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Here It Is: The All Singing All Dancing HTMCPS

The VLOMCs with very low loading may be very critical re actual loading, it was so with an O'fon MC-20MkII where the suggested 10^ loading was optimal when adjusted by ear.
 
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Here's my compact cnc & htmcps phonostage. . :-)

20130312_082559_zpsbc7d0fa3.jpg
 
I still have at least one board for this project but built the AD797 LOMC front end first so haven't actually heard the HTMCPS.
 
Nice build andy.I like your other projects too:thmbsp:
EDIT: did you put CNC board under HTMCPS?

Regards,
Sachin
 
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Obankenobi said:
I was hoping for the Dead Quiet Ideal, especially with the shielding of the case I completed. But I think the hiss is louder than ever before - probably also from the lantern battery 12V supply (I was using 9V's before).

I went a bit nuts and replaced all my solid hookup wire with dual pair, stranded, twisted Cat-5E cabling. I then used the foil from the cut Cat-5 to wrap & shield, held together with shrink wrap. Very ugly, I gotta say, and since I still have hiss I can't say it was worth it.

But I still can't stop fiddling... now I'm seeing these dual channel to dual-mono opamp adapters, and dreaming of opamp rolling
Click to expand...

I had a lot of noise when I used lantern batteries. Lots of RFI. Very little when using 9Vs. That may be because I had to use unshielded jumpers that were pretty long with the lantern batteries. It was quieter when I twisted them together, but still too loud to use. So I stuck with the 9Vs, which have a very short connection (3 inches) to the phono stage.
 
hi sachin,

thanks! diy is fun and fulfilling when it is done nicely.

the cnc board is under the htmcps in which the supply is switchable between the two boards to save battery life.


sachu888 said:
Nice build andy.I like your other projects too:thmbsp:
EDIT: did you put CNC board under HTMCPS?

Regards,
Sachin
Click to expand...
 
Hi Andy,

Nice build :thmbsp:
I've finished building and testing the CNC and want to start the HTMCPS too. Thought to build it in one single case, switchable for the very reasons you mentioned. Do you also switch the RCA for input and/ or output ?

Regards :)
Mario
 
maco said:
Hi Andy,

Nice build :thmbsp:
I've finished building and testing the CNC and want to start the HTMCPS too. Thought to build it in one single case, switchable for the very reasons you mentioned. Do you also switch the RCA for input and/ or output ?

Regards :)
Mario
Click to expand...

It would perform better without switching on the input. That said, I would build it to fit the situation. If the MC is in one arm or TT and the MM in another, then you would have separate leads and two sets of inputs make the most sense. If the MC and MM carts are in separate head shells and you just switch them out then input switching makes the most sense.

Shelly_D
 
Assistance needed..please

When Hypnotoad built my HTMCPS, it was based off the AT33PTG/II. That cart had
Coil Impedance 10Ω (1kHz)
Direct Current Resistance 10Ω
.3mv

So R1 and R9 say 10R0F
R2 and R10 were at 250ohm (not sure why)

Now I have the ATOC9/III which is
Coil impedance: 12 ohms
- DC resistance: 12 ohms
.4mv

so based on what I have read earlier in this thread shouldn't I change R1 and R9 to 12ohms?

And R2 r10 should be 120ohms (based on the 10x factor)?

so please, correct me if I am wrong and, what type of resistors are these..they are not the typical ones with the color codes..they are brown ..special low noise type?

Thanks to all
 
You can leave the resistor at 10 ohms it so close it makes no difference.

The resistors are Vishay Dale and have the values printed on them they are easier to read than the ones with color codes, it will make no difference which ones you use.
 
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Thanks Phil

HypnoToad said:
You can leave the resistor at 10 ohms it so close it makes no difference.

The resistors are Vishay Dale and have the values printed on them they are easier to ready than the ones with color codes, it will make no difference which ones you use.
Click to expand...

Wasn't sure how close it needed to be, if there would be a better compliance, whatever...THANK YOU
 
+1 on this

GreatTone said:
I had a lot of noise when I used lantern batteries. Lots of RFI. Very little when using 9Vs. That may be because I had to use unshielded jumpers that were pretty long with the lantern batteries. It was quieter when I twisted them together, but still too loud to use. So I stuck with the 9Vs, which have a very short connection (3 inches) to the phono stage.
Click to expand...

I mentioned it to Phil. Since I went to the two 12v rechargeable pack batteries, I have a gain hiss...with the 9v..dead quiet. I may just go back to the 9V...or is there some way to filter it ?

Just a guess but is it because I am feeding almost 25v vs 18v ?

Been doing some reading...so gain hiss is caused when GAIN is higher than volume...so it seems like the voltage is driving the gain, while the volume is fixed or set by the pre-amp its going to...so is there a way (maybe via diode) to feed a static 18v from the 24 volts coming in?

Sorry to be a pest but would something like this work ? How would you do it and how would you calculate it ?

http://www.ehow.com/about_5405629_zener-diode-regulator.html
 
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It seems you get more shot noise at the higher voltage. Zener regulators tend to generate noise, properly implemented active low-noise series-pass regulators like LM7809/LM7909 would be better. Is the hiss at full-tilt or audible at normal listening levels during quiet portions of program?
 
the hiss

Pio1980 said:
It seems you get more shot noise at the higher voltage. Zener regulators tend to generate noise, properly implemented active low-noise series-pass regulators like LM7809/LM7909 would be better. Is the hiss at full-tilt or audible at normal listening levels during quiet portions of program?
Click to expand...

My volume control works like this. -60 to 0 with 0 as max volume. Normal listening is between 40 & 32. At 40 I can hear it with my ear near the speaker. With no music on, as I raise the volume, it raises the hiss. Never notice it with music playing but hey, its noise, right ?

With 2 9v batteries instead of 2 12v, no hiss (maybe at full tilt near zero but I never go there). How do I do low pass regulators? Thanks!
 
Not really noticable

Pio1980 said:
First, does it have more gain at 12V than 9V?
Click to expand...

Maybe it does but not really noticeable by me..

Phil had me change out R2 and R10 to a lower Ohm value...It might have reduced the hiss some but again, not that noticeable. What is noticeable is the sound cleared up..was feeling it was "off"

I KNOW it is hiss free at 18v and may test just to be sure...but that goes back to the PITA of the 9 volts...would love to have the duration of these (pictured below) with the output of 18V

308669_643911855624280_1717176950_n.jpg
 
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