Hello all,
I'm back after a long sortie and going through my 14yr old storage unit of project materials.
Came across two input transformers that I'd love to have your thoughts on (how do they sound? what applications are there for them?).
I have a germanium transistor preamp build going on and I'm curious about popping one of these in the front of it.
Or, how about a D.I., or a transformer color box? Has anyone used these types of transfos in a build?
They are both Ampex and never used.
I searched their part numbers but at first glance found very little info on them.
4580200-01 Bridging input
4580116-20 Matching input
Much thanks for your thoughts!
I'm back after a long sortie and going through my 14yr old storage unit of project materials.
Came across two input transformers that I'd love to have your thoughts on (how do they sound? what applications are there for them?).
I have a germanium transistor preamp build going on and I'm curious about popping one of these in the front of it.
Or, how about a D.I., or a transformer color box? Has anyone used these types of transfos in a build?
They are both Ampex and never used.
I searched their part numbers but at first glance found very little info on them.
4580200-01 Bridging input
4580116-20 Matching input
Much thanks for your thoughts!
Attachments
Thanks for those links - you're better at Google than I am! That first link didn't have the 4580116-20 in there, I'll keep poking around for that one.
Had any experience with these?
Had any experience with these?
Found this on the 4580116-20 Matching input trannie:
A Balanced matching step-up ratio transformer with 14db gain. Input impedance of the system with this installed is 600 ohms and is designed for use with a source impedance of 600 ohms. Used on the input of the Ampex 354, 602 , MX10, PR-10, MX-35, MR-70, and AG-350.
Would this be best as a line-level input, or as a D.I., or will it handle modern mics (150ohm area) as the front of a preamp?
I am reading up on impedance, which I've been putting off long enough!
A Balanced matching step-up ratio transformer with 14db gain. Input impedance of the system with this installed is 600 ohms and is designed for use with a source impedance of 600 ohms. Used on the input of the Ampex 354, 602 , MX10, PR-10, MX-35, MR-70, and AG-350.
Would this be best as a line-level input, or as a D.I., or will it handle modern mics (150ohm area) as the front of a preamp?
I am reading up on impedance, which I've been putting off long enough!
They will work best at their rated impedance.
These should help.
https://www.jensen-transformers.com/application-notes/
These should help.
https://www.jensen-transformers.com/application-notes/
For DI you typically need a 10:1 step DOWN transformer. The Ampex MATCHING transformer has 1:5 step up ratio or 600:15K ohms. Using it in reverse is only 5:1. It might work depending on the headroom of your mic preamp. Most Ampex BRIDGING transformers are typically 1:1 at higher impedance 15K:15K and they're great for balanced input for preamp, which is what I did, or the input of power amp. It's also a great phase splitter to the grids of input tubes of power amp, provided you use two 7.5K resistors to form a virtual center tap to ground, for the input of a push-pull or differential circuit.
Got it, thanks a lot, DirectDriver. So, it's not good as a DI, and since mics apparently want 10x the impedance load, what in the world is it good for! 🙂 I'm trying to look over the original Ampex units that used this and try to understand the best use for it (other than in an Ampex device!).
I do build tube amps, so maybe I'll find a use there, sort of copying the MX-10 or other.
I do build tube amps, so maybe I'll find a use there, sort of copying the MX-10 or other.
Let's say you're building a preamp that has too much gain, a common occurrence, and need to knock down some gain without using feedback, the matching transformer wired in reverse, 15K:600, can drop 14dB gain at the input, plus you get balanced input.
Another approach is to use it in a power amp with driver tubes that lack gain and you place the Ampex to boost some gain at the input.
Be creative!
Another approach is to use it in a power amp with driver tubes that lack gain and you place the Ampex to boost some gain at the input.
Be creative!