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Sampling Rate/Frequency, Conversion, and Signal Processing of MultiEffects

Nhoj

Senior Member
Messages
1,461
Boss GT100/ME/MS3/GT1/GT10/GT8/GT6/GT5
Sampling Frequency
44.1 kHz
AD Conversion
24 bits + AF method
* AF method (Adaptive Focus method) is a proprietary method from Roland & BOSS that vastly improves the signal-to-noise (SN) ratio of the AD and DA converters.
DA Conversion
24 bits
Boss GT3
Sampling Frequency
44.1 kHz
AD Conversion
24-bit with 128x oversampling
DA Conversion
20-bit with 128x oversampling


Boss GT1000
Sampling Frequency
96 kHz
AD Conversion
32 bits + AF method
* AF method (Adaptive Focus method) is a proprietary method from Roland & BOSS that vastly improves the signal-to-noise (SN) ratio of the AD and DA converters.
DA Conversion
32 bits

Zoom G.1ut/1/1x/1u/nu/2/3/3x/7/9

Sampling frequency
96 kHz
A/D conversion
24-bit, 64-times oversampling
D/A conversion
24-bit, 128-times oversampling
Signal processing
32-bit

Zoom GFX8/GFX4/
Sampling frequency
40 kHz
A/D converter
20 bit, 64 times oversampling
D/A converter
20 bit, 128 times oversampling

Zoom GFX3/GFX5/GFX707/606//707II
Sampling Frequency
31.25 kHz
A/D Conversion
20-bit, 64-times oversampling
D/A Conversion
20-bit, 8-times oversampling

Zoom 505
Sampling Frequency
31.25 kHz
Analog/digital conversion
18 bit, 128 times oversampling
Digital/analog conversion
16 bit, linear


Zoom Gn/On/MS/CDR/5/ Series
Sampling frequency:
44.1 kHz

A/D conversion:
24-bit with 128x oversampling

D/A conversion:
24-bit with 128x oversampling

Signal processing:
32-bit


Headrush

Sampling rate
96 khz

Line6 Helix/HD/POD

Sampling rate
48 khz
16 bit
(correct me if im wrong Frank ;) )

Digitech RP/XP/IPB/GSP/GNX

A/D/A Converter:
24-bit high performance audio
Sampling Frequency:
44.1 kHz


Mooer GE200

Sampling rate
44.1 kHz
24 bit
 
Last edited:

phil_m

Have you tried turning it off and on again?
Gold Supporting Member
Messages
13,270
Line6 Helix/HD/POD

Sampling rate
48 khz
16 bit
(correct me if im wrong Frank ;) )
If you’re talking about the actual converters, they’re 24-bit, 192kHz... Although, the highest sampling rate you can get out of the USB out is 96kHz.

The internal sampling rate in the signal path is oversampled to much higher rates at different points.
 

aleclee

TGP Tech Wrangler
Staff member
Messages
13,425
IMO, sampling rates are kind of like power amp wattage ratings: once you get above a certain threshold, there are other factors that are going to make a bigger difference.
 

Nhoj

Senior Member
Messages
1,461
If you’re talking about the actual converters, they’re 24-bit, 192kHz... Although, the highest sampling rate you can get out of the USB out is 96kHz.

The internal sampling rate in the signal path is oversampled to much higher rates at different points.
Thanks for the info, i dont know line6 hardware , because i dont own one yet, tried the Helix Native , and its awesome im pleasantly surprise!
 

Nhoj

Senior Member
Messages
1,461
If you’re talking about the actual converters, they’re 24-bit, 192kHz... Although, the highest sampling rate you can get out of the USB out is 96kHz.

The internal sampling rate in the signal path is oversampled to much higher rates at different points.
Im really surprised about the 96 kHz sampling rate specs of the old Zoom G series , i still got my G2 that why it sound so good back from that days.
 

Jay Mitchell

Member
Messages
5,543
This kind of speculation is largely misinformed. Two facts are relevant:

1. System sampling frequency determines bandwidth. The absolute upper limit on bandwidth in a sampled-signal system is the Nyquist frequency, which is one half the sampling rate.

2. Bit depth determines dynamic range (the difference between the noise floor and the strongest signal the system can produce), which affects signal to noise. The greater the bit depth, the lower the digital noise floor.

When considering the sonic performance of guitar modelers, neither of the above two parameters is ever a limiting factor. The difference between 22.05kHz (44.1kHz SR) and 24kHz (48kHz SR) bandwidth is utterly irrelevant to guitar sounds. The smallest digital dynamic range is 96dB (16 bit). There's never been a guitar that has that much dynamic range, and any processing that introduces compression will reduce dynamic range (e.g., every amp sim) to well below the guitar's intrinsic capability.

The greatest differences in sonic quality are due to modelers' outboard analog electronics, conversion devices (A/D and D/A), internal oversampling rate for nonlinear processes, and the quality of the processing algorithms. The information you need to identify such differences will never be provided by manufacturers. Some of it is proprietary, and none of it would be understood by the target market.
 
Last edited:

Nhoj

Senior Member
Messages
1,461
This kind of speculation is largely misinformed. Two facts are relevant:

1. System sampling frequency determines bandwidth. The absolute upper limit on bandwidth in a sampled-signal system is the Nyquist frequency, which is one half the sampling rate.

2. Bit depth determines dynamic range (the difference between the noise floor and the stronget signal the system can produce), which affects signal to noise. The greater the bit depth, the lower the digital noise floor.

When considering the sonic performance of guitar modelers, neither of the above two parameters is ever a limiting factor. The difference between 22.05kHz (44.1k R) and 24kHz (48kHz SR) bandwidth is utterly irrelevant to guitar sounds. The smallest digital dynamic range is 96dB (16 bit). There's never been a guitar that has that much dynamic range, and any processing that introduces compression will reduce dynamic range (e.g., every amp sim) to well below the guitar's intrinsic capability.

The greatest differences in sonic quality are due to modelers' outboard analog electronics, conversion devices (A/D and D/A), internal oversampling rate for nonlinear processes, and the quality of the processing algorithms. The information you need to identify such differences will never be provided by manufacturers. Some of it is proprietary, and none of it would be understood by the target market.

Thanks for the info youve shared! Maybe this is why some companies are not telling specifications and not including it on their manual.
 

Fractal Audio

Member
Messages
1,240
To elaborate on Jay's statements.

1. 44.1 or 48 KHz is more than adequate for not only guitar processors but ANY audio processor. 88.2 or 96 K makes for nice marketing but, in reality, performance can often decrease when running converters higher than necessary. This is due to activity at the converters digital I/O pins injecting noise into the converters themselves. Personally I wish the industry would adopt a 64 KHz sample rate standard but this is for esoteric reasons.

2. The dynamic range of a guitar, UNDER IDEAL CONDITIONS (i.e. inside a Faraday cage) is not much greater than 100 dB. To capture this you would theoretically need 17 bits (17 bits gives about 102 dB). To allow sufficient "overhead" one should add a couple bits. 20 bits is plenty and yields about 120 dB of dynamic range. Anything greater than 20 bits is marketing. There isn't a converter made that gets much better than 100 - 120 dB dynamic range in the real world. You only need 20 bits for that. AKM has these new 32 bit converters (AKM557x). This is comical as they only have 112 dB of dynamic range so they give 19 bits of data and 13 bits of noise. Once you put a guitar in a real-world EMI environment that dynamic range drops precipitously (60 dB or even less).

The ANALOG electronics before and after the converters is far more important. Knowing when to use JFET vs. bipolar op-amps, knowing how to select the right op-amp for the task, etc. far outweigh the sampling rate and advertised bit depth of a converter. Good quality components aren't cheap though.

Internal oversampling determines aliasing performance in nonlinear processing. The higher the oversampling, the lower the aliasing but the more processing power required (= $$$$). Aliasing noise can easily dominate output dynamic range. So, again, sampling rate and bit depth are immaterial in comparison to the things that really matter.
 

Briandress

Member
Messages
498
This kind of speculation is largely misinformed. Two facts are relevant:

1. System sampling frequency determines bandwidth. The absolute upper limit on bandwidth in a sampled-signal system is the Nyquist frequency, which is one half the sampling rate.

2. Bit depth determines dynamic range (the difference between the noise floor and the strongest signal the system can produce), which affects signal to noise. The greater the bit depth, the lower the digital noise floor.

When considering the sonic performance of guitar modelers, neither of the above two parameters is ever a limiting factor. The difference between 22.05kHz (44.1kHz SR) and 24kHz (48kHz SR) bandwidth is utterly irrelevant to guitar sounds. The smallest digital dynamic range is 96dB (16 bit). There's never been a guitar that has that much dynamic range, and any processing that introduces compression will reduce dynamic range (e.g., every amp sim) to well below the guitar's intrinsic capability.

The greatest differences in sonic quality are due to modelers' outboard analog electronics, conversion devices (A/D and D/A), internal oversampling rate for nonlinear processes, and the quality of the processing algorithms. The information you need to identify such differences will never be provided by manufacturers. Some of it is proprietary, and none of it would be understood by the target market.
So basically if we have an interface with converters on par with the Helix, and we are running Helix Native on a pc with enough spec to run the algorithm they would sound the same when monitored through the same monitor source?
 

yeky83

Member
Messages
2,982
So basically if we have an interface with converters on par with the Helix, and we are running Helix Native on a pc with enough spec to run the algorithm they would sound the same when monitored through the same monitor source?
Yup. There's already a few demos online to demonstrate this.
 

teleocity

Member
Messages
30
All great info, thanks. I know this is an old thread but the initial post has some incorrect specs listed
The Zoom G3(X) has different specs:
Sampling frequency 44.1 kHz
A/D conversion 24-bit, 128-times oversampling


As for my opinion of the G3X... well, all the clean effects/modulations sound OK but only the clean leaning amp models sound OK. High gain distortion sounds harsh and synthetic unless it is used very sparingly.
I've heard the G2.1u which has Sampling frequency 96 kHz , but only 64 times oversampling
and it, to my ears, sounds better with high gain amp models. But after reading the above informative posts, that's maybe just me...
.
 
Messages
2,239
As for my opinion of the G3X... well, all the clean effects/modulations sound OK but only the clean leaning amp models sound OK. High gain distortion sounds harsh and synthetic unless it is used very sparingly.
I've heard the G2.1u which has Sampling frequency 96 kHz , but only 64 times oversampling
and it, to my ears, sounds better with high gain amp models. But after reading the above informative posts, that's maybe just me...
.
The difference you hear may be real, but probably has nothing to do with the digital portion of the signal path. Differences that you can hear would have to do with the software, the analog portions of the signal path, and the various gain settings through the chain.
 




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