Mystery specs

[Mark Hammer]

Somebody locally was selling their Carl Martin DC Drive for what seemed like a decent price, so I decided to go to the website and check out the pedal.  At the bottom of the product web-page we see the following specs:

Power consumption:  20 mA
S/N ratio:  54dB
Input impedance:  1M Ohm
Output impedance:  560 Ohm
Tone:  High Cut
Distortion:  +68dB

It all makes perfect sense  (although that 54db figure is a little disappointing) until that last number.  +68db distortion?  What the hell does that even mean?

[R.G.]

Distortion at +64db?? Wow. Never seen that before.

Maybe "2511 times as much distortion that you'd get without it".
Maybe "2511 times as much distortion as the remaining signal left in the output".

I actually have some questions about the 54db signal to noise ratio. Is that really a way of saying that the output noise is -54db compared to the maximum distorted signal? If it's 54db on the bypassed signal, that's pretty ugly.

[dschwartz]

i´d say that it´s 68dB of clipped signal..

when designing with LT spice, the ac analysis doesnt take the clipping into account, so i set an imaginary "limit" which correspond to the dB´s where the device clips, ussually 20dB..
i ussually get levels of 60-70 dB on the graphs, so, i could say that i have 40-50dB of clipping, or distortion in this case..

anyway, it´s a lousy measure..i would better use specs like
Noise: a little hiss, very low hum (tested with a regulated-clean DC supply)
Distortion: Brutal (or mild, or heavy)

[PRR]

> +68db distortion?  What the hell does that even mean?

In super-clean hi-fi studies, "-92dB residual" has a clear meaning. 0.0025% distortion. When you push to many-zero THD, dB become clearer than oh-oh-oh.... numbers.

So is this + number meaning 251,100% distortion? Hash is thousands of times larger than original signal? That's not easy, not if you want any hint of what the player is doing.

I'm sure it is another case of the copy-writer not understanding what s/he is cutting and pasting.

[Mark Hammer]

I'm sure it is another case of the copy-writer not understanding what s/he is cutting and pasting.

Bingo.

[DougH]

The Carl Martin advertising seems to favor a hi-fi "techie" presentation. I'm guessing it's all part of the image spin. It may not mean anything at all.