Home » Audio » General » My headphone amp for my bass
My headphone amp for my bass [message #24843] Thu, 17 February 2005 11:15 Go to next message
SirPoonga is currently offline  SirPoonga
Messages: 3
Registered: May 2009
Esquire
Just sharing with you guys. I made a headphone amp for my bass based on the Ruby schematic with bassman mods from www.runoffgroove.com

http://img.photobucket.com/albums/v472/SirPoonga/Ruby/ruby.jpg
http://img.photobucket.com/albums/v472/SirPoonga/Ruby/ruby2.jpg
http://img.photobucket.com/albums/v472/SirPoonga/Ruby/ruby3.jpg

I made some recording, however they are old. I will have to try and make new ones. I just found out my pbass's electronics were wired incorrectly. The tone cap was going between the volume pot and the tone pot, not between the tone pot and ground lke it is suppose to. It sounds much better now that my bass has better tone control

Maybe you guys would know. One thing I would like to do is add a CD AUX jack that is basically a pass through so I can hook my CD player to this and listen to music and play along. The problem is this is a mono amp. On the output jack I just have a jumper wire to output to left and right speakers. If I do a straight pass through the CD output will get converted to mono. Anyway to keep the CD player output in stereo without having to make a dual channel amp?

Re: My headphone amp for my bass [message #24844 is a reply to message #24843] Sun, 20 February 2005 16:55 Go to previous messageGo to next message
Wayne Parham is currently online  Wayne Parham
Messages: 18793
Registered: January 2001
Illuminati (33rd Degree)

If I understand you properly, you want to be able to connect both left and right together to your headphone amp's input, but you want them to be isolated to go to another parallel set of RCA jacks as a pass-through connection. If that's the case, I would suggest using a series resistance between each channel and the amp's input. That will isolate the channels from each other so that separation is maintained.


Re: My headphone amp for my bass [message #24845 is a reply to message #24844] Sun, 20 February 2005 17:06 Go to previous messageGo to next message
SirPoonga is currently offline  SirPoonga
Messages: 3
Registered: May 2009
Esquire
I am enough of a newbie to electronics to not understand what that means.

Right. I want two 1/4" jacks on my amp. One for headphone output (which I have) and one for cd input. But I don't want cd input to be converted to mono since right now I convert the amp's mono output to both channels on the 1/4" jack.

Re: My headphone amp for my bass [message #24846 is a reply to message #24845] Mon, 21 February 2005 08:34 Go to previous messageGo to next message
Wayne Parham is currently online  Wayne Parham
Messages: 18793
Registered: January 2001
Illuminati (33rd Degree)

Sounds like your solution will be pretty simple then. I'd use a resistor in series between the amp input and each of the left and right channel RCA plugs. Can you send me the schematic of your headphone amp? The input impedance should be known to decide what value resistors to use.


Re: My headphone amp for my bass [message #24847 is a reply to message #24846] Mon, 21 February 2005 09:50 Go to previous messageGo to next message
SirPoonga is currently offline  SirPoonga
Messages: 3
Registered: May 2009
Esquire
http://runoffgroove.com/ruby.html
I think I linked to that in my original post too.

Re: My headphone amp for my bass [message #24848 is a reply to message #24847] Mon, 21 February 2005 19:16 Go to previous message
Wayne Parham is currently online  Wayne Parham
Messages: 18793
Registered: January 2001
Illuminati (33rd Degree)

Your amplifier has very high input impedance, so your series resistors can be high too. The higher resistance you go, the more isolation you'll have. That will improve stereo separation on the pass-through plug signals. I think I'd probably go with 22k ohm in most cases, but you might try 100k first and see how it works. Might even get away with something between 100k and 470k. What we're looking for is the highest value that doesn't attenuate the sound level.

Connect one end of the resistor to the left RCA center and the other to the the circuit "in." Do the same for the right RCA center, both connected to the amplifier input It forms a sort of a "Y." Then you can connect a second pair of left and right RCA plug straight to the first pair for a pass-through connection. Don't put resistors between the RCA jacks, only from the RCA jacks to the amplifier input.


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