[jdkJake]

I find that the chocolate Altoids tins make my amps sound dark

Hmmm, I wonder what the wintergreen would sound like....

 

[jdkJake]

i didnt cut them yet thank god. i just read the post above that says theres less attenuation with the 250ohm setting. how do i wire up the switch for 250ohm? i can kind of see in the picture but its hard to tell
 

The switch is Dual pole, dual throw. so, there are two sets of three pins for each channel. The jacks have tip, sleeve and ground (return) connections. I am not sure which is which as I no longer have the jack schematic. The key is to use the same connections for each channel.

With that said, the blue wire from each transformer goes to the respective tip/sleeve connection. Just be sure to be consistent across the transformer so that the red and white wires of the secondary follow suit and you do not swap channels. The ground connection goes to the center positions of the switch (in my pictures, this is a white wire). The green wire for each channel goes to one set of throws (one side) and the black wire for each channel goes to the other. If you look at the switch from the back and assign a left and right designation to the channels, the hookup would be as follows:

GreenRight / Ground / BlackRight
GreenLeft / Ground / BlackLeft

Hope this is clear, if not, I will try to take another picture later in the week.

 

[kchapdaily]

makes sense to me thanks! ill give it a go now and let you know what happens

 

[kchapdaily]

definitely has less attenuation in 250ohm mode. much more useable. 

 

[Eee Pee]

Cool.  I gotta find some more transformers.  What headphones are you using?

 

[kchapdaily]

Quote:

Cool.  I gotta find some more transformers.  What headphones are you using?

im using sennheiser hd555's

 

[jdkJake]

Glad to hear it worked out for you.

I suppose the next logical step is to make the 8 transformer version switchable as there were two switches in the package. Too bad I removed the center tap on the previous one I built.

Maybe the next time we have a rainy Sunday....

 

[nikongod]

 
Quote:

I suppose the next logical step is to make the 8 transformer version switchable as there were two switches in the package. Too bad I removed the center tap on the previous one I built.

 
You could put all 4 secondaries in series rather than series/parallel. Crunching numbers it should have the same effect on winding ratio, output impedance is a little higher though.

 

[kchapdaily]

what effect does the 8 transformer version have on performance? is it still -21db attenuation? 

 

[jdkJake]

 

 
You could put all 4 secondaries in series rather than series/parallel. Crunching numbers it should have the same effect on winding ratio, output impedance is a little higher though.

Certainly an option.

To be honest though, the overall cost of the transformers is low enough to make it easier to rebuild a new one rather than rewire the old one.

 

[jdkJake]

what effect does the 8 transformer version have on performance? is it still -21db attenuation? 

Built using the serial/parallel design jcx outlined in previous posts, the input and output impedance is the same (resistance math makes it so). The attenuation performance is identical. The distortion should be less and overall performance better (see jcx comments early in this thread). Personally, I think it performs better.

Overkill? Perhaps. But at this price point, it is fun and relatively cheap to experiment.

 

[kchapdaily]

if anything its a great way to learn about transformers and there effect on signal. im a computer engineering student so its fun to be able to apply all that math i learned

 

[jdkJake]

if anything its a great way to learn about transformers and there effect on signal. im a computer engineering student so its fun to be able to apply all that math i learned

I agree completely. For me, that is the draw of this project; the opportunity to learn through experimentation and practical application of theory.

Heck, with the right amount of switches, you should be able to switch in and out of a wide variety of serial/parallel configurations.

 

[kchapdaily]

funny you should say that i was thinking about grabbing one of those rotary switches used in the cross-1 and doing exactly that

 

[Eee Pee]

I was sitting around listening to some tunes last night and I had an idea.  What about plugging my CD player right into this thing?  I got it hooked up and used some sacrificial Apple ear buds in case it was too loud, but much to my surprise it wasn't, it was pretty close to where I like it.  Alright, so what other headphones do I have that are around 32 ohms... Sennheiser MM60s which are also 32 ohms, but not very efficient at 96 db.  Holy cow this is almost perfect!
 
Then at work today I had another idea.  Plug my currently unused Theta Cobalt 307 DAC into my iMac then the transformer box into the DAC and I got better computer audio.  Or hopefully I do.  
 
Thanks again for showing me this thing.