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Two Halves (Read 28663 times)
Blotch
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Re: Two Halves
Reply #15 - 08/18/07 at 01:39:04
 
5A at how many volts? Most Mosfet amps are about 70% efficient - soooo - assuming its 32volts that gives us 160 watts of input power which will be about 112 watts of music power (approximately) 70volts@5A would be 350 in and 245 out. On discrete amplifiers you don't want to drop the load below the amplifiers rating IE if its rated for a 4 ohm load don't wire it to a 2 ohm load. Tube amplifiers are different (depending on their construction) most of the ones I've dealt with like lower loads than higher ones Smiley . Don't believe everything your read on packaging. I had a book showing some amplifier circuits. Had a stereo 70Watt amp with tone control and it required a +-35 volt transformer @ 5 amps (350 watts) not very efficient Tongue (40%). Reminds me of pyramid car amplifiers - boasted 2000+watts but when tested in the real world could barely eek out 70watts.
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wayan
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Re: Two Halves
Reply #16 - 08/18/07 at 02:31:51
 
yes, the amp requires 32V to power it, + 12V for some kind of safety thing~

Bart, what do better dynamics do? and how do i double the capacitors? i get 8, instead of 4, and instead of having one where it says to, put two in the circuit? ill scan the diagram and post it here in a bit to clarify this.

since i don't plan to bring down my house, or disturb the neighbors (much more than i already am) with this addition to my home stereo, I'm sure this should be sufficient to just add the kick i want while watching movies and listening to music.

i think ill just try and use this amp without any volume or equalizer in between and see what happens. I've decided also to change the input on the amp that i'm building and keep it as a stereo amplifier, ill just splice the cable from mono to stereo. like this some day if i need a stereo amp i can use it without having to modify the box~

was my b-day yesterday (17th Aug.) 26 now... ehh~ getting old  :P

thanks for the info to bart n blotch. hope to hear again from you two then.
cheers
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Blotch
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Re: Two Halves
Reply #17 - 08/18/07 at 03:14:38
 
happy birthday Smiley. Don't forget pictures of your finished projects.
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wayan
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Re: Two Halves
Reply #18 - 08/18/07 at 04:20:53
 

this is what comes with the amp, doesn't make much sense to me, but posting in case someone has any advice about it.


this is what i understand by doubling the capacitors up in parallel, is that correct bart?

well on second thoughts, that looks like i linked them up in series~ ehh.... I'm confused, lol

thanks, Smiley
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« Last Edit: 08/18/07 at 04:22:52 by wayan »  
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wayan
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Re: Two Halves
Reply #19 - 08/18/07 at 04:48:05
 


for those that wanna see how far I've come with the actual box construction.

its been in that state since about a week, been too busy with work to get it finished. which is quite annoying... so close yet so far, he he.

still need to cut the angles, and hopefully it will all fit together without too much trouble. i noticed that our table saw isn't cutting quite as straight as it should be. so i think ill be getting some slight gaps (0.5~1 mm). I've found a rubber like material that i will glue to the top edge of the walls to create an airtight seal when i screw on the top. the rubber is like 2-3 mm thick (thats less than 1/8th of an inch i think).
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Bart_West-VL.
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Re: Two Halves
Reply #20 - 08/18/07 at 10:02:30
 
You're last drawing shows the capacitors in series, this halves the capacity.
If you want to double the capacity, put a second one; plus to plus and negative to negative.
(Like you would put two 4ohm-speakers in parallel to get 2ohm)

Dynamics gives the bass some more reserve so not to draw the voltage down too fast.
See it like a water reserve, giving small drops won't matter much, as you can refill the bucket in time.
Draw a big stream of water out of it, through a one inch/25mm hose, the bucket will run empty or will not get full anymore, you just cant fill it up in time, just like you're transformer can't fill up those caps on time.
So get two buckets, if there is a sudden big draw, two will have more reserve then one, being it a bucket or a capacitor.
I wish my English was a bit better, but that's about the best I can explain.

Specially for bass, reserve is important, that's why they put big cap's in cars; one farad and more.

Hope this helped.
Bart
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« Last Edit: 08/18/07 at 10:16:10 by Bart_West-VL. »  
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Blotch
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Re: Two Halves
Reply #21 - 08/19/07 at 15:08:17
 
Yeah....what bart said Smiley
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Blotch
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Re: Two Halves
Reply #22 - 08/19/07 at 21:06:02
 
As promised I made drawings of the 1/2 WO.

Here is the original 24X36 I based it on (made drawings in Windows Paint):


Here is the same drawing cleaned up:


Here is the modifications (red lines):


Same image cleaned up:


Likes like a normal 45Hz horn now. Should make one and find out Smiley What do you all think? BTW the finished outside dimensions are 24x24. The mouth opening area remains the same as the original mouth opening area (thus the modified line).



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« Last Edit: 08/19/07 at 21:07:28 by Blotch »  
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wayan
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Re: Two Halves
Reply #23 - 08/20/07 at 02:22:30
 
oooo~ if this WO that im building works as good as i hope, and i find the free time and $$ to buy more parts, id be very tempted to try out the half WO! in the meantime if anyone beats me to it, let us know how it sounds. just one half, and then, two halves. i would imagine placing two halves in the room to watch movies and listen to music could work out nice.



so back to the capacitors, i redrew it, i assume this is correct? I'm just doubling the buckets right? Tongue

how much would the equivalent of this sub be worth if it was ready made? i was looking around and didn't find many options for active subs (that were sold without the 5.1 tweeters) best one i could find (excluding the Bose shop which is just overpriced) was from Yamaha, it was a single drive, down firing sub at 10" or 12", and it was selling for over $500 i think (compared to the WO I'm making now which is so far costing me like $110) saving a lot, and hoping that it will sound better than the Yamaha! he he.

hope everyone had a good week end!
cheers.
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Blotch
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Re: Two Halves
Reply #24 - 08/20/07 at 05:30:09
 
Yup - thats how you need it Smiley keep us posted.
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Bart_West-VL.
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Re: Two Halves
Reply #25 - 08/20/07 at 17:13:15
 
Have a look at Klipsch, they have a few subs, but you might have to look around to find out the price.
There are others that build subs only, I read a review a few days ago, can't find it anymore, sorry.
http://www.klipsch.com/products/lists/subwoofer.aspx
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wayan
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Re: Two Halves
Reply #26 - 08/21/07 at 05:19:20
 
ah~~ if only i could afford some of their hardware!   but then again, it wouldn't be half as fun as building your own sub, and amp!

and yea, i still haven't had time to get anything done >.< wanted to work on the sub yesterday, but the worker had to leave, lol.

probably try and get my hands dirty tomorrow.

cheers.
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wayan
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Re: Two Halves
Reply #27 - 11/05/07 at 03:43:29
 
wow, how time flies!

well its been over two months since i last posted, and i still haven't managed to finish the sub Smiley

however i have at least completed the amp! it took me almost all of last Saturday to assemble it. i was lucky enough to know someone who's hobbie is to build his own audio hardware. he managed to give me some basic welding advice, and supervised me during the assembly.

he told me that the best way to upgrade this amp now would be to change the capacitors completely to 4 or eight better quality ones, since the four that i bought are like the lowest of low quality capacitors that are out there, he he...

i tested the amp yesterday with two Sony speakers that are around 80~100 watt each. it was not so bad. about as loud as my Yamaha amp which has 80W per channel. i would assume that once i change the capacitors it could be even louder. i hope that it is currently powerful enough to get the subs booming a bit once i get around to completing them.

once the amp is dry from the finishing room (giving it the final touches), i will take a couple pictures and post them. i meant to take some pictures during the assembly, but i forgot the camera.

i plan to get the WO sub done ASAP now to test it out with the completed amp.

cheers.
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wayan
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Re: Two Halves
Reply #28 - 11/05/07 at 11:51:51
 
here is my amp!







nice and simple, a volume button in the front left, stereo output to the drivers on the top (didn't have space in the back panel) and the stereo input above the heat sink (i decided to go stereo with the amp so i could eventually use this amp for regular speakers as well), big passive cooling on the outside back, power jack, fuse, switch, and the power placed off to the side to reduce electrical interference with the rest of the hardware.

i just tested it with the two drivers (free standing) and it was able to kick out enough audio to keep up my hopes. however i did not parallel the double coil drivers yet, so i think there might be a little improvement once i do that. i did try and connect both left and right outputs to one driver, and that resulted in a more impressive kick.

I'm already tempted to go out and find some proper capacitors since these don't seem to be up to the task, lol.

well maybe once i actually manage to get the WO built it will sound the way i want it to and leave it at that.

has anyone had experience with a Yamaha Amp that has a Sub out? i tried to set it up so that the sub out was turned on, and hooked that up to the amp that i built which i then hooked up to just some ordinary Sony speakers, i was expecting to hear some bass, but to my dismay... nothing came out... not even a buzz or hum! am i doing something wrong? i set it up through the Yamaha settings so that a sub was present in the system.

I'm afraid that maybe they made it so that only Yamaha Subs will work with this amp, is that possible? if so i guess ill have to just connect the amp i built directly to the source (in my case the DVD player) and build in a equalizer or something into my amp so only the low frequencies are sent to the WO.

unless of course someone has a solution to my SUB out problem on the Yamaha amp, he he...

hopefully ill get the time to complete the rest and have the set up ready for testing. ill try and keep taking pictures of the assembly process.
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« Last Edit: 11/05/07 at 11:54:45 by wayan »  
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Bart_West-VL.
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Re: Two Halves
Reply #29 - 11/06/07 at 08:43:28
 
First of all, congratulations!! Wink
It must have felt good to finish this baby.

I was just a little confused when I read:
"i did try and connect both left and right outputs to one driver, and that resulted in a more impressive kick."
I agree that it has more 'kick' because of the doubling in power, but be careful with that, if not fot the SQ, then for the life expectation of you're amp and driver.

That LFE output may only work with DVD's? I'm only guessing here because it is the .1 channel of a 5.1 setup.
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