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Low gain amp that I can build that would output cleanest signal possible  

post #1 of 36
6/25/11 at 7:52am
Thread Starter 

I will need an amp for my highly sensitive IEMs.  ER4P, 1964-T customs, UM3X.  I want to reduce hiss so I want low gain, but I want highest quality Amp possible.  I want the cleanest signal possible out of the amp.  I have a Gamma 2 DAC already, but it only attenuates volume through software.  Should I just add an attenuator? If so what is a good attenuator(that I can add externally) that will keep the signal clean as possible?  

 

Please also recommend me the highest quality low gain amp that I can build.  Thanks.

 

Also, there is no reason to build a Beta 22 for sensitive IEMs right, it's an overkill right?  Beta22 is designed for high impedance headphones right?


Edited by user02 - 6/25/11 at 8:00am
post #2 of 36
6/25/11 at 9:00am

I like the little transformer box a bunch. Sounds quite nice, and is cheap!

 

Link to thread

 

The B22 has some applications for low impedance headphones, and particularly a few medium impedance (like 60-100ohms) headphones that have very low efficiency, but you are right to look out for noise. Noise with IEM's is IMO the biggest problem unless you listen above about 90-100db.

post #3 of 36
6/25/11 at 10:02am

What's the audible noise level with these sensitive IEMs you talk about?

Say,most portable amps have -90 dB noise level(1.4 VRMS for 0 dB),is that audible ?

post #4 of 36
6/25/11 at 11:40am
Thread Starter 

Transformer looks kinda useless IMO.  I don't see a purpose of a transformer.  It's like adding extra impedance(adding phase and resistance) to the path, it's kinda useless.  I'm looking to control volume.
 

Quote:
Originally Posted by nikongod View Post

I like the little transformer box a bunch. Sounds quite nice, and is cheap!

 

Link to thread

.



 


Edited by user02 - 6/25/11 at 11:45am
post #5 of 36
6/25/11 at 12:15pm

 

Quote:
Originally Posted by user02 View Post

Transformer looks kinda useless IMO.  I don't see a purpose of a transformer.

 


Im sorry you dont see it.

 

The point is to attenuate voltage ~21db, provide a low output impedance for the load, and isolate the output devices from the load.

 

Quote:
Originally Posted by user02 View Post

 It's like adding extra impedance(adding phase and resistance) to the path, it's kinda useless.  I'm looking to control volume.
 


Not really. 

 

Adding impedance - The transformers have very low output impedance. Its basically the secondary DCR as they are used here, about 0.8ohms on mine. Adding impedance screws with crossovers in multi-driver headphones/speakers in unpredictable ways this does not. 

 

Phase shifts - Not here. Sorry. Other transformers do have issues with phase shifts in the audio band though.

 

Control volume - 21db of voltage attenuation without simple wasteful attenuation. This should get you to a range where you can use the digital attenuator in the gamma2 nicely. 

post #6 of 36
6/25/11 at 12:31pm
Thread Starter 

^You seem to be fixated with your transformer than giving out proper advice.  Read OP again.  You've avoided the fact that the transformer does nothing useful, it's something you put in the path that has no functionality.


Edited by user02 - 6/25/11 at 12:34pm
post #7 of 36
6/25/11 at 12:35pm

You remind me of another head-fier :)

post #8 of 36
6/25/11 at 12:37pm

 

 

 


Quote:
Originally Posted by user02 View Post

^You seem to be fixated with your transformer than giving out proper advice.  Read OP again.  You've avoided the fact that the transformer does nothing useful, it's something you put in the path that has no functionality.

 

 

Heres how I read it:

You want a low gain amp with minimal noise contribution to the system. You also ask if you should just add an attenuator (I assume between the headphone output and the load, could you clarify?) and whether the b22 would be a suitable amp for IEM's.

Did I condense that appropriately?



Quote:
Originally Posted by user02 View Post

I will need an amp for my highly sensitive IEMs.  ER4P, 1964-T customs, UM3X.  I want to reduce hiss so I want low gain, but I want highest quality Amp possible.  I want the cleanest signal possible out of the amp.  I have a Gamma 2 DAC already, but it only attenuates volume through software.  Should I just add an attenuator? If so what is a good attenuator(that I can add externally) that will keep the signal clean as possible?  

 

Please also recommend me the highest quality low gain amp that I can build.  Thanks.

 

Also, there is no reason to build a Beta 22 for sensitive IEMs right, it's an overkill right?  Beta22 is designed for high impedance headphones right?


Edited by nikongod - 6/25/11 at 1:27pm
post #9 of 36
6/26/11 at 3:43pm
Thread Starter 

I want to build a device I can control the volume out of a DAC.  One option was a volume attenuator.  I was asking for a volume attenuator so that I don't get any bit-loss if Gamma 2 DAC volume is done through software.  What is the best analog attenuator solution that would provide me with the cleanest signal possible?  Should I use the PGA2320 that you have mentioned on the LOD thread that I have started or is there are better attenuator?  I guess it would depend on the voltage range. 

 

My other option is to add a amp at the output of the DAC line out.  If I do choose that option.  My question was should I build a Beta22.  Is it intended for high load?  I have always been interested in building a Beta22.  For IEMs is it an overkill since I do not want noise amplified to a level that I can hear it?  Should I build a CMOY with low gain, would that be good enough?  Is Beta22 for low efficient phones or also good for IEMs?  I want to build the best sounding amp because I know my IEMs pick up the slightest details.

 

What are my options for headphones that have less than 32 ohms impedance with around 120 sensitivity?  I want to build that best sounding system for highly sensitive headphones.  I have a Buffalso 2 kit, should I work with that?  If so, can anybody list me the parts I need to build a good buffalo that I can adjust volume for IEMs, and have just enough gain to lose the hiss for sensitive IEMs?  Thanks.

 

Quote:
Originally Posted by user02 View Post

I will need an amp for my highly sensitive IEMs.  ER4P, 1964-T customs, UM3X.  I want to reduce hiss so I want low gain, but I want highest quality Amp possible.  I want the cleanest signal possible out of the amp.  I have a Gamma 2 DAC already, but it only attenuates volume through software.  Should I just add an attenuator? If so what is a good attenuator(that I can add externally) that will keep the signal clean as possible?  

 

Please also recommend me the highest quality low gain amp that I can build.  Thanks.

 

Also, there is no reason to build a Beta 22 for sensitive IEMs right, it's an overkill right?  Beta22 is designed for high impedance headphones right?






 

 


Edited by user02 - 6/26/11 at 4:45pm
post #10 of 36
6/26/11 at 5:55pm
Did you think of the α20? http://www.amb.org/audio/alpha20/
post #11 of 36
6/26/11 at 6:15pm
Thread Starter 


Can you tell me the reasons for recommending alpha20?

Quote:
Originally Posted by Lil' Knight View Post

Did you think of the α20? http://www.amb.org/audio/alpha20/


 

post #12 of 36
6/26/11 at 7:55pm

The α20 can be run in unity gain, perfect for IEMs.

post #13 of 36
6/26/11 at 8:01pm
Thread Starter 

If would run it strictly for unity gain, would it be overkill?  If were to use it for other headphones, It could be worth it.  Is it easy to switch to unity gain, and back and forth?  I'm thinking about getting a LCD-2 and building a Beta 22 or 24, but can't decide which.  I would like something that I can change the gain on the fly.  Am I asking for too much?  I would go for the Beta 22 or 24 if I were to get LCD-2 or HD800.  I would really like something I can change the gain on the fly.
 

Quote:
Originally Posted by ShinyFalcon View Post

The α20 can be run in unity gain, perfect for IEMs.



 


Edited by user02 - 6/26/11 at 8:04pm
post #14 of 36
6/26/11 at 8:14pm
So, the beta24 is targeted as a speaker amp. The beta22 is targeted as a headphone amp. As such, we may have eliminated one from the conversation. wink.gif

Are you looking for more volume, more control or a different sound characteristic?

There are solutions for each of these areas. The solutions may or may not overlap. What is most important to you?
post #15 of 36
6/26/11 at 8:21pm
Thread Starter 

It's down to beta22 and alpha20 and any other suggests.  I want to power LCD-2 or HD800 at sufficient level and also be able to switch the gain so that my customs will not pick up noise from headphone out.  I wonder how the noise performance on the beta22 is even at high gain.  Does noise depend on the circuit as a whole or on the opamp?  I know if I reduce gain on my CMOY opamp, it get rid of the hiss at low volume level.  
 

Quote:
Originally Posted by jdkJake View Post

So, the beta24 is targeted as a speaker amp. The beta22 is targeted as a headphone amp. As such, we may have eliminated one from the conversation. wink.gif

Are you looking for more volume, more control or a different sound characteristic?

There are solutions for each of these areas. The solutions may or may not overlap. What is most important to you?


 


Edited by user02 - 6/26/11 at 8:22pm
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