power amp and preamp pedal

[agedhorse]

17 hours ago, mario_buoninfante said:

that's fair. I did see some official videos (in Italian though) on YT where the presenter was saying one could even go straight into that with their bass.
I think it's the gain stage they have in place that allows that.

Maybe, but this is the reason for published specs... to be able to answer these kinds of questions without guessing.

[mario_buoninfante]

6 hours ago, agedhorse said:

Maybe, but this is the reason for published specs... to be able to answer these kinds of questions without guessing.

absolutely, I 100% agree.
I'm a big fan of detailed specs.

[Waddycall]

 What’s not helping me is the mix of specs and a lack of understanding of their correlation.

My QSC amp has a rated input sensitivy at full output into 8 ohms of 1.15 Vrms (+3.4 dbu).

the microbass 3 has a nominal output level of 0dbv. 

Consumer line level is -10dbv so it’s clearly higher output than that.

Pro line level is +4dbu. 

A bit of playing around with an online calculator puts 0dbv at 1 Vrms (+2.21 dbu).

im concluding from this that the microbass won’t get my power amp to full output but it should get it fairly close.

does that seem right?

[Waddycall]

The Crown XLi has switchable input sensitivity down to 0.775v so the microbass should definitely drive that ok

[Ed_S]

9 minutes ago, Waddycall said:

The Crown XLi has switchable input sensitivity down to 0.775v so the microbass should definitely drive that ok

 

Their XLS DriveCore 2 series do as well. The original silver ones didn't, so my previous attempt at a rig based around a Sansamp RBI and XLS1500 was very disappointing indeed. I picked up an inexplicably cheap XLS2002 a few months back, though, and whilst I haven't tried it out with a preamp yet, I'm generally more hopeful for when I finally get round to it.

[Bunion]

I have a bit of a collection of preamps and pedal preamps and was having the same problem with some of them being below the 1.15vrms.

I solved this by getting myself a crown xls 2502 which has Selectable input sensitivity; 1.4Vrms and 0.775Vrms options I think all the other models in the XLS line have this option.
I got mine off the flea bay virtually unused for a few hundred pounds. 
I also use a powersoft LD 2004 which I plug my Noble into via the DI this has a sensitivity of 0.87vrms 

[agedhorse]

10 hours ago, Waddycall said:

 What’s not helping me is the mix of specs and a lack of understanding of their correlation.

My QSC amp has a rated input sensitivy at full output into 8 ohms of 1.15 Vrms (+3.4 dbu).

the microbass 3 has a nominal output level of 0dbv. 

Consumer line level is -10dbv so it’s clearly higher output than that.

Pro line level is +4dbu. 

A bit of playing around with an online calculator puts 0dbv at 1 Vrms (+2.21 dbu).

im concluding from this that the microbass won’t get my power amp to full output but it should get it fairly close.

does that seem right?

Nominal output level doesn't tell you all that much, what's more important is the maximum rated output level of the preamp. Generally, it needs to be about 6dB greater than the rated sensitivity of the amp to be sure you have sufficient drive capability to drive the amp into limiting (most pro audio power amps have internal limiting, and you want to be sure you can drive into this rather than clip the output of the preamp).

 

Also, all numbers need to be expressed as volts rms.

[NancyJohnson]

I try to read some of the more technical posts here and it's like I just go word blind; I'm not saying this data isn't useful in some capacity to some people, but by and large surely, given the amount of Poweramps and stomps out there, a lot of this is no use to anyone?

 

As previously posted, I ran (several) rack set ups for 30+ years.  Not once have I suffered from anything not working or under performing.  Not once did I refer to the manual of any unit to read up on input sensitivity (or anything). The only thing I didn't do 'properly' was to always have the poweramp outputting at 100% and controlling the output volume off the pedals/rack kit.  

 

Maybe I was just lucky.  

[Downunderwonder]

1 hour ago, NancyJohnson said:

Maybe I was just lucky.

Not really. I don't know of any rack mount preamp that isn't proper line level.

 

One poster above complained of a lack of oomph from his RBI. That guy didn't read his manual!

[MrDinsdale]

I’m running an EAE Model FeT with a Boss GT-1000core into a GK Fusion S 800 return and bypassing the preamp entirely. I do have the option to 4cm the GK preamp back into the signal chain if I ever need more tonal options. Super happy with it though.

 

I was super tempted by the GSS Sumo but for not much more size (or £ if you buy 2nd hand) you can get a solid class d which gives a little more redundancy/flexibility. It’s very superficial but having something sat on top of a cab is nice, even if it is still pretty tiny 😂

[Tech21NYC]

When I spoke to one of the techs at Crown he said the specs on power amps make sense when using them for the proper application. They measure the wattage with a 1kHz sine wave for comparative purposes. In a pro-audio application they calculate how much power they need in relation to the amount of speakers they need to power. A rule of thumb is that if you are powering speakers with a 500 watt rating you will need a 1000 watt amplifier. This will give you the proper amount of power and headroom to handle peaks. The sound tech that we hire for our band told me with class D amps he likes to have 3 times the power needed. 

 

The problem that players trying to use these amps for a musical instrument application encounter is that they are trying to use a product that was not designed for that application and don't understand how the amps operate. Pro-audio power amps are expecting the output of a mixer. A 32 channel mixer can output over +22 dBu which is why they have a higher input threshold than a typical guitar or bass amp. The gains on those amps are really used to attenuate the input so the mixer's high output doesn't clip the input to the power amp.

 

You don't want any SS amp especially a Class D amp operating on the verge of clipping. Here is more info from Crown regarding amp power.  

[Waddycall]

2 hours ago, Tech21NYC said:

When I spoke to one of the techs at Crown he said the specs on power amps make sense when using them for the proper application. They measure the wattage with a 1kHz sine wave for comparative purposes. In a pro-audio application they calculate how much power they need in relation to the amount of speakers they need to power. A rule of thumb is that if you are powering speakers with a 500 watt rating you will need a 1000 watt amplifier. This will give you the proper amount of power and headroom to handle peaks. The sound tech that we hire for our band told me with class D amps he likes to have 3 times the power needed. 

 

The problem that players trying to use these amps for a musical instrument application encounter is that they are trying to use a product that was not designed for that application and don't understand how the amps operate. Pro-audio power amps are expecting the output of a mixer. A 32 channel mixer can output over +22 dBu which is why they have a higher input threshold than a typical guitar or bass amp. The gains on those amps are really used to attenuate the input so the mixer's high output doesn't clip the input to the power amp.

 

You don't want any SS amp especially a Class D amp operating on the verge of clipping. Here is more info from Crown regarding amp power.  

Interesting stuff but doesn’t get me any clearer. Surely in a pro Audio PA installation you’d size your speakers to the venue and the amp to the speakers to maintain the headroom as stated? 

My cab has a power handling of 1200w and can apparently handle double that intermittently but there’s no way anyone’s going to power a single 210 with 3600W or even 2400W so as you say it’s a different application.

im asssuming that you can plug what you want into the front of a power amp and as long as it’s not clipping and it gets the output level you want it’s all good. 

I plugged my bass direct into my QSC the other day. Sounded lovely but was only at living room volume when maxed out. Bit of fun though.

 

 

Edited October 31, 2022 by Waddycall

[agedhorse]

9 hours ago, Tech21NYC said:

When I spoke to one of the techs at Crown he said the specs on power amps make sense when using them for the proper application. They measure the wattage with a 1kHz sine wave for comparative purposes. In a pro-audio application they calculate how much power they need in relation to the amount of speakers they need to power. A rule of thumb is that if you are powering speakers with a 500 watt rating you will need a 1000 watt amplifier. This will give you the proper amount of power and headroom to handle peaks. The sound tech that we hire for our band told me with class D amps he likes to have 3 times the power needed. 

 

The problem that players trying to use these amps for a musical instrument application encounter is that they are trying to use a product that was not designed for that application and don't understand how the amps operate. Pro-audio power amps are expecting the output of a mixer. A 32 channel mixer can output over +22 dBu which is why they have a higher input threshold than a typical guitar or bass amp. The gains on those amps are really used to attenuate the input so the mixer's high output doesn't clip the input to the power amp.

 

You don't want any SS amp especially a Class D amp operating on the verge of clipping. Here is more info from Crown regarding amp power.  

Since I spent much of my career in the pro audio industry, there are a lot of misconceptions going around.

 

First, it’s acceptable to power an amp at 2x the RMS rating of a speaker provided there’s is minimal clipping or OD/distortion components in the signal. As soon as distortion is added, no matter where in the signal path, this recommendation changes and the power handling of the speaker and amp (in RMS metrics) should be pretty similar, and for heavier distortion, and heavy compression, the speakers should be capable of greater power handling than the amp provides (by ~50% if you follow the guidelines of some driver manufacturers including JBL).

 

This also assumes that a proper HPF is also used.

 

Crown’s recommendation is being taken out of context when quoted for bass guitar amplification.

[agedhorse]

18 hours ago, NancyJohnson said:

I try to read some of the more technical posts here and it's like I just go word blind; I'm not saying this data isn't useful in some capacity to some people, but by and large surely, given the amount of Poweramps and stomps out there, a lot of this is no use to anyone?

 

As previously posted, I ran (several) rack set ups for 30+ years.  Not once have I suffered from anything not working or under performing.  Not once did I refer to the manual of any unit to read up on input sensitivity (or anything). The only thing I didn't do 'properly' was to always have the poweramp outputting at 100% and controlling the output volume off the pedals/rack kit.  

 

Maybe I was just lucky.  

If you can’t understand the specs, than you either need to have somebody help you, by lucky or buy products designed to work together.

 

It’s no different than taking gigs where you need to sight read, if you can’t do it, don’t take the gig and don’t criticize those who do. 

[mario_buoninfante]

interestingly enough, I got in touch with Laney to ask about the Digbeth Pre, since I have one, and they told me the output level is +10 dBV.
unless I'm missing something obvious, that seems quite a bit to me. (I also sent a second email asking to confirm it's +10 and not -10 dBV, they confirmed it's +10).

Edited November 1, 2022 by mario_buoninfante

[Hooch]

If you aim at using a separate power-amp, mains preamps are the way to go imo. A preamp pedal won't be juicy enough in most case, whatever power-amp it sees. Totally relies on power-amp input sensitivity of course, but even with what i *think* are good ones in this field (Acoustic Image Focus SA), had thinner and much noisier results than with mains preamps - with the noticeable exception of the Grace Alix, whose output is on par with preamp pedals.

Edited November 4, 2022 by Hooch

[agedhorse]

11 hours ago, Hooch said:

If you aim at using a separate power-amp, mains preamps are the way to go imo. A preamp pedal won't be juicy enough in most case, whatever power-amp it sees. Totally relies on power-amp input sensitivity of course, but even with what i *think* are good ones in this field (Acoustic Image Focus SA), had thinner and much noisier results than with mains preamps - with the noticeable exception of the Grace Alix, whose output is on par with preamp pedals.

My experience and testing suggests that it's very dependent on the preamp and preamp pedal. There are a good number of pedals that have no issues driving power amps to rated output, the real issue is a shortage of specifications that provide the definitive answer. 

 

For example the TwoNotes revolt preamp's MOL is +11dBu (from their specs) and it operates from a standard 12V DC power supply.

[Baloney Balderdash]

Yes, I utilizes and "amp-less" setup, predominantly exactly for the reason you mention, to keep as much consistency as possible tone wise between practicing at home with a high quality set of studio grade headphones, recording, band rehearsal with power amp and full frequency flat response PA speaker, and live going DI to venue PA.

 

Check out my forum profile for a detailed description of my setup: https://www.basschat.co.uk/profile/50585-baloney-balderdash/?tab=field_core_pfield_1

 

What you need for this to work is something that simulates the amp, something that simulates the cab part, and then eventual, to actually to obtain consistency, for home practice somekind of headphone amp, for example a mini mixer, and a studio grade set of proper quality approximately full frequency flat response headphones, and for band rehearsal a power amp and then an approximate full frequency flat response cab or PA speaker, or active PA speaker. 

 

 

Edited November 4, 2022 by Baloney Balderdash

[Bunion]

12 hours ago, Hooch said:

If you aim at using a separate power-amp, mains preamps are the way to go imo

You still need to be aware of the input sensitivity with mains/rack mount preamps. The SWR interstellar overdrive is notorious for not being able to power a lot of power amps at .775vrms 

[mario_buoninfante]

I see what you are saying @Baloney Balderdash, but just to be clear, I'm not trying to get rid of the amp. I would simply like to find a neutral amp (to pair with a cabinet) that doesn't affect my bass+preamp+pedals sound, if that makes sense.
At least on paper, I just find redundant going through 2 preamps (pedal and amp preamp). Not because you won't get a good sound, thousands of people do, but because I'd like to have 1 sound, whether or not I'm using the amplifier.

Hope that makes sense.

Edited November 4, 2022 by mario_buoninfante

[Baloney Balderdash]

3 hours ago, mario_buoninfante said:

I see what you are saying @Baloney Balderdash, but just to be clear, I'm not trying to get rid of the amp. I would simply like to find a neutral amp (to pair with a cabinet) that doesn't affect my bass+preamp+pedals sound, if that makes sense.
At least on paper, I just find redundant going through 2 preamps (pedal and amp preamp). Not because you won't get a good sound, thousands of people do, but because I'd like to have 1 sound, whether or not I'm using the amplifier.

Hope that makes sense.

 

No, it doesn't.

 

In order to that you need full frequency flat response cabinet or PA speaker.

 

In combination with a preamp and poweramp or preamp and active PA combination will do that exactly, just like I explained.

 

Any reason it has to be a regular amp, seems kind of backwards to me.

 

And why would you need to go through 2 preamps, unless you insist on using a regular amp, for whatever reason, which is beyond me, which will have a preamp build in, unlike a poweramp, like i suggested?

 

It seems to me that you either didn't read what I actually wrote or didn't understand it, cause that is exactly what I explained how to achieve.

 

When I wrote you needed a preamp, it means you need a preamp, not that you need an additional preamp, if you already got one that can drive a poweramp.

 

A regular amp will have a preamp build in, unlike a poweramp. 

 

But absolutely most crucial for consistency of tone and for this to work is to run it all though a full frequency flat response cabinet or PA speaker, or, if practicing with headphones, a set of studio grade, that is full frequency flat response, headphones.

 

Exactly as I already wrote once.

 

Edited November 5, 2022 by Baloney Balderdash

[mario_buoninfante]

@Baloney Balderdash that's quite a reply, isn't it?
let's recap and see what I (have not?) understood

 

Quote

Yes, I utilizes and "amp-less" setup, predominantly exactly for the reason you mention, ...

I never expressed an interest in going "amp-less" (with amp here I mean the amplifier circuit), so I was clarifying that.
 

 

Quote

What you need for this to work is something that simulates the amp, something that simulates the cab part,...

what is "this" that I'd need to work? and why would I need anything that simulates amp and cab. actually since my initial post I'm saying that I'm after a "neutral" amp (amplifier circuit), so I shouldn't have to simulate anything there at all.
 

 

Quote

...for home practice somekind of headphone amp, for example a mini mixer, and a studio grade set of proper quality approximately full frequency flat response headphones, and for band rehearsal a power amp and then an approximate full frequency flat response cab or PA speaker, or active PA speaker.

 

I do have a studio, so professional mixer, headphones, studio monitors, etc.
this is not the problem, and that's why I believe my initial post might have been misunderstood and hence why I replied to you before trying to clarify what I meant.
 

then, about your last kind reply:

 

Quote

In order to that you need full frequency flat response cabinet or PA speaker.

In combination with a preamp and poweramp or preamp and active PA combination will do that exactly, just like I explained.

again, what is "that"?

 

Quote

Any reason it has to be a regular amp, seems kind of backwards to me.

I don't think I ever mentioned a "regular" amp anywhere. but also, could you define what "regular" means?

 

Quote

And why would you need to go through 2 preamps, unless you insist on using a regular amp, for whatever reason, which is beyond me, which will have a preamp build in, unlike a poweramp, like i suggested?

I never said I want, this whole post is started with me expressing an interest in not doing that.

 

Quote

It seems to me that you either didn't read what I actually wrote or didn't understand it, cause that is exactly what I explained how to achieve.

When I wrote you needed a preamp, it means you need a preamp, not that you need an additional preamp, if you already got one that can drive a poweramp.

honestly, I'd invite you to be a bit more polite and less "hostile".
I did read what you wrote, and am also sure I understood what you wrote. but even if I didn't, please just be polite. no need to be rude or aggressive, seriously. the beautiful thing about this forum is that people can freely talk and share experiences and knowledge.
so, if there is something I don't know or understand, help me understanding it, teach me, but don't write things like this, because it's just counterproductive.

 

Quote

But absolutely most crucial for consistency of tone and for this to work is to run it all though a full frequency flat response cabinet or PA speaker, or, if practicing with headphones, a set of studio grade, that is full frequency flat response, headphones.

couple of things about the cabinet. that has never been at the centre of the conversation, I mentioned it because I do wanna use one, and yes a full range (just for the records). but I wasn't thinking I want to mic that up, atm at least.
anyway, the cab thing is one for another time.

Edited November 5, 2022 by mario_buoninfante

[Baloney Balderdash]

1 hour ago, mario_buoninfante said:

@Baloney Balderdash that's quite a reply, isn't it?
let's recap and see what I (have not?) understood

 

I never expressed an interest in going "amp-less" (with amp here I mean the amplifier circuit), so I was clarifying that.
 

 

what is "this" that I'd need to work? and why would I need anything that simulates amp and cab. actually since my initial post I'm saying that I'm after a "neutral" amp (amplifier circuit), so I shouldn't have to simulate anything there at all.
 

 

 

I do have a studio, so professional mixer, headphones, studio monitors, etc.
this is not the problem, and that's why I believe my initial post might have been misunderstood and hence why I replied to you before trying to clarify what I meant.
 

then, about your last kind reply:

 

again, what is "that"?

 

I don't think I ever mentioned a "regular" amp anywhere. but also, could you define what "regular" means?

 

I never said I want, this whole post is started with me expressing an interest in not doing that.

 

honestly, I'd invite you to be a bit more polite and less "hostile".
I did read what you wrote, and am also sure I understood what you wrote. but even if I didn't, please just be polite. no need to be rude or aggressive, seriously. the beautiful thing about this forum is that people can freely talk and share experiences and knowledge.
so, if there is something I don't know or understand, help me understanding it, teach me, but don't write things like this, because it's just counterproductive.

 

couple of things about the cabinet. that has never been at the centre of the conversation, I mentioned it because I do wanna use one, and yes a full range (just for the records). but I wasn't thinking I want to mic that up, atm at least.
anyway, the cab thing is one for another time.

So you don't know what the common expression "amp-less setup" mean, despite me meticously explaining exactly what that does imply, and your intention of consistency of tone, which I, obviously wrongly, though was your main objective, is not relevant or important, right... 

 

And you chose to focus on single words, which you insist to misinterpretate, rather than reading what I wrote in its actual full context.

 

Got it...

 

Sorry for trying to help you. 

 

Edited November 5, 2022 by Baloney Balderdash

[mario_buoninfante]

9 minutes ago, Baloney Balderdash said:

So you don't know what the common expression "amp-less setup" mean, and your intention of consistency of tone, which I though was the main objective, is not relevant or important, right...

 

Sorry for trying to help you.

Ok, I see! I think we just keep misunderstanding each other.

But, don't be sorry

I appreciate the thought.

[agedhorse]

On 04/11/2022 at 15:03, mario_buoninfante said:

I see what you are saying @Baloney Balderdash, but just to be clear, I'm not trying to get rid of the amp. I would simply like to find a neutral amp (to pair with a cabinet) that doesn't affect my bass+preamp+pedals sound, if that makes sense.
At least on paper, I just find redundant going through 2 preamps (pedal and amp preamp). Not because you won't get a good sound, thousands of people do, but because I'd like to have 1 sound, whether or not I'm using the amplifier.

Hope that makes sense.

Yes, it makes perfect sense IMO.