[grrr223]

I am trying to build my first headphone amp now, the Pocket Headphone Amp from the Headwize.com project library, as I anxiously await the arrival of my first pair of real headphones, the Sennheiser HD580.

This little amp's schematic says to use a 9-volt battery, but I keep seeing posts on here for people using AAs. I'm curious what the pros/cons of each are.

Aren't AA batteries heavy and don't they take up a lot of space?

 

[JMT]

Quote:

Aren't AA batteries heavy and don't they take up a lot of space?

They can be, depending on how many you use. I have made versions of the cmoy with a 9v, 2 - 9vs, 8 AAs, and 16 AAs. Obviously, the more batteries you use, the larger the case, hence portability and weight may definitely become an issue. Sonically, I like the 8 or 16 AA set up with 470uF or even 1000uF caps. There seems to be more of a deep bass with my 580s to my ears. My home amp has the 16 AA set-up. I wouldn't want to tote that sucker around though.

 

[artmusic247]

Aloha JMT!
In your post, you mention that you changed the capacitors in accordance to 16 AAs. These capacitors that you are talking about are the two electrolytic capacitors in the power supply? How did that modification improve the sound other than extending the lower range? The reason why I'm asking is because I built a Apheared "47"/Chu Moy portable amplifier and I run 16 AAs and I'm always looking to improve the beautiful sound that come out of this amp. Thanks.

 

[JMT]

artmusic, yes its the electrolytic in the power supply. To me, with the 470s or the 1000s, the sound has more fullness to it. More body, if you will.

 

[artmusic247]

Thanks JMT. I'm ordering some new caps ASAP.

 

[ppl]

I have Been using AAA's in my portable amps for a while now Great compromize between Size and weight and Portability. I see from the Pole that i must be the only one doing this. I have an outboard battery Pack With 16 1500 MAh AA's as a Back-up. Also i set the amp up so Charging of the Internal AAA's only when the amp's Power switch is Turned off. This way when i use the Battery Pack I control the power on/off from a switch on the Pack so as not to use Power from the Outboard Pack to attempt to Charge the Internal batteries. With this setup i have an Amp i can carry around in a Sholder bag (Case Logic DM-1) Get about 13 Hours of runtime, Or use the outboard Battery pack For Stationary use Like Fishing. I Tell Ya Fishing while Listing to Steve roach The Magnificent Void. is one of the Best Fixes i get Now days. Then Theres the Oregon Contry fair whare the Outboard Battery pack with the Internal AAA's Get me Through the Weekend including some Electric Nights. I Know I am a Headphone Addict But It takes one hell of a great Loudspeaker to sound evean Close to Headphones. Plus Your Tuneswill Not Bother Anyone.

 

[grrr223]

JMT, you said that you ahd versions of the cmoy pocket amp with many different power supplies. Do you have to change anything else in the circuits (resistor or capacitor values, maybe the op amp) or do you just add more/different batteries and it gets louder? Thanks you guys, you've been a big help.

 

[topher]

ppl,

Have you found a battery case that holds 16 AAA's?

 

[JMT]

grrr223,

No, I didn't change anything in the signal path (with the exception of experimenting with the gain resistors), just the power supply. It doesn't get louder so to speak, to me it just accentuates certain qualities. Specifically the low end. It provides for the deep bass that sometimes is lacking.

 

[ppl]

Quote:

Originally posted by topher ppl, Have you found a battery case that holds 16 AAA's?

I Use a LMB Crown royal Alumunium Case #CR-632. This is 2.125" H X 3.5"W X6"D. The Amp is upon 2 Boards one main Board that Holds all the Circuitry Except the Battery Pack and the Charging. The Main Board is 3.5" X6" and just Fills this Case. Mounted above this Board is the Smaller Battery Board that Is Nested Between The Large Capacitor banks. The 16AAA cell Pack is arranged by 2 battery Dia. Deep and 2 batteries Lenght Long. and 4 Dia. Wide. This is a compact packageing but all The Components fit rather well. My Dual Mono version is in a slighty Bigger hammond 1590 Series case

16 AAA's do not take up mutch more room than 2 9 volts. and if you use 12 AAA's to get the 7.2 volts that a 9 voltt has takes just a hair more space. I tell ya a good solution for me are these AAA's