Mach 5 18", 180lt, 500watts tuned to 20hz

[davidburn]

Thats Great. Thanks Mike.

What about the filler for the screw holes? Anyone got any ideas?

[davidburn]

Sorry Mike, I need to read the entire response. I think the idea on putty fill is great, much better than the plaster fill I previously used.

Thanks.

[Mike P.]

Most wood filler shrinks as it drys, you may have to apply it twice to get it level depending on how deep the fill spot is. Make sure it is totally dry beofre you sand it. It may look dry on the surface but will be gummy underneath. Check the drying times on the package.

[davidburn]

Thanks Mike.

Will be ordering the driver tonight, so it should come the middle or end of next week. Should I wait for the driver before cutting the hole?

Does anyone know of good priced O-Audio 500w amps in australia? I can use a different brand if there is something similar? but it needs to come with a high pass filter.

Thanks for the help.

Dave.

[Mike P.]

I can use a different brand if there is something similar? but it needs to come with a high pass filter.

You'll get the most out of your sub design with the O-Audio amp due to the HPF at 20 hz with the included boost and the fact the boost can be cut back if needed with the amp's EQ. I know there is an Australian website that sells the amp, I can't remeber where.

[davidburn]

http://www.audiomarketplace.com.au/c...art/Itemid,49/

It may seem they are not stocking the O-Amps anymore?

Any suggestions?

[davidburn]

It maybe best to just import straight from the US, Any thoughts as i've never bought online let alone import something from the US.

[Mike P.]

Contact audiomarkerplace and inquire. It may be that they are just out of stock at the moment. You can also contact O-Audio and see what they have to say about an Australian distributor.

[davidburn]

Will give them a call Monday. Was still cheaper to import than buy in Australia??? I will look into it a little more and make sure before I decide which way to go.

Cant wait to hear it fired up. I still think its too big, but im sure it will be big on spl so im sure I can live with the large cloths dryer in my small lounge.

Thanks.

[davidburn]

Its ordered and paid for

Just a look at the beast

Still unsure about the Amp? Has anyone imported Amp's for a cheaper price than buying them local?

[davidburn]

I will be setting up the sub with my current amp until the O-Audio amp arrives. It is modelled with 240w 6db of boost @ 35hz, Looks great for a music sub?

[evilskillit]

I would think for music you wouldn't want that fat hump in the middle of the response around 30-40hz. You can try it but I think you would want a bit flatter response or notes in that range are really going to stick out.

[davidburn]

http://www.audiomarketplace.com.au/c...art/Itemid,49/

audiomarket are no longer selling the O-Audio amps, has anyone ever heard of these amp, or if they are any good.

Mike, Could this amp work with my design or should I just import the 500w O-Audio into Australia?

Thanks.

[Ryan Anderson]

if your goal is music, tuning around 30Hz-40Hz and having some boost in that region as well may be what you're after, but tuning to 20Hz may have excursion issues in that range, where you want the most gain. If you want HT/music, I understand the tuning but not the boost.

[davidburn]

Sorry Ryan for the misunderstanding, My goal is to have no boost, I will only be using my current plate amp (Which has boost at 35hz) untill I take ownership of the new one, which should give a flat response, good for Music and Ht.

[Ryan Anderson]

then I think you'll be happy it's a good compramise

[Mike P.]

Inquire if this one has a "cut only" EQ like the O-Audio. Not sure on the currency conversion or importing costs.

http://www.bkelec.com/Modules/bsbp500.htm

[davidburn]

Will do. Looks good.

Thanks

[MarkDN]

I'm in Australia and I imported an O-Audio 500 amp from the US about 7~8 months ago. I purchased directly from the O-Audio website. Works great and was approximately 33% cheaper to import than source locally. A major factor of this was the currency conversion was jumping wildly at the time. It has plenty of power for my needs, but you should be aware of the significant boost with the subsonic filters when planning your design. Either that or be prepared to get the soldering iron out.

I'm jealous of the choice and price of HT gear in the US!

Either way nothing in Australia can be found even close to AUD$300 delivered with similiar power and features. Just about all the other amps in a similar price range also had boost anyway.

[Mike P.]

The design is for a HPF at 20 hz, the EQ on the O-Audio can defeat the boost at 20 hz if required.

[MarkDN]

Mike, yes you're correct, this is possible to do when you are tuning around 20hz. My apologies for generalizing. It should be noted that it is not completely possible to cancel out the boost with the PEQ.

I have previously contacted OAudio in an effort to better model with the OAudio 500:
20hz Subsonic Filter: Filter Fc = 17.33Hz, Filter Q = 1.72
25hz Subsonic Filter: Filter Fc = 23.06Hz, Filter Q = 1.42
PEQ Q control varies Q from ~ 3 (LOW) to HI (20) with PEQ Level set at Maximum.
You can model these the subsonic filters with a HPF SOS Second Order Filter in WinISD.
Obviously there will be some variation from amp to amp but it should give you a good idea.

Below are models using a signal of 440w:


The graph above shows the amount of boost the OAudio amp will provide.




The amp would clip before the excursion is a problem here however. This also means that the real SPL that will be achieved will be a few dBs less than shown. Note that the 25hz subsonic filter with no PEQ on is in yellow. White is 20hz subsonic filter with some PEQ.

In my opinion the amp is ridiculously good value. However the issue is that the lowest the PEQ can be centred is 20hz and it is designed to combat room modes, not broad equalisation. Hence, it can be used somewhat to negate the subsonic boost but it is not ideal.

The graphs may not look pretty but realistically this is fine. Room interaction will make things look far worse.

I hope this enables informed decisions. For any other Aussies, the OAudio 500w amp is fantastic value for money. I'd buy it again in a flash.

Cheers

[davidburn]

Thanks Mark for the great info on importing O-Audio amps.

Mike, Is the modelling right? Seems to have a big hump in the 20hz range? Can it be eliminated with the Amps eq?

I still haven't bought the amp so im up for any suggestions on how to proceed.


Thanks for the help.

[davidburn]

Just tracked the delivery of the Driver and it will be arriving tommorow. What are the best bolts for the driver as i've only ever used screws???

The entire front of the box is still removable and can make any adjustments to secure the sub into place or add more bracing. I have noticed in other builds threads that extra timber has been added were the screw from the driver enter the box, is this recomended?

With lining the internal of the box I have always used this...http://jaycar.com.au/productView.asp...g&form=KEYWORD
Is this the right material or should I look for the egg crate foam?

[robbo266317]

The best way to mount it is using T-nuts and hex screws.
The T-nuts have spikes that bite into the timber and it is recommended to put a ring of ply on the back where they attach as mdf will sometimes strip and they will just spin and you cant tighten or loosen them. The ply is less prone to stripping.
The hex bolts have circular heads and are tightened using allen keys. Typically you would use M4 or M5 with appropriate washers.

[Mike P.]

davidburn wrote:

Thanks Mark for the great info on importing O-Audio amps.

Mike, Is the modelling right? Seems to have a big hump in the 20hz range? Can it be eliminated with the Amps eq?

I still haven't bought the amp so im up for any suggestions on how to proceed.


Thanks for the help.

The EQ will eliminate most of the boost at 20 hz.