Tube preamp loses high end

[woutersnoei]

Hi,

I’m fooling around a bit with the Tube Stage Preamp deep plugin, and I find that in all settings (except High Drive) there seems to be a loss of high frequency content. Is this intended behavior? Do real tubes also loose high frequencies? It sounds a bit like a high shelving filter on minus a couple of dB’s at 4k. To see if I wasn’t making it up I took some measurements with pink noise. Attached are two pictures of analyzed signal (using Logic’s MultiMeter analyzer), one dry and one through the tube preamp (recorded at 96k using usb i/o). In this case it was the first setting, but I saw similar results on the other settings. As you can see the signal is about 4dB’s lower at the 16k mark, and starts to roll off around 4k. If this is intended behavior, it would be nice to have some sort of compensation setting to make up for the lost high-end, or perhaps an option to dial in the effect more smoothly..

(please note that the bumps in the low end of the analysis are just artifacts of fast metering in this case)

cheers,
Wouter

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[KeithJ A&H]

Hey Wouter,

There are a lot of things that go on in Tube Stage to create an accurate model of a vintage preamp, including biasing, distortion, harmonics, compression and frequency response.
You’ll notice that the all of these ‘components’ of the model change subtly as you adjust the control and are also dependent on how much you drive the input.
So yes, this is absolutely intended behaviour!
It’s a complement to the ‘standard’ transparent preamp sound.

I’m afraid we have no plans to redesign Tube Stage, but if you could explain what you are wanting to achieve with the sound, I could note it as a feature request for any future preamp models we may look at.

Cheers,
Keith.

[Mr-B]

They sound pretty realistic to me, certainly as good as my previous relatively hi end favourite modelling Pre amp. I use them quite a lot on my D Live, I find some modern PA systems a little harsh and the nature of the Pre amp in some respects counters this without reaching for the EQ controls. Again I tend to go with if I like the sound and is it pertinent ? If the answer to both is yes go with it.😉

Regards
Ian B.

[SteffenR]

@Mr-B well said

[woutersnoei]

Hi guys, thanks for answering, I now understand the purpose of the Tube Stage a bit better. Looking at the dlive version it is apparently based on the dual valve stage preamp, which has more controls, including a “hf-lift”. The latter is exactly what I’m talking about, and it is there but I guess the design choice for the tube stage was to have a bit more “lo-fi” sound in quick presets, and without hf-lift. Searching on the net I found that tubes indeed have a tendency to loose high frequencies, depending on the impedance of what they are connected to (interestingly when used for amplification they actually interact with the loudspeaker, exaggerating its resonant frequency). In any case, I guess I will just have to wait until A&H ported the dual valve stage to SQ ;-). Other than that, the tune stage does sound very nice and is useful for many applications.

Cheers,
Wouter

[KeithJ A&H]

Hi Wouter,
I’ll put that down as a request 🙂
Cheers!
Keith

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