2-Channel Set-Up

[Phaedrus]

I may have asked this question before, but I can't find it...

I'd like to run a 2-channel set up - one clean, one effected. I'm attaching a pic of what I fancy.

The VXL can split the signal; parallel out continues instrument-level into the other effects and ultimately out to one channel of a power amp. The XLR DI out then feeds PA with clean/no effects signal, and the 1/4" jack DI out feeds line-level signal (clean/no effects) into the second channel of the power amp.

I hate the bottom end dropping out when using effects, so this is how I want to try to address that.

I welcome any comments or advice as to why this is not a good idea (forget the complexity/weight arguments - I'm OK with those issues), and any heads-ups on dangers or risks.


Thanks gang. 👍

Edited July 5, 2021 by Phaedrus
OCD

[uk_lefty]

Why aren't you sending an effects signal in to the PA? 

[paul_5]

Instrument level straight out of your pedals won’t be enough to feed a power amp input - you’ll need some sort of preamp to amplify the signal to line level.

[Downunderwonder]

Your problem changes from the lows to the mids when an effect that causes a large phase shift is used. Everything gets woolly.

My old heavily effected rig got around the clean blend problem with a bunch of gear. I sent lows through unaffected and blended them back in with a phase adjustable blending system using three channels of a Wounded Paw blender.

If you only use pedals that maintain phase you can skip the phase flipping but blending clean bass lows with effected skinny string guitar range is very fun.

The other way to skin the cat is only use pedals that don't gut the lows. They are out there.

[Phaedrus]

12 hours ago, uk_lefty said:

Why aren't you sending an effects signal in to the PA? 

Typically small gigs - local pubs kinda thing, so I'm thinking that the amp channel running the affected signal will be enough.

12 hours ago, paul_5 said:

Instrument level straight out of your pedals won’t be enough to feed a power amp input - you’ll need some sort of preamp to amplify the signal to line level.

My initial version 1.0 of this was with two 2x10 combo amps (Eden Terra Nova TN2252), but they're not available anywhere now (new or used), and I'm not aware of any affordable (for me) alternative. I'd still be more interested in this set-up (two combo amps) than the power amp/speaker cabs set-up - I may return to my searching for appropriate combos...

3 hours ago, Downunderwonder said:

Your problem changes from the lows to the mids when an effect that causes a large phase shift is used. Everything gets woolly.

My old heavily effected rig got around the clean blend problem with a bunch of gear. I sent lows through unaffected and blended them back in with a phase adjustable blending system using three channels of a Wounded Paw blender.

If you only use pedals that maintain phase you can skip the phase flipping but blending clean bass lows with effected skinny string guitar range is very fun.

The other way to skin the cat is only use pedals that don't gut the lows. They are out there.

Not gonna be shopping for more FX pedals - sticking with what I have. 

 

Thanks for your responses guys. 👍

[uk_lefty]

9 hours ago, Phaedrus said:

Typically small gigs - local pubs kinda thing, so I'm thinking that the amp channel running the affected signal will be enough.

But in a small pub you are going to take two bass amps and have a PA running subs? Seems a lot of gear for a pub, most I play in don't even have enough mains sockets for the bare minimum of kit in a 4 piece band, nevermind space for spare guitars and additional amps. Also, assuming all kit has reasonably equal power you're only sending your effects to 1 third of the output gear, and not the third that's up front and centre sending sound to the audience. I can understand bi-amping etc but I just think you'll lose the effects in this set up, making having them at all almost pointless. Surely better off finding a way to mix the sound on your effects board?

[itu]

You want two channels, not bi-amp?

Keep the low end intact and put effects to the high side. This is a tried and true option. Two sets of amps and cabs equals good abs, I certainly would opt for a bi-amp system. You talk to a cab builder (barefaced etc.) and you could have everything in a single box.

I am using IE Divaricator in my FX board to mix fuzz to the high side. This is kind of cheapish solution compared to a true bi-amp system but seems to work very well.

[Phaedrus]

12 hours ago, uk_lefty said:

But in a small pub you are going to take two bass amps and have a PA running subs? Seems a lot of gear for a pub, most I play in don't even have enough mains sockets for the bare minimum of kit in a 4 piece band, nevermind space for spare guitars and additional amps. Also, assuming all kit has reasonably equal power you're only sending your effects to 1 third of the output gear, and not the third that's up front and centre sending sound to the audience. I can understand bi-amping etc but I just think you'll lose the effects in this set up, making having them at all almost pointless. Surely better off finding a way to mix the sound on your effects board?

The Eden TN2252 combos (and similar, I expect) have DI outs - that would have been good...

[Downunderwonder]

12 hours ago, itu said:

You want two channels, not bi-amp?

Keep the low end intact and put effects to the high side. This is a tried and true option. Two sets of amps and cabs equals good abs, I certainly would opt for a bi-amp system. You talk to a cab builder (barefaced etc.) and you could have everything in a single box.

I am using IE Divaricator in my FX board to mix fuzz to the high side. This is kind of cheapish solution compared to a true bi-amp system but seems to work very well.

No guarantee an effected channel comes back in phase with the unaffected one whether it's biamped or mono mix.

[cheddatom]

if it's biamped it wouldn't matter if each channel was in phase?

I used to blend two channels and use EQ pedals to make my crossover. I used a compressor on the low side, and all the weird effects on the high side. It sounded ace! Then just one channel out to the PA, no amp

[itu]

8 hours ago, Downunderwonder said:

No guarantee an effected channel comes back in phase with the unaffected one whether it's biamped or mono mix.

True. I did not find that the most crucial thing when setting up my equipment. I still do not. But the effects do sing!

[Jus Lukin]

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Edited March 15, 2022 by Jus Lukin

[Phaedrus]

Phase you say...

Tell me more?

I'd presumed my plan would effectively equate to two basses being played - one dry, one effected. This isn't the case?

[Phaedrus]

This article below suggests to me that a two combo approach won't work because a combo's preamp won't handle the VXL's line-level output. 

But am I correct in interpreting that a power amp will a) handle a line-level signal OK, and b) handle an instrument-level signal that has passed through an FX pedal chain that included the VXL?

I did say I'd be asking a few questions...

I never said they wouldn't be dumb questions...

 

https://www.sweetwater.com/sweetcare/articles/whats-the-difference-between-mic-instrument-line-and-speaker-level-signals/#:~:text=Instrument level signals fall between,an electric guitar or bass.&text=Line level signals are the highest level signals before amplification.

 

Mic Level

Mic level is the voltage of signal generated by a microphone. This is the lowest, or weakest, level signal of the four and requires a preamplifier to bring it up to line level.

 

Instrument Level

Instrument level signals fall between mic level (lower) and line level (higher) signals. These signals refer to any level put out by an instrument, commonly from an electric guitar or bass. A preamplifier is required to bring the signal up to line level.

 

Line Level

Line level signals are the highest level signals before amplification. This is the type of signal that typically flows through your recording system after the preamplifier stage and before the amplifier that powers your speakers. The two types of line levels are consumer and professional.

IMPORTANT: Be careful not to send a line level signal to a preamplifier expecting a mic or instrument level signal.

Consumer line level is rated around -10dBV and is what you’ll find in products like a CD player.

Professional line level is rated around +4 dBu and can be found in equipment like mixing desks, preamplifiers, and signal processing equipment.

 

Speaker Level

Speaker level signals are post-amplification. After a line-level signal enters an amplifier, it exists to the speakers at what is called speaker level. These signals are much higher in voltage than line level and require speaker cables for safe signal transfer.

IMPORTANT: You should never plug a speaker level signal into a source expecting anything less than a speaker level signal.

 

Edited July 7, 2021 by Phaedrus
OCD

[Downunderwonder]

3 hours ago, cheddatom said:

if it's biamped it wouldn't matter if each channel was in phase?

Yes it matters. That is the very reason many blend pedals come with a phase switch option. I guess you have to hear a phase mismatch to understand.

The clearest demonstration is twin cabs miswired from a single source. The bottom drops right out.

In my case I wrote of up the page my crossover zone was affected by some pedals coming back inverted relative to the clean lows.

In the usual series line up of effects the various phase shifts are immaterial w.r.t our hearing. Not so when blending parallel effected signals, either before the amp or "in the air" with the bi-amp/ cab.

 

[Downunderwonder]

2 hours ago, Phaedrus said:

Phase you say...

Tell me more?

I'd presumed my plan would effectively equate to two basses being played - one dry, one effected. This isn't the case?

Two basses are a VERY different ball of wax to slightly messing with half of the signal and putting it back with its unmessed twin.

Iirc doubling up on incoherent sounds gets you 3dB louder. Coherent sounds x2 is 6dB louder.

But adding coherent sounds out of phase results in a cancellation!

Trouble is effected sounds retain much of their original form but could be 90 or 180 deg phase shifted if unlucky. Chorus and distortions commonly return 180 deg out. The blending of clean with the effected then suffers.

[itu]

5 hours ago, Downunderwonder said:

Yes it matters. That is the very reason many blend pedals come with a phase switch option. I guess you have to hear a phase mismatch to understand.

The clearest demonstration is twin cabs miswired from a single source...

I do partly agree.

1) Out-of-phase is one really serious issue when two signals are in the same frequency band (like signal + effected signal).

2) It is not that bad when they are separated (like bi-amp or X-over). This issue exists but it does not have to be so crucial. If you hear it, you have to act. If not, let it be.

A system that can measure phasing is rare. I have used them earlier in my work (broadcasting company), but not with a bass system. I can only rely on my ears. Or I could use my two channel 'scope.

[Downunderwonder]

6 hours ago, itu said:

bi-amp

A lot of people use that term when they are actually parallel effected. There is no OR in biamp and crossover if you are doing it right.

[itu]

6 hours ago, Downunderwonder said:

A lot of people use that term when they are actually parallel effected. There is no OR in biamp and crossover if you are doing it right.

True, yes! I have played with X-overs in my effect boards for a few years (IE, KMA). Parallel is (too) common, and I did go away from that after trying to manage with comb filtering and yes, phase issues. X-overs have opened a new way of using effects.

[cheddatom]

19 hours ago, Downunderwonder said:

Yes it matters. That is the very reason many blend pedals come with a phase switch option. I guess you have to hear a phase mismatch to understand.

The clearest demonstration is twin cabs miswired from a single source. The bottom drops right out.

In my case I wrote of up the page my crossover zone was affected by some pedals coming back inverted relative to the clean lows.

In the usual series line up of effects the various phase shifts are immaterial w.r.t our hearing. Not so when blending parallel effected signals, either before the amp or "in the air" with the bi-amp/ cab.

 

Surely phase cancellation only happens in the same frequencies, so if you have high frequencies out of phase with low frequencies, no cancellation will occur?

[Downunderwonder]

6 minutes ago, cheddatom said:

Surely phase cancellation only happens in the same frequencies, so if you have high frequencies out of phase with low frequencies, no cancellation will occur?

The extent to which the bands are separated determines how much of your spectrum is vulnerable. Unfortunately it's not possible to brick wall it without some serious rack gear so we always wind up with several hundred Hz that is in common between the effected and unaffected. That's all assuming a crossover and blender is in play.

With your 'garden biamp' of a distorted signal playing over a clean signal the usual approach is heavy EQ separation. That's even less reliable than a crossover.

[cheddatom]

5 minutes ago, Downunderwonder said:

The extent to which the bands are separated determines how much of your spectrum is vulnerable. Unfortunately it's not possible to brick wall it without some serious rack gear so we always wind up with several hundred Hz that is in common between the effected and unaffected. That's all assuming a crossover and blender is in play.

With your 'garden biamp' of a distorted signal playing over a clean signal the usual approach is heavy EQ separation. That's even less reliable than a crossover.

I do it in the studio just using EQ on 2 separate channels, never had phasing issues. On my old board I used two EQ pedals and never had issues. I'd never really considered the overlap you're referring to but I guess I'll know if I ever hear it!

[Al Krow]

On 07/07/2021 at 11:02, Jus Lukin said:

As much fun as multi-amp setups are, something like a Boss LS-2 would be a very simple way to run an effects chain alongside a clean, unaffected signal, with a single blended output. Following that with a passive DI would then give you instrument level to your amp and mic level to the board.

+1^^ exactly my thoughts, too.

[Phaedrus]

Gotta scratch the 2-amp itch for myself.

I now have a TC BG250 115 (for clean/not-effected signal, collecting this Friday) and a TC BG250 112 (for effected signal), and a few pedals that I'm enjoying experimenting with. So the DI from the BG amp section will allow me to run both clean and effected signals to PA.

I'll be on the lookout for a BG250 210 or two...

[Jus Lukin]

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Edited March 15, 2022 by Jus Lukin