MF 1000

Sub bass & bass Speakers with 18" Volt RV4564 drivers

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Posted (edited)

Speaker builder is giving 122cm for a 16 hz tuning. Easy enough to make cardboard tubes of various lengths and slot them into the existing port to see which floats your boat. Also lagging the box will give you some extra 'virtual volume'-around +10% or so.

TBH looking at the curves a 16hz tuning gives you a -10dB point @22hz and -8dB@30hz, however a  26hz tuning gives a -10dB point at 22hz, and -4dB@30hz.......

Edited by cooky1257

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Super Wammer

I'll probably also experiment with long hair wool in the long port which works well on transmission lines at lifting low end bass which might assist the -10 dB points in the 20-30 Hz range 

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Posted (edited)

I'll not be able to much testing etc till the weekend, but just tried the infamous Blake  - Limit to your Love on the system.  Even with the untuned port setup these beasts go LOW the room was filled with sofa shaking bass 😀😀😀😀

Edited by MF 1000
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Super Wammer

Lifted the bonnet on the speakers as they say earlier today and was pleasantly surprised at the internal construction.  Inside there is a cruciform brace (with lots of air vents fixed to the rear baffle with legs bracing each side and a full width cross brace (again with air vent holes) just above the top of the front port.

ive worked out a route for the square port tube that should give me around 120-130 cm length and it will integrate with the cruciform brace too.  All access will have to be via the driver hole, but with it being 18" dia it's not really limiting me 😀.

I have taken pics, but my email is not sending them to my iPad at the mo ....so I'll post them once that's sorted 

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Super Wammer

Just for reference, Unibox is my favourite box calculator (excel spreadsheet)

http://audio.claub.net/software/kougaard/ubmodel.html

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Super Wammer

Sorted my pics issue so here are some internal shots

IMG_0051.JPG.065e303b52a4a9e6b42a29fe60606156.JPG

nice cruciform brace that's fixed to 5 sides.  The sides are 18mm mdf and the front baffle is 36mm mdf.  On the rhs of the pic you can see the "shelf' seoeratimg the main enclosure from the port.

Here are some naked shorts of the Volt driver 

IMG_0054.JPG.d5faf6964158a91054d0d0895ca2a7f3.JPG

huge 8" magnet !!

IMG_0052.JPG.8e59b53846617cd1e218b65c054dad11.JPG

IMG_0053.JPG

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Posted (edited)

Cabinets look fine to me Keith, I dont know why your bothering, take them to a spray shop and get them sprayed piano black or something :) I still say get one of those bargain 500 W aside amps, but you may do some structural damage :D

Edited by eddie-baby
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And I think you might have just become 'the bass master' here on Wam you know :D

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Posted (edited)

I'll prob make a second skin to go over them ....I quite like the idea of them in an oak or cherry veneer.  Just finished upgrading the internal wiring and the drivers now held in place with M8 stainless steel cap heads.

it is tempting to run another A500 in bridge mode - one fir each speaker ......maybe later in the year 

Edited by MF 1000

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3 minutes ago, MF 1000 said:

I'll prob make a second skin to go over them ....I quite like the idea of them in an oak or cherry veneer.  Just finished upgrading the internal wiring and the drivers now held in place with M8 stainless steel cap heads

I quite like the professional black finish myself and it matches your mains as well, but each to their own, woods do look nice as well. Nial, did a fantastic on his JBLs real wood veneer, like a walnut finish, but then again it should be good, he is a profession in that area after all :)

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If you tune to 19Hz instead and use a 10cm dia port it only needs to be 33.5cm long and could be mounted inside the existing port with nice flange on front baffle.

Port air velocity is still ok too.

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Super Wammer
26 minutes ago, cooky1257 said:

If you tune to 19Hz instead and use a 10cm dia port it only needs to be 33.5cm long and could be mounted inside the existing port with nice flange on front baffle.

Port air velocity is still ok too.

Thanks Frank

it would be an easier option .....I'll order a couple of off the shelf ports and do some testing.

Just noticed your on the Wirral, you could come across to Wrexham easily for a listen once I'm further along this mad journey 

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Posted (edited)

These look great Keith 

You can't beat big drivers in my view. I would be careful with the port tuning

If you go too low you can start to hear the ports effect on the bass (although some may like that), my view is the drivers fs at 26 Hz is low enough..probably tuning it to 30-40 Hz may well sound better.

With larger drivers the port seems to have less of a negative effect on the sound, which is another positive for big drivers.

Effortless ..  you will soon be needing to update the main speakers to keep up..😉

My set up uses both a heavy weight 18 and a 12 

My daughter has played her 5 string bass through them, there is no noticeable loss of volume on the lowest notes. That alignes with my measurements. That covers most music's bottom end.

Can't wait to hear them next year ?

Edited by steve 57
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Super Wammer

Thanks Steve ....I'll bear the port tuning advice in mind, I think there might be a few weeks of tweakery ahead to find an optimised point twixt technically correct and what sounds best to me etc.

I'm hoping the twin b200 on mid bass and the twin b110 for Midrange in the Kef 104's allows them to cope with the Volt 18's.......I couldn't resist the Volts as they were on a buy it now as a pair inc cabinets for much less then buying 1 new Volt 18" 😁😁😁😁😁

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