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Mini3 + Etymotic ER4-S

post #1 of 9
4/13/10 at 1:17pm
Thread Starter 
First post!

I'm planning to build a Mini3 amplifier for my ER4-S. I don't have the ER4-S yet, but that's not the point. I'd like to know what would be the best voltage gain for the above configuration.

According to amb's site, I have the following options:
  • 2x
  • 3x
  • 5x
  • 8x

ER4-S's impedance is 100 Ohms nominal, according to its product page.
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post #2 of 9
4/13/10 at 2:20pm
Voltage gain of 2 will drive ER4s to dangerous levels off of a 2v nominal source.
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post #3 of 9
4/13/10 at 2:48pm
Thread Starter 
So, is that a bad thing?
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post #4 of 9
4/14/10 at 12:26am
No, it's just the highest you want to go as any gain higher than 2x and you're going to loose all travel on the volume pot.
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post #5 of 9
4/14/10 at 12:37pm
Thread Starter 
Quote:
Originally Posted by nattonrice View Post
...you're going to loose all travel on the volume pot.
Meaning the pot would be rendered useless?

I guess I'll be setting it for 2x gain then. Thank you for the replies!
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post #6 of 9
4/14/10 at 1:04pm
Meaning it will go from being off to being VERY loud with only a small turn of the knob.
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post #7 of 9
4/14/10 at 2:35pm

Mini3 - ER4S

I've used a mini 3 (standard x5 gain) with the ER4-S for nearly 2 years. I drive it from an Archos 504 with the player volume always at max. Typical pot setting is at about 11 o'clock, sometimes I go as high as 1 o'clock, but not often. I've been meaning to drop the gain but can't be bothered. If it works don't desolder it

Now if you were to drive it from a 2V rms source there would be an issue, the Archos is about 0.5Vrms at max and doesn't drive ER4S at all well.

So the question really is - what's your source level?
Kevin
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post #8 of 9
4/14/10 at 4:44pm
Thread Starter 
Quote:
Originally Posted by knorthover View Post
So the question really is - what's your source level?
Kevin
I don't really know.

I'm planning to connect it to a BantamDAC or the Gamma1. I still haven't decided between the two.
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post #9 of 9
4/14/10 at 9:25pm
Just to give you a frame of reference (output @ 0dBFS):

- Bantam: 1Vrms
- γ1: 1.6Vrms w/ WM8501 or 1Vrms w/ WM8759
- Most CD players: 2Vrms

The difference between 1V and 2V is 6dB. The difference between 1V and 1.6V is 4dB. Not a night and day difference.
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