Active DI box - would removing endpin preamp improve sound?

[MisterRiemann]

Hello!

I initially posted this in the amplification section, but I was recommended to ask here as well.

Influenced by Mayer's amplified acoustic tone, I recently got my hands on an Avalon U5 preamp/DI. I am pairing it with a Fishman Matrix Infinity system in my Martin OM28.

I was planning to use this rig for recording to start with, and then (hopefully) at gigs later on. However, when recording I have to say that I notice only minimal differences when plugging the guitar directly into my audio interface (Scarlet 2i2) versus going into the U5 first, and then into the interface. I found this very surprising since people generally seem to praise the Avalon, and also considering its pricetag, I was expecting to hear more of a difference to be honest.

After reading online a bit, I noticed that the general rule of thumb is to use an active DI with a passive pickup, so I was wondering - would I see an improvement in sound if I "passified" my Matrix system by removing the endpin preamp and just connecting the UST directly to the endpin jack?

Or do you have other suggestions perhaps? Let me know!

Thanks!

[shufflebeat]

Contrary to previous advice (oops) I'd suggest this isn't really a recording question as much as an acoustic amplification one, although they're not mutually exclusive of course.

The Matrix Infinity preamp is quite decent and will give you a good representation of your pickup sound.

The idea of "passive pickup/active DI" is usually to remedy the mismatch between passive piezo pickups and (most) passive DIs. However, an onboard preamp will deal with that before it leaves the guitar, which is ideal because the connection between pickup and preamp should be as short as possible.

The preamp/DI you reference is a great solution to a problem you don't have, but it's still a good box.

[keith.rogers]

JM probably has to run a signal a fair distance to get the acoustic guitar output to the PA system, so using an actual DI to convert to a balanced signal would be necessary to preserve the quality of the signal.

If you don't have a long cable run or noisy environment, as noted, the preamp output going into the DI in the 2i2 (effectively what that 1/4" input is acting as when switch to INST), is not going to be "improved" by using a different DI and going into the mic input, unless that DI is specifically designed to color the tone in some way.

If you're recording, I'd just mic it up!

[MisterRiemann]

Alright, many thanks for the replies! That clarifies the situation

[shufflebeat]

Originally Posted by keith.rogers

JM probably has to run a signal a fair distance to get the acoustic guitar output to the PA system, so using an actual DI to convert to a balanced signal would be necessary to preserve the quality of the signal.

True enough.

For many people in a live situation a Boss (or other) tuner with a high impedance and mute function coupled with a DI of your choice, passive or active, is as good a solution as any other unless, as mentioned, you want colouration, FX, "boost" button, etc.

[RJVB]

Originally Posted by MisterRiemann

just connecting the UST directly to the endpin jack?

Doesn't a piezo pickup require power, contrary to an electromagnetic PU?

[Rudy4]

The reason why the end pin preamp was developed in the first place is because ideally you want the shortest possible cable length between the transducer and the preamp. Shufflebeat alluded to this earlier, but it's helpful to know a bit of the technical reasoning for this.

Manufacturers originally specified this cable length as no more than 6" as ideal. The combination of the ultra-high resistance (actually impedance) of the transducer coupled with even a small amount of cable capacitance forms a rudimentary RC filter network, effecting the tonal quality of the pickup. That's the real reason for the end pin preamp, which is commonly referred to as an impedance matching device.

You can get away with not using a preamp at the instrument if you're using good quality cabling, and preferably keep it short. A 10' guitar cable is a good candidate for this if you're connecting to a floor DI box or preamp / effects unit.

In answer to the basic question posed, getting rid of the end pin preamp and using a pre or other impedance matching device may or may not improve or degrade your sound based on your cabling capacitance, and it may not be enough to discern either way. Connection cabling has generally improved in quality since internal piezos were first developed, so this truly is one of those "YMMV" situations.

[MisterRiemann]

Originally Posted by Rudy4

The reason why the end pin preamp was developed in the first place is because ideally you want the shortest possible cable length between the transducer and the preamp. Shufflebeat alluded to this earlier, but it's helpful to know a bit of the technical reasoning for this.

Manufacturers originally specified this cable length as no more than 6" as ideal. The combination of the ultra-high resistance (actually impedance) of the transducer coupled with even a small amount of cable capacitance forms a rudimentary RC filter network, effecting the tonal quality of the pickup. That's the real reason for the end pin preamp, which is commonly referred to as an impedance matching device.

You can get away with not using a preamp at the instrument if you're using good quality cabling, and preferably keep it short. A 10' guitar cable is a good candidate for this if you're connecting to a floor DI box or preamp / effects unit.

In answer to the basic question posed, getting rid of the end pin preamp and using a pre or other impedance matching device may or may not improve or degrade your sound based on your cabling capacitance, and it may not be enough to discern either way. Connection cabling has generally improved in quality since internal piezos were first developed, so this truly is one of those "YMMV" situations.

Thanks for the thorough explanation! It might be fun to try this for the sake of science, even though it probably won't turn out to be worth the hassle.

[shufflebeat]

Originally Posted by RJVB

Doesn't a piezo pickup require power, contrary to an electromagnetic PU?

No, the onboard preamp does, the pickup element itself can be used passively. Some, like K&K, Ultratonic can work well, others, including most (all?) USTs - not so much.

[RJVB]

Originally Posted by shufflebeat

No, the onboard preamp does, the pickup element itself can be used passively. Some, like K&K, Ultratonic can work well, others, including most (all?) USTs - not so much.

Interesting, last time I research this the answers all said piezo elements are active, making me assume they work a bit like electrets. But it's true that the clamp-on sensor of my tuner (presumably containing a piezo) works with my Behringer UMC audio interface and I think my mic preamp too, both of which do not put out a voltage over their TS input as far as I know.

[Doug Young]

Originally Posted by RJVB

Interesting, last time I research this the answers all said piezo elements are active, making me assume they work a bit like electrets. .

"Piezo" is a rather generic term for any material that produces electricity when stressed. The majority of pickups other than magnetics are some type of piezo material. The piezo element itself does not require electricity, and piezo materials can be used as "passive" pickups, meaning no other electronics or batteries in the guitar. "Piezo" does not mean "undersaddle." All (or nearly all) undersaddles are piezos, but so are K&Ks, Dazzos, Trance, etc. And there are both passive and active undersaddle pickups, as well.

Passive piezo elements present some challenges. Some have low output. Most must be fed into a high impedance input, and some require extremely high impedances. In most cases, they benefit from having a properly designed electronic circuit that acts as a buffer and amplifier, as close to the pickup as possible, along with some way (usually a battery) to power the electronics. That's what makes a pickup "active".

In your case, you have the piezo pickup going into the onboard amplifier, then into the U5, then into your Scarlet. The U5's a good box, but other than it's tone shaping controls, it's meant, I think, to be "transparent", that is, to not change your tone, and you still have all the other pieces of your signal chain in place, so it's not surprising you hear no difference. The U5 is doing its job and not altering your tone, and you're still hearing the rest of your signal chain.

John Mayer's using one because (presumably) it's a high quality box with lots of headroom. He may "feel" a difference when playing loud and digging in. Remember that he's not playing at home into a Scarlet. He's going into an equally impressive mixing board, probably a large PA system, etc, with professional sound engineers tweaking his sound.

[MisterRiemann]

Originally Posted by Doug Young

"Piezo" is a rather generic term for any material that produces electricity when stressed. The majority of pickups other than magnetics are some type of piezo material. The piezo element itself does not require electricity, and piezo materials can be used as "passive" pickups, meaning no other electronics or batteries in the guitar. "Piezo" does not mean "undersaddle." All (or nearly all) undersaddles are piezos, but so are K&Ks, Dazzos, Trance, etc. And there are both passive and active undersaddle pickups, as well.

Passive piezo elements present some challenges. Some have low output. Most must be fed into a high impedance input, and some require extremely high impedances. In most cases, they benefit from having a properly designed electronic circuit that acts as a buffer and amplifier, as close to the pickup as possible, along with some way (usually a battery) to power the electronics. That's what makes a pickup "active".

In your case, you have the piezo pickup going into the onboard amplifier, then into the U5, then into your Scarlet. The U5's a good box, but other than it's tone shaping controls, it's meant, I think, to be "transparent", that is, to not change your tone, and you still have all the other pieces of your signal chain in place, so it's not surprising you hear no difference. The U5 is doing its job and not altering your tone, and you're still hearing the rest of your signal chain.

John Mayer's using one because (presumably) it's a high quality box with lots of headroom. He may "feel" a difference when playing loud and digging in. Remember that he's not playing at home into a Scarlet. He's going into an equally impressive mixing board, probably a large PA system, etc, with professional sound engineers tweaking his sound.

Thanks for the explanation!

Would you then say that having the extra headroom from the U5 would be noticeable even when playing at smaller venues, such as bars or coffee shops? Or am I better off just selling the U5 then, as I doubt I will ever play on stages anywhere near the size of those John plays on?

[ChuckS]

Agreeing with what's already been said, but also want to mention that the 'quality / performance' of your signal chain is very inconsistent.

The Avalon is a very high-end DI and preamp. The Scarlett 2i2 provides high value for its cost, but its internal preamp (which cannot be bypassed) and ADC are not of the performance level of the Avalon. I'd assume the same to be true for the preamp in the Fishman system. If you want to have performance improvement (which you may or may not even notice) your gear (DI, preamp, ADC) should ideally be of a similar level of performance.

For recording, you might be better off getting a nice microphone or two and nice audio interface (versus having money tied up in the Avalon).

For playing live, using the Avalon may not result in any noticeable improvement unless you bypass the Fishman and the rest of the system (mixer, amp, speakers) are high end. Even then, you might not hear the benefit of the Avalon.

[Doug Young]

Originally Posted by MisterRiemann

Thanks for the explanation!

Would you then say that having the extra headroom from the U5 would be noticeable even when playing at smaller venues, such as bars or coffee shops? Or am I better off just selling the U5 then, as I doubt I will ever play on stages anywhere near the size of those John plays on?

Well, good gear is always great to have, and you may grow to appreciate the U5. Right now, as ChuckS stated more clearly, you're being limited by the rest of your chain - you're only as good as your weakest link. So it's hard to suggest throwing out your strongest link! If it was me, I'd use this as an excuse to bring the rest of the chain up to the quality of the U5.

Totally agree with Chuck as well, that for recording, use mics. A pickup will never compete with even the cheapest mic for recording, no matter what you run it through.

For playing Open Mics, I don't know. This may be overkill. You'd have to check out your open mics. The ones I'm familiar with in my area discourage or even disallow any gizmos. You have limited time, sit down in front of a mic, or plug in using the cable they hand you, and play. No sound check, no fiddling with gear. Showing up with an AC powered box that needs an XLR cable to the sound system would throw some open mics for a loop. And an Open Mic where the sound person knows what they're doing will probably already have a DI.

At most open mics I'm aware of, the sound system ranges from poor to mediocre, as well. So you have the same issue as you have with your Scarlett, where the U5 won't make up for the weakest link. I get wanting to do something to sound your best, but at most Open Mics, everyone just usually sounds bad, it's part of the scene :-).

What I'd do if playing open mics and wanting to have some buffer between me and what I have to plug into is have something fairly cheap and simple on hand, like even one of the $29 Whirlwind DIs, or the RedEye DI in case it was needed (and allowed). When I used to play Open Mics more, I often took a Baggs MixPro, which hangs on my belt, and has 1/4 inch outs, so when they'd hand me the guitar cord, I'd just plug into the Baggs as if it was my guitar, and they were none the wiser. But I at least had a buffer against whatever terrible board they were using, and had basic volume and tone controls at my finger tips.

[MisterRiemann]

Thanks again for all the replies and the advice! I found this conversation really helpful.

Truth be told, I am one of the three people in the world () who actually enjoy the sound of a UST, so that's why I'm trying to squeeze the most out of it. In my opinion, the quality of the UST sound is definitely a spectrum and I think it's unfortunate that sometimes people just instantly dismiss it as being a necessary evil meant to only be used in a live setting.

For example, I would argue that this recording of JM's Sucker or this one of Man on the Side sound absolutely fantastic (but don't get me wrong - it's not hard find recordings of DI which sound horrendous, on the other hand). So this is what I was aiming for, and what I'm trying to achieve with a high-end setup.

So I felt a bit disheartened at first, when I learned that the Avalon might not do the trick (or at least get me closer to doing the trick). But I definitely agree - the quality/performance of my chain is definitely inconsistent, so I think I will also use this as an excuse to improve the other components of my setup, and maybe then I will hear a difference. Whether or not this will be worth it is a different story I suppose, but as Doug said, it can't hurt to have high-end equipment if one can afford it.

I guess that, in the end, it might be best to do some sort of blend between the mic signal and the DI when recording, so as to capture the actual sound of my guitar, while keeping some of the UST "flavour".