Non-inverting amp or not

[pyonc]

Hi guys,

I hear most of the JBL transducers and speakers in the 1960s and 1970s had negative polarity.
Then, what about the preamps and amps of JBL from the same eras, such as SE401, SE408, SE400S, SE460, etc?
Are they inverting amps or non-inverting amps?
If you look at the attached pic of SE408, for example, you see black and red terminal inputs.
Are they normal positive polarity just like modern amps, namely red to +, black to - or negative polarity just like the transducers?
Thanks for your comments and feedback in advance.

http://audiolab.co.jp/global-image/units/img/3251-1-20131213195957.jpg

[grumpy]

In this case, red is plus and leave it at that. That is how it is intended to be connected.

If you want to know if a positive pulse on the input will result in a positive pulse on the output, it only matters if you are mixing amps. It's straightforward to measure with a dual channel oscilloscope, but it only matters that the amps match (or not and you flip one output), so you could just compare two amps by seeing if they add together or nullify each other... I don't suggest connecting the amp outputs, but you could drive two identical drivers (same input to both amps) and face the speakers toward each other... see what happens, then wire only one speaker backward and repeat.

[pyonc]

In this case, red is plus and leave it at that. That is how it is intended to be connected.

If you want to know if a positive pulse on the input will result in a positive pulse on the output, it only matters if you are mixing amps. It's straightforward to measure with a dual channel oscilloscope, but it only matters that the amps match (or not and you flip one output), so you could just compare two amps by seeing if they add together or nullify each other... I don't suggest connecting the amp outputs, but you could drive two identical drivers (same input to both amps) and face the speakers toward each other... see what happens, then wire only one speaker backward and repeat.

Thanks a lot for your kind reply, as always. :) That's what I want to confirm. This negative polarity of JBL's in the bygone years would confuse me whenever I run into vintage JBL amps and preamps.