The Boominator - another stab at the ultimate party machine

[Love Below]

Quick question?
And you are going to use the amp6 BASIC and HP10W as speakers again?

[Buckapound]

And wasn't there some discussion of a fuel cell the last time around?

--Buckapound

[Saturnus]

The HP10Ws are definite keepers. They simply outclass anything up to twice it's price or more in performance, both in sensitivity and sound quality. I'll be making some minor changes though, like adding a phase plug with a rod that will connect the 2 speakers mechanically through the center.

The amp6basic is going to be replaced with an amp9basic, and it's going to run on LFP cells instead of SLAs. A new 15W amorphous solar panel will cover the entire top. It's also going to have a switch to toggle between 12V and 24V mode.

The methanol fuel cell idea is dropped as it's not practical and it's highly dangerous to combine methanol with ethanol (the former being the fuel, and the latter being what the user is intoxicated by).

Some minor changes to the design is also considered and I'm testing different tweeter solutions but a high quality piezo driven horn with a Geddes-style waveguide is showing the most promise right now.

[saulty]

Saturnus, while you wait to start your next project, maybe you can shoot me some pointers with my new project. First off, thanks for sharing your project with us and even more thanks for all the advice you've given on this forum.

What are your thoughts on the piezos listed below.
I'm building a 2 woofer version much like the green machine whelibob posed a couple pages back.
2x woofers = Goldwood GW-1058
amp = sure electronics 2*100 t-amp
power = probably 2x 7ah SLAs wired for 24V
solar = TBD
piezos = Need help deciding between the KSN1005A (http://www.adelcom.net/MOTOROLA_ksn1005b.htm) and the motorola/CTS powerline version KSN1141A (http://www.adelcom.net/MOTOROLA_ksn1141a.htm)
This post is the reason I'm even thinking of the powerline version. http://www.audiokarma.org/forums/showthread.php?t=79659

You are right that the GW-1058 charts very similarly to the p.audio woofer. The GW1058 appears to have just a little more low end reach at the expense of a little sensitivity. I'm still playing around with the enclosure volume/tuning and find myself leaning towards a larger volume to gain a lower F3. With a 25L enclosure, I'm seeing an F3 in the lower 60s hz range. Although I loose a little of the peak at around 100-110hz when doing this. Or a 20L enclosure brings the F3 up to somewhere in the 70s.
Early on in this thread you mentioned that trying to tune for lower than 100 hz isn't worthwhile for outdoor environments. If the additional size isn't a major issue, can you think of any reason why one wouldn't try to achieve a lower F3? With the bigger t-amp, I have a bit more headroom to play with as well which could come in handy in this frequency range. Thoughts?

Thanks

[Love Below]

Saturnus!.

I am wondering about why you are going with the amp9 BASIC.

Is it because you have found some HP10Ws with 4 ohm
And why is it that you want the BASIC version? Because of its high voltage input?

I hope its okay with all these questions..

[Havoc08]

amp 6 and others can drive 4 ohm also. I presume the choice of amp9 is because of the higher output (he mentions 24v operation).

The basic version is cheaper as it has no rectifier and bulk caps, but other than that they are similar. It does not matter with the rectifier when he uses 12/24v DC.

[Havoc08]

reg. amp9 it has 4 channels also on smaller footprint than 2 amp 6.

[Saturnus]

Your assumptions are very accurate, Havoc08. Indeed the amp6b plays 4 Ohm, and even 2 Ohms for that matter but the amp9b has 24V potential to get 4 times as much output power. Now the 24V mode will only be available when supplied with external (usually grid) power.

Indeed I have found the HP10W in 4 Ohms, it's called the HP10W4. But I also need 4 channels as I'm going to use an active x-over to drive the tweeters and the woofers separately.

I don't need the rectifier and power supply in the amp9s, nor I'm a masochist that enjoys winding 4 sets of coils myself when the ready-made ones in the amp9b (and amp6b) are much better.

Saulty, to answer you question most thoughroughly. I'd like you to make 3 mp3, one each with a 60, a 80 and a 100 Hz sinus wave. Now take a speaker you know is capable of playing those at fairly loud levels outside and put in the middle of a grassfield. Stand back 4-5 meters and play the mp3s. Then you'll know why it's completely redundant going lower than roughly 100Hz for semi-loud applications outdoors.

The Motorolas have a good reputation but they aren't the best piezos you can get regardless of claims to the contrary. The Zomax HP100s I use in the Boominator simply are the best piezo horns I have ever heard. It beats every Motorola horn by a mile. You can get even better ones though but those are dedicated horn drivers that need a (normally threaded) horn, and at a very different price point.

Btw, you do know that with your amp and 2 7Ah SLA in series for 24V you'll only get around 2½-3 hours playing time max, right?

[saulty]

Saturnus, that sounds like a very good experiment. I'll definitely try it out blind then again with an SPL meter to see. I think I get what you are talking about though. Lower frequencies have to be much louder to be audible in general. Then you add in the great outdoors where low frequencies float away. Outdoor concerts probably boost the lower frequencies quite a bit to achieve nice bass which requires some big time amplification.

[mor2bz]

I really like this boominator. I can't stand loud music, but if you are going
to listen to loud music, outside is the place to do it.

I have read that sealed boxes really do not give up anything in bass to ported, it is just that they do not go as low or drop off so quickly below F3. And the
boxes can be about half the size. Maybe we have given up too quickly on the
sealed box?

I am interested in portable battery powered sound reinforcement so that bands do not have to mess with cords and generators. If they do not want to be stupid loud, it seems like your box would work well. Well I appreciate the long run times of your system, it seems like with more power the same
box could go alot louder, although for shorter periods. I do understand what doubling drivers does for efficiency for both the speakers and for the amps (non-tube).

As cheap and light as amps and batteries are (compared to drivers and boxes), would it not be lighter and louder to use fewer drivers and more
watts and batteries?

Would not fold out wings help greatly with reinforcement?

In colorado (and elsewhere in the u.s.) we have the Fat Tire bike rallies .
It started in Ft. Collins (where I live and where the brewery that hosts are).
Upwards of 12,000 people rode in the last bike parade here. Sheer genius on the part of the brewery to get people to do their advertising for them!
Alot of the the people strive to create battery powered PAs for their bikes, but i haven't seen anything really outstanding. http://www.newbelgium.com/tour-de-fat

If you could market your new model, what would you ask for it? I wish I could help fund your project; you are really doing a great job. Maybe some day you could market a upgraded model with a tube preamp and / or tube amplifier from doc bottlehead or Dodd audio.

best wishes

and all respect david sundby sundbyd2@gmail.com