diy stealth subamp

[tmyr]

hi ! all u audio fanatics !
here is my idea
@
450rms 8x irfp250 mosfet mono amp
+/-60v rails from 28Ax4x4 mosfet smps with double discrete 1000v rectifiers
temp controled fan cooling
0.8~x volt input
to drive a JBL p1220 400rms 19.5kg! woof in a seald all fiberglass enclosure

and its out of my way and sight... with fully operational trunk

just sits and waits headunits 20 day delivery for 300miles distanse in united europe
from 12voltshop... :( shkit . .

[300Z]

Very nice... DIY amp... :)

20 days for a 300 miles distance? are they walking? :confused:

Leo

[DvMxDv]

Hey tmyr,

Nice DIY. Are there schematics/instructions available for this amp? LMK.

Thanks!

[KingSVT]

AWESOME! how do you like your JBL p1220?

[ArcL100]

That amp is so sweet!

-aaron

[tmyr]

for schematics google or yahoo for a.holton n-channel amp(the updated ver)
or realy any amp will do for the given rail voltage etc
the smps is an ESP-site design as common as it gets
overengineerd with what i had ...


just make a list of specs and realize them with the usual compromizing
as we cant have everything but be we can avoid the worst.. (some philosophising)

protection is minimal.. fused at crusial points only.. for the worst case
mistake scenario.. if i avoid short cirquiting anything (whitch i once did and i got away with it) ..it should work for some time .. forever would be nice.

p1220 is still waiting adequate amp to drive it witch hangs on hu's delivery
but i dit test at home with from 100w to even with a 2w tude diy and its quite nice for the mass of it all... jbl has some experience in the field so it mast be something ..the motor is something to talk about anyways

its time for vacation friends
the best summer to all !!

[tmyr]

..well.. the amp is a nice surprise. :rolleyes:
it drives the jbl p1220 out of its x-max so easy ill have to gain it down a bit.
with no audible distortion up to the woofs nominal excursion except for the
cars falling appart harmonics.. The bass setup is a hair-raiser
the ugly surprise is the JVC KD-SH1000... :confused:
the x-over wich is essential for my setup is ... so fichting stupid
it delivers a 3-way system setting the front speakers as tweaters
the rear speakers as mids and uses sub-out preamp for bass..
no other setup is possible.
my car is a usual 4+1 seater sedan and i wanted the usual 2 audio stages, front and back with fader control and the speakers filtered high pass say @125Hz and
low pass @same Hz for the sub. with the jvc x-over this is impossible. :mad:
the engineer who thought this out must be driving a truck or some fansy 2seater cabrio .... aaaaaargggg
now ill have to sell the stupid hu and buy me some alpine or dissmantle the car once again, run more speaker wires, connect the tweets and mids in series respectively to be @ nominal Z for hu amp and lose fader control..
...
dont i say dont buy JVC

[chad]

the x-over wich is essential for my setup is ... so fichting stupid
it delivers a 3-way system setting the front speakers as tweaters
the rear speakers as mids and uses sub-out preamp for bass..
no other setup is possible.
my car is a usual 4+1 seater sedan and i wanted the usual 2 audio stages, front and back with fader control and the speakers filtered high pass say @125Hz and
low pass @same Hz for the sub. with the jvc x-over this is impossible. :mad:
the engineer who thought this out must be driving a truck or some fansy 2seater cabrio .... aaaaaargggg
now ill have to sell the stupid hu and buy me some alpine or dissmantle the car once again, run more speaker wires, connect the tweets and mids in series respectively to be @ nominal Z for hu amp and lose fader control..
...
dont i say dont buy JVC

Woah, that's how most work!

Most headunits have front/rear/sub output. IF it has a 4th output for an active 2 way front satge then it would be obscure! It is not in the maker's best intrest to do this, very few people run an active rig from the headunit.

So if you go Alpine headunits it will be the same, I'm not sure about the assignability of the H701 but it would be a good question to ask. May want to make room for 2 DIN units!

Without me sounding like a smartass... or pissing anyone off..... How did you think your were going to get more than 8+ channels of audio out of 6 preamp output channels. I could be missing something here.

Chad

[tmyr]

Woah, that's how most work!

Most headunits have front/rear/sub output. IF it has a 4th output for an active 2 way front satge then it would be obscure! It is not in the maker's best intrest to do this, very few people run an active rig from the headunit.

So if you go Alpine headunits it will be the same, I'm not sure about the assignability of the H701 but it would be a good question to ask. May want to make room for 2 DIN units!

Without me sounding like a smartass... or pissing anyone off..... How did you think your were going to get more than 8+ channels of audio out of 6 preamp output channels. I could be missing something here.

Chad

....well thats unfortunate..
my firtst setup some years ago was very successfull.. that sony hu had only HPF for the 4 speakers and it played them with small distortion only at volume end for 125hz and above . not much regarding power but enough for an imprecive listening experience at say 70% volume..
i realy like this kind of setup wich uses only one amp for bass x-overed by the hu . modern hu's may have changed their way of doing things.
i dont i say i dont wana go with passive crossovers
for sure i was a bit hasty picking the hu

do u know if the ALPINES V-drive units do this HP filtering for the 4 speakers?

ps. The damn JVC got pissed of me swering it so this morning it refused playing cd's. if it continues like this ill throw in the fire.

[300Z]

Most of the newer HU's can do 2way... low pass for the sub and high pass for the other speakers... Clarion, Kenwood, Pioneer, Panasonic, Sony, Eclipse, they all have built-in crossovers. Not sure if the newer Alpines have any crossovers tho...

Leo

[chad]

I think there is a mis understanding, mainly on my part. The Alpines with Bass engine Pro allow you to do a 3 way rig with sub/mid/hi coming out of the 6 outputs. The other mode is F/R high passed and a sub output. In order to do 3 way up front with rears you would need to add another stereo crossover to slice up the HP outputs. This will work but you will lose individual TA for each driver.

Do you plan to do passively crossed over front and rear stages or do you plan to do a fuly active setup? Are you intending to use the head unit's built in amplifier?

BYW that sub enclosure looks VERY nice! I drive a hatch too and plan to put the sub where you have your amp and a conventional amp to the side in a false floor raised up about 2-3". I too need to utilize my hatch area.



Chad

[tmyr]

the idea is to get clear music to my ears up to the point were it feels livelike (0db) with minimal but effective installation.
i find that most hu amplifiers can deliver this volume for the mids and highs range. using passive x-overs here drops hu's efficiensy wich i dont want since here every watt counts to the better. so the hu must have this hp filter for its amped outputs wich is also easilly adjustable .
then all we need is the bass engine..: a robust sealed enclosure . a large motor woofer . oversized amp gained down . and fat i say fat cabling
this way tha car stays a car and not some dedicated music platform with the ability to rattle or massage your body and please your ears with not much fuss and minimal sound polution to the rest of the world.

here are some box pics
ill post some more of the construction fase next time
its an all fiberglass 20kg, 1.5~2cm thick bolted down at protruding metal brackets and a steel wire plexing thru woofer frame to see what happens if someone hits me hard in the rear left .. :rolleyes:

[tmyr]

i've posted the box construction foto sequence @ http://www.diymobileaudio.com/forum/showthread.php?t=5346