The Two notes Captor impedance curve comparison

I own a TwoNotes Captor 8ohm. I've been using this load box for quite a while, but was never really satisfied with it. When I used it as a DI box between amp and cab, it was fine (the amp was seeing a real cab load). But when used as a load box, it sounded like the amp wasn't really getting a reactive load. So I made an experiment. Took the Matrix, plugged into the captor, made a cable with just 0.2 ohm 50W resistor and measured the impedance curve. I also measured the DC resistance of the captor and even the voltage of the Matrix at the output through the whole spectrum, so that I can then correctly calculate the impedance.

And now the reveal ==>

The DC resistance of an 8 ohm load box was 25.1 ohm!!!! (What????) -> I'm not sure if this is just a bad battery in my multimeter, but I'll verify.

And this is the actual impedance curve plot made with a 20Hz-20kHz sine wave sweep. This just confirmed, that the captor is not really a reactive load as it should be...

TwoNotes Captor 8ohm:

CaptorPlotSmall copy.jpg

And this is the frequency plot of the Aiken Amps designed load box (well ... it really looks different than the Captor's)

AikenAmps designed load-box:

ReactiveLoadSmall copy.jpg

Bonus -> The Matrix frequency output plot
It may seem that it's not really flat, but it is veeery flat indeed. Notice just a difference of not even 1dBu between 20Hz and 20kHz!!
VoutMatrixSmall copy.jpg
 

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And as a bonus, here's my setup :D

The multimeter with DC resistance reading:
IMG_20210123_163045.jpg

The overall setup with the Matrix, PicoScope, the Captor and computers used for the measurement:
IMG_20210123_212426.jpg

And a detail of my super duper cool measurement resistors!
IMG_20210123_212440.jpg
 
Thanks for measuring. The OX box has a similar curve to the captor, where the Suhr is very similar to the Aiken, and mimics an actual speaker impedence curve.

I’ve always been real curious about the Fryette power station but never seen anyone measure it.

Randall Aiken has some good articles on his site about impedence curves, their affect on the amp, etc. It seems the less negative feedback an amp has, the more sensitive it is to the cab (or load) impedence curve, and vice versa. I’m guessing a lot of people who use and love the captor are using amps with high levels of negative feedback in the power amp design, and therefore the captor is ‘close enough’ for them.
 
Thanks for measuring. The OX box has a similar curve to the captor, where the Suhr is very similar to the Aiken, and mimics an actual speaker impedence curve.

I’ve always been real curious about the Fryette power station but never seen anyone measure it.

Randall Aiken has some good articles on his site about impedence curves, their affect on the amp, etc. It seems the less negative feedback an amp has, the more sensitive it is to the cab (or load) impedence curve, and vice versa. I’m guessing a lot of people who use and love the captor are using amps with high levels of negative feedback in the power amp design, and therefore the captor is ‘close enough’ for them.
Actually that with the negative feedback is true. Just don't switch the Rectifier to it's red channel with the Captor! This would put an insane load on the amp in frequencies, where it shouldn't! I guess I've already seen some post about the Recto not really being a friend with the Captor.
 
Thanks for measuring. The OX box has a similar curve to the captor, where the Suhr is very similar to the Aiken, and mimics an actual speaker impedence curve.

I’ve always been real curious about the Fryette power station but never seen anyone measure it.

Randall Aiken has some good articles on his site about impedence curves, their affect on the amp, etc. It seems the less negative feedback an amp has, the more sensitive it is to the cab (or load) impedence curve, and vice versa. I’m guessing a lot of people who use and love the captor are using amps with high levels of negative feedback in the power amp design, and therefore the captor is ‘close enough’ for them.
My Fryette Power Station measures properly like a cab (or a Suhr or FAS reactive load). Interestingly, the Fryette GPDI's internal load looks more like the Two Notes stuff though.
 
The reason the Two Notes, Ox, etc. look like that is it's a much less costly design. By removing the low frequency resonance you do away with the need for a large and very expensive inductor.
Yes, exactly what I thought when I opened it. There should be two coils and the bigger (low res one) is missing. I couldn't even imagine where they'd put it in case of the Captor, since it's such a small case. I've measured also my ENGL Standard 4x12 impedance curve and will post the results later :)
 
My Fryette Power Station measures properly like a cab (or a Suhr or FAS reactive load). Interestingly, the Fryette GPDI's internal load looks more like the Two Notes stuff though.
Interesting, if you saved a picture of the plot I would love to see it, I had assumed it would be two-notes-like as it runs into a tube power amp, but maybe not!

GPDI load is interesting, but that thing is incredibly cramped inside so no big surprise. I use mine often running the line-out into my 2/50/2, but I noticed it does sound better if I connect a small 1x12 cab to its speaker-out rather than just relying on the internal load.
 
Interesting, if you saved a picture of the plot I would love to see it, I had assumed it would be two-notes-like as it runs into a tube power amp, but maybe not!

GPDI load is interesting, but that thing is incredibly cramped inside so no big surprise. I use mine often running the line-out into my 2/50/2, but I noticed it does sound better if I connect a small 1x12 cab to its speaker-out rather than just relying on the internal load.
Here you go:
o9Cligc.png

FAS X-Load US
FAS X-Load UK
Suhr Reactive Load
Fryette PS-1
Fryette GPDI Internal Load
Revv D20 Internal Load
 
The X-Load is really, really good. If I could get one with a 2x10 and 2x12 curve I'd be in heaven. I will say the amp "feels" right when I play through the X-Load. The Ox box felt stiff and unresponsive. I think their cab emulation was really solid though. If it had impedance settings switch I'd buy another one.
 
Excuse me to bump an old thread, but I’d like to share my measurement of BOSS WAZA Tube Amp Expander (https://www.boss.info/us/products/waza_tube_amp_expander/).

I bought it because this is, other than Two Notes, the only “reactive load” that support the use with 16ohm amplifiers including a VOX AC30 that I have. The Day 1 task is to check out if TAE’s impedance curve matches with SIC of AC30 cabs. What I got is:
SIC_BOSS TAE (2x12 Diamond).jpg

Definitely a must NOT buy. My TAE, without being plugged to my amp, was immediately packed again and will be sold somewhere.
I wish LB-2 had 16ohms version with IC of 2x12 open-back cabs.

Just For comparison, here’s the SIC of my AC30 cab, captured in the same equipment as above:
SIC_AC306TBX.jpg
 
Excuse me to bump an old thread, but I’d like to share my measurement of BOSS WAZA Tube Amp Expander (https://www.boss.info/us/products/waza_tube_amp_expander/).

I bought it because this is, other than Two Notes, the only “reactive load” that support the use with 16ohm amplifiers including a VOX AC30 that I have. The Day 1 task is to check out if TAE’s impedance curve matches with SIC of AC30 cabs. What I got is:
View attachment 111383

Definitely a must NOT buy. My TAE, without being plugged to my amp, was immediately packed again and will be sold somewhere.
I wish LB-2 had 16ohms version with IC of 2x12 open-back cabs.

Just For comparison, here’s the SIC of my AC30 cab, captured in the same equipment as above:
View attachment 111384
Thanks for measuring the TAE, it’s been out for years yet still no technical information about the impedence curve to be found, until now.

I figured it would be unlike a real cab but nice to have confirmation
 
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