Discuss Quantum Thunderbolt Interface Here
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I know that this is a super naive question but after paying more than $1,000 for this interface I’m asking it anyway. If I plug my bass guitar into inputs 1 or 2 with a standard TS instrument cable and switch to “instrument” is it correct that I don’t need a DI Box ?

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by SwitchBack on Tue Sep 17, 2019 3:53 am
You got it, no DI needed :)
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by frank.crow on Tue Sep 17, 2019 6:59 am
SwitchBack wroteYou got it, no DI needed :)


Thanks

I had previously run my bass guitar through a hardware unit with light EQ and Compression and then that unit went into my interface at line level. I only just recently started plugging directly into the interface and was enjoying the difference in input level (not having to use a gain plugin) but then I started overthinking about my preamps & my active pickups, etc and YouTube wasn’t helping.

I’m on YouTube right now and they are saying that when the instrument button is activated that it routes to a totally separate preamp.

What I’m hearing about all the auto routing functionality seems pretty fantastic. It arrives today and I’m looking forward to testing it out.

I use outboard gear with pipeline and I’m thinking this is really going to help with that too.

Thanks again

Mac Mini (Late 2014)
Processor: 3.0 GHz Intel Core I7
Memory: 16 GB
Presonus. Studio One Pro V4
Hardware Quantum
Hardware DBX 160a
Hardware DBX 160XT
Hardware Pro VLA II
Hardware WA76
Hardware Klark Teknik EQP-KT
Presonus. V2 Monitor Station
Presonus. FaderPort 8


"God's grace" :D
User avatar
by SwitchBack on Tue Sep 17, 2019 8:42 am
The two main differences between line inputs and instrument inputs are input impedance and balanced vs. unbalanced. Since required gain is similar for both types of inputs one preamp can do both functions. What the “inst” switch needs to do is lift a tip-to-ground input resistor (to raise the input’s impedance) and to ground the ring contact.

Do make sure to use a TS instrument cable (not a balanced TRS cable) for two reasons:
- signals from pickups are not balanced. Noise protection relies on a coaxial (core + shield) cable design between instrument and preamp input.
- active circuits in a guitar often use the ring contact in the guitar’s socket to engage the battery. A TRS plug won’t close the circuit.

Active pickups are far less sensitive to a preamp’s input impedance than passive pickups. Your guitar may even be happy with the “inst” switch off. No harm in trying ;)
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by frank.crow on Tue Sep 17, 2019 11:06 am
Thanks, this is super useful information.

So I’m basically overthinking it. Nothing is going to explode because I’m using active pickups?

Mac Mini (Late 2014)
Processor: 3.0 GHz Intel Core I7
Memory: 16 GB
Presonus. Studio One Pro V4
Hardware Quantum
Hardware DBX 160a
Hardware DBX 160XT
Hardware Pro VLA II
Hardware WA76
Hardware Klark Teknik EQP-KT
Presonus. V2 Monitor Station
Presonus. FaderPort 8


"God's grace" :D
User avatar
by SwitchBack on Tue Sep 17, 2019 11:55 am
No, you should be fine.

The “amplifier” in active pickups isn’t really increasing output level but it's mainly lowering the instrument’s output impedance. That way the output is capable of driving lower impedance cables and inputs, so fewer issues with (parasitic) cable/input capacitance and cable noise.

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