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Old 4th October 2011, 09:20 PM   #2361
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What makes the recommended construction grade plywood different from regular plywood is the fact that it's glued with and surface coated with epoxy resin which makes it much stiffer and harder than all other types of plywood. So if you want something to stick to it you must either sand it, or use epoxy resin for gluing as epoxy resin will chemically bond to the coating resin. It's also a much better alternative than wood glues as it's creates very solid joints without needing clamping, and it has excellent joint filling capability as it doesn't shrink under curing as wood glues does which makes the need for siliconing the joints afterwards redundant.

Just note that it's also a fair deal more expensive, and make sure you read and follow the safety instructions.

Last edited by Saturnus; 4th October 2011 at 09:26 PM.
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Old 6th October 2011, 08:13 PM   #2362
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I was looking through this thread for advice on different types of glue and sealant and I just want to make sure that I got it right.
- Use a chemical metal product like this PLASTIC PADDING KEMISK METAL - Best.nr. 1139 for glueing the woofers to the center brace and the outer cabinet.
- Use a non-corrosive acrylic sealant like this Bostik Diy Akrylfuge - kÝb online hos SILVAN for sealing the cabinet airtight.
- Use epoxy or regular wood glue for the cabinet depending on courage/budget.
Is this more or less correct?

Also, I got the plunge router from elextra.dk which was recommended somewhere in this thread and I was wondering if I can make the holes for the woofers using the straight router bit that comes with it?
I think I read somewhere that spiral bits are considered superior, but since I already got the straight bit I might as well ask.
Since the recommended plywood is a pretty hard material, is it possible/recommendable to cut through all 12 mm at once or should I adjust the depth stop on the router to do it in 2-3 goes instead?

Saturnus, I think it's no secret that you're a perfectionist (which is probably a good thing since the Boominator wouldn't exist otherwise) but how important would you say that the rounding of the holes in the center brace is?
I'm asking because my router skills are very limited and I would love not having to do it.

I was thinking about making a DIY grill for the port out of chicken wire, speaker cloth and impregnation spray to help keep moist and dust out of the cabinet. Is this doable or will it affect the air flow too much?
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Old 8th October 2011, 10:40 AM   #2363
rubennn is offline rubennn  Denmark
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Quote:
Originally Posted by Djimmi View Post
Also, I got the plunge router from elextra.dk which was recommended somewhere in this thread and I was wondering if I can make the holes for the woofers using the straight router bit that comes with it?
I think I read somewhere that spiral bits are considered superior, but since I already got the straight bit I might as well ask.
Since the recommended plywood is a pretty hard material, is it possible/recommendable to cut through all 12 mm at once or should I adjust the depth stop on the router to do it in 2-3 goes instead?

Saturnus, I think it's no secret that you're a perfectionist (which is probably a good thing since the Boominator wouldn't exist otherwise) but how important would you say that the rounding of the holes in the center brace is?
I'm asking because my router skills are very limited and I would love not having to do it.
You should do the woofer cutouts in 2-3 turns. I made the mistake doing it in 1 turn, which after a few cutouts made my router bit break in 2 pieces because it got too hot.

A straight bit should be just fine for the cutout.

Rounding with a router is not difficult at all and it's kind of fun too in my opinion. So I would recommend doing it (just make sure the piece of wood you want to round is held tight by something so it doesn't slip).

Happy building

EDIT: You could look up some youtube videos about using a router for rounding and making circular cutouts. That helped me a lot.
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Old 9th October 2011, 04:56 PM   #2364
rubennn is offline rubennn  Denmark
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I saw this on elextra.dk today:
https://elextra.dk/main.aspx?page=article&artno=H20587
My thoughts were that it could be used to plug into the 12V socket when you want to charge the batteries with an external charger. You would avoid the hassle taking the batteries out of the boominator to charge them. Is this a slick solution or a dumb thought?
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Old 9th October 2011, 07:30 PM   #2365
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Quote:
Originally Posted by rubennn View Post
I saw this on elextra.dk today:
https://elextra.dk/main.aspx?page=article&artno=H20587
My thoughts were that it could be used to plug into the 12V socket when you want to charge the batteries with an external charger. You would avoid the hassle taking the batteries out of the boominator to charge them. Is this a slick solution or a dumb thought?
I think that it's a smart plan.
I'm going to do kind of the same but with Neutrik Powercon instead. Also if you need to attach an extra backup battery. NEUTRIK NAC3MPA-1 POWERCON - Thomann danske Cyberstore NEUTRIK NAC3FCA POWERCON - Thomann danske Cyberstore
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Old 9th October 2011, 09:06 PM   #2366
rubennn is offline rubennn  Denmark
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Oh yes! That seems like a good idea also. AND it would look nice on the actual box... I can just imagine people asking "what's that gonna do?".

Wasn't it also NEUTRIK who made the recommended transformer for the boominator? This one: NEUTRIK NTE 4 AUDIO ‹BERTRAGER - Thomann danske Cyberstore?
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Old 10th October 2011, 07:22 PM   #2367
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You don't need a trafo with the AMP6-B, you can choose which sensitivity that suits your device.

Quoted from 41Hz.com
Quote:
  • The amplifier input stage, inside the Tripath chip
    Is of the operational amplifier type. The maximum possible voltage the input stage should handle is about +/-2V peak to peak (4Vpp=1.41 Vrms). You can set the gain of the input stage so that it matches your signal source.
    The gain is calculated as for a normal inverting operational amplifier: Input Gain=-1*Rfeedback/Rin V/V. The minus sign is due to the fact that the input stage is inverting (ignore).
    On the board, R2 + R4 are the Rin and R5 + R6 are the Rfeedback. With the kit, there are four 22kΩ resistors and two 56kΩ (and/or 82kΩ). With these resistor values, you can choose one of three different input sensitivities as shown in table 1 below.
    If you use other input resistors, they should be of a low noise (metal film) type.

R-in, R2+R4 - R-feedback, R5+R6 - Input-gain - Suitable signal source.
22 kΩ - 82 kΩ - 3.7 - Even more sensitive input (Ipod)
22 kΩ - 56 kΩ - 2.5 - For older type portable MP3/CD player with built in volume control.
22 kΩ - 22 kΩ - 1 - General use
56 kΩ - 22 kΩ - 0.4 - (Pro) preamplifier with fairly high output signal
82 kΩ - 22 kΩ - 0.27 - Even less sensitive if needed
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Old 10th October 2011, 08:38 PM   #2368
rubennn is offline rubennn  Denmark
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Ah I see. So I would need to use 22 kOhm resistors for R2 and R4 and use 82 kOhm resistors for R5 and R6 for maximum output, right?

My signal source is an iPod so I guess I could try that first. Thanks for the heads-up though.
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Old 11th October 2011, 08:30 PM   #2369
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What a great thread. Lots of good information here.

I've started planning next years festival sound already, and will probably use all of the components of the boominator for the speaker box.
Tripath amplifier, 4x HP10w and bubble piezos.
Being a big camp with a lot of ideas, we will go for a cart solution however, as we need more room for lights and a small bar.


A big must-have is the ability to play mp3 from usb drives, so everyone can contribute with their own music.
The easy solution would be to install a head unit from my car, but as I've learnt from this thread, that would be an unnecessary drain on battery power.

Instead I've been looking for a better solution. Something like this:
1.5" LED MP3 Player Module with Remote Controller/FM/USB/SD (3.7V) - Free Shipping - DealExtreme
Click the image to open in full size.
All basic needs covered, display and remote is a bonus. The input voltage is tricky at 3.7v however. And a $8 pricetag suggests a pretty low quality.

VMP3202-3.3V High Efficiency DC-DC Module - Free Shipping - DealExtreme
I'm guessing this will do the job of supplying ~4v.

I wouldn't mind paying more for a better quality player, with better controls and a more detailed display, but I'm in need of ideas here.

Have any of you builders gone down this path?
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Old 11th October 2011, 09:04 PM   #2370
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Quote:
Originally Posted by Astraldk View Post
What a great thread. Lots of good information here.

I've started planning next years festival sound already, and will probably use all of the components of the boominator for the speaker box.
Tripath amplifier, 4x HP10w and bubble piezos.
Being a big camp with a lot of ideas, we will go for a cart solution however, as we need more room for lights and a small bar.


A big must-have is the ability to play mp3 from usb drives, so everyone can contribute with their own music.
The easy solution would be to install a head unit from my car, but as I've learnt from this thread, that would be an unnecessary drain on battery power.

Instead I've been looking for a better solution. Something like this:
1.5" LED MP3 Player Module with Remote Controller/FM/USB/SD (3.7V) - Free Shipping - DealExtreme
Click the image to open in full size.
All basic needs covered, display and remote is a bonus. The input voltage is tricky at 3.7v however. And a $8 pricetag suggests a pretty low quality.

VMP3202-3.3V High Efficiency DC-DC Module - Free Shipping - DealExtreme
I'm guessing this will do the job of supplying ~4v.

I wouldn't mind paying more for a better quality player, with better controls and a more detailed display, but I'm in need of ideas here.

Have any of you builders gone down this path?
Single cell Li-ion and LiPo are both 3.6-3.7 V.
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