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Old 25th April 2017, 04:07 AM   #1
bcodemz is offline bcodemz  Canada
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Default Interpreting input sensitivity and voltage gain?

I'm looking at the ICEpower amp I have, and something jumped out at me.

The voltage gain is only 21dB. The input sensitivity is 2.7V. Does that mean it will take 2.7V on the preamp side to reach full power on the amp? That seems like an awful lot. My DAC only outputs 1V.

Am I interpreting these results correctly? If I am correct, what can I do to increase the output on the preamp besides buying a new DAC?
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Old 25th April 2017, 04:10 AM   #2
rayma is offline rayma  United States
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Originally Posted by bcodemz View Post
If I am correct, what can I do to increase the output on the preamp besides buying a new DAC?
That's right. What equipment are you using? You need more gain, at least 2.7 times (8.6dB) more.

Last edited by rayma; 25th April 2017 at 04:14 AM.
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Old 25th April 2017, 04:33 AM   #3
bcodemz is offline bcodemz  Canada
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Originally Posted by rayma View Post
That's right. What equipment are you using? You need more gain, at least 2.7 times (8.6dB) more.
OK that's a real problem. I never expected this problem, but understandable since it is probably designed that way so it won't easily clip from high input gain, but this is bad for home audio use. The amp is the ICEpower 50ASX2. I'm using the Asus Xonar U7. The output voltage is only 1V, and I will lose 8.6dB of headroom if I use it as is.

Are there anything that can boost a line level signal?
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Old 25th April 2017, 10:41 AM   #4
ICG is offline ICG  Germany
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You could use a preamp/buffer preamp in between or - probably the better solution - use an autoformer/audio tranformer.
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Old 25th April 2017, 03:34 PM   #5
rayma is offline rayma  United States
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Originally Posted by bcodemz View Post
Are there anything that can boost a line level signal?
You can use an opamp 10dB gain stage, that's easy enough to put together.
There are lots of China pcbs for this, even with power supplies on board.
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Old 25th April 2017, 03:39 PM   #6
bcodemz is offline bcodemz  Canada
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Originally Posted by rayma View Post
You can use an opamp 10dB gain stage, that's easy enough to put together.
There are lots of China pcbs for this, even with power supplies on board.
Can you provide a link for one of these so I know what keywords to look for when searching? I don't really know anything about opamps. Right now all I find is just the raw opamp chips. Ideally I want an assembled PCB that'll provide at least 10dB of gain for 2 channels, can work with 17V DC power, and uses raw wires for input/output (not RCAs). Thanks

Last edited by bcodemz; 25th April 2017 at 03:49 PM.
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Old 25th April 2017, 03:48 PM   #7
rayma is offline rayma  United States
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Originally Posted by bcodemz View Post
Can you provide a link for one of these so I know what keywords to look for when searching? I don't really know anything about opamps. Right now all I find is just the raw opamp chips. I want an assembled PCB that'll provide at least 10dB of gain. Thanks
Here's an example that looks good. You'll need to add a power transformer.
https://www.aliexpress.com/item/Upda...e-106161a9e9c0
Another one: https://www.aliexpress.com/item/LM46...e-106161a9e9c0
Another: https://www.aliexpress.com/item/Free...ceab50e2&tpp=1

Last edited by rayma; 25th April 2017 at 03:57 PM.
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Old 25th April 2017, 03:55 PM   #8
bcodemz is offline bcodemz  Canada
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Originally Posted by rayma View Post
Here's an example that looks good. You'll need to add a power transformer.
https://www.aliexpress.com/item/Upda...e-106161a9e9c0
Another one: https://www.aliexpress.com/item/LM46...e-106161a9e9c0
Thanks!

I don't need one with all the knobs for volume and tone control. I just need a simple one for gain. How do I tell how much gain the opamp provides? It doesn't mention on the product pages I see. I'm seeing ones for NE5532 for example, but since there is no knobs, I can't find how much gain they provide. Any tips?
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Old 25th April 2017, 04:00 PM   #9
rayma is offline rayma  United States
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Originally Posted by bcodemz View Post
Thanks!

I don't need one with all the knobs for volume and tone control. I just need a simple one for gain. How do I tell how much gain the opamp provides? It doesn't mention on the product pages I see. I'm seeing ones for NE5532 for example, but since there is no knobs, I can't find how much gain they provide. Any tips?
With some more searching you'll find a tone control-less pcb.
Once you find a pcb of interest, email the vendor and verify the amount of gain.
Most should have around 15-20dB. These listings have few specs.
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Old 25th April 2017, 04:11 PM   #10
rayma is offline rayma  United States
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Originally Posted by bcodemz View Post
Thanks!

I don't need one with all the knobs for volume and tone control. I just need a simple one for gain. How do I tell how much gain the opamp provides? It doesn't mention on the product pages I see. I'm seeing ones for NE5532 for example, but since there is no knobs, I can't find how much gain they provide. Any tips?
Here's a basic one. Again, email the vendor and ask about the amount of gain.
You add the power supply. https://www.aliexpress.com/item/NE55...9-89529782c175
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