Need advice for a preamp or a good place to go to learn about what I need. I have a JBL ES250P that the plate amplifier broke on and I’m trying to piece together an amplifier for. I got a Sure Electronics T-amp AA-AB31511 500w mono amp. It works, but there isn’t enough power to work off of my Onkyo receiver. So I need a preamp and need advice on what to get or what i need to look for. I would like to keep using my LFE output of the receiver, but could set up a crossover as well.
The one I think is the most basic and should work is the Ne5532. I can just set LPF to the highest and use mono input and output, correct? Also, can I use ground and +24 VDC from an SE-600-48?
Any help would be appreciated.
The one I think is the most basic and should work is the Ne5532. I can just set LPF to the highest and use mono input and output, correct? Also, can I use ground and +24 VDC from an SE-600-48?
Any help would be appreciated.
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Hi
The wondom amp has a gain of 31dB and a max of 50V. your planned smps us 48V so you are on the safe side.ok.
your Voltage at max power will go down lets say to 46V or less.
so Gain = 20*log( Uout/Uin) --> 31 = 20*log (46V/Uin)
Uin = 1,29Volt input Voltage what you need from the onkyo.
why you dont get this? maybe the original amp use more Gain and a bigger Voltage to get more power...
can you measure the old power supply in the subwoofers amp?
chris
The wondom amp has a gain of 31dB and a max of 50V. your planned smps us 48V so you are on the safe side.ok.
your Voltage at max power will go down lets say to 46V or less.
so Gain = 20*log( Uout/Uin) --> 31 = 20*log (46V/Uin)
Uin = 1,29Volt input Voltage what you need from the onkyo.
why you dont get this? maybe the original amp use more Gain and a bigger Voltage to get more power...
can you measure the old power supply in the subwoofers amp?
chris
It was 70 VDC to the amp, I believe it had a preamp as well though. It was rated at 400W, but I don’t think the amplifier was doing all of the work.
It also looks like the spec sheet of the subwoofer says the gain was 49db so it only need 0.89v, correct?
It also looks like the spec sheet of the subwoofer says the gain was 49db so it only need 0.89v, correct?
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What ohm load is the 12" woofer? the Wondon is rated at 350W @1% THD and 500W @10% THD all at 3-ohms (FYI 10% would not be listenable IMO).
Your JBL claims 400W with a max of 700W and running at 70Vdc, might be able to actually hit those figures. Since they give no distortion figures to back up their claim.
IMHO - you have two options:
1) you could buy a pre-amp, but only to boost your Onkyo's signal. However, 1V should be able to drive most amps just fine.
2) your Wondon amp is highly over-rating it's output, so you are hearing that difference. Could be solved by buying bigger amp, 750W or 1000W, since those are likely over-rated too.
3) Turn down your other channels - so they more closely match the subwoofer gain.
Your JBL claims 400W with a max of 700W and running at 70Vdc, might be able to actually hit those figures. Since they give no distortion figures to back up their claim.
IMHO - you have two options:
1) you could buy a pre-amp, but only to boost your Onkyo's signal. However, 1V should be able to drive most amps just fine.
2) your Wondon amp is highly over-rating it's output, so you are hearing that difference. Could be solved by buying bigger amp, 750W or 1000W, since those are likely over-rated too.
3) Turn down your other channels - so they more closely match the subwoofer gain.
Speaker is 4 ohms, 3.9 measured.
I only ever ran the other plate amp at half volume and I still had to lower the output of the receiver by 10dB. My room is a 10’x16’ rectangle and I have another identical sub. Which is why I thought the 350W would be enough. Would that Ne5532 be what I’m looking for? I could just drive it off of one leg of my 48VDC PS?
I only ever ran the other plate amp at half volume and I still had to lower the output of the receiver by 10dB. My room is a 10’x16’ rectangle and I have another identical sub. Which is why I thought the 350W would be enough. Would that Ne5532 be what I’m looking for? I could just drive it off of one leg of my 48VDC PS?
You can't use "half" of the PSU, because it's not a +/- supply, only a +/Gnd, so there is no "middle" to be had.
You could buy a buck converter, assuming it is proper amerage, and reduce the voltage from 48 down to 15.
I would find a good headphone amplifier that produces ~0.5-1watt, which should give you more then enough added gain. It will also run off a wall wart transformer and can sit it right next to the Onkyo and use the same LFE cable to your sub, so no changes except behind the Onkyo. Set it so you can just barely get the subwoofer to clipping, then you will never mess with the pre-amp again.
You could buy a buck converter, assuming it is proper amerage, and reduce the voltage from 48 down to 15.
I would find a good headphone amplifier that produces ~0.5-1watt, which should give you more then enough added gain. It will also run off a wall wart transformer and can sit it right next to the Onkyo and use the same LFE cable to your sub, so no changes except behind the Onkyo. Set it so you can just barely get the subwoofer to clipping, then you will never mess with the pre-amp again.
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