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Old 26th January 2013, 06:18 PM   #3421
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Join Date: Oct 2012
Hi
Me and my friend are currently doing our last year in college or high school (dont know what its called in english :P) and need to do some kind of project work. So we decided to build a boombox, but we have some questions that we need to answer. With that said, we would really appreciate some answers on these questions:
1. First of, Ive seen Saturnus setting the "Qbox" to 1.1, so i wonder what that is and how it affects the sound/box/whatever.
2. It seems to me that u can tune the box to whatever Hz you like, but ive seen in a guide (http://se.search.yahoo.com/r/_ylt=A7...Enclosures.pdf) that the optimal, or so it seems, tuning frequency is given by this formula
Fb = 0.42(Fs)/Qt^0.9.
3. It would be awesome if someone could link a page where they explain how the T/S "formulas" (not parameters) were determind in the first place. For example this one F3=0.26(Fs)/Qt^1.4. Why is the F3 given with these formula? Where does the ^1.4 come from?
Would be really happy if someone could help me with this project
/André
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Old 26th January 2013, 11:19 PM   #3422
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Early on, you suggested using these caps: AVX CB038B0154JBA with these attributes, 150 NF, 16V, 1812, PPS. But I think this is recommended for use with the SN-10MB and the 407N.

You mentioned WIMA caps as an alternative, if I didn't want to solder. If I can't get these particular brand/model, what would be a similar type and at what attributes or if there is a part number I can search for? Mouser and Digi-key are the main electronics distributers here in the US.

And what is the best way to install it? Diagrams are one thing, but real-world execution is very different and confusing, especially to someone who is new to the whole audio electronics world. Any help you can provide is very much appreciated.
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Old 28th January 2013, 05:00 PM   #3423
floxer is offline floxer  France
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Quote:
Originally Posted by Saturnus View Post
No worries.

1) Yes
2) I believe that filter is for the Boominator LITE with Basslite S2010 woofers.
3) Yes

May I inquire what the purpose of your "halfinator" is? I've recently designed the Boominator MINI for people that find the full Boominator too large, too heavy, and too expensive. I've not yet built one so a full test might change a few minor details but all simulations have been satisfactory so I have full confidence that it is extremely close to the final design.

Have a look here. Boominator MINI (development thread) - Speakerplans.com Forums - Page 1
Yes, it's to use outdoor and indoor, to play reggae/dub/hip hop music ( bass and middle frequency are important ), and the halfinator will be store in my van ( the size 500*300 for halfinator is perfect ).

So a full boominator would be too large and too expensive for me, i have chosen to go with p.audio 407N to increase middle range frequency. Hard for me to know what's the better choice betwen halfinator ( 407N + HP10W combo ) or the Boominator MINI, what do you think about the pros and the cons ?

- Sorry about the mistake for the filter, i have found the filter for HP10W + 407N, so if somebody can correct it for Halfinator stereo version it will be great !
Click the image to open in full size.

Thanks for you help
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Old 29th January 2013, 09:57 AM   #3424
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Hello All

I am a complete noob here, I'm not well versed with speaker enclosure design, I'm not well versed in electronics but I am perfectly capable of sound engineering, soldering and I can recone speaker drivers, so I'm a noob in some ways but OK in others.....
I'm based in the UK, I want to build a boominator and stay true t the original design because Saturnus, quite obviously knows more about enclosure design and electronics than I.

However, P.Audio may be based in the UK and “Blue Arran” are their UK distributor but you cannot get the HP10W here......

I wrote to Blue Arran for advice on potential replacements and I really helpful guy called Jon Harriman sent this reply...... I thought that some of the readers of this forum would find it useful.........

Thank you for your enquiry. Looking at the available info on the Boominator, the speaker selection doesn't actually seem to have been a particularly critical part of the design of the box - quoting from the original diyaudio thread, "I used 4 P.Audio HP10W woofers because they're cheap, sounds great, and not least because they had the perfect depth for magnet to magnet mounting". It looks less as if the box has been designed to work specifically on the back of a particular driver, and far more as if that driver has been chosen as a matter of convenience, and the lack of a wealth of other drivers listed on the website is more a case of low end-user feedback on the matter rather than other drivers being technically precluded.
The box has been tuned to 82Hz, and is functioning as a straightforward bass reflex enclosure, so realistically you will have successful results with any 10" driver of suitable size and power handling, with a resonant frequency lower than the tuning frequency of the box. P-Audio's SN-10MB, which is also listed as being suitable, has a mounting depth of 122mm, so I'll take that as the maximum depth (both the original choice and the Eminence S2010 have a depth of 109mm).
Regarding the loudspeaker options listed on the Boominator site - we can't, unfortunately, get hold of the Goldwood driver at all, I believe this is solely available in the US market.
HP-10W - P-Audio now only make this driver to order. Whilst we are P-Audio's UK importer and distributor, we would need an undertaking for an order of 12 off drivers, and would be on an lead time of approximately six months from point of order.
SN-10MB Series II - This is still available from P-Audio, but unfortunately we don't have any in stock at the moment, so again we'd be looking at quite an extensive lead time (probably 3-4 months absolute best).
Eminence Basslite S2010 - Again, not in stock on the shelf, but available on a shorter lead time than the P-Audio options, usually around 2 weeks or so.

Recommended options:
http://www.bluearan.co.uk/index.php?id=PAUE10200S P-Audio’s E10-200S performs extremely well – resonant frequency of 73Hz, around the same as the SN-10MB. The quoted sensitivity figure of 93dB is actually quite misleading, it performs significantly better than that, and will actually deliver 100dB-plus across almost everything from 100Hz right up to 5kHz. Checking out the spec sheet, the E10-200S significantly out-performs the SN-10MB in many respects, with the exception of the Xmax being a little lower and the fact that it’s a heavier driver. Depth 109mm. Available from stock.

http://www.bluearan.co.uk/index.php?id=EMIDEL10A Eminence Delta 10 – 350W RMS will also work , resonance 66Hz, 98.8dB/W. Depth 108mm, available from stock.

Incidentally, for the tweeters: Motorola sold their piezo production line over a decade ago, and production has since passed through several hands. Currently available in the same profile as the KSN1001A is this:
http://www.bluearan.co.uk/index.php?id=SKT900298

I note that Saturnus also recommend use of P-Audio’s PHT-407N tweeter. The sound of this high frequency horn and driver is significantly more refined than you’ll be able to achieve from piezo drivers, and if budget will allow, it’s definitely worth looking at. One caveat, though – it will need a crossover, whereas the piezo driver will not. Here’s the PHT-407N:
http://www.bluearan.co.uk/index.php?id=PAUPHT407N

Obviously, this guy is at work and doesn’t have time to read all of the threads here, so I put him right about a couple of issues (ie, the drivers being an integral part of the box structure) and this was his reply back....
“Glad to help. Obviously I don’t have unlimited time, so hadn’t looked into the project as far as the construction details, and hence was unaware of the structural nature of the driver coupling. As you say, it’ll help make for a compact box, but that’s going to be a nightmare if you blow one! In light of the info, though, the SN-10MB doesn’t seem to make a lot of sense as it’s around half an inch deeper per driver. Not insuperable, but something to take into account when building.
Fortunately, both of the drivers I’ve recommended are around the 108-109mm region, as (or at least so it would appear) per the HP-10W. Interesting claim regarding the idea of the magnets coupling – not sure how effective that would actually be in practice, particularly with the pole pieces in place. Incidentally, indoors or outdoors is largely irrelevant – although setting up near walls/corners can reflect sound which would otherwise be disappearing in an unproductive direction.

You’re absolutely right, the E10-200S is heavier than your original choice, actually by 1.4kg. Frankly, I’d say for the extra 5.6kg per box, it’s well worth it, you’re getting better power handling and significantly better sensitivity (as I say, ignore the quoted 93dB, it’s wildly misleading at best). Delta 10 actually a little heavier; decent enough driver, but I think you’ll get more mileage from the E10-200S.

Eminence Gamma 10 should work too, and are at a pretty keen price: http://www.bluearan.co.uk/index.php?id=EMIGAM10A

And Fane’s Sovereign 10-125 is another option, although a little shallower, so you may need to rebate the driver into the baffle to compensate: http://www.bluearan.co.uk/index.php?id=FANSOV10-125

There are a LOT more drivers to choose from, what I’ve put forward here is really the budget end of the market. Budgetary constraints are realistically likely to rule out both the Eminence S2010 and the SN-10MB – this is a knock-on effect from the automotive industry using a lot of neodymium in motors for hybrid vehicles, which has largely priced it out of the market fro speaker magnets unfortunately.

Tweeters – piezos are actually remarkably efficient, and as they don’t need a crossover they make for a very straightforward solution. As cheap drivers which need no other fittings except arguably a resistor, they’re extremely hard to beat on the cost-front. On the other hand though, with a suitable crossover in place a tweeter won’t affect the resistance of your box overall – your biggest hassle will be finding an off-the-shelf crossover designed for a 4 ohm woofer and an 8-ohm tweeter. Building your own is a lot less difficult than some people will make out, but of course this may well be an avenue you’re not keen to explore. Tonally, you’ll have a far nicer box with the PHT-407N, but whether it’s worth the expenditure and effort is entirely your call.”

So, this has given me plenty to consider, I still have to go for the budget option because a boominator lite or a signature boominator is going to be too pricy for me (Looking at £700+). I may have to swallow the extra weight and try the P.Audio E10-200S. It may be well be worth a punt........

Comments more than welcome
BJ
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Old 30th January 2013, 06:32 AM   #3425
hwcons is offline hwcons  United States
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Hello all

I'm a newbie and I have previously built the Podzuma. My next challenge is to build the Boominator but I have a couple of questions for Saturnus or whoever would be able to help me. I live in California and I'm having problems purchasing the recommended drivers but I read that I can get from PartsExpress the GOLDWOOD GW-1058 and I also saw that Saturnus recommends MONACOR MPT-001. My question is if I use GOLDWOOD driver with the MONACOR MPT-001, are they compatible? and if they are can I use the Resistors 33 or 47 Ohm 3W 5% Metal?

Thank you for your help!
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Old 30th January 2013, 07:17 AM   #3426
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hwcons's and brummiejons questions,
both regarding the use of which speaker,
are best addressed to the multi-way subForum.

BTW In Brummiejon's reply the guy at Bluearan had written extensively enough ! Not that bad!

From what I 'captioned' from this thread, the double woofer is chosen
in function to have : high sensitivity ( 4Ω=more power) and efficiency ( double radiation area ) at the price of the extension given by the size and solidity of
the enclosure/box, as also the highish Q is a result of all these factors .
Price is also...money. No doubts that some coaxials would outperform the-I
extimate quite good the performance suggested by Saturnus...-HP10W+piezo

Ehm...That P audio is HUGE !!! Maybe it would deserve a double volume, so better to offset and put the magnes nearly aside, opposing.

Last edited by picowallspeaker; 30th January 2013 at 07:24 AM.
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Old 30th January 2013, 12:16 PM   #3427
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Location: Whitstable, Kent, England
Hi

The guy at blue arran didnt really understand the concept behind the boominator, however, he did seem to know a thing or two about speaker drivers.......

The price of the P.Audio HP 10W shipped from Germany is no more than the price of the P.Audio E10-200S and I like the idea of purchasing locally to keep my children in work and cut the CO2 emmissions on transport.....

Obviously the extra weight is an issue but I'm planning to mainly transport this to the beach or picnic by bicycle trailer or car anyway.... Accordiing to Blue Aaran, the E10-200S, although not reflected in the specs, is a better speaker and no more expensive (for me anyway)........ I'd like to hear Saturnus veiw on this anyway..... it would be good to find speakers, available in the UK, that are suitable for the boominator design. I think that it would encourage more UK builders........

I love the efficient design of the boominator and intend to stay as close to the original as poss.....

I shall use the AMP6 basic and intend to have a go at building the kit myself, even tho I have never soldered electronic components on a PCB before..... it cant be that hard...... There will be times when I may require more volume at the expense of battery life, as long as I can get 10-12 hours at full volume with a single charge, I'd be happy. So I am planning to make two. removable amp modules, one optimised for length of play (amp6 basic) and another optimised for volume and 10hrs play... Would the AMP9 be suitable for that?

Final question, blue arran suggest that a tweeter could be used without affecting the overall impedence, this is not what I have read on this forum, is this true or rubbish? I ask because I am aware that a "proper" tweeter will sound better than a peizo and would prefer to use one if it is possible....

Regards

BJ
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Old 30th January 2013, 01:05 PM   #3428
LJNorth is offline LJNorth  United Kingdom
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I think you have got some good advice from the Blue Aran guy, as far as the x-over goes he is probably right, crossover design is a complex thing but you can usually design them [crossovers] to maintain a reasonable (i.e. not too low) impedance across the entire frequency range (its not just a case of parallel drivers). A piezo tweeter will look to the amplifier like a capacitor, so the magnitude of its impedance drops as the frequency increases. At audio frequencies its impedance is pretty high so if it is in parallel with your other speakers it will hardly effect the overall impedance seen by your amplifier. However, at very high frequencies (ultrasonic) the impedance can drop to low values and put your amp at risk hence the resistor in series. A crossover for any tweeter (moving coil or pizo) driver will require proper measurement (acoustic measurement) and design. If your not prepared to do the work then the piezo route is cheapest and will likely give you a good performance to price ratio, i.e. dont waste money on expensive horns.
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Old 30th January 2013, 03:28 PM   #3429
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Thanks LJ

Point taken, I'm just not technical enough to be able to design the tweeter crossover properly even though I think I have the capability to construct it..... Piezos, safer option but I may choose the front mounted type so if I meet a spaker guru who could improve tweeters in the future, I have the option to replace (I do prefer the look of the rear mounted piezos tho).

Cheers
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Old 30th January 2013, 09:02 PM   #3430
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Quote:
Originally Posted by brummiejon View Post
The guy at blue arran didnt really understand the concept behind the boominator...
That unfortunately shows. None of the driver he suggest can be used for a Boominator. None of them.

If you are in Europe or Australia, you use the p.audio HP10W. And nothing else. It is the only driver that will work.

If you are in the USA, you can use the Goldwood GW-1058 as a direct replacement. It will not be as good but it will work, and the difference will be miniscule.

If you want a light version you use the Eminence Basslite S2010.

There are no other drivers that can be used. At. All.

Last edited by Saturnus; 30th January 2013 at 09:06 PM.
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