacitor values and halve inductor values, cheaper.
YMMV, but IMO if you want an OB, what I suggested is very cost effective.
rgds, sreten.
IMO it is fairly clearly laid out at the start of this thread. Dual GRS units
and the Zaph mid/tweeter combo (with in wall c/o) makes most sense.
The Alpha's don't come into it (in this thread).
For 4 ohms you double capacitor values and halve inductor values, cheaper.
YMMV, but IMO if you want an OB, what I suggested is very cost effective.
rgds, sreten.
Hi,
Yes, I've re-read it again just now. You seem to believe that dual GRS will work well with MJK's original X/O, appropriately modded for 4 ohm, but have you built it? Has anyone? I intend to fool around with a full range 8" on top because that is what I have at hand and I can bi-amp to help mitigate SPL differences... only looking for a good lower end solution that has not only been modeled but also actually built and tested.
I like the looks of the Jamo and Quasar type builds but am also wondering how dual H-frames, something like the Orion, might work out... I'll post in a new thread.
Many thanks!
Yes, I've re-read it again just now. You seem to believe that dual GRS will work well with MJK's original X/O, appropriately modded for 4 ohm, but have you built it? Has anyone? I intend to fool around with a full range 8" on top because that is what I have at hand and I can bi-amp to help mitigate SPL differences... only looking for a good lower end solution that has not only been modeled but also actually built and tested.
I like the looks of the Jamo and Quasar type builds but am also wondering how dual H-frames, something like the Orion, might work out... I'll post in a new thread.
Many thanks!
Hi,
TBH the curved baffle has so little effect its simply not worth the effort
IMHO, it complicates driver mounting no end, for very little purpose.
It will look the part if you copy the outline curves.
However if you want to do it I'd suggest bending multilayer ply wood.
Which ever way its done a sand filled ply sandwich seems a good idea.
rgds, sreten.
Acrylic
Hello
Im a audio novice from sweden.
im thinking about making a Jamo R909 in clear Arylic/plexiglas that is 1200x4880x40mm in size. What do you guys think about that?
Is 40mm plexiglas a good size for depth?
The baffle will weight around 28 kg, i will see if a acrylic company could make the baffle curved as the jamo r909.
I will then use the drivers you have recommended, grs 15" and the zaph kit.
Could you make a list on all the items i need as crossover kits and so on.
Could you also let me know how big the holes for the drivers should be so they could drill the holes on the acrylic sheet.
Thanks
Hello
Im a audio novice from sweden.
im thinking about making a Jamo R909 in clear Arylic/plexiglas that is 1200x4880x40mm in size. What do you guys think about that?
Is 40mm plexiglas a good size for depth?
The baffle will weight around 28 kg, i will see if a acrylic company could make the baffle curved as the jamo r909.
I will then use the drivers you have recommended, grs 15" and the zaph kit.
Could you make a list on all the items i need as crossover kits and so on.
Could you also let me know how big the holes for the drivers should be so they could drill the holes on the acrylic sheet.
Thanks
Hello,
Use jamo geometry is a bad idea and use this thread as a model is also a bad idea.
Plexiglas ? why not ? but a little expensive ! note you should have beautiful drivers which are expensive ...
Have fun !
Thanks for the answer.
I have contacted a company that works with acrylic, and wait for a answer about if they can curve and drill holes. But the design could be other then r909.
Maybe i could make the speaker a little lower in height, and only use one 15", would it sound as good with one 15"?
I have seen that the woofer need to be between 1-2 in qts.
So do you know a better choice then the Grs woofer, maybe a one that also look better?
Zaph kit looks like value for many. and i was thinking to use passive crossover (MJK).
Acrylic will be bought directly from manufacture if they will allow me to buy.
and i thought 4cm thickness would be good and also look good.
Maximum thickness is 5cm, but the weight will be quite much then. The foot for the speaker would be a later problem, but cnc a metal foot would be the option.
I have contacted a company that works with acrylic, and wait for a answer about if they can curve and drill holes. But the design could be other then r909.
Maybe i could make the speaker a little lower in height, and only use one 15", would it sound as good with one 15"?
I have seen that the woofer need to be between 1-2 in qts.
So do you know a better choice then the Grs woofer, maybe a one that also look better?
Zaph kit looks like value for many. and i was thinking to use passive crossover (MJK).
Acrylic will be bought directly from manufacture if they will allow me to buy.
and i thought 4cm thickness would be good and also look good.
Maximum thickness is 5cm, but the weight will be quite much then. The foot for the speaker would be a later problem, but cnc a metal foot would be the option.
Hi,
Your numbers seem way out from anything sensible, and using acrylic is
going from something cheap and cheerful (multilayered wood) to very
expensive, with very expensive machining and finishing costs.
40mm depth requires extensive rear chamfering for the midrange.
The point of the Jamo design is a baffle full of big drivers, and clear
acrylic will hardly reduce the impact of that, and makes little sense.
The point of this clone is budget, or bang for buck, all the way.
rgds, sreten.
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Hi,
Anything informative to add rather than just opinionated criticism ?
rgds, sreten.
Hello
The cost of acrylic is around 3usd/kg, so it would be 80usd per speaker just for the acrylic.
Shipping will apply also offcourse, container shipping as the only option off course.
Would acrylic not be as good as mdf? I didnt understand "acrylic will hardly reducee the impact of that"?
You said the size is way out from anything sensible, did you thought about the thickness, or which numbers is way out, and what numbers do you recommend?
Regards,
Mattias
The cost of acrylic is around 3usd/kg, so it would be 80usd per speaker just for the acrylic.
Shipping will apply also offcourse, container shipping as the only option off course.
Would acrylic not be as good as mdf? I didnt understand "acrylic will hardly reducee the impact of that"?
You said the size is way out from anything sensible, did you thought about the thickness, or which numbers is way out, and what numbers do you recommend?
Regards,
Mattias
Maybe mdf would be better then, but i dont have the all the specs on the size for cnc the baffle.
I think acrylic would be even better looking then a nice finished mdf baffle, but as you said it will most likely be expensive. But i the manufacture has all the machines to make it i just need the sizes for the cuttings.
Im a complete beginner in diy, and have never built a speaker, thats why i need all the information you could give me.
I think acrylic would be even better looking then a nice finished mdf baffle, but as you said it will most likely be expensive. But i the manufacture has all the machines to make it i just need the sizes for the cuttings.
Im a complete beginner in diy, and have never built a speaker, thats why i need all the information you could give me.
Eminence alpha 15 vs GW-15
Comparing the alpha 15 to the GW 15, via specs on paper as well as a real build in H-frames, the GW 15" does extend lower, but at the huge cost of
efficiency (which is so dear for OB use) and also the max SPL possible. On specs, the GW 15 has about 10db lower efficiency and also lower peak power handling than alpha 15. Having at least two GW 15 on one side is a minimum. OTOH, a single alpha 15 each side can provide satisfying max SPL levels.
From practical experience, I started with the GW 15 in h-frame for the lure of "flat down to 30hz" (in contrast to the 40hz "only" for the alpha 15). But the Gw-15 bottomed out too soon even before the bass started to hit.
When I "upgraded" to the alpha 15, there was a significant improvement of max SPL delivered. Afterall a kick drum also has to be "loud" enough to sound like one, and the single alpha on each side could do it without a sweat...the GW15 could not do it. Perhaps the better build quality and accordion suspension of pro woofers like alpha do have some benefits of better control, particularly in free air OB applications. The GRS woofer looks almost the same as the GW15 for OB apps and would likely behave the same acoustically. There are supplemental monopole subs for sub-40hz, but I rarely need them, allowing a smaller overall package than using 2 GW per side on OB and still going down to only 30hz at less than realistic max SPL levels.
Comparing the alpha 15 to the GW 15, via specs on paper as well as a real build in H-frames, the GW 15" does extend lower, but at the huge cost of
efficiency (which is so dear for OB use) and also the max SPL possible. On specs, the GW 15 has about 10db lower efficiency and also lower peak power handling than alpha 15. Having at least two GW 15 on one side is a minimum. OTOH, a single alpha 15 each side can provide satisfying max SPL levels.
From practical experience, I started with the GW 15 in h-frame for the lure of "flat down to 30hz" (in contrast to the 40hz "only" for the alpha 15). But the Gw-15 bottomed out too soon even before the bass started to hit.
When I "upgraded" to the alpha 15, there was a significant improvement of max SPL delivered. Afterall a kick drum also has to be "loud" enough to sound like one, and the single alpha on each side could do it without a sweat...the GW15 could not do it. Perhaps the better build quality and accordion suspension of pro woofers like alpha do have some benefits of better control, particularly in free air OB applications. The GRS woofer looks almost the same as the GW15 for OB apps and would likely behave the same acoustically. There are supplemental monopole subs for sub-40hz, but I rarely need them, allowing a smaller overall package than using 2 GW per side on OB and still going down to only 30hz at less than realistic max SPL levels.
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