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AUDIO FORUMS >> Headphones >> Headphone Power Amp Adapter!
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Message started by 4krow on 11/24/17 at 23:37:29

Title: Headphone Power Amp Adapter!
Post by 4krow on 11/24/17 at 23:37:29

Just now, in my favorite coffee shop, and idea sprang loose from my brain. I was reading about headphone amplifiers of all kinds. Of course, I have a favorite in my own rack, BUT then an idea came about. I already know that the Rachel is an excellent choice for such service. The 'challenge' would be to try different arrangements of resistors for the best load to the amp, and the least fatal to the headphone. Sound quality is at the peak of it all somewhere. Now, here is the idea that I am going to float soon enough:
Instead of finding the right combination of resistors, I will be using a Decware Audio "Gizmo" for the connections. I have kept these babies around for years, just to use in such instances. Great for experimentation, and in this case, I am hoping for a revelation.
More to follow......

Title: Re: Headphone Power Amp Adapter!
Post by 4krow on 11/25/17 at 04:55:32

Front w/headphone jack:

Title: Re: Headphone Power Amp Adapter!
Post by 4krow on 11/25/17 at 04:57:02

Last shot. I used silver plated binding posts that accept wire up to 16 gauge.

Title: Re: Headphone Power Amp Adapter!
Post by 4krow on 11/25/17 at 05:12:33

Close up of transformer model. It was designed for use with such speakers as Fostex to help with a midrange problem, but may well work in this case also since it is adjustable. We'll see soon enough.

Title: Re: Headphone Power Amp Adapter!
Post by 4krow on 11/27/17 at 00:17:05

Ok, got her up and running. I hooked up the transformers' primary winding -Across- the amp output, giving the amp a load. Then I placed 50 ohm resistors in series with each channel. The headphones sound great, and I can even use the potentiometer to adjust for my brighter sounding Grado cans. This idea is a keeper.

Title: Re: Headphone Power Amp Adapter!
Post by 4krow on 06/29/18 at 23:45:12

I just wanted to add a bit more to this idea. There are different ideas out there, and i found this diagram useful for one application.

NOTE: This is not to be confused with the transformer idea that I am showing in this post. It is a voltage divider using resistors alone. It is the more common method for using headphones and power amplifiers together.

Title: Re: Headphone Power Amp Adapter!
Post by AC on 09/03/18 at 22:30:02

I have built a load box with Mills resistors similar to the diagram above, with very good results.

Title: Re: Headphone Power Amp Adapter!
Post by funch on 09/05/18 at 21:14:59

4krow, you might want to double check your diagram above.

Title: Re: Headphone Power Amp Adapter!
Post by 4krow on 09/06/18 at 03:58:00

Looks good to me, but maybe where the wire jumps across another wire, it appears to be a connection. Is that what you are referring to?

Title: Re: Headphone Power Amp Adapter!
Post by funch on 09/06/18 at 05:11:47

The labeling for R1/R2; the channels are switched.

Title: Re: Headphone Power Amp Adapter!
Post by 4krow on 09/07/18 at 01:33:00

Those bastards.... just when you thought that you could trust someone. I got this diagram from the internet. Now I hafta put my headphones on backwards. But thanks for pointing it out.