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Passsive EQ @ Markbass TTE - what's so special about it?

oo.viper.oo

oo.viper.oo

Sep 23, 2010
61
61
Brno, Czech Republic
#1
Hello,

I'm reading through the articles about Markbass TTE 500/501 and 800/801 and they all rave about passive eq. They all just fail to mention why it should be superior or how it's different from classical eq. Could someone elaborate on this, please?

Also another point. Owner's manual says:

EQUALIZATION (Passive)
Bass: Level ±6 dB @ 80 Hz
Middle: Level +4 / -6 dB @ 800 Hz
High: Level +5 / -4 dB @ 5 kHz

How can passive eq boost frequencies? I thought passive would only cut frequencies, but the manual clearly states otherwise...
 
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#3
Just spitballing here, but if noon for the knob in question already had some of that frequency rolled off, then technically, anything above noon would be putting more of it back...

Not sure if that's the case, but logically it seems like that would be at least one way that it would make sense, at least to me.
 
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#4
Kro said:
Just spitballing here, but if noon for the knob in question already had some of that frequency rolled off, then technically, anything above noon would be putting more of it back..
Click to expand...

I see what you're saying, but then the nominal or "noon" level of this 3-band eq would anyway mean you actually already have those 3 frequencies @ 50% "pre-cut" (sort of), to allow for boosting them (un-cutting in fact) from this nominal state. But it wouldn't be whole signal level cut, it would only be those 3 frequencies cut. That doesn't sound normal to me.

And it brings another question. What is the position of knobs where signal is not altered by this eq? Is it @ 12 o'clock or is it @ max?
 
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#9
This http://www.samadhilounge.com/esa/bass/FMV_Tone_Stack.pdf which was linked from the thread mentioned above.

The way I understand it is that it isn't really a passive 3-band eq, it's more like a passive 3-parameter tonal filter. Because one would expect from eq that at least the middle band behaves like band-bass filter (in case of boosting) or band-stop (in case of cutting) filter. But it is not the case, this passive circuit has one low-pass filter for bass frequency, another low-pass filter for mid frequency and high-pass filter for high frequency. And shapes of some of those filters are changed by more than one knob. Granted one can tweak the tone in many different ways, but the outcome is just not that intuitive.
 
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#12
oo.viper.oo said:
Then the question remains why even bother with passive eq when it's control is most likely less intuitive than that of traditional eq. Could it be that simpler passive circuit with few discrete components is potentially more musical than active eq with operational amplifiers?
Click to expand...
I don't think people think that much about it. I think they try an amp, see if they can get their favorite sounds out of it, and buy or don't buy as the mood strikes. They just want to eat the steak and don't care how you kill the cow. I spent well over 30 years not caring my own self, and honestly, I still don't care very much other than mild curiosity about how things work.
 
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#13
JimmyM said:
I still don't care very much other than mild curiosity about how things work.
Click to expand...

Fair enough. But I have a degree from electronics, I ought to care ;). Thing is I recall we had lessons on these filters, but that was decades ago and the principles faded away... It is actually interesting to revisit this topic after so long time now that it actually matters to me. I did play double bass and violins back then and didn't care about amplifiers and those lessons seemed so dull. I started playing bass guitar much later.
 
#15
This thread has made for some good reading.

Last night using my Markbass TTE501 for the first time in a full band setting, i was getting very frustrated with my lack of note clarity when i had the tone knobs dialled in to a typical gritty rock setting at Bass - 1oclock; Mids - 2-3oclock; Treble - 4oclock. I ended up swithing on my MXR81 Preamp and cranking the mids and treble on it to get a usable tone.

I wasn't even aware of Passive EQ or that there was a different type of EQ model than what standard class D amps use. (Please pardon my ignorance!!!). So after looking at of the other threads linked up here about passive eqs, I need to raise everything full to get an open tone and then only use the eq knobs to cut specific frequencies?! Am i right in saying this?!
 
#16
Try taking the compressor and contour valves out of the equation first by setting the controls to 0 to begin with. As a starting point I set the bass and treble at 6-7 and reduce the middle when practising at home. Raise the mids when in a band environment. The compressor will tighten the bottom end considerably so use sparingly especially if the gain is high.
The contour control can then be added gradually until you have the right amount of treble rolled off. This can be subtle when listening to just the bass. If you want clarity keep it low or off.
I also find leaving the tone controls at midpoint and buying a RMI Lehle Classic Boost pre worked really well !
 
#17
Thanks kasbrey,

I had a go with my amp today in my garage and found my preferred settings were bass 2 o'clock, mids full and treble full. The sound was so much nicer, full clear notes. Im also aware i just did a test run in a little box garage, probably 8ft by 15ft, so there will inevitably be condition changes when in a real gigging environment.

I have the onboard tube compression switched off at all times anyways. My Cali76 is my main compression unit so I don't need any further limiting/compression.

The Contour I usually have around 10 o'clock mainly to take away the background hiss. But you are right it is subtle.
 
#18
Smit_Dogg said:
Thanks kasbrey,

I had a go with my amp today in my garage and found my preferred settings were bass 2 o'clock, mids full and treble full. The sound was so much nicer, full clear notes. Im also aware i just did a test run in a little box garage, probably 8ft by 15ft, so there will inevitably be condition changes when in a real gigging environment.

I have the onboard tube compression switched off at all times anyways. My Cali76 is my main compression unit so I don't need any further limiting/compression.

The Contour I usually have around 10 o'clock mainly to take away the background hiss. But you are right it is subtle.
Click to expand...

Have you gigged it again since your frustrating first? Any better now?
 
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#19
Sparky Mark said:
Have you gigged it again since your frustrating first? Any better now?
Click to expand...
Yes, what a difference! Just what the doctor ordered. It's the tone I've been after. The vintage warmth from the preamp section and enough clarity for a modern player from the digi power section. Contour is turned right down ( nearly off) and the built in compressor just in so clipping the low-end now and again. Sounds nice having it at the end of chain in conjuction with my cali76 at the start.

Thanks for the feedback and advice. I was considering selling this amp after that gig using the EQ in the wrong way.
 
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