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Can someone please explain?

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when i used to use all valve amps both were 100w (ashdown ctm and orange rockerverb) i would put a two notes between the amp and cab ir emulation on the power amp sounded better every time, not to a mic tho would 100% prefer that however this is a much more consistent way of getting your sound into foh, ive also played cabless with this setup as the two notes act as load boxes aswell

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Check out the @darkglass Element. Amongst all sorts of other cool attributes it can be used as a speaker level DI - and has a built in EQ as well as speaker cabinet emulation IRs. It appears to be, absolutely brilliant.

You can also feed external audio via Bluetooth or line in to play along with and there’s two headphones outs!

 

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On 27/12/2020 at 12:02, warwickhunt said:

The actual signal levels are 'approx'.  

.015v - mic/inst

1.0v - line

12v - speaker

So the level out of an amps own DI is line level (about 1 volt) whereas the voltage from the speaker out is 12v (ish).  External DI boxes are generally used to boost from instrument level up to line level.  I've never associated a DI with lowering/attenuating the level from speaker levels; obviously they must but I'd be interested to know if that is true of all DI boxes.    

External DI's are almost never used to boost the signal level from instrument level to line level. In fact, since the numbers you posted above are incorrect, let's clarify what happens with a typical direct box. For bass guitar:

Mic levels are typically in the range of .01V to .1V

Instrument levels are typically in the range of .1V to 1V

Speaker levels are typically in the range of 10V to 50V

A typical DI drops instrument level signal down to mic level (approx. -20dB) and for a DI with a speaker level input, drops the level down to mic level (approx. -40dB). This is (often but not always) done by the use of an step-down audio transformer (in combination with an input pad in the case of a speaker level signal). The transformer also galvanically isolates the signal source from the destination.

One very important thing to make note of... in the case of any amplifier that is configured in bridge mode (either externally or as an internal topological design element which is how many class D power amps operate), taking the output from a speaker out is a bad idea because neither the + or - terminals of the speaker output are ground referenced. When connected to a DI, the pin 1 connection becomes tied with the speaker - and results in shorting 1/2 of the output bridge. Also, the resulting fault current (which can be as high as 30 amps on some newer amps) will flow through pin 1, through the snake and into the console's grounding system. Since this grounding system is not designed for high currents, catastrophic damage can result. If this is an expensive console, somebody is going to be unhappy.

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5 minutes ago, agedhorse said:

External DI's are almost never used to boost the signal level from instrument level to line level. In fact, since the numbers you posted above are incorrect, let's clarify what happens with a typical direct box. For bass guitar:

Mic levels are typically in the range of .01V to .1V

Instrument levels are typically in the range of .1V to 1V

Speaker levels are typically in the range of 10V to 50V

A typical DI drops instrument level signal down to mic level (approx. -20dB) and for a DI with a speaker level input, drops the level down to mic level (approx. -40dB). This is (often but not always) done by the use of an step-down audio transformer (in combination with an input pad in the case of a speaker level signal). The transformer also galvanically isolates the signal source from the destination.

One very important thing to make note of... in the case of any amplifier that is configured in bridge mode (either externally or as an internal topological design element which is how many class D power amps operate), taking the output from a speaker out is a bad idea because neither the + or - terminals of the speaker output are ground referenced. When connected to a DI, the pin 1 connection becomes tied with the speaker - and results in shorting 1/2 of the output bridge. Also, the resulting fault current (which can be as high as 30 amps on some newer amps) will flow through pin 1, through the snake and into the console's grounding system. Since this grounding system is not designed for high currents, catastrophic damage can result. If this is an expensive console, somebody is going to be unhappy.

honestly tho this thread is surely about using di boxes that are meant for this, ie something like the two notes, radial or palmer stuff so these issues arent a problem please tell me no one is considering putting a standard di box between the amp and speaker

 

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When I was doing live sound I never used a speaker level Di as they were usually very noisy/hissy compared to either instrument or line level. The best results were usually an instrument level clean Di (or pre-eq Di out of the amp) blended with a mic’d cab. Obviously the blend would be tweaked to suit each time. e.g players that used a lot of effects would be mostly cab.

(note that I was mixing before two-notes and the like were a thing!)

Edited by nilebodgers

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14 minutes ago, 0175westwood29 said:

honestly tho this thread is surely about using di boxes that are meant for this, ie something like the two notes, radial or palmer stuff so these issues arent a problem please tell me no one is considering putting a standard di box between the amp and speaker

 

That's EXACTLY what is being discussed, and what the OP's situation involved.

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1 minute ago, agedhorse said:

That's EXACTLY what is being discussed, and what the OP's situation involved.

i figured they were confused with what the seller was suggesting, seems to me he would put a Di box meant for going between an amp and cab, so it wouldnt be overloaded by the higher input.

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3 minutes ago, agedhorse said:

That's EXACTLY what is being discussed, and what the OP's situation involved.

                                                                                    This ^^^

From posts on this thread I've been getting concerned that I've had levels /outs / DI boxes completely wrong for 40 years.  However, aside from me giving specific voltages for the 3 levels (agedhorse has rightly used more generalised values but not miles away from my guesstimates), I was saying the right thing.  I tried to say from the outset that sticking a standard DI box between the combos speaker out and the speaker seemed like a bad idea.  I was unaware that the range of DIs available would allow this, so I've learned something... I think.  LOL 

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Are there any times people would really want to use a speaker level DI from the output of a class-D amp (or other bridged topology)? I was aware of using a DI on the speaker output as an occasionally useful trick with vintage style valve amps where you might want the colouration, there's usually no built-in DI output and the amp output is via a transformer anyway. But I wouldn't think to try it outside of that.

So it's a useful caution, but also, I'm not sure what the motivation would be to do that with a bridged power amp. Though I'm sure people will have attempted it...

Edited by Beer of the Bass

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Just now, Beer of the Bass said:

Are there any times people would really want to use a speaker level DI from the output of a class-D amp (or other bridged topology)? I was aware of using a DI on the speaker output as an occasionally useful trick with vintage style valve amps where you might want the colouration, there's usually no built-in DI output and the amp output is via a transformer anyway.

So it's a useful caution, but also, I'm not sure what the motivation would be to do that with a bridged power amp. Though I'm sure people will have attempted it...

Yes, I deal with this sort of thing often enough that these warnings (including warnings in the newer owner's manuals) are entirely justified.

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3 hours ago, Beer of the Bass said:

Are there any times people would really want to use a speaker level DI from the output of a class-D amp (or other bridged topology)?

Whilst I'm sure somebody will be along with a counterexample within 5 minutes of my post, I'm unaware of any class D amp for which the sound of the power amp is a selling point. As you've said, tube amps and vintage amps yeah, but I bet the sound from (for example) a GK Fusion's preamp out and speaker out are near enough the same, one's just bigger. 9 - 49.9V bigger, if you believe certain people in this thread. 😉

So yeah, why would you bother? People though, right? Can't trust 'em. 

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34 minutes ago, Jack said:

Whilst I'm sure somebody will be along with a counterexample within 5 minutes of my post, I'm unaware of any class D amp for which the sound of the power amp is a selling point. As you've said, tube amps and vintage amps yeah, but I bet the sound from (for example) a GK Fusion's preamp out and speaker out are near enough the same, one's just bigger. 9 - 49.9V bigger, if you believe certain people in this thread. 😉

So yeah, why would you bother? People though, right? Can't trust 'em. 

Not necessarily true, in that some class D output stages have additional emulation and modeling circuitry as well as damping adjustments and symmetry control at the point the POWER amp begins to overdrive.

That said, taking a signal from the speaker output using a conventional direct box is not a safe application. There are ways to do this, but with specialized hardware only.

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This popped up on my Facebook feed. I think the clever chaps at Ashdown have answered the OP 😎

D88F6DF8-928F-4B88-93AE-158499F5D17A.jpeg

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18 minutes ago, JPJ said:

This popped up on my Facebook feed. I think the clever chaps at Ashdown have answered the OP 😎

D88F6DF8-928F-4B88-93AE-158499F5D17A.jpeg

 

I've been struggling to figure out what the point of this box is. I can't think of many amps modern enough to use Speakons that don't also have a DI output already. And when would it be useful to take a headphone output from the speaker signal without muting the speaker?

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I dare say they are Neutrik combi connectors that can take speakon or regular jack plugs? 

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5 hours ago, Beer of the Bass said:

 

I've been struggling to figure out what the point of this box is. I can't think of many amps modern enough to use Speakons that don't also have a DI output already. And when would it be useful to take a headphone output from the speaker signal without muting the speaker?

If your cab is in an iso box or the next room you might want to hear what you're sending.

But it's still a magic smoke release tool when applied to most of your class D amps.

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6 hours ago, Beer of the Bass said:

 

I've been struggling to figure out what the point of this box is. I can't think of many amps modern enough to use Speakons that don't also have a DI output already. And when would it be useful to take a headphone output from the speaker signal without muting the speaker?

this is just a way of adding a di to an amp without one basically! i see nothing about loading so it worries me how many people will use these for home practice and murder there amp or melt this box........its a cheap way to do an inears set up love tho....

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I can certainly see a couple of scenarios someone could use it in, though it just seems like an odd combination of functions to put together in one unit. And I hope the outputs are fully isolated from the speaker inputs, or the issues discussed further up the thread could kick in.

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I have not seen anything that specifically states that the + and - signals are fully isolated from pin

This is an essential requirement for use with ANY amp that contains bridged topology.

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There is zero point in using a post-power amp DI unless the power amp itself makes a significant contribution to the sound, i.e. it contains valves being driven hard.

Even then IME it is the least important part (sound-wise) to the signal chain.

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As most have said, this is really a solution for amps that do not have a DI out where you want your amp ‘tone’ to go to front of house. 
One of our guitarists uses something similar with his 100w Marshall. My personal preference is a DI box before my amp or at worst using the ‘pre eq’ option on built in DI.

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9 minutes ago, JPJ said:

As most have said, this is really a solution for amps that do not have a DI out where you want your amp ‘tone’ to go to front of house. 
One of our guitarists uses something similar with his 100w Marshall. My personal preference is a DI box before my amp or at worst using the ‘pre eq’ option on built in DI.

For guitar amps it makes even less sense unless the DI box also includes speaker emulation and perhaps more importantly speaker break-up emulation.

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39 minutes ago, BigRedX said:

For guitar amps it makes even less sense unless the DI box also includes speaker emulation and perhaps more importantly speaker break-up emulation.

Yet they exist?

(I don't own one).

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