Valid questions. A frequency sweep shows all of the transformers to be completely flat, however this is deceiving, as you can clearly tell with your ears. Not only is a line output (which would drive such test) much lower impedance than an electromagnetic pickup, the output impedance is also flat while that of a pickup is curved. There is also the issue of transient response. I could attempt to model it all, but in the end I believe the ears are a better test. Transformers are one of those things that seem simple but get more and more complicated the deeper you look at them.

Good question. That is exactly what I expected and I had hoped to perhaps use any sound difference to advantage, but what I found in practice is what ribbon makers have known for a long time. As long as the ribbon is uniform (not piston corrugation), then the response is dominated by the mass of the ribbon and the resonant frequency. These can be equal between standard corrugation and herringbone, and they do not sound different, so long as the ribbons are tensioned to the same resonant frequency.

@@alderaudio that is interesting!!

The one place I know to point you to is retrogearshop. They've got a lot of desirable vintage transformers and maybe comparing to their photos can help with identification? They have a lot but are priced accordingly.

Hi Dirk, thanks for the feedback. I've struggled to manage the technical depth of these transformers while still making the content accessible. There is a lot to it! But I'll try to let you in on just a bit more in what I can fit here in a comment. The biggest huge difference in this case is that my transformer is toroidal, which comes with a whole host of changes. I've highlighted a few, but really the whole design just ends up different because you have different inductance per wrap, wire gauge, capacitance, just kind of everything. So my intention was never to clone, I just took the high inductance and low leakage away from the vintage model as guiding principles. As far as saturation we are WAY far away from that using just a pickup. I have intentionally pushed these both to saturation and it takes a decent bit of juice. As far as phase, I know Jensen likes to talk about that, which I assume is where you are coming from? Their point is that phase shift can occur in the low end as a result of the natural high pass filter of every transformer. What's the key to pushing that shift lower and lower out of audio range? Higher and higher inductance. So both of these perform really well in that regard. The TL-20 also measures lower in THD at 30hz.

@@alderaudio interesting, thank you for sharing!!

Big questions here, hard to answer quickly. First, unless you are running miles of cable the capacitance is going to be the biggest thing that that has an effect on the input. There's been a lot written about this and it's interaction with pickups that you can find and read online if you like. And as far as input stages, manufactures don't get to just set it wherever they want, the input impedance that is appropriate is linked to the design choices of the first stage. So if you have an op amp vs a FET vs a tube, things change. The input impedance options are limited by the overall design.

shots fired :) what's wrong with A? Won't that glowing midrange around 1k translate best within a full mix?

Well, you won't have impedance matching problems, so that part is sort of fine, but you will have level problems and possibly ground problems. Because both devices are referenced separately to ground you may get a hum. The input level will also be really loud. But you can turn down the level in your daw and give it a try if you like. It may work. If you have hum, you can probably solve it with a reamp box, which will also bring down the level.

@@alderaudio no ground problems here, but about the level, would the pad button on the preamp help, or is that not enough or at a different point in the circuit?

@@alvincornistamusic8754 the pad could help and is probably a good idea but really if you have no hum it's just a gain staging thing. All you need is to not distort the input on your preamp, so whether you want to use the pad, turn down the output on your interface, or turn down the source right inside the DAW, you can get it to the right level using any combination.

If you watch the video, his explanation say that impedance change by frequency. He didn't want it to be super technical so he didn't convey inductive and capacitive reactance.