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August 20, 2019, 11:43:56 AM

Author Topic: High output level with MM cart  (Read 767 times)

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Offline Karl5150

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High output level with MM cart
« on: January 25, 2018, 06:17:21 AM »
I have been slowly digitizing my vinyl using a Cocktail Audio X12. Since moving up to the Eros I have noticed that some of the transfers are distorted. I am using an Ortofon 2M Blue with a listed output of 5.5mV. The X12 lists the analog inputs as 1Vrms, and I don't find any input level adjustment information in the manual or the menu.
I know the input of my Stereomour II can be padded to get more usable range out of the volume pot with the Eros and HO cart on the front end. Is there a way to drop the output of the Eros, short of switching to a lower output cart?
I love the sound of the 2MB>Eros>S II, but I would like to have digitized copies of my albums that have higher output levels, Brothers in Arms (MoFi, 45 RPM) comes to mind.
TIA, Karl 
Karl
Analog: Planar3>Eros>Stereomour II>Tekton OB4.5 & DIY "S8" subs
Digital: CD5004>Quickie>Seductor>FH3
Office: Schiit Modi Uber 2/Sirius Tuner>SEX 2.1.1>µFonken/FF85WK

Offline Paul Birkeland

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Re: High output level with MM cart
« Reply #1 on: January 25, 2018, 08:05:25 AM »
With a 5.5mV cartridge, the Eros will output about 1.75V. 

I can't imagine why they would limit the analog input to 1V; that's unsuitable for a wide variety of sources.


Normally I would just recommend padding down the source at the input of the X12 (there should be a level trim back there anyway for this exact purpose!), and you could try making a custom set of cables to do this.  Add one 10K resistor between the center post of the jack and the signal hot on the X12 end, then another 10K resistor between the center pin and the shell of that same plug for each channel.  You may notice some HF loss with this implementation, so there's another option...

Redo the circuit for less gain. 45dB would be a safe number.  This will require completely redoing the EQ, replacing the EF86 load resistors and current set resistor.  I'm not a huge fan of this idea.

You could use a different analog to digital converter. 

You could also put a preamp/buffer between the X12 and the Eros.  Even just adding a Quickie in between them would take care of the level problem and remove the impdeance concerns. 

(You could also snag a Tube Phono with the third active stage and trim pots between)

-PB
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Karl5150

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Re: High output level with MM cart
« Reply #2 on: January 25, 2018, 08:31:54 AM »
Thanks for the quick reply!
Nah, no trim pots accessible. This is their entry-level, all-in-one unit, no doubt many compromises.
Mess with the Eros beyond "premium" caps and dress-up hardware; I'm not that guy.
The cables are probably my speed, and if that causes enough HF info loss for me to detect I have a Quickie upstairs I can press into service.
I now have a path forward, thanks again. 
Karl
Analog: Planar3>Eros>Stereomour II>Tekton OB4.5 & DIY "S8" subs
Digital: CD5004>Quickie>Seductor>FH3
Office: Schiit Modi Uber 2/Sirius Tuner>SEX 2.1.1>µFonken/FF85WK

Offline Paul Birkeland

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Re: High output level with MM cart
« Reply #3 on: January 25, 2018, 11:43:33 AM »
Oh, just put the Quickie in there!
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Karl5150

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Re: High output level with MM cart
« Reply #4 on: June 02, 2018, 07:15:54 AM »
Finally got around to a workaround. I built a little RCA in/out box with an Alps pot. Now I can fine-tune the input to the Cocktail X12 by first finding the highest level on the album and adjusting the pot accordingly. Seems to work fine. (I didn't use the Quickie as it is upstairs, mounted in the same enclosure as the Seductor)
Karl
Analog: Planar3>Eros>Stereomour II>Tekton OB4.5 & DIY "S8" subs
Digital: CD5004>Quickie>Seductor>FH3
Office: Schiit Modi Uber 2/Sirius Tuner>SEX 2.1.1>µFonken/FF85WK

Offline aragorn723

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Re: High output level with MM cart
« Reply #5 on: April 21, 2019, 01:30:25 AM »
Can we see more pics of your EROS?  Looks very cool!  What knobs are those?

Dave

Offline Karl5150

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Re: High output level with MM cart
« Reply #6 on: April 22, 2019, 03:05:18 AM »
Thanks Dave. The knobs (on the SII) are gold on brass from Parts Connexion which have since been replaced when I added the Mour Quiet. If you are talking about the tube shields on the EROS, they are from Mapleshade Audio. (Just a customer in both cases) Sorry, I don't have any photos of the Eros with those shields and the ground ribbons.
Karl
Karl
Analog: Planar3>Eros>Stereomour II>Tekton OB4.5 & DIY "S8" subs
Digital: CD5004>Quickie>Seductor>FH3
Office: Schiit Modi Uber 2/Sirius Tuner>SEX 2.1.1>µFonken/FF85WK