Calculating primary impedance on my original Express, help!

[novosibir]

Pacific is still in business?!?!?!
Anyone know if they have a website?

Here it is:

http://pactran.com/

Larry

[dartanion]

Hey Larry,

Thanks for the url. I found it last night, but looks like a different company all together. The Pacific brand transformers in my MUTANT18 build are from the 1950's. The site says they started in 1981. Oh well.

[novosibir]

Here on their website: http://pactran.com/inner/audio_equipment.shtml it says:

World-Class Transformer Solutions for Simple and Complex Audio Applications.



Pacific Transformer has designed and manufactured audio transformers for many of the major manufacturers and sound contractors. This industry has come to rely on our many years of experience and our ability to quickly get from design phase to some very important installations and applications.



* At Disneyland we power all the park announcements and background music.

* We also provide the transformers for many sport stadiums and public places, including St. Peters Square at the Vatican.

* When it comes to guitar amplifiers we’ve done some award winners. In fact Pacific transformers are powering the guitar amplifiers of many popular artist around the world. ( See: Guitar Amplifiers)

* Line matching, audio output, plate filament, filter chokes, amplifier power. Put us to work for you.

But I couldn't find the 'Guitar Amplifiers' section

Larry

[dartanion]

I couldn't find that section either even after searching every iteration of guitar, amplifier, etc.

[kec]

Here on their website: http://pactran.com/inner/audio_equipment.shtml it says:

* When it comes to guitar amplifiers we’ve done some award winners. In fact Pacific transformers are powering the guitar amplifiers of many popular artist around the world. ( See: Guitar Amplifiers)

But I couldn't find the 'Guitar Amplifiers' section

Larry

I was looking for that too.

[Jack]

Good call on the NFB loop! Also, not such up to which amount it would influence the results, since Allyn uses that method with succes, but the impedance is a function of frequency, I believe.

Can anyone confirm or infirm that?

Glen, IMO the "simplest" (yet most expensive) way to figure out the best OT for your clone(s) is to get a couple of transformers with carious impedance, say a 4K, 5.2K, 6.6K and 8K and any values in between or beyond. Test these "test" OT to make sure the impedance match the factory specs. Plug them in your favorite clone and play with them until you get an exact tone match or as close as possible then locate an OT that seems to fit the original's.

I do believe that you could get the same tone out of a OT with a different impendance than the original since there are other factors at play beside the actual impedance. I believe that "mismatching" 2 parameters could cancel out and give the proper result.

Another less expensive way to figure out how to clone proprely the original would be using a sine generator and a scope and track the differences stages by stages between the clone and the original and try to figure out what makes the differences to fix them. My point is that if the signal, say, before the PI are different enough between the original and the clone, the OT might NOT be the culprit for the "lack of feel" from the clone. Messing with OTs can be an expensive venue so making sure ALL the rest is nailed 99.999% will be more profitable in the long run IMO.

It's my physics researcher/programmer background that taught me to go step by step to find a "mistake". Start at the begining and go stage by stage. The OT is the end of the line and beyond that point since you use the same speaker cab and the same guitar/cords, the differences must lay somewhere between input jack and speaker out.

Use the sine wave, check the first stage. Play with frequency between, say 100Hz and ~8ish kHz. then move on the next stage until you find significant differences between the clone and the original. Then fix THAT stage and move on until you reach the OT. It's not rocket science but science nonetheless Good luck!