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Worth changing drivers from 8 Ohm to 4 Ohm to get more power?


richrips
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I just purchased an ashdown little giant and played my first gig last night.

I found the both the pre-gain and master volume were both nearly maxxed and this was a jazz gig in a room barely bigger than a large living room.

The LG 1000 has a rated output of 1000 watts in to 4 Ohms (and before i get jumped on, i know it is 2 seperate power amps and you would need 2 4 ohm cabs to get full power).

i have 2 cabs rated at 8 Ohms. they contain kappalite 3012HO drivers with rms 400watts each.

I'm guessing the power i should be getting in to 8 ohms would be between 250-350 watts per speaker (this depends on output voltage from the amp i believe??)

Oddly, my previous amp, a crown xls 402 with peavey alpha valve preamp, kicks out 450watts per side in to 4 ohms- apparently less than the ashdown, but seems much much louder....

[url="http://www.crownaudio.com/amp_htm/xls.htm"]http://www.crownaudio.com/amp_htm/xls.htm[/url]

is there something i have overlooked which makes the crown more powerful with my cabs than the ashdown?
would it be worth swapping my kappalites for some 4 ohm 12's?

tech help much appreciated!

cheers,
rich

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[url="http://klaas.homeip.net/wb/pages/diy/amps/ashdown-little-giant-350.php"]http://klaas.homeip.net/wb/pages/diy/amps/...e-giant-350.php[/url]

i don't know if anyone would know, but is there, or is there likely to be a difference in the preamp section for the 1000 and 350? I saw the link above recently on here and wondered if it applied to both models, as maplin sell all the necessary.....

also, what's the deal with overdriving a class d power amp? does it clip? or does it just expire? i'm worried about damaging it if i run a boost pedal in to it (got an aphex punch factory which i guess would do)

any thoughts?

Edited by richrips
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[quote name='richrips' post='727551' date='Jan 28 2010, 01:30 PM']i don't know if anyone would know, but is there, or is there likely to be a difference in the preamp section for the 1000 and 350? I saw the link above recently on here and wondered if it applied to both models, as maplin sell all the necessary.....[/quote]

pPre-amp is exactly the same in both models. I have the schematic if anyone needs it

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[quote name='richrips' post='727531' date='Jan 28 2010, 01:19 PM']I just purchased an ashdown little giant and played my first gig last night.

I found the both the pre-gain and master volume were both nearly maxxed and this was a jazz gig in a room barely bigger than a large living room.

The LG 1000 has a rated output of 1000 watts in to 4 Ohms (and before i get jumped on, i know it is 2 seperate power amps and you would need 2 4 ohm cabs to get full power).

i have 2 cabs rated at 8 Ohms. they contain kappalite 3012HO drivers with rms 400watts each.

I'm guessing the power i should be getting in to 8 ohms would be between 250-350 watts per speaker (this depends on output voltage from the amp i believe??)

Oddly, my previous amp, a crown xls 402 with peavey alpha valve preamp, kicks out 450watts per side in to 4 ohms- apparently less than the ashdown, but seems much much louder....

[url="http://www.crownaudio.com/amp_htm/xls.htm"]http://www.crownaudio.com/amp_htm/xls.htm[/url]

is there something i have overlooked which makes the crown more powerful with my cabs than the ashdown?
would it be worth swapping my kappalites for some 4 ohm 12's?

tech help much appreciated!

cheers,
rich[/quote]

Yes, I think you are confusing GAIN with POWER. In all probability, if these amps have the rep for being a bit low on gain, in order to extract the power you need more gain, which you should be able to get either by putting a pre-amp pedal between bass and amp, or in the effects loop (if it has one).

Robustness of that product notwithstanding, you shouldn't be able to kill the amp by overdriving it - certainly not into 8 ohms anyway - it should be clipping well before it reaches any thermal limits, and it's internal protection should take care of all of that anyway...

Those 3012 HO drivers are quite efficient - IMHO it should get very loud.

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Thanks guys. All good answers. i think the weak preamp may be the problem indeed and from whats been said, there seems to be little to gain from swapping out speakers. i'm keen to put in the boost circuit from the link above as this would mean no boost pedal needed and give me the plug and play portability i want. i hope boosting the gain in this way works as my other band (i've only used this in the jazz/funk group) need loud deep bass as it is ska/reggae.

has anyone tried the preamp boost mod on their little giant? looks like a cool fix to a simple problem in what is otherwise a very good amp, and much improved over the much tackier superfly.

cheers.
rich

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[quote name='Bill Fitzmaurice' post='727874' date='Jan 28 2010, 05:44 PM']Make sure the EQ isn't the culprit. I get enough output from a 1x12 on one channel of my Superfly, but only using my own EQ presets. The factory presets were all set to less than unity.[/quote]

Bet you've got one of them funny 1x12s that guy sells pictures of though. The Titans are monolithic and Doom, but otherwise, whats the point if you can't see how loud the speaker looks?

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[quote name='richrips' post='728174' date='Jan 28 2010, 05:13 PM']This is my rig, 2 x BFM jack 12's

[url="http://basschat.co.uk/index.php?showtopic=60932&hl="]http://basschat.co.uk/index.php?showtopic=60932&hl=[/url]

and an ovation magnum or stingray[/quote]
My rig is one J112, loaded with a 2512, so yours is better than mine. You should be able to do stadiums with those cabs, so something in the amp setup is out of whack. Be very sure the cabs aren't out of polarity.

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