Running pedals straight into a power amp

[jacoby75]

Hey gang,

I imagine this must be discussed somewhere else on the threads, but a search didn't reveal anything helpful. So forgive me if this has been discussed before, but . . .

Does anybody run pedals straight into a power amp? It has been said that a pedal that I have coming in the mail has enough headroom and output to push a power amp. That got me thinking. Why have I never tried that before? Well, I'll answer that. Because I didn't think it would work. I assumed a pedal wouldn't have the output, the power, or the output impedance, etc, to adequately push a power amp. I assumed the level would be too quiet, too noisy, or both. I assumed I needed to use my rackmount preamp to get the signal to line level to sound halfway decent through a power amp.

But I found the thought of not having to lug my huge rack around in my old age all too appealing. I couldn't leave well enough alone. Just carrying my pedalboard, which I would definitely bring anyway, and a Carvin DCM2000L power amp in a 2-space rack that weighs next to nothing would be amazing.

So I tried running my pedals straight to my power amp tonight just for poops and giggles . . . and you know what? . . . it kind of worked! It sounded good, but it didn't sound great. It certainly was plenty loud, but it didn't have the punch that my rack pre has (a Geddy 2112 run clean with subtle EQ). My pedalboard is pretty Broughton-heavy, ending in an SVPre and RFE. I find the SVPre to be pretty quiet compared to other preamps. It sounds good in headphones through a DI, but lacked the same punch coming through the power amp and cab.

What is the solution? Do you need to have something with a line level output to really get a great tone when running from a pedalboard straight to a power amp? Something like a Sansamp (that I don't really love the sound of) that has a +10db switch on the 1/4" out, maybe?

Does anybody even do that, or am I crazy . . . or both?

If so, what are you guys using?

Or could I get away with just a boost pedal of some kind at the end of my pedalboard to bring the output up to line level? Maybe? Or do you need something that actually physically converts the signal to line level to give it more strength and not just more volume? Something like what a rack pre is designed to do, I can only imagine. I'm not adequately educated in the physics/science/electronic engineering side of things to even know how to ask the question.

Thanks

 

[Killing Floor]

Difference between instrument level and line level? Although there are some devices that are capable.

 

[PeaveyPlayer]

How sensitive is the poweramp

I’ve run a tone hammer into a CROWN xls 1500 bridges into a tranyor 810

and I’ve run my trace Elliot 12 band pedal into a ipr

and it worked well but you’d want Possibly a dual di

so you can go quarter out from the pedal to XLR and then xlr of the other side to your FOH

 

[jacoby75]

Difference between instrument level and line level? Although there are some devices that are capable.

I guess that's partly my question. And perhaps a stupid one at that. But is instrument vs line level simply a matter of volume? And would that difference be something that can achieved with a boost pedal? Or is there some other inherent difference in the quality/attributes of a line level signal?

 

[jacoby75]

How sensitive is the poweramp

Yes, I need to look into the input impedance of the power amp vs the output impedance of whatever I'm running into it, maybe. But I don't understand what that means well enough to know what I'm looking for. I'll look into that.

 

[Alan Ace Cooper]

Aguilar Tone Hammer DI can push it

 

[jacoby75]

I have a Sansamp Bassdriver I can try, just to get the output up high enough, maybe. If I run it clean and bypass the amp coloration.

I wonder if feeding the power amp an XLR signal would make a difference. I'll try that next as well. I have a Radial JDI on my board. My half-baked plan is to take the XLR to FOH off of my board, and then run the 1/4" thru from the JDI out to my amp . . . likely with something in between to boost the signal via 1/4". Or I could maybe just have a second DI or the Sansamp (to use as basically a glorified DI) on my board and run the 1/4" thru of my JDI into the Sansamp to run the XLR from that to my power amp.

 

[Snaxster]

Hello. Some pedals are true preamps, made to properly drive a power amp directly. Using one in that capacity at the end of the pedal chain negates the need for a final preamp after (rackmount or integrated). For example:

Herbert Pedal by Deizel Amplification

ALiX by Grace Design

Basswitch (various models) by Lehle/RMI

Blue 360 AIAB by One Control

Sonic Silver Peg by One Control

Rusty Box by Tronographic

 

[davelowell2]

I bought a Ganz Straight Ahead to use in this way. I usually use the Archetype preamp but sometimes to travel light I just use pedals. Just have to find the ones with enough juice, I don’t know the technical aspect, lol.

 

[Longtortoise]

The Tech21 YYZ manual suggests running it into an effects loop return, which should be the same as straight into a power amp. I do this on my Rumble 200 and it sounds great!

 

[MTN.bass72]

When I had my Noble, I ran it into a bridge Crest Prolite 2.0 and it was stellar.
I have a Mesa Subway DI now, I've never ran it directly to a power amp, but I know I can if the need came up...

I don't know the correct terminology, but the output of the pre needs to be a very mega ohms... I think that's what it is... I want to say 1 mega ohm, or maybe it's 10..

Those more knowledgeable can confirm the actual number.

 

[-Stingray]

I run pedals into my Sansamp VT-Bass DI, then straight into the mixing board for small/med inside venues (90% of what we play). Works amazingly well as long as you have a decent PA with good subs.

The Sansamp has two outs so you could run one to the board (xlr) and the other (1/4") to an amp.

 

[Hurricane Jimmie]

I have a Sansamp Bassdriver I can try, just to get the output up high enough, maybe. If I run it clean and bypass the amp coloration.

I wonder if feeding the power amp an XLR signal would make a difference. I'll try that next as well. I have a Radial JDI on my board. My half-baked plan is to take the XLR to FOH off of my board, and then run the 1/4" thru from the JDI out to my amp . . . likely with something in between to boost the signal via 1/4". Or I could maybe just have a second DI or the Sansamp (to use as basically a glorified DI) on my board and run the 1/4" thru of my JDI into the Sansamp to run the XLR from that to my power amp.

So Anyway, years ago I ran my Sansamp straight into a Peavey Power Amp. I sounded like me.

But this was after I tried to plug my passive bass straight into the power amp.... with no preamp. I'm not sure what I sounded like...couldn't get much volume out of it. Live & Learn.

 

[DonaldR]

Don't want to offense you, but you are mixing a lot of things.
First let discard XLR and 1/4" for a moment, they are just two kind of connectors.

There are mic level (a microphone), instrument level (your bass guitar) and line level (either -10dBv or +4dBu).
Your bass and your pedalboard are running at instrument level.
Your power amp is running at line level.

So to "drive" your power amp you need a preamp at the end of your pedalboard (instrument level) to output a signal strong enough for your power amp input (line level). The output (not the thru/parallel output) of your Sansamp BDDI should be strong enough to drive your power amp, DEPENDING of your power amp input sensitivity. Sadly Tech21 didn't published the specs but from the user's manual:

TO DRIVE A POWER AMP: Run the 1/4” Output, or the XLR Output to the corresponding input of a power amp, and adjust your stage volume with the Level control of the SansAmp Bass Driver DI.

NOTE: When running into the power amp input of an amp or a power amp alone, make sure to set the Output Level Switches as follows:
If using 1/4-inch: +10dB engaged (in position).
If using XLR: -20dB disengaged (out position).
Then adjust Level as needed. If you are so inclined, this is the time to crank it!​

Your Carvin DCM2000L has an input sensitivity of 1.4Vrms so it needs a +4dBu level at it's input (a 0.775Vrms would accept a -10dBv). So if your Sansamp is not outputting a strong enough signal you have 2 choices: buy a more powerful preamp or a more sensitive power amp.

Now regarding XLR vs 1/4".
- XLR are used for mic level and line level (mostly +4dBu).
- 1/4" (TS) are used for instrument level and for line level (mostly -10dBv but sometime up to +4dBu).
- 1/4" (TRS) are used for line level (mostly for -10dBv stereo unbalanced or +4dBu mono balanced).

Your JDI will take an instrument level at its 1/4" input and output mic level at XLR (as you can see, it will not drive your power amp). So to use it for FOH you'll need to feed it using the 1/4" Thru/Parallel output of your Sansamp BDDI.

 

[BurlyLemur]

I run the 1/4" out of my darkglass pedal directly to the effects return (power amp in) jack and use the tone controls on the pedal for my preamp settings. One thing to watch is not all effects returns on amps are true power amp in's, and some controls on the amp may still affect the sound

 

[mexicanyella]

I drive a rack power amp directly with an old Zoom B2 and it works great. Plenty of output for my older Peavey power amp, which wants to see ~1 volt line level at the input. The Zoom can slam the clip light pretty hard.

I also have an older Crown power amp that has an internal switch to select between ~0.775 volt and ~1.4 volt; I have it on the 0.775 setting for more input sensitivity.

 

[PeaveyPlayer]

I used quarter out of my Aguilar DI and trace as well
No di straight in

active bass worked super well!

 

[singlemalt]

I’m not getting it. Your one rack space Geddy can’t weigh that much. The Carvin amp doesn’t weigh anything. So you need a what? A two or three space light weight rack? Like a SK roto molded kind of thing?

Or maybe integrate the Geddy into your board, or replace it with the stomp box form?

What’s the goal here? Reducing the schlep? Downsizing?

 

[2112]

I do:

TC Polytune3
>> MXR81 Compressor
>> Digitech Drop
>> Broughton HPF/LPF
>> Sansamp BDDI
>> power amp

And lately I've been using TE ELF, TE AH400SMX, Crown XLS2502, our FOH mixer, etc. It all works and sounds great.

 

[jacoby75]

Don't want to offense you, but you are mixing a lot of things.
First let discard XLR and 1/4" for a moment, they are just two kind of connectors.

There are mic level (a microphone), instrument level (your bass guitar) and line level (either -10dBv or +4dBu).
Your bass and your pedalboard are running at instrument level.
Your power amp is running at line level.

Yes, I'm with you so far. Thank you.

So to "drive" your power amp you need a preamp at the end of your pedalboard (instrument level) to output a signal strong enough for your power amp input (line level). The output (not the thru/parallel output) of your Sansamp BDDI should be strong enough to drive your power amp, DEPENDING of your power amp input sensitivity. Sadly Tech21 didn't published the specs but from the user's manual:

TO DRIVE A POWER AMP: Run the 1/4” Output, or the XLR Output to the corresponding input of a power amp, and adjust your stage volume with the Level control of the SansAmp Bass Driver DI.

NOTE: When running into the power amp input of an amp or a power amp alone, make sure to set the Output Level Switches as follows:
If using 1/4-inch: +10dB engaged (in position).
If using XLR: -20dB disengaged (out position).
Then adjust Level as needed. If you are so inclined, this is the time to crank it!​

Your Carvin DCM2000L has an input sensitivity of 1.4Vrms so it needs a +4dBu level at it's input (a 0.775Vrms would accept a -10dBv). So if your Sansamp is not outputting a strong enough signal you have 2 choices: buy a more powerful preamp or a more sensitive power amp.

So if I understand this bit correctly, the Sansamp 1/4" output with the +10dBu engaged should actually output more than enough signal to drive the power amp. Like, +6dBu more than the requisite +4dBu. Is that a thing? Or would give it more than it needs actually clip the input of the power amp? (Only one way to find out, I guess). Or the XLR out of the Sansamp into the power amp might work swimmingly.

Now regarding XLR vs 1/4".
- XLR are used for mic level and line level (mostly +4dBu).
- 1/4" (TS) are used for instrument level and for line level (mostly -10dBv but sometime up to +4dBu).
- 1/4" (TRS) are used for line level (mostly for -10dBv stereo unbalanced or +4dBu mono balanced).

Your JDI will take an instrument level at its 1/4" input and output mic level at XLR (as you can see, it will not drive your power amp). So to use it for FOH you'll need to feed it using the 1/4" Thru/Parallel output of your Sansamp BDDI.

Good to know, thank you. I'm thinking I'll run the pedalboard into the JDI for FOH, because that sound is stellar, and take the 1/4" thru of the JDI into the Sansamp to run the XLR out of the Sansamp into my power amp. (Or I suppose it doesn't matter which one I take a 1/4" thru out of into the other. The end result would be the same.) And then I'd have the added bonus of additional volume and EQ controls on the Sansamp that would help me dial in my amp tone, but wouldn't effect my FOH signal.