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?
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?
That's right. What equipment are you using? You need more gain, at least 2.7 times (8.6dB) more.
Last edited:
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?
You could use a preamp/buffer preamp in between or - probably the better solution - use an autoformer/audio tranformer.
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:
Here's an example that looks good. You'll need to add a power transformer.
https://www.aliexpress.com/item/Upd...lgo_pvid=4f933c30-2946-488e-a99e-106161a9e9c0
Another one: https://www.aliexpress.com/item/LM4...lgo_pvid=4f933c30-2946-488e-a99e-106161a9e9c0
Another: https://www.aliexpress.com/item/Fre...id=fe8f89dd-96be-4d10-8e55-0fbbceab50e2&tpp=1
Last edited:
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.
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/NE5...lgo_pvid=5f2edf2d-e1ed-4af7-9719-89529782c175
Inverting Operational Amplifier - The Inverting Op-amp
Tells you how to set the gain by altering the resistors.
Tells you how to set the gain by altering the resistors.
Ofcourse a preamp is more flexible and often a better solution but it brings a few problems with it too, i.e. probably the need for a symmetrical power supply or GND problems. Well, all the suggested solutions add noise, a transformer does not though and solves a GND/hum loop instead of possibly creating one. I'm not saying it's generally the better solution but there are some cases in which it is.
If you want to go for an OP, I can recommend this one (eBay), cheap, no unneded tone/EQ stuff, works with AC and DC, rectifier and stabilizer on the board and the OP is even socketed.
If you want to go for an OP, I can recommend this one (eBay), cheap, no unneded tone/EQ stuff, works with AC and DC, rectifier and stabilizer on the board and the OP is even socketed.
I'm looking at that and I'm seriously considering it. My question is how much gain does it provide? My use purpose is to take my 1V output from my DAC and boost it to at least 2.7V for my amplifier. The eBay NE5532 link says 5x magnification. What does that mean? Does that mean 1V input --> 5V output?
You won´t find an exact 2.7X gain preamp board , but you can easily halve the 5x gain by adding just 2 resistors (one per channel).
Only problem is they must certainly be tiny SMD parts.
Plan B: attenuate signal at the preamp input with 2 resistors per channel, which can be normal (through hole) size
Plan C: use as is (with the 5X gain preamp in between), you won´t need to set your DAC that high and you´ll be effectively getting 6 dB headroom on the DAC side. Not bad 😉
Only problem is they must certainly be tiny SMD parts.
Plan B: attenuate signal at the preamp input with 2 resistors per channel, which can be normal (through hole) size
Plan C: use as is (with the 5X gain preamp in between), you won´t need to set your DAC that high and you´ll be effectively getting 6 dB headroom on the DAC side. Not bad 😉
Plan C is definitely my intention 🙂. The amp has clip and overload protection anyways, so I'm not worried. My DSP has a limiter for the bass, so the only way to overload is through over 200W of low midrange 😱
Either way this is perfect. I need extra gain anyways because I'm having headroom problems with JRiver as the DSP processor.
Either way this is perfect. I need extra gain anyways because I'm having headroom problems with JRiver as the DSP processor.
21dB=20*log(V/V), thus V/V=10^(21/20)=11.220V/V
Just to clarify, is the DAC output figure in Vdc or Vrms? 1V peak is 0.707Vrms, but 1Vrms is 1.414V peak. That would change your gain requirements.
The ICEpower modules appear to be designed so that a 2Vrms signal (2.828V peak) would drive the output to the rail. I used to have an old (mid 80's) CD player that had 2Vrms line level outputs. I thought most newer equipment had ~1Vrms line level outputs.
You obviously didn't look very closely but I don't blame you for that. On the first picture within the description you can see an image with arrows to two resistors (/r5, /r7). If you replace these two resistors, you can get a really wide range of gain, from 0dB to around 30dB (haven't changed the resistors and measured the gain myself yet) which should be enough for about any application you'd need. Even unmodified it should be enough for your needs.
- Status
- Not open for further replies.