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Mini3 gain, sq - Page 2

post #16 of 26
5/26/11 at 11:45am
Thanks for the mathematics.
All of the above means that, with a gain of 2 with the Mini^3, the loudness at 90% level would be the same as halfway on the CMoy at a gain of 11, right?
Does all of the above mean that a gain of 5 would be better for the volumes i listen to?
Thanks
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post #17 of 26
5/26/11 at 12:16pm
Quote:
Originally Posted by nullstring View Post

EDIT: Although.. I am thinking that maybe the output impedance matters in all this.

The gain is a voltage gain.. but I think the loudness works with the power gain.

So, I think this is wrong.

 


For figuring out gain, output impedance only matters if it is more than about 1/4 of the load impedance. 

 

For example: there will be very little difference in gain due to output impedance between 2 amps with 1 and 6ohm output impedance with a 32ohm load. 

If one amp had a 120ohm output, and the other a 3ohm output and the same 32ohm load the output impedance will have a significant effect on gain, and must be taken into account. 

On that note, amps with lots of global feedback generally have VERY low output impedances - usually in the single-ohm range.

 

I dont think power gain is the right term here, but Im not sure what is. 

Loudness does follow power, which follows the SQUARE of voltage into a constant impedance. 

Doubling voltage output quadruples output power into the same load. 

 

As long as the amp plays as loud as you want it cleanly Id say your doing OK. Its always nice to have a bit of extra spin in the pot & some extra power on tap to handle an especially low voltage source or a recording that was mixed with an unusually large amount of dynamic range. 

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post #18 of 26
5/26/11 at 1:41pm
Quote:
Originally Posted by psgarcha92 View Post

Thanks for the mathematics.
All of the above means that, with a gain of 2 with the Mini^3, the loudness at 90% level would be the same as halfway on the CMoy at a gain of 11, right?
Does all of the above mean that a gain of 5 would be better for the volumes i listen to?
Thanks

 

No, with a gain of 5 on the Mini^3, 90% loudness will be the same as 60% on the CMOY.
I would recommend gain 8.

 

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post #19 of 26
5/28/11 at 1:38pm
Thread Starter 
Quote:
Originally Posted by nullstring View Post



 

No, with a gain of 5 on the Mini^3, 90% loudness will be the same as 60% on the CMOY.
I would recommend gain 8.

 

wouldnt gain of 8 on a mini3 high performance, especially for iems, be complete overkill?
 

 

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post #20 of 26
5/29/11 at 1:54am
Quote:
Originally Posted by Fin1211 View Post



wouldnt gain of 8 on a mini3 high performance, especially for iems, be complete overkill?
 

 


Err, you tell me. You used a gain of 11 on the CMOY.

IIRC, Your IEMS have higher impedance than normal IEMS. Maybe they need it?

 

Because you said "on a mini3 high performance", you still don't seem to be getting it.

As I said. A gain of 11 on a CMOY is the same as a gain of 11 on the mini^3.

The M^3, a much more powerful amp comes with a default gain of 11.

Beta22 has a default gain of 8.

 

Since a gain of 11 on the CMOY only seemed slightly overkill.. a gain of 8 on the mini^3 should be just what you need.

 

The question is... is a gain of 11 overkill in general or not

is a gain of 8 in general over kill or not.

(You can add an IEM qualifier int here, but not a Mini^3 one)

 

You can always change your mind and switch out the resistors

Buy resistors for all four (or more) configurations. See which one you like best.

They are really cheap. No use sweating over it.

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post #21 of 26
5/29/11 at 12:55pm

 

Quote:

A gain of 11 on a CMOY is the same as a gain of 11 on the mini^3.

 

No it's not.

 The OPA2132 is not a rail to rail op-amp and would require a 20 volt supply to swing as much voltage as a Mini3 does from a single 9 volt battery (even more if the CMoy has the R5s). wink_face.gif

 

 

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post #22 of 26
5/29/11 at 1:02pm
Quote:
Originally Posted by MisterX View Post

 

 

No it's not.

 The OPA2132 is not a rail to rail op-amp and would require a 20 volt supply to swing as much voltage as a Mini3 does from a single 9 volt battery (even more if the CMoy has the R5s). wink_face.gif

 

 


Err, sure.. But as far as actual volume, they should be equal, right?

I never meant to imply the performance of a CMOY would match the Mini^3.

 

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post #23 of 26
5/29/11 at 2:18pm

Yup.  Sensitivity matters dB/mW, the power is where it matters.  So, even if its high impedance, it can have high sensitivity. Vice Versa.  Depending on how high the output impedance is, would limit the voltage to the load, not to mention the current is effected.

 

Look up Bode plot.  Real gain is  
 

 

Logarithmic units and decibels

[edit]Power gain

Power gain, in decibels (dB), is defined by the 10 log rule as follows:

\text{Gain}=10 \log \left( {\frac{P_{\mathrm{out}}}{P_{\mathrm{in}}}}\right)\ \mathrm{dB}

where Pin and Pout are the input and output powers respectively.

A similar calculation can be done using a natural logarithm instead of a decimal logarithm, and without the factor of 10, resulting in nepers instead of decibels:

\text{Gain} = \ln\left( {\frac{P_{\mathrm{out}}}{P_{\mathrm{in}}}}\right)\, \mathrm{Np}

[edit]Voltage gain

When power gain is calculated using voltage instead of power, making the substitution (P=V 2/R), the formula is:

\text{Gain}=10 \log{\frac{(\frac{{V_\mathrm{out}}^2}{R_\mathrm{out}})}{(\frac{{V_\mathrm{in}}^2}{R_\mathrm{in}})}}\ \mathrm{dB}

In many cases, the input and output impedances are equal, so the above equation can be simplified to:

\text{Gain}=10 \log \left( {\frac{V_\mathrm{out}}{V_\mathrm{in}}} \right)^2\ \mathrm{dB}

and then the 20 log rule:

\text{Gain}=20 \log \left( {\frac{V_\mathrm{out}}{V_\mathrm{in}}} \right)\ \mathrm{dB}

This simplified formula is used to calculate a voltage gain in decibels, and is equivalent to a power gain only if the impedances at input and output are equal.

[edit]Current gain

In the same way, when power gain is calculated using current instead of power, making the substitution (P = I 2R), the formula is:

\text{Gain}=10 \log { \left( \frac { {I_\mathrm{out}}^2 R_\mathrm{out}} { {I_\mathrm{in}}^2 R_\mathrm{in} } \right) } \ \mathrm{dB}

In many cases, the input and output impedances are equal, so the above equation can be simplified to:

\text{Gain}=10 \log \left( {\frac{I_\mathrm{out}}{I_\mathrm{in}}} \right)^2\ \mathrm{dB}

and then:

\text{Gain}=20 \log \left( {\frac{I_\mathrm{out}}{I_\mathrm{in}}} \right)\ \mathrm{dB}
Quote:
Originally Posted by nullstring View Post

 

EDIT: Although.. I am thinking that maybe the output impedance matters in all this.

The gain is a voltage gain.. but I think the loudness works with the power gain.

So, I think this is wrong.

Ok, so, it's 20* instead of 10* for voltage gain. I've fixed above.

The conclusion is the same.. 90% of the pot to get to the same voltage.

 

http://www.diyaudio.com/forums/tubes-valves/32334-db-into-voltage-gain.html

 

I am still thinking output impedance matters in all this....



 


Edited by High_Q - 5/29/11 at 2:22pm
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post #24 of 26
5/29/11 at 3:53pm

I might try gain of 4-5 rather than 8. 

If its possible do it on the cmoy first, where changing gain resistors is easier than on the mini-3.

 


Quote:
Originally Posted by High_Q View Post

Look up Bode plot.



what does a frequency based graph have to do with anything here?

 

Quote:
Originally Posted by Wikipedia View Post

A Bode plot is a graph of the transfer function of a linear, time-invariant system versus frequency, plotted with a log-frequency axis, to show the system's frequency response.


 

Quote:
Originally Posted by High_Q View Post

 Real gain is  


Which of those 3 defines real gain? The power and current gains (considered separately as there is not necessarily any relationship) are generally in the "whoa a lot range" for an active amplifier. Easily in excess of 60db for most.

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post #25 of 26
5/29/11 at 4:40pm
Quote:
Originally Posted by nikongod View Post

I might try gain of 4-5 rather than 8. 

If its possible do it on the cmoy first, where changing gain resistors is easier than on the mini-3.

 




what does a frequency based graph have to do with anything here?

 

Umm gain over the whole spectrum?  Its just an example.
 


Which of those 3 defines real gain? The power and current gains (considered separately as there is not necessarily any relationship) are generally in the "whoa a lot range" for an active amplifier. Easily in excess of 60db for most.

 

Power. dB/mW?



 


Edited by High_Q - 5/29/11 at 4:42pm
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post #26 of 26
6/2/11 at 3:27pm
Thread Starter 
Quote:
Originally Posted by nullstring View Post




Err, you tell me. You used a gain of 11 on the CMOY.

IIRC, Your IEMS have higher impedance than normal IEMS. Maybe they need it?

 

Because you said "on a mini3 high performance", you still don't seem to be getting it.

As I said. A gain of 11 on a CMOY is the same as a gain of 11 on the mini^3.

The M^3, a much more powerful amp comes with a default gain of 11.

Beta22 has a default gain of 8.

 

Since a gain of 11 on the CMOY only seemed slightly overkill.. a gain of 8 on the mini^3 should be just what you need.

 

The question is... is a gain of 11 overkill in general or not

is a gain of 8 in general over kill or not.

(You can add an IEM qualifier int here, but not a Mini^3 one)

 

You can always change your mind and switch out the resistors

Buy resistors for all four (or more) configurations. See which one you like best.

They are really cheap. No use sweating over it.


err, no. that wasnt me

 

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