Stereo rig - one valve, one digital - latency?

JodyJames

Looking for some advice - I'm considering buying a Tone Master amp, and my heart says Princeton. Problem is, the whole reason I'm looking is that my Pro Jr IV isn't quite loud enough when the band is at its loudest, which points me in the direction of a Deluxe. 

However, I love the idea of running a Princeton and a Pro Jr in stereo. I've heard that mixing valve and digital will introduce latency issues, but can't find that much info - is it inevitable and insurmountable, or can it be worked around? Obviously I could get a valve Princeton, but at that point I'd be carrying two valve amps, so I'd be better off with one big amp of either shade... thanks.

ecc83

It is indeed the case that a valve amp (or transistor for that matter) has a virtually zero 'transit time' whereas any digital process must take a finite time. Normally this does not matter as you are not hearing the input sound as well as the delayed output but yes! A digital amp* will be delayed compared to analogue if reproducing the same signal and even less than one mSec could make a difference.

One solution would be to put a delay pedal in the audio path of the valve amp. It might take some experimenting to find the precise delay you need. A problem might be that 'guitar delay' pedals might not go short enough to help or have such course setting that you cannot set it finely enough?

*By that I do NOT mean a "Class D" amplifier!

Dave.

robinbowes

Short answer: No, it will not cause any practical issues

Longer answer:

I don't know what latency is for the Tone Master amps, but let's assume its 5 ms (milliseconds)

• Sound travels at approx 343 metres per second
• Therefore, sound takes 2.92 ms to travel 1 metre.
• Therefore, the distance travelled in 5 ms is 1.72 metres

So, an analogue amp and a digital amp positioned next to each other would sound similar to two analogue amps with one of them 1.72 metres further away.

I'd be very surprised if this causes you any issues.

Sporky

It's probably worth remembering that each additional 1ms latency is the same as you'll experience standing about 30cm further away from your amp.

There might be phasing./comb filtering between the two, but with two different amps that's probably not going to matter. 

JodyJames

Thanks all - this is the kind of thing that I suspected/hoped was the case! 

ecc83

Yes, the further apart the amps, the less effect will be heard, same applies for two identical amps with the speaker polarity flipped. However do bear in mind that if the digi amp has 2mS of delay it is already two feet away and there will come a point I think where the 'ping pong' buggers your timing?

Stand closest to the digital amp.

Dave.

Roland

There is indeed latency in a digital system. How much varies by modeller. Fender claim 2.5msec, but that’s just for the analog/digital and digital/analog conversions. How much latency occurs  in digital processing depends on the modelling algorithms, and how many items (amps, speakers, pedals) are being modelled. Consequently Fender don’t release any figures. The Fractal FM-9 modelling just an Amp and Cab has been measured at 4.2msec, including AD/DA.

Speed of sound in air is 343metres/second, or 343mm/msec. If my arithmetic is correct them 6msec latency is equivalent to having them amps about 2metres apart.

springhead

One foot per millisecond is a good rule of thumb. You won’t hear a delay but there could perhaps be some phase cancellation. Try it and see. 

Secret_Sam

Move the cabs until it sounds right?

Sporky

And here we see an excellent demonstration of latency, as I was standing a little further away than robinbowes, and Roland was standing a little further away than me.

Roland

Sporky said:

And here we see an excellent demonstration of latency, as I was standing a little further away than robinbowes, and Roland was standing a little further away than me.

In my case it was my wife issuing a high priority interrupt. For the life of me I can’t remember what it was..

Sporky

Priorities are fleeting.

High priorities doubly so.

Danny1969

You generally will only get an issue when both an analog and digital signal are combined. Because the slight delay in the digital processing will mean  the digital signal will be slightly behind and thus out of phase with the analog signal. This is quite common and noticeable with amps with parallel effects loops .... you have to set any effect 100 % wet to avoid the phase issue. The JMP-1 rack Marshall I used for 15 years or so had a parallel loop and suffered from that issue. 

If you don't mind a heavier amp then for£400 ish you could get a Hot Rod,  which will sound better than the Tonemaster and also be louder. 

blobb

Play the amp, not the guitar, as I was once told. Good advice.

victorludorum

It'll save you money on a Chorus pedal!

Sporky

Especially if you put one of them on a swing, or have a chum hold it and walk backwards and forwards a bit. 

snowblind

Does depend to some extent on the digital amp how bad the latency is. I've used some of the nasty little Blackstar DSP jobs and you can hit the strings, go away, raise a family, walk to Mars and back and still have time for a cup of tea before the amp deigns to put the note out of the speaker.

I may be exaggerating slightly but the delay on some of those things is enough to be intrusive and once you notice it there's no unhearing it.  

Sporky

Have you tried convincing yourself that it's actually a really big amp, far away? 

revsorg

Sporky said:

Especially if you put one of them on a swing, or have a chum hold it and walk backwards and forwards a bit. 

Isn't this what gave rise to the Leslie speaker?  The inventor didn't want to keep paying the labour cost.

Sporky

That's certainly how I heard the story.