Which DIY portable amp should I build first? - Page 2

Quote:

Originally Posted by naptunian 

Here's a question from a newbie...  Will a CMoy improve the sound from a portable player to a pair of Ultimate Ears SuperFi 5 buds?  I understand that it can boost the power to drive bigger open circumaural type headphones but I haven't read anything about CMoys being used for earbud type headphones.

Yes, it will drive earbuds also.  I liked my super.fi 5ebs before I built my cmoybb, I loved them after.

Sdotfire, you're going to enjoy building a cmoy.  Remember that you don't have to put it in a mint tin and can use a box similar to the mini3.  I originally had my cmoybb in an altoids tin (see avatar) but I just ordered a hammond case from mouser to move it to a sleeker case.

Let us know how it goes!

Might want to check the gain with the IEMs. I think I recall that being an issue with some models. It should be easy enough to modify on a CMoy if necessary, a matter of changing resistor values, but you should verify that the new params are in spec for your op-amp as well.

I am using this combo. I think the SF5s sound audibly better. Hard to describe - I would say that all frequencies feel more "deliberate" and "driven". I don't have the proper audiophile terms to describe it, but I think you'll see what I mean. Mine have a minor hiss - can't hear it when the music is actually playing. I am going to add decoupling caps at the op-amp to see how much that helps, and then drop the gain as necessary. My gain is still at the default 11 which is total overkill on the 13ohm SuperFis, but I left it so far, not knowing what full size cans I may use it on later. That being said, I recently ordered the AD700s, which are only 32ohm, so I may drop the CMOY gain to 6.

Hope this helped..

Quote:

Originally Posted by naptunian 

Here's a question from a newbie...  Will a CMoy improve the sound from a portable player to a pair of Ultimate Ears SuperFi 5 buds?  I understand that it can boost the power to drive bigger open circumaural type headphones but I haven't read anything about CMoys being used for earbud type headphones.

the process requires a little math but seach for the headphone model and add "ohm" and "dB" to the search

I get 21 Ohms and 115 dB/mW - quite typical of sensitive iem - if you do the rms power math the SuperFi 5 requires ~ .2 V, 10 ma peak drive for 115 dB SPL - which is proably adequate dynamic peak SPL headroom for most listeners

even if you want over 120 dB SPL peak capability you would only need ~ 0.4 V, 20 mA

basically no you shouldn't need a amplifier with a DAP - most LiIon power DAP put out ~1 Vrms and enough current for 16 Ohm loads

most DAP will have a purpose designed op amp better at driving low Z loads like 21 Ohms than any DIP op amp normally used with the CMOY

so loudness or even distortion is no reason to prefer a CMOY class amp over most DAP for the SuperFi - the coupling C issue I metioned earlier is likely the only objective spec that may be improved by an external amp and a series attenuator can help with that and the hiss

large circumaural headphones may have 100x less sensitivity and 10x higher Z both requiring more V than a DAP can provide

I could be wrong, but I thought I recalled a 13ohm impedance on my SuperFi5s. Sure that the 21ohm result you found wasn't referring to the SuperFi5 Pro or something?
 

Quote:

Originally Posted by jcx 

Quote:

Originally Posted by naptunian 

Here's a question from a newbie...  Will a CMoy improve the sound from a portable player to a pair of Ultimate Ears SuperFi 5 buds?  I understand that it can boost the power to drive bigger open circumaural type headphones but I haven't read anything about CMoys being used for earbud type headphones.

 

the process requires a little math but seach for the headphone model and add "ohm" and "dB" to the search

 

I get 21 Ohms and 115 dB/mW - quite typical of sensitive iem - if you do the rms power math the SuperFi 5 requires ~ .2 V, 10 ma peak drive for 115 dB SPL - which is proably adequate dynamic peak SPL headroom for most listeners

 

even if you want over 120 dB SPL peak capability you would only need ~ 0.4 V, 20 mA

basically no you shouldn't need a amplifier with a DAP - most LiIon power DAP put out ~1 Vrms and enough current for 16 Ohm loads

 

most DAP will have a purpose designed op amp better at driving low Z loads like 21 Ohms than any DIP op amp normally used with the CMOY

 

so loudness or even distortion is no reason to prefer a CMOY class amp over most DAP for the SuperFi - the coupling C issue I metioned earlier is likely the only objective spec that may be improved by an external amp and a series attenuator can help with that and the hiss

 

 

large circumaural headphones may have 100x less sensitivity and 10x higher Z both requiring more V than a DAP can provide