Here It Is: The All Singing All Dancing HTMCPS

HypnoToad

Ms Puss Puss
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Never being satisfied for long I have been working on a new moving coil phono stage the Hypnotoad Moving Coil Phono Stage. Here is the first working prototype, well the only one actually. It worked first time I fired it up to my surprise and I only finalized the design last night. As you can see I had a few different options on the PCB and some of the component values were changed after I etched the PCB.

It's super simple to build, is dead quiet and has plenty of gain which can be adjusted easily to suit different carts. I used the trans-impedance concept for the input stage as I believe that it's the best way to go. Makes me wonder since the idea has been around so long that it hasn't been used a lot more.

I nearly went with a non-inverting output stage but changed my mind as I realized it would be out of phase. I have a personal preference for active equalization as well so that's the way I went.

RIAA is accurate, less than 0.4db deviation.
2 x OPA2134 dual circuit op amps.
Very few caps in the signal path and bypassed output caps.
Only 10ma's current draw.
Runs very nicely on 9v batteries at the moment but will try it later with my lantern batteries setup which seems to always sound a bit more authoritative on my other stages.

Right out of the blocks it sounded special, the bass was a tad heavy and the highs a little laid back at the first needle drop, but after only a couple of hours it's opening up nicely. So nicely I am thinking I don't need to change a thing, yeah right who am I kidding.

I did a comparison between it and the Phonoclone 3 and even though the PC3 is a fierce contender and the best phono stage I have heard. That was up until now, the HTMCPS has a slightly more forward sound stage compared to the PC3 with a slightly smoother more open sound to it. It's like another veil has been lifted from the sound.

I am listening to The Carpenters and Karen's voice can be a little harsh on some systems but it's as sweet as sweet and this is only after a couple of hours use.:music:

HTMCPS.jpg
 
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Congratulations Phillip,that's a great news.Too bad I don't have an MC cart for this.

Regards,
Sachin
 
I'm still in, I have 2 LOMCs and a Mitz LT-30 waiting on this project
 
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I will be doing more listening over the weekend and working on the Gerber files so I can get some PCB's made.

I need to listen to it through my SSP as well, the OPA2134's are surprising in this design, I was never really keen on them. I will try some other op amps as well but doubt they could be better.
 
More listening and the more I listen the more I am impressed, I tried a LME49720 op amp in the RIAA stage and found the soundstage collapsed a bit so put the OPA2134 back in.

I played my favorite test track Because on Beatles The Love album and the birds chirping and flapping as well as the fly/buzzing are clearer than I have heard so it has detail, smoothness and soundstage in spades.:banana:

I haven't tried the AD823 as I am liking the OPA2134's so much.

Sachin has kindly offered to get PCB's made for this.
 
Fantastic project. I'm actually going to be building one as soon as Sachin gets the boards to me :)

Hypnotoad, thank you so much for offering this to the community. I really can't wait to hear it on my MC carts.

I was wondering about the R1 and R2 values. Should I just use the Phonoclone3 calculator or is there another way to calculate the R1 and R2 values.

For example, here is what I am picking for the following cartridges using the PC3 calculator:

1) Clearaudio Accurate:
Cart Impedance: 50 Ohms
Cart Output: 0.7mV
R1: 50 Ohms
R2: 715 Ohms

2) Koetsu Black:
Cart Impedance: 5 Ohms
Cart Output: 0.6mV
R1: 5 Ohms
R2: 82.5 Ohms

3) Shelter 90x:
Cart Impedance: 20 Ohms
Cart Output: 0.65mv
R1: 20 Ohms
R2: 309 Ohms

Thanks so much!

Are those right or should I be picking some other R1, R2 Values?
 
Fantastic project. I'm actually going to be building one as soon as Sachin gets the boards to me :)

Hypnotoad, thank you so much for offering this to the community. I really can't wait to hear it on my MC carts.

I was wondering about the R1 and R2 values. Should I just use the Phonoclone3 calculator or is there another way to calculate the R1 and R2 values.

Using the PC3 calculator you will end up with too much gain. Simply multiply the value of R1 x 10 to get R2 for lomc carts that should be close enough.
 
Oops! I better go change my order at Mouser then :) Should add in the 500 Ohms, 50 Ohms and 200 Ohms resistors.
Thank you for such a quick reply!

Also, what is a typical gain value range that we are shooting for?
 
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Oops! I better go change my order at Mouser then :) Should add in the 500 Ohms, 50 Ohms and 200 Ohms resistors.
Thank you for such a quick reply!

Also, what is a typical gain value range that we are shooting for?

Overall around 60 - 65db, the second stage has 35db, the first stage will vary so it the whole thing can easily go up to 75db.
 
Parts ordered! All should be ready before I get the boards from Sachin.

As I type this, I am listening to the new 45 rpm Reissue of Oscar Peterson Trio - We Get requests. Chain is basically a VPI TNT 6 Hot Rod --> Clearaudio Accurate --> Einstein "The Turntables Choice" Phonostage. It is sounding absolutely out of this world and I am completely smitten by it.

I really am looking forward to hearing this HTMCPS Phono. I pray that it outdoes the Einstein because then I can sell it and reinvest in other parts of the system. Maybe get another MC cartridge (probably a Mono) and JMW12.7 armwand to play with (just the thought brings a smile).

I will just patiently wait...
 
Parts ordered! All should be ready before I get the boards from Sachin.

As I type this, I am listening to the new 45 rpm Reissue of Oscar Peterson Trio - We Get requests. Chain is basically a VPI TNT 6 Hot Rod --> Clearaudio Accurate --> Einstein "The Turntables Choice" Phonostage. It is sounding absolutely out of this world and I am completely smitten by it.

I really am looking forward to hearing this HTMCPS Phono. I pray that it outdoes the Einstein because then I can sell it and reinvest in other parts of the system. Maybe get another MC cartridge (probably a Mono) and JMW12.7 armwand to play with (just the thought brings a smile).

I will just patiently wait...

Since the Einstein "The Turntables Choice" Phonostage has a MSRP of around $10,000.00 I will be interested to see how the HTMCPS stacks up.
 
Do we need to calculate only R1,R2 or R9 and R10 also needs to be changed?

Regards,
Sachin
 
Do we need to calculate only R1,R2 or R9 and R10 also needs to be changed?

Regards,
Sachin

Yikes,

I thought only R1 and R2 needed to be changed. I definitely haven't ordered any calculated resistor values for R9 and R10.
 
Yikes,

I thought only R1 and R2 needed to be changed. I definitely haven't ordered any calculated resistor values for R9 and R10.

R1/R9 are the same as the cart resistance and R2/R10 are the gain resistors. Free PCB won't let you have the same component number more than once so you have R1 for right channel and R9 for left channel etc.

So if you have a ordered a pair or resistors for R1 and a pair for R2 you are set, hope this makes sense.
 
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QUOTE=HypnoToad;
R1/R9 are the same as the cart resistance-----.

DC Resistance or rated impedance?
 
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