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Author Topic: Problem with Great river pre and ribbon mics  (Read 4557 times)

Kassonica

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Problem with Great river pre and ribbon mics
« on: October 13, 2009, 07:25:51 PM »

Hi

I've noticed a problem with my great river pre and ribbon mics, when i use Ribbons (AEA 92 and a M160) if I have the gain over 45 dB it introduces crackling on some recordings.

Running under 45 seems to be fine.

I've used many other mics (mainly dynamics) and have run them up to 55 dB  of gain on quiet sources and had no problems.

Any help or advice, appreciated.


Ps I love this pre.

 
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Mark Ludwig

Should have been a Drummer


rick-slo

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Re: Problem with Great river pre and ribbon mics
« Reply #1 on: October 13, 2009, 11:47:39 PM »

There was just a thread on a Great River MP-H with a AEA R88. You may want to take a look and perhaps ask the OP of the thread.
http://69.41.173.82/forums/showthread.php?t=165995

Jim Williams

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Re: Problem with Great river pre and ribbon mics
« Reply #2 on: October 14, 2009, 10:16:40 AM »

Noise is speced on mic preamps as the equivalent input noise or EIN. It's the sum of gain plus noise.

Any transformer input design will limit EIN to about -127 db with a 150 ohm source impedance due to transformer insertion losses.

The amount of available gain isn't a gauge of the noise floor of a given preamp. The EIN spec is. Look for it, if it can be found.

Ribbons are not noisy. They are low output so the preamp requires more gain = more noise. Some ribbons are 50 ohms impedance. That makes the transformer input preamps worse as all audio mic input transformers are speced at a 150 ohm source impedance. The noise floor will degrade further at 50 ohms.

Compared to a transformerless design, 50 ohms is actually better EIN, on my preamp it's -133 db EIN. That's 6 db less noise, or 1/2 of the iron front end. Take 6 db of noise off that ribbon mic and it's pretty quiet.

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Jim Williams
Audio Upgrades

mdbeh

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Re: Problem with Great river pre and ribbon mics
« Reply #3 on: October 14, 2009, 03:56:18 PM »

On the MP2NV, if you fully clip the first gain stage -- red lights on the first LED ladder -- it will crackle the way you're describing.  So it may just be a matter of turning the gain pot down a click and compensating with the output trim.
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Brian Harper
Chicago, IL

Kassonica

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Re: Problem with Great river pre and ribbon mics
« Reply #4 on: October 15, 2009, 08:31:11 AM »

Thanks for your replies.

I never clip the input of the river and it was metering on the first or 2nd stage of green.

The crackling sounds almost like a digital clocking issue but it's can't be as it only ever happens on the river with Ribbon mics.

It really has me beat.

I use high quality leads both mic and from the river to the Convertors  (RME FF 800)

I'll will try the daking and see if it happens but the river and Ribbon combo is just so damn nice.

Ps I have the impedance switch in on the river which brings out the presence a bit more, that wouldn't be the cause surely?

Yours confused.  
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Mark Ludwig

Should have been a Drummer


Dan Kennedy

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Re: Problem with Great river pre and ribbon mics
« Reply #5 on: October 15, 2009, 08:59:41 AM »

Hi Mark,

That is a strange complaint, one I've not heard before.

Can you send me an MP3 or something?

The MP-2NV isn't the worlds quietest mic pre, but it's far from
the noisiest, so I would expect you to hear some hiss with low level sources and low output mics, but crackling is a different
issue.

Dan Kennedy
Great River Electronics
dkennedy@greweb.com
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Kassonica

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Re: Problem with Great river pre and ribbon mics
« Reply #6 on: October 15, 2009, 10:26:49 AM »

Hi Dan

Thanks for your reply.


I sent you an email earlier as well but in over 4 years of owning this pre I have nothing but the highest of praise for this pre, so hence why I'm a little perplexed.

I will send you an email with a sample of the crackling.

Ps at this point it has only appeared on Viola's that I've been tracking and has never happened with condenser or dynamic mics.

I would like to clarify as well it is not a complaint, I am just trying to negate all user error.



Cheers

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Mark Ludwig

Should have been a Drummer


compasspnt

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Re: Problem with Great river pre and ribbon mics
« Reply #7 on: October 15, 2009, 11:21:40 AM »

Dan will get to the bottom of it.
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Dan-O

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Re: Problem with Great river pre and ribbon mics
« Reply #8 on: October 15, 2009, 12:19:16 PM »

I have to mention that Dan & company are really fabulous stand up people that stand behind their products. My MP-2NV, which I've had since 03' and never given me a problem, finally had a slight problem a month or so ago. Turned out to be some leaky caps which Great River replaced no charge even way out of warranty.

Sorry for going OT.
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Dan-O
Snake Oil Recording
http://www.snakeoilrecording.com
Richmond, VA

marcel

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Re: Problem with Great river pre and ribbon mics
« Reply #9 on: October 15, 2009, 08:02:14 PM »

+1  

Although his equipment is virtually bullet proof (the 2 pieces I own are well into 5 years of daily use), the one encounter I've had with Dan's customer service was easy, pleasant, and totally above the call of duty.

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Best, Marcel

Kassonica

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Re: Problem with Great river pre and ribbon mics
« Reply #10 on: October 15, 2009, 10:13:27 PM »

Well all I can say is unbelievably  great service.

He is sending the parts to Australia free of charge (after offering to fix it if I sent it over to the states but the expense would of been to great) .

I sent him a AIFF file of the crackle and he got back to me very quickly and said it was a defective part, either a cap or transistor in the 2nd gain stage that kicks in after 40db gain.

It seems their customer service and support is just as good as their products.

Much thanks  for everybody's input.
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Mark Ludwig

Should have been a Drummer


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