[Bill Epstein]

My wonder at the sounds coming from the new AT-1005/DL-103r combo is restrained a bit by HUMMMM. A lot of HUMMMM.

I copied Abes Altec schematic and both the old and new Cinemag diagrams along with another I found on AA. With the unit open and the power on to teh amp (kids, don't try this at home) I did white and black to neutral, white only black only, black to neutral white to chassis ground, so many I forget where it is now. The hum is down by about 50% but still annoying.

I've got a wire from Cinemag chassis ground to Cornet which was the biggest improvement. I'm pretty sure the stock cable is shielded but I wonder if the arm ground might be broken. Didn't get a chance to try a wire from the arm, the amp went on and off so many times it began to oscillate!

My standby Piccolo has issues, too. Last time I powered it up one channel cut out and I haven't had a chance to look at it. Darn 

[PatOMalley]

Here's what I did and it is quiet.

http://home.comcast.net/~omaille/audio/cinemag/cinemag.html

[amandarae]

Hi Bill,

Have you tried connecting a wire from the base of your tonearm to the phono preamp chassis ground lug?


If the Altec wiring scheme I posted does not work for you, you can try following the schematic as posted by Cinemag with the black wires connected to the output negative phase of the output RCA.  You can leave the White wire un-connected as long as you do not touch the transformer case, or connect it to the ground tab of the SUT box if you want.

The reason why the 103R hums is because it has lower output than any of your other carts, thus needs much gain.

As for the Piccolo one channel cutting out, I had the same problem way back.  It turned out that it is from the plug of the walwart PSU to the power connector on the pcb that I  am using.  I confirmed this because when I was using the Bugle PSU that I built, the problem never showed up, only with the walwart.

[Bill Epstein]

Thanks guys.

I pulled apart the whole thing earlier; gonna mount the 'Mags inside the case with Goop and re-do all the wiring. Occurs to me the screws thru those holes in the 'Mags holding them to the case could have caused a ground loop. Isolating may be the way to go. We'll see.

[amandarae]

Hi Bill,

That should make a difference in my opinion.








I did not use screws to mount my cinemags.  The first pic shows a teflon washer plate interface between the Cinemag case/body to the metal box.  The second shows rubber pads with velcro strips to isolate the case.

Goodluck!

[Mr Ed]

Bill
I had to ground the case of the cinemag to my box to get mine totally quite. Also they can not be placed near any ac lines or any equipment with transformers. Even too close to my turntable motor will yield hum. Totally quite once I figured these two things out.

Home this helps
Ed

[analog97]

I was considering building one of these SUT's w/Cinemags to compare to my Denon SUT and Piccolo.  Would shielding the transformers with aluminum or copper foil suufficiently shield the transformer from RFI and EMF??

[WGH]

Jim's weblog from 2008 says this:

Ok, the text description of what I did for the SU-10 (now STEP-UP) in weeks
past may be confusing.  So I finally got the schematic done.  This is how I get
the CineMag CMQEE-3440A tranny to work best for me.  The outputs float, getting
their ground reference from the phonostage inputs.  The case gets a copy of the
separate TT ground wire (no signal on it).  I then tie this to the tranny
inputs, as they need some sort of common mode reference.  I don't like floating
them in space.  This gives the cart a reference ground, yet it has no signal
currents on it.  It is the exact same ground as what the tonearm gets.  This
works best for coaxial cart cables.  If they are twisted pair, it is also fine,
although you might be able to do better by balancing it.  This is done by
splitting the primary side loading into two resistors, each of R/2 value.  The
center tap to earth ground.  This forces the cartridge to operate in true
balanced mode, by providing the necessary 3rd terminal.  Anyway, my machine
will be with single-ended RCA connectors.  S1 selects primary side loading.  S2
changes gain.  Gain is set by selecting a primary tap, and then the same switch
kicks in the proper secondary tuning for optimum transient response.  You can
have your cake and eat it too.  Not a huge range of loading (LO, MED, HI, and
extra HI), but it covers the full range.  You'll also find that primary side
loading is NOT as sensitive as secondary side loading is.  Hence, relatively
big steps are ok. 

CineMag wiring diagram

The result is gains of 16dB, 22dB, and 27dB.  Lowest possible loading on cart
is roughly 21 ohms. 

[Bill Epstein]

OK, OK, I finally found the solution. Sent it out to my good pal Steve Brown, well-known SET builder to straighten out.

Cool unintended consequence: on a whim, I put the Sonata in the way-too-heavy AT-1005 arm with the way-heavier-than-stock Sumiko headshell ( total effective mass 24 grams) and it sounds fabulous.

[taskerc]

Hi Bill,

What was the final solution?  What magic did Steve perform?

Has anyone else tried Jim's balanced solution?  Mine are quiet but not yet as quiet as I would like.  At 4 on my headphone amp I can hear the hum but not against a music background.  I have tied the RCA -ve to ground as that cleaned it up immensely.  Positioning has also helped.  I moved the cans inside the case and that did not seem to help at all.

Chris

[Bill Epstein]

Hey Chris, the brown truck only left yesterday. I'll update, may be awhile.

[taskerc]

Thanks Bill,

Can you tell I REALLY want to find the final solution myself 

Chris

[amandarae]

Has anyone else tried Jim's balanced solution?  Mine are quiet but not yet as quiet as I would like.  At 4 on my headphone amp I can hear the hum but not against a music background.  I have tied the RCA -ve to ground as that cleaned it up immensely.  Positioning has also helped.  I moved the cans inside the case and that did not seem to help at all.

Chris

Hello Chris,

I did!




So far, I have no time to test it yet.  Apologies for the crude wire dressing, as this is my "experimental" Cinemag transformer thus the leads are still long.  I will test this tonight with 0.8, 0.4, 0.25, and 0.18 mV cartridges and three phono stages.

I wonder if the negative phase of the input (Blue) for both channels should meet at the phono preamp ground instead of the wiring diagram where they meet instantly at the GND lug of the SUT box from Jim's schematic.  I asked because looking at the input, there's a ground loop staring at me between the L&R input channels.  Maybe I wired something wrong...

We'll see.....I will report back

[taskerc]

Looks nice amandarae!  One question - why does the orange wire go to a separate chassis ground point?  Should it not just terminate right on the back of the ground post where you tied the collection of other ground connections?  To me that appears to add the chassis as a separate path to the common grounding post.

I might just try the balanced form myself.

Chris

Hello Chris,

I did!




So far, I am still testing it.  Apologies for the crude wire dressing, as this is my "experimental" Cinemag transformer thus the leads are still long.

I wonder if the negative pahe of the input (Blue) for both channels should meet at the phono preamp ground instead of the wiring diagram where they meet instantly at the GND lug of the SUT box from Jim's schematic.  I asked because looking at the input, there's a ground loop staring at me between the L&R input channels.  Maybe I wired something wrong...

We'll see.....I will report back

[amandarae]

Looks nice amandarae!  One question - why does the orange wire go to a separate chassis ground point?  Should it not just terminate right on the back of the ground post where you tied the collection of other ground connections?  To me that appears to add the chassis as a separate path to the common grounding post.

I might just try the balanced form myself.

Chris

Hello Chris,

Ahh yes, because all I have at the moment is a speaker binding post use as a ground lug and it is insulated from the chassis.  So, I have to add the chassis connection.  If your ground lug touches the chassis, then no need for the Orange wire.


If you are going to try it, maybe you can clear something for me...

According to the notes, the config yields 16, 22, and 27dB gain which is 1:6, 1:13, and 1:22 respectively.  So the highest loading we can get from the secondary is 1.3K, 278, and 97.1 ohms.

A 40 ohm load for the cart to see will require 1.48K at 1:6, 7.8k at 1:13, and 32.9k for 1:22.  Similarly, a 100 ohm load will require 3.8k for the 1:6 and 26.4k for the 1:13, nothing on the  1:22 (since the highest we can go is 97.1 ohms!).  Now, here's my question, Jim's notes have 160k, 82k, and 39k selectable resistors on the secondary, why?

regards,

Abe

[amandarae]

Okay, I tested it.  I employ another dpdt switch so I can have the inputs grounded as per Jim's schematic or floating when I flipped the switch.  Also, I am only using 1:13 and 1:22 taps as outputs.  I will post pictures later if necessary.

When using 1:18 as per Cinemag schematic wiring diagram, I marked the position where the hum starts to develop, which fortunately is way past my volume level position when listening even at very loud volume inside my listening room.

With the present wiring, the hum shows up a bit lower from the marked position.  This result is as expected because I am using 1:22 (27dB) gain settings.  What I cannot explain is that it seems to have a slight delay as I switch from low (1:13) to high(1:22) before I can discern the difference in loudness level.  It sounds like it ramps up the signal and I can hear it going up, or down when the procedure was reverse.

Also, the ground switch for the input, floating or not, does not seem to influence the hum level.
So, to those who tried, do you have the same observations?  BTW, the above results was from using Cornet 2 as phono preamp.


With my 6SL7 base phono preamp, I compared my Altec 4722 to the Cinemag with the same wiring.  The Altec was set to 1:18 and the Cinemag at 1:22.  The Altec was much quieter than the Cinemag, again because of the difference in gain.  But here, the position of the ground switch affects the range of the volume pot where the hum starts to resurface and become audible.  When the input is floating, the vol pot position is lower than when the inputs are tied to ground.

In retrospect, I would say that I can live with Jim's schematic even if I do not have the 1:36 gain anymore (I do not use 1:9 and have a different SUT to cover that range if necessary) which sounds best for my Denon 304 at 0.18mV output.  So far, initial impressions on how it sounds are positive but it is still to0 early to say if there's a difference compared to the other wiring scheme since the gain settings were changed and I need more time to listen and change other variables like TT's and phono stages, not to mention SUT.  Also, I will not try to add the loading to the parameters and just run the SUT using its transformed impedance per gain settings.

Hope this is useful....

[amandarae]

Great News!

I oriented the transformers differently and found that it is now as quiet as the original wiring scheme as publish by Cinemag.

But, Jim's wiring which provides 97.1 Ohms load to the cart without any resistor loading sound much better than loading my Denon's (103,103R, 103 wood body, 103R wood body, etc.) at 100 ohms using resistors!   Unbelievable right?  Try it is all I can say.  It sounds more dynamic and with great balance from top to bottom to this ears, which of course were based on what I heard in my system. 

Was it from the increase in output as a result of not shunting the secondary with loading resistor?  I do not know, but for sure the ouput current increase is benificial in driving the phono preamp.  Later on, I will run a test tone and will try to measure (I think my Fluke 187 can do it plus measure the freq.) the difference correctly if I can.

I am done with my experimental Cinemag.  Finally, I have two identically made SUT's with different "flavors".  This really helps me to evaluate phono preamp builds I have in the pipeline. 

Regards

[taskerc]

Great News!

I am done with my experimental Cinemag. 
Regards

Done Abe?  Like really done?  Forever?  You can't kid a kidder ....   

Everytime I get close to thinking I am done, I find another post and then the merry-go-round starts all over again - and I love it (kind of).

(Not yet done) Chris

[amandarae]

Done Abe?  Like really done?  Forever?  You can't kid a kidder ....   

Everytime I get close to thinking I am done, I find another post and then the merry-go-round starts all over again - and I love it (kind of).

(Not yet done) Chris

   Done with wiring the Cinemag that is!

Audio in general, never.

I still have three amps and maybe two preamps that I want to build.  After that, I will sell the equipment I have (amps and preamps only) with audio manufacturers name on it.   Just kidding!  At least, in my mind, that's my plan.