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Can someone explain how DSP is "used up"?


Cerebrus
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I'm trying to decide whether to get the HD500 or 500X and from what I've seen, one of the main advantages of the 500X is more processing power, but I'm not sure what kinds of settings demand this extra power. I'd be getting the HD500(x) just as a way for me to not need an amp for practicing in my room, all I care about is getting some good punk and metal guitar tone out of it. 

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DSP gets used up based on the number of effects and amps in your signal chain.  Generally speaking this comes into play when you have built a fairly exotic signal chain but not always so.  Some effects are more demanding than others and you can run into these limits earlier with extensive use of demanding ones.  But generally speaking from what I've seen it typically shows up when you begin to split the signal chain to use double amps or multiple parallel effects.  Probably not much of a concern with punk, but some metal styles can use some pretty wild setups.

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+1

 

The extra DSP in the HD500X is certainly useful in dual-amp presets. With two amps there is relatively little DSP remaining for FX. If you are a two-amp lover then definitely go for the 500X. But the 500, even with less DSP power, can handle single-amp presets with plenty of room for the 'normal' set of FX. While it is certainly possible to exceed the DSP capacity of the 500 with a single amp preset, there is usually enough capacity for one amp plus wah, compressor, distortion, chorus/mod, delay, reverb and an EQ or two.

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Each process the DSP is called on to perform requires so many clock cycles - reverb, delay, EQ, modulation, etc. Each sample is coming in at a 48kHz (or 44.1kHz) rate. This isn't entirely accurate, but the way I like to think of it is: a block of samples comes in, gets processed, gets outputted, then the DSP waits for the next block. If the processing takes too long, the next block will arrive before processing was completed on the previous block. There are no more clock cycles available. The DSP is "used up". The HD500X uses DSPs that run at a faster clock rate than those in the HD500 so processing occurs faster. There is more time available so it can be loaded up with more processing tasks.

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If you're just practicing in your room then the 500 should be fine.  The difference in DSP between the 500 and 500x isn't much but if you run a lot of effects it could be helpful.  Typically the 500 is fine running a compressor, gate, distortion, delay, reverb and single amp model. 

 

One of my patches use: 3 compressors, 2 delays, reverb, gate, pitch glide, and of course an amp model, all in one preset without running out of DSP.

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When/why would someone use two amps? 

 

One reason would be to enable the use of a dual cab and mic for an expanded palette of tones. For this configuration, both amps would essentially have the same settings, although they can also be different.

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When/why would someone use two amps? 

A clean amp and a dirty amp. Which can sometimes be better than one amp that is both clean and dirty. 

Two simultaneous dirty amps. 

Left channel, right channel. 

Or, like everything else in sound creating ---- just because I can, therefore I will.

 

 

If you have never used two amps to get your sound in the real world, there is no reason to think you would need one in the virtual world. 

 

 

For the record, I have plenty of dual amp patches on the 500. While amps will use up the most DSP, it isn't simply 'dual amp patches' that are going to give you an issue. In fact, I don't think I have ever ran into DSP problems with patches that I created - only ones I have downloaded. And it is usually, for me, an easy fix, because I just remove something useless, like a volume pedal, to get me within the DSP limit. 

 

There really isn't that much extra DSP and you are still limited to two amps and 8 blocks. 

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When/why would someone use two amps?

The best reason as far as I'm concerned, is having one clean tone, and one dirty...you can then assign each to the expression pedal, and morph seamlessly between them. For live use, it's priceless. Makes transitions much smoother, without the abrupt change that always accompanies changing between two patches with very different tones.

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My old GNX4 had this feature referred to as "warping" mixing amps/cabs and the technique can make some pretty cool tones. Try using a Q-Filter at a different setting for each, different mix levels, etc. Easy way to spend a bunch of time trying it out.

 

I like Cruisin's exp pedal tip too. So +1 Dude!

 

-B

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Just discovering dual amps/cabs and liking it.  What is this changing tones with the expression pedal?  Do you mean assigning amp gain,drive or tone controls to the pedal?

 

On dual amp/cab, I've been paying attention to Meambobbo's suggestions on mic/cab combinations that work without causing phasing issues.    http://foobazaar.com/podhd/toneGuide/cabsMics#dualCab-faves

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Assign each amp's Volume control to the pedal. Assign the min/max range oppositely for each pedal so that as the pedal moves it is turning up the volume of one amp and simultaneously turning down the volume of the other. At both the heel and toe positions one amp's volume is at max while the other is silent.

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Assign each amp's Volume control to the pedal. Assign the min/max range oppositely for each pedal so that as the pedal moves it is turning up the volume of one amp and simultaneously turning down the volume of the other. At both the heel and toe positions one amp's volume is at max while the other is silent.

That's it...works wonders. Most of my live patches are set up this way, even if it's not clean/dirty tones. I'll set up a crunchy rhythm tone with a slightly more overdriven, mid-rangey lead sound, and just glide from one to the other. I've grown to hate the sudden changes from switching to a separate patch...sometimes it's unavoidable, but for most tunes, I don't have to do it anymore. Makes me wonder how I tolerated it all those years...this is infinitely better.

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Ok so a smooth gradual transition as opposed to clicking on an overdrive.  I'll try it out.  So far I've been putting a volume pedal effect at the end of each patch for volume transition from 50% to 100%, which of course gives me volume control but does nothing with the tone.

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Ok so a smooth gradual transition as opposed to clicking on an overdrive. I'll try it out.

It's a little more than that. I'm not talking about clicking an overdrive on and off in front of the same amp model for just a little extra dirt...I mean switching between two tones that are galaxies apart. Going from crystal clean to a thick, saturated distortion on two completely different amp models...there's no way to do that smoothly by switching to a different patch. But fade in/fade out transitions are worth the price of the POD, imho.

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Nice. Only theoretical downside is I'm liking the sound of dual amps/cabs. But this is definitely another tool to put in the box.

Nothing wrong with that either. Here's something else to try if you're liking the dual amp patches. It's an old studio trick for artifically "doubling" tracks. Set up your two amps (for this it works best if you use the same amp model), but place a very short delay (+/-20ms) in front of one of them, then pan them hard L and R. Through headphones (or stereo amps) it gives a nice fat sound for crunchy rhythm tones...sort of simulates the slight timing discrepancies that you'd get with two separate performances.

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I do that trick all the time and lug two real amps around for live performances.  Really fattens up the sound.  I do it without having to use dual amps in my PODHD.  I assign a delay to the Left channel with a 20ms delay then hard pan both channels.

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