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[stringy_]

So I just recently re-read OzNimbus' thread on drums again, and I've decided to follow up on his talks about microphone preamp impedance and SM57s.

I went to Recording's website and you can order back-issues, but you can't order any from 2006 yet. Oz mentioned that it was an article by Paul J. Stamler, in probably the May 2006 edition, and he laid out plans for an inline "gizmo" that would lower the impedance of pres that didn't have an impedance switch.

I really, really, want this article...and I haven't found anything similar on the Internet.

Is there anybody who has this article/issue that they could scan for me? Or I would also be willing to buy the mag from you for cover price and cover shipping.

Anybody?

 

[Keiffer]

I built such a cable some time ago and I use it with my 57 often.

In my cable I have one 680 ohm resistor between pins 2 and 3. My preamp is about 1500 so that's about 467 ohms total. I soldered the resistor inside the Neutrik XLR connector on one end. My cable is about 2 ft long.

[EDITED]

 

[stringy_]

Did you get those plans from a schematic of some sort?

Oh yes, and have a look here :

Mic (Dynamics) output impedances + recommended load.


Shure SM-7: impedance - 150 ohms; suggested load - 300 ohms
Shure SM-57: impedance - 310 ohms; suggested load - "low impedance,"
Shure Sm-58: impedance - 300 ohms; suggested load - "low impedance,"
Shure Beta 57A: impedance - 290 ohms; suggested load - "low impedance,"
Shure Beta 98h: impedance - 150 ohms; suggested load - 1000 Ohms
Shure Sm-58: impedance - 300 ohms; suggested load - "low impedance,"
Sennheiser 421: impedance - 200 ohms; recommended load - 200 ohms
Sennheiser 441: impedance - 200 ohms; recommended load - 1000 ohms
Sennheiser 431: impedance - 250 ohms; recommended load - 1000 ohms
AKG D112: impedance - 210 ohms; suggested load - 600 ohms or greater


Mic (Condensers) output impedances + recommended load.

Sennheiser 416: impedance - 25 ohms; recommended load - 800 ohms
Neumann U-87: impedance - 200 ohms; suggested load - 1000 ohms
Neumann KM-184: impedance - 50 ohms; suggested load - 1000 ohms
Neumann TLM-103: impedance - 50 ohms; suggested load - 1000 ohms
Neumann TLM-70: impedance - 50 ohms; suggested load - 1000 ohms
Neumann M-149: impedance - 50 ohms; suggested load - 1000 ohms
Neumann U87: impedance - 200 ohms; suggested load - 1000 ohms
Neumann U89: impedance - 150 ohms; suggested load - 1000 ohms
Schoeps CVC6: impedance - 35 ohms; suggested load - 600 ohms or less
AKG C-460B: impedance - 120 ohms; suggested load - 2000 ohms or greater
AKG C-414B-ULS: impedance - 180 ohms; suggested load - 600 ohms
AKG new C 451 B : impedance - 200 ohms; suggested load - greater than 1000 ohms
Soundelux E47: impedance - 200 ohms; suggested load - 1000 ohms
Royer: impedance - 300 ohms; suggested load - bigger than 1500 ohms

Preamps input impedances: (and output impedances)

Buzz: 3000 ohms/1200 ohms
Great River NV: 1200 ohms/300 ohms
Standard Great River:1600 ohms
Avalon 737: 850 ohms
VIPRE: 300-600-1200-2400
Chandler TG-2 : 300-1200
Great River MP2NV: 1200/300
Summit 2BA-221: variable from 100 to 10000 Ohms
Millennia Media HV-3B: 6200 Ohms.
Ridge Farm Gas Cooker : 1100 Ohms (500 ohms balanced, 1.5 k ohms unbalanced)
Amek CIB: 5000 Ohm.
Focusrite Red1 : 1200 Ohms (+24 dBM into 600 ohm / +26 dBm into 10000 ohm)
Neve 1272: 600 ohms
Vintech x73i: 1200/300
DBX 1086: 1700 Ohm (Balanced 120O Ohms unbalanced 60 Ohms)


AD-Converters input impedances

Apogee AD-8000: 9000 Ohms (+4dB) / 15000 Ohms (-10dB)
Apogee PSX-100: 9000 Ohms (+4dB) / 15000 Ohms (-10dB)
Apogee AD-1000: 10000 Ohms (+4dB) / 5000 Ohms (-10dB)
Nuendo 8 I/O: 10000 ohms

Other:

Summit TLA-100a : Input inpedance 20kOhms / Output impedance is 75 Ohms
The recommended output load is 600 Ohms or more.
Focusrite Red2 : Input inpedance 10kOhms / Output impedance +26 dBM into 600 Ohms
Focusrite Red3 : Input inpedance 20kOhms / Output impedance +26 dBM into 600 Ohms

 

[Keiffer]

Did you get those plans from a schematic of some sort?

No, schematic. I probably read it somewhere.

I told you wrong. I've edited my original remark.

 

[stringy_]

No, schematic. I probably read it somewhere.

I told you wrong. I've edited my original remark.

That's it? All you did is just solder a resistor between pins 1 and 2 and leave everything else the same?

Do you think the sound changes much? I've heard some guys say it is a pretty big difference, but then I've heard some other big-named engineers say it's not really that big of a deal.

 

[Keiffer]

yeah that's it...

yes the mic flavor changed for the good with my preamps. the nice thing about the cable method is you can use it or not.... even make several cables.

 

[stringy_]

yeah that's it...

yes the mic flavor changed for the good with my preamps. the nice thing about the cable method is you can use it or not.... even make several cables.

Cool man, I appreciate the help.

One last question, should I pick a different value of resistor for my preamps? I'm running 1000 ohms right now...

 

[Keiffer]

I think I stayed up in the 600ohm range... 1K will put you at 500ohms.

 

[Where She Wept]

If you want to calculate it, the formula is (R1)(R2)/(R1+R2). make one value your mic impeadance and the other the value of your resister, and you get the total impeadance.

 

[Glenn Fricker]

Of course, the easiest way to achive this is to simply get a Great River MP2NV, which has an impedance switch right on the front panel. You can change from 1200 ohms (default) to 300, which is perfect for a 57. Not to mention, it's about as killer a mic preamp as you'll ever find. Do yourself a favour & save your pennies.

-0z-

 

[MKS]

Of course, the easiest way to achive this is to simply get a Great River MP2NV, which has an impedance switch right on the front panel. You can change from 1200 ohms (default) to 300, which is perfect for a 57. Not to mention, it's about as killer a mic preamp as you'll ever find. Do yourself a favour & save your pennies.

-0z-

I think the M-Audio tampa has the same feature but about 1/8th the price.

 

[JeffTD]

This has got me really curious - anyone have any A/B clips?

Looks like I might pick up a spare short cable and 400Ω resistor.

 

[stringy_]

Of course, the easiest way to achive this is to simply get a Great River MP2NV, which has an impedance switch right on the front panel. You can change from 1200 ohms (default) to 300, which is perfect for a 57. Not to mention, it's about as killer a mic preamp as you'll ever find. Do yourself a favour & save your pennies.

-0z-

Yeah, now that I've actually had my eyes open for this feature, there are a few other higher-end preamps that have selectable impedance too.

Thanks for the tip in the first place!

 

[Seizure.]

In few days i'll have a Audient ASP 008 which has switchable impedance, i'll see if i can post some different impedance samples!

 

[Jackal_Strain]

I think the M-Audio tampa has the same feature but about 1/8th the price.

Yeah, but the great river sounds way better!

 

[Nebulous]

In few days i'll have a Audient ASP 008 which has switchable impedance, i'll see if i can post some different impedance samples!

Thank you!

 

[Glenn Fricker]

I think the M-Audio tampa has the same feature but about 1/8th the price.

True, but the Great River slaughters it in the quality department.

 

[MKS]

True, but the Great River slaughters it in the quality department.

I'm sure it does but I wanted to point out a cheap alternative. The tampa is a decent pre-amp at a decent price. I actually regret selling mine.

 

[Keiffer]

buying a GR Preamp to load a 57 is sure overkill.

 

[Glenn Fricker]

Allow me to clarify: Of course it's overkill for the sole purpose of loading. The impedance switch is an added bonus. An sm57 on a great cab with a great amp & player sounds unreal properly loaded on a Great River... that's my point.

If I'm coming off as a 'gear snob' it's certainly not my intention. Believe me, I've worked with plenty of the lower priced stuff. But, sometimes it's worth it to wait & save for a great piece of gear that you know will last a lifetime.