AMS-Neve 1073 DPD Imdedance switch

[blackcom]

I notice that the 1073 DPD has an impedance switch for the mic input.
Anyone with experience about how this changes the sound, much or little? What do you guyes generally use this switch for?

[blackcom]

bump

[joaquin]

I have not used it on the Neve, but, usually will affect the frequency response of the Mic/Pre a bit.

[George Necola]

1073 DPD has an impedance switch

I own the audient ASP008 and it has 3 options of impedance. mostly I use the "normal" position.. one option more to control..

[Geoff_T]

Originally Posted by blackcom

I notice that the 1073 DPD has an impedance switch for the mic input.
Anyone with experience about how this changes the sound, much or little? What do you guys generally use this switch for?

Hi

Neve modules from way back had a Secme toggle switch on the rear panel that switched between high and low impedance. All the switch does is to wire the two 600 ohm primary windings of the input transformer either in series (= 1200 ohms) or parallel (= 300 ohms).

If you connect the windings in parallel the turns ratio of the transformer raises the gain from the normal 6dB to 12dB... but, if the source impedance (ie the output impedance of the microphone) is significantly high, the source impedance will create an attenuator with the module's 300 ohm input resistance and you would get little or no gain.

The general rule is that you want to go from a low impedance into a high impedance. I suspect that 99.9% of the time the high position (1200 ohms) is adequate for the majority of microphones. It would only affect frequency response (as raised in another post) if the mic was expecting a high resistance and was damped by making it drive the lower impedance.

The answer to when to use it is to try it and see. If you can't hear any difference, leave it in 1200 ohms. If it makes an improvement (always a subjective matter) put it in 300 ohms.

From my observations, I've noticed several cloners permanently wire the transformer in 300 ohms. Not a good idea.

[blackcom]

Di'd some testing....
Seems like low z sounds a abit moore open while high z sounds moore scooped....

[Geoff_T]

Originally Posted by blackcom

Di'd some testing....
Seems like low z sounds a abit moore open while high z sounds moore scooped....

Hi

What did you have connected to the input?

[joaquin]

Originally Posted by blackcom

Di'd some testing....
Seems like low z sounds a abit moore open while high z sounds moore scooped....

for what I remember, to my ears, with most mics, is the other way around!?stike

[Geoff_T]

Originally Posted by joaquin

for what I remember, to my ears, with most mics, is the other way around!?stike

That's what I thought, too!

[Moofie]

FWIW, when plugged into my TG2 on the 300 ohm setting, my 30 ohm 4038's (yes, they're that old) get noticably louder and the top end lifts just enough, in most cases, to avoid the need to shelve too much (if any) HF into the mic with Eq .



Tom

[Geoff_T]

Originally Posted by Moofie

FWIW, when plugged into my TG2 on the 300 ohm setting, my 30 ohm 4038's (yes, they're that old) get noticably louder and the top end lifts just enough, in most cases, to avoid the need to shelve too much (if any) HF into the mic with Eq .


Tom

Hi

That's because the low source impedance only causes about a 0.8dB drop into the 300 ohm input so you'll get a 5.2dB gain increase.

[musicmansell]

I did a little test with the DPD and a C414 on the first chanel. Tried recording a vocal with the switch set to Hi and then set to Low. The low setting seemed a little louder and more "full" sounding in the low mids and mids. The Hi seemed a little quieter and I have to agree with the previous listeners, but it sounded a little scooped. Weird, because like Mr. Tanner and others, I have found it usually to be the opposite?

[digitrax]

FWIW, I find on SM57's, a lot of ribbons, and a few other dynamics, I prefer 300Ω. Condensers, OTOH are usually more "open" at 1200Ω and more "in your face" at 300. I always try both.