Anyone with experience with this 12 inch speaker

Do not think anyone here has any hands-on experience with these yet.
They fall in line with a progression of large FR units from China, originally stemming from some of the items offered from commonsenseaudio.com and various L. Cao adaptions, mixed in with inspiration from certain Diatone drivers of the past.

Probably "not bad", but it's difficult to have any opinion about them other than: Seems to me there's a lot of copying good ideas from others.
Not that there's anything wrong with that, I guess that's more or less how it is in most industries.
 
I can only assume, not enough information for me to form any opinion about them.

Seems cheaper on aliexpress:
Buy Products Online from China Wholesalers at Aliexpress.com
Seems some stores call it "HF-139".
Some places 0.41 qts and Vas of 108 liters is mentioned. No specific FS, but 28hz is implied. A bit hard to believe they have 28hz fs.

Edit:
Basket looks nice.
 
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sumotan

Member
2013-10-16 4:18 pm
Hi Kaffimann,
Thanks for the link. Well at least we get some specs here. Sensitivity & FS might be over zealous though. Q looks high, does this mean that it can't work on a BLH cabinet ?
 

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Hi Kaffimann,
Thanks for the link. Well at least we get some specs here. Sensitivity & FS might be over zealous though. Q looks high, does this mean that it can't work on a BLH cabinet ?

It can; be prepared for it to be of 'manly' proportions though if you want reasonable LF gain / extension (less an issue if you're OK tuning higher & a classical pro-audio type balance).
 

sumotan

Member
2013-10-16 4:18 pm
Hi Kaffimann,
There's a 3 part article in TNT Audio on using the a modified Coral BLH cabinet to house a 12 inch Goodmans Axiom 210. Axioms are hard to come by, besides they're asking for crazy prices so was just browsing to see if other modern drivers can be used & I stumbled upon this woofer. Trying to understand as much as I can about horn speakers.

Many thanks again.
 
Scott is much better on horns and TL's (and probably equal or slightly better on most other designs) than I am, so any questions should be directed towards him.

Better to choose design type after knowing a few other things such as desired driver, desired size, desired low frequency capabilities (the latter usually comes at the cost of max spl on a "FR").

At any rate, if you decide to order this driver I am certain there's quite a few of us on here that would be interested in simulating a box for you. Just state what kind of size (+/- somewhat exact dimensions) you want, and anyone running the sim will probably try to tease out whatever low frequency performance is possible based on that.
 

sumotan

Member
2013-10-16 4:18 pm
Thank you again Kaffimann. For the last couple of months I've been reading up & trying to understand TS parameters for BLH & FLH cabinets but there don't seem to be much info. Seems like normal TS for sealed & br cabinets are in conflict when it comes to building horn enclosures. Still trying to wrap my head around in trying to understand.

Thank guys again
 
They aren't, but there is a lot of misinformation (rarely, if ever, intentional) out there.

I haven't much time this morning, but a condensed version:

-A back horn (viz. loaded by the rear of the driver) is typically a bass horn. They aren't much use for anything else due to group delay considerations and as a rule of thumb, have an upper operating limit of about 300Hz, above which you need to be rolling them off to avoid issues with the aforementioned group delay. The exact frequency is not set in stone; this is partly subjective, partly system related and the amount of delay is inherently a function of the horn path length.

-A chambered back loaded horn is in essence best viewed as an extreme variation of a vented box or bass reflex. Ergo, if a driver is suitable for a vented box, it is also suited to a back horn. Contrary to widespread myth.

-The myth of low Q drivers being required comes from a couple of places. Firstly, front horns (viz. loaded by the front of the driver), where it's often / usually beneficial. And secondly, many early moving coil horn drivers had very large motors and a lot of electromechanical damping. So there was an assumption that was what was necessary. Unfortunately what people missed was the other half of that particular matter. Those drivers were designed with large motors partly because power was expensive, and partly because the amplifiers they were designed to be used with had a high output impedance, which has the effect of artificially raising the driver Q. Effective Qts = Qts + any series R (or amplifier output impedance). Many amplifiers actually had an adjustable output impedance to allow easy tuning.
 
I've just taken a look at the numbers above, since my suspicious mind -well, let's not go there.

The values don't appear to agree with each other. Qe, Qm are fine for the stated Qt (more or less). But the rest go completely pear-shaped; for example, if that Qt is correct, & ditto for the given Re, Mms & B*L, then Vas can't possibly be what is printed (and so on). This is not implying the driver is bad, just that there are major inconsistancies with the spec. as shown above from aliexpress.
 

sumotan

Member
2013-10-16 4:18 pm
Thank you kindly for the tutorial Scott. Take for instance Front horns most that I've seen are with sealed rear chambers this in general would mean to select a woofer that suitable for seal enclousre right & yet articles that I've read mentions the Q of 0.35 or less. In normal speaker TS this driver spec would be used for a BR box & this is 1 confusion that I have. Would the Q of the woofer increase when horn loaded & if so then I understand.

Many thanks again
 
Thank you kindly for the tutorial Scott. Take for instance Front horns most that I've seen are with sealed rear chambers this in general would mean to select a woofer that suitable for seal enclousre right

No; the sealed rear chamber of a front-horn is for loading / reactance annulling purposes; while there are certain aspects of base physics in common, in general the requirements are different.

& yet articles that I've read mentions the Q of 0.35 or less. In normal speaker TS this driver spec would be used for a BR box & this is 1 confusion that I have.

See above. It also depends to a point on what the purpose of the horn is. HF & midrange horns usually use drivers with high motor power as they're targeting efficiency as their No.1 criteria. A front-loaded bass horn might be, but there is sometimes some more variation in this as many are undersized and they're being used for other purposes.

Would the Q of the woofer increase when horn loaded & if so then I understand.

Well, it's not normally described in quite that way, but a compression horn can have an effect which includes something akin because the air mass-loads the moving components. This is typically going to become more apparent as compression ratio increases.
 

sumotan

Member
2013-10-16 4:18 pm
Thank you kindly again Scott. For tutorial sake, lets say I want to build a FLH bass box with F3 of 50hz. Putting aside calculation of box dimension, design etc, what are the proper fundimental woofer specs that one should be looking for in the first place ?


Thank you again
 
Unfortunately you can't put that aside. There is no single 'ideal' set of driver specs. that works equally well in all circumstances. An enclosure is designed for a given set of driver characteristics. Assuming you have a choice in the matter, you select a driver which possesses characteristics that best suit whatever your particular goals might happen to be. Those include box dimensions and an almost infinite variety of other factors related to the rest of the system and your intentions for it.

With that basis, you'd have to include a lot more information; to name a few of the major ones: type of horn (there are a number); size limits of driver and enclosure; bandwidth required; sensitivity / dynamic range required, and any separate power applied; distortion performance, impedance load &c.
 
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sumotan

Member
2013-10-16 4:18 pm
Thank you again Scott. In my mind I was thinking there must be some fundamental TS that we can look at to know if a particular woofer is suitable for FLH enclosure. There after with the selected woofer we can then start modeling the enclosure to see how it behaves. Guess my thinking is wrong. Lol

Thank you Scott
 
Thank you again Scott. In my mind I was thinking there must be some fundamental TS that we can look at to know if a particular woofer is suitable for FLH enclosure.

I will say that it's the same as for any other type and size of enclosure design: It depends.

The general rule will have to be that it's much better/easier to design an enclosure on the basis of one particular driver, than trying to find a new driver that is a perfect match for an existing enclosure.

Edit:
If you want to try and understand roughly what size box you might end up with, vas and qts can point you in some general direction. But again, it depends.
 
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