DI or Line ISO for Modeler Signal

[ColonelZulu]

I’m getting flooded with videos about using Line Level Isolators instead of DI boxes to send signals from modelers (Helix, Iridium, Kemper, etc.) to the board.

Anyone have experience with this? I think the Line ISO gives a super hot signal to the board (which the sound guy would not expect) but that gives you a really good signal to noise ratio.

So, in theory, it would be optimal to send a Line ISO signal, but the sound guy may not be equipped to deal with an optimal signal in practice.

If you don’t know what I mean, look at demos of the Pinstripe DISO+ and MISO, or the Walrus Canvas.

 

[CatOnTheBass]

Sub'd to follow and learn more. I agree with your basic premise (that a DI box is redundant for a modeling device that already has a balanced, low-impedance output).

A line level isolator neither boosts nor cuts the signal (they use 1:1 transformers), so if the levels are okay with your modeler connected directly to the board with a balanced cable, that's the exact same level it would be with the isolator. I don't see why this should freak out the sound guy: you are using the device exactly as intended. This is what it was designed to do. If the XLR jack on the back of a Kemper isn't for connecting to a mixer, then what is it for?

Which modeler specifically do you have? Have you ever tried connecting your modeler directly to the mixer with a mic cable (or balanced 1/4" TRS as the case may be)? Were you happy with the results or no? Was it too hot a signal? Was there any noise or hum?

 

[ColonelZulu]

Sub'd to follow and learn more. I agree with your basic premise (that a DI box is redundant for a modeling device that already has a balanced, low-impedance output).

A line level isolator neither boosts nor cuts the signal (they use 1:1 transformers), so if the levels are okay with your modeler connected directly to the board with a balanced cable, that's the exact same level it would be with the isolator. I don't see why this should freak out the sound guy: you are using the device exactly as intended. This is what it was designed to do. If the XLR jack on the back of a Kemper isn't for connecting to a mixer, then what is it for?

Which modeler specifically do you have? Have you ever tried connecting your modeler directly to the mixer with a mic cable (or balanced 1/4" TRS as the case may be)? Were you happy with the results or no? Was it too hot a signal? Was there any noise or hum?

I have a Line 6 HXFX and a Line 6 HX Stomp.

 

[Mike Caldwell]

For what it's worth anytime someone has a modeler with balanced XLR outputs I'll take those direct. So far I have not had to but if there was a hum/noise issue I would reach into the work box and grab an iso transformer.

.......Now maybe for your protection a 1:1 iso transformer would block the modeler's outputs from getting hit with phantom power from the mixer, though I would think that the outputs on the modeler should be able to take that without issues.

 

[sawzalot]

There is a video out there with about 25K views that is basically totally wrong its fundamental premise that the HX Stomp’s outputs aren’t differential. Beware of that one. A line isolator does what it sounds like, it uses 1:1 transformers to physically isolate the unit from the board (as long as it has a ground lift also). A direct box will convert an unbalanced signal to balanced and also change the level depending on the transformer inside the box. So two different use cases, with some overlap in the solution: one is isolation and the other is unbalanced-to-balanced conversion. Transformers are involved in both, and isolation happens in both, but they’re not designed for the same problem set.

 

[CatOnTheBass]

I have a Line 6 HXFX and a Line 6 HX Stomp.

If I am understanding the manuals correctly (I could be wrong):

• The Line 6 HXFX does not have balanced outputs. The outputs are unbalanced TS 1/4" suitable for connecting to an amp or another pedal. Using a DI box with the HXFX would be beneficial, to convert your signal from unbalanced to balanced.
  
• The Line 6 HX Stomp outputs can accommodate your choice of unbalanced 1/4" TS or balanced 1/4" TRS cables. There is a diagram in the manual showing the HX Stomp connected directly to a mixer. You could carry the manual around and show this diagram to skeptical sound guys.

 

[MYLOWFREQ]

Well, there's conversion from instrument level signal to either line level or mic level. You can't say which one is better without knowing how the board and the line level isolator accomplish that.

 

[Wasnex]

There is a video out there with about 25K views that is basically totally wrong its fundamental premise that the HX Stomp’s outputs aren’t differential. Beware of that one. A line isolator does what it sounds like, it uses 1:1 transformers to physically isolate the unit from the board (as long as it has a ground lift also). A direct box will convert an unbalanced signal to balanced and also change the level depending on the transformer inside the box. So two different use cases, with some overlap in the solution: one is isolation and the other is unbalanced-to-balanced conversion. Transformers are involved in both, and isolation happens in both, but they’re not designed for the same problem set.

Here's an example: MISO - Mono Line Isolator | Pinstripe Pedals The technical description and specs are considerably veiled/opaque. It's not super clear to me what the MISO does or how it varies from a regular DI. I believe it has a differential 1/4" input and also it works with a line level signal at all inputs and outputs.

Hopefully the 1/4" thru is also transformer isolated, or the differential input becomes single sided when you patch to a regular amp. I can tell you from personal experience, a line level signal is not going to work well going into the front end of a regular instrument amp.

Here's another example: Canvas Line Isolator / D.I. (walrusaudio.com) This one specifically says it has an unbalanced 1/4 in.

I think in the purest sense, this is an example of a Line Isolator. XLR in and XLR out.
Twin-Iso - Radial Engineering IMHO the previous two are essentially a chimera of a Line Isolator and a DI.


Here's another device that deals with 1/4" and XLR, but does not have a separate thru:
Hum Eliminator – Morley (morleyproducts.com) Pure line isolator here with 1:1 transformers.

Here another variation with XLRs only: JS3 Specifications - Radial Engineering It has one hardwired thru and two 1:1 transformer isolated outs. The hardwired thru is intended to pass phantom from the mixer to a mic or DI...works at mic or line level.

 

[sawzalot]

Hopefully the 1/4" thru is also transformer isolated, or the differential input becomes single sided when you patch to a regular amp. I can tell you from personal experience, a line level signal is not going to work well going into the front end of a regular instrument amp.

Very true. I think these gadgets are targeted mostly at the guitarist community, who tend to use the Helix/QuadCortex/Kemper/etc as a front end to a power amp or powered FRFR speaker, which would be expecting a line-level signal. Here's what I don't get, though: at least the Helix Floor and LT have separate 1/4" an XLR outputs; you can set the 1/4" outputs to be line level (send to an FRFR) and the XLR's to be mic level, so at least on that platform neither the DI or isolator are a cost-effective tool; all you need is either a $10 ground lift adapter or to modify your own cable to snip the shield connection to the XLR connector.

 

[frankie5string]

You've worked hard to create your sound. To me a good, durable DI with a known track record like a JDI is worth the investment.

 

[Geri O]

Sounds like yet another situation where my (rather expensive, I’ll admit) REDDI Tube DI is an ideal solution.

 

[Windreaper]

There is also the issue of the impedance ratio (square of the turns ratio). An ideal 12:1 transformer would have an input impedance of 144kOhm when loaded by a preamp with a 1kOhm input impedance. Should be sufficient for any source.

Line-level devices might have output impedances ranging from 600Ohm to 1kOhm and up. I would always use a DI box when expecting to connect to a mic preamp (which might have an input impedance ranging from ~5-10kOhm on a mixer, and <2kOhm on studio grade preamps).

 

[-Asdfgh-]

Sub'd to follow and learn more. I agree with your basic premise (that a DI box is redundant for a modeling device that already has a balanced, low-impedance output).

A line level isolator neither boosts nor cuts the signal (they use 1:1 transformers), so if the levels are okay with your modeler connected directly to the board with a balanced cable, that's the exact same level it would be with the isolator. I don't see why this should freak out the sound guy: you are using the device exactly as intended. This is what it was designed to do. If the XLR jack on the back of a Kemper isn't for connecting to a mixer, then what is it for?

Which modeler specifically do you have? Have you ever tried connecting your modeler directly to the mixer with a mic cable (or balanced 1/4" TRS as the case may be)? Were you happy with the results or no? Was it too hot a signal? Was there any noise or hum?

Whilst it might be redundant, a stereo jack with a balanced signal may cause the sound engineer's brain to melt, whereas a DI box obviously on view with an XLR will not. I know, as I've been that sound engineer. I don't necessarily have thirty minutes free to read your modeller's manual. I don't even read my own modeller's manual.

 

[micguy]

A Di usually steps the impedance (and therefore the signal level as well) down a LOT (your instrument is a relatively high impedance device). A line level isolator , if you have a source which is already low impedance, doesn't - it just make sit balanced to avoid ground loops. I have a couple pedalboard DI's that I made, that are in between - pedals are lower impedance that basses, but that always THAT low, so it's a compromise that works well.

 

[Manticore]

If the XLR jack on the back of a Kemper isn't for connecting to a mixer, then what is it for?

This is precisely how I use my Kemper, XLR output direct to the board.

 

[Jack]

Most of the time I'm the soundman for our band and I use the trs output on the Stomp straight into the mixer with a trs to xlr cable. I know that it's balanced and I know I won't shove phantom power into it.

However, about 10% of our gigs are with external companies and I long ago (back in my kemper days) learned that they need an xlr from a box, not even from an adaptor cable. They just don't believe that it's balanced. And if they don't understand that then I don't trust them not to press the phantom power button.

To answer the actual question I think a di is better suited to this as it ensures a mic level signal going to the board. Again, purely for convention. There's no reason a hotter signal from a line isolator wouldn't work but my situation is festivals, bike rallies, that kind of thing. Not all soundmen at these gigs are brilliant and even the ones that are tend to be in a hurry. If my band was always providing our own sound or conversely on a big tour with a consistent crew then we could trim it down but we're not and I need foolproof.

I take a LBP Inc DI to every gig, just in case. I always get given a Klark Teknik either way.

 

[Windreaper]

Most of the time I'm the soundman for our band and I use the trs output on the Stomp straight into the mixer with a trs to xlr cable. I know that it's balanced and I know I won't shove phantom power into it.

However, about 10% of our gigs are with external companies and I long ago (back in my kemper days) learned that they need an xlr from a box, not even from an adaptor cable. They just don't believe that it's balanced. And if they don't understand that then I don't trust them not to press the phantom power button.

To answer the actual question I think a di is better suited to this as it ensures a mic level signal going to the board. Again, purely for convention. There's no reason a hotter signal from a line isolator wouldn't work but my situation is festivals, bike rallies, that kind of thing. Not all soundmen at these gigs are brilliant and even the ones that are tend to be in a hurry. If my band was always providing our own sound or conversely on a big tour with a consistent crew then we could trim it down but we're not and I need foolproof.

I take a LBP Inc DI to every gig, just in case. I always get given a Klark Teknik either way.

Convention, sure, but there's no particular advantage to using a LI, so why do it? The sound guy will have no problem bringing up your DI signal to a suitable level with no appreciable noise or coloration. A DI box also ensures good fidelity under all conditions - no need to worry about input/output impedance or read manuals.

Pinstripe etc. seem to make well thought out products, but their marketing copy is dubious, claiming that you should use line isolators instead of DI boxes with modelers. Their marketing point seems to be that the lack of volume drop "keeps your tone intact" (also implying that DIs significantly color your tone). Sure, because going through the mic preamp on a $20k desk is going to totally destroy your toanz.

 

[fretlessman71]

So.... what can a Line ISO do that the little volume knob on the HX Stomp can't? Is it just a matter of signal to noise ratio? This tech stuff is way over my head, but I do want to know if I should get a MISO for my pedalboard instead of the Countryman DI I have. Passive is a bonus, but other than that...?

 

[frankie5string]

So.... what can a Line ISO do that the little volume knob on the HX Stomp can't? Is it just a matter of signal to noise ratio? This tech stuff is way over my head, but I do want to know if I should get a MISO for my pedalboard instead of the Countryman DI I have. Passive is a bonus, but other than that...?

If you already have a Countryman DI, I can't think of a reason to switch to an isolator. That DI is already doing that and more. The Countryman even has voltage/current protection for the stuff that's plugged into the line side which is a big benefit for something like an HX Stomp.

 

[Geri O]

I’m getting flooded with videos about using Line Level Isolators instead of DI boxes to send signals from modelers (Helix, Iridium, Kemper, etc.) to the board.

Anyone have experience with this? I think the Line ISO gives a super hot signal to the board (which the sound guy would not expect) but that gives you a really good signal to noise ratio.

So, in theory, it would be optimal to send a Line ISO signal, but the sound guy may not be equipped to deal with an optimal signal in practice.

If you don’t know what I mean, look at demos of the Pinstripe DISO+ and MISO, or the Walrus Canvas.

I’m wondering how you are flooded with videos about this. Did you visit a site or a page and possibly being flooded with ads from the tracking that goes on incessantly from our use of social media?

In any case, I looked over this product. It looks, acts, and smells like an off-beat solution searching for a problem.