Here It Is: The All Singing All Dancing HTMCPS
- Thread starter HypnoToad
- Start date
R1/R9 won't make any difference, they are just there to balance out the op amp inputs, they have no effect on the actual gain. That's set by the difference between the carts internal resistance and R2/R10.
Look at the feed back loop on an op amp there is a resistor that goes from the inverting input to ground, the carts coils take the place of that resistor, so in fact it's part of the feed back loop and is fixed. The only way to increase the gain is to alter the value of the resistor (R2) that goes between the inverting input and the output of the op amp.
Qwin
Active Member
Kappaholic - using 16 AA batteries seems a bit wastfull?
$32 for 40+ hours play before needing a charge.
My 12V SLA batteries are 1.2Ah cost £6.25 each off fleabay and will run a cou[ple of hundred hours before needing a charge. Voltage after full charge is 13.6v settling to 13.1v after 24hrs. The long edge of the battery is the same length as the long edge of the HTMCPS PCB so quite compact.
Something for you to consider.
$32 for 40+ hours play before needing a charge.
My 12V SLA batteries are 1.2Ah cost £6.25 each off fleabay and will run a cou[ple of hundred hours before needing a charge. Voltage after full charge is 13.6v settling to 13.1v after 24hrs. The long edge of the battery is the same length as the long edge of the HTMCPS PCB so quite compact.
Something for you to consider.
GreatTone
Super Member
Hey guys, thanks for the replies. Good news -- whatever grain/distortion I was hearing disappeared after about an hour of listening. It was subtle, but my system is pretty revealing. I don't know what that was, but it sounds excellent now -- big and clean and detailed and musical. Maybe it just needed a little burn in.
I'm not worried about the gain -- turning the volume up to 2 o'clock gets me full listening volume. I used to get that at 12:30 on the dial, but unless there is a compelling reason to change R2/10, I'll just leave it.
So thanks a lot, esp HypnoToad! Nice project. My next step is a LOMC -- prob the AT-OC9II.
I'm not worried about the gain -- turning the volume up to 2 o'clock gets me full listening volume. I used to get that at 12:30 on the dial, but unless there is a compelling reason to change R2/10, I'll just leave it.
So thanks a lot, esp HypnoToad! Nice project. My next step is a LOMC -- prob the AT-OC9II.
Kappaholic
Active Member
You're right. Those Eneloop rechargeable batteries aren't cheap, if you need to get them just to drive phono stage. We happened to have tons of those to power toys for the kids and remote controls.
I would think the long term savings on the cost and gain of convenience would be building a power supply like the OPS. Don't need to worry about wife leaving the unit on through out the day.
GreatTone
Super Member
I must say, the more I listen to this phono stage, the more impressed I am with it. I have been using the built-in stage in my refurbished Dynaco SCA-35. The phono section has the new Audioregenesis board and the original smooth plate Telefunken 12AX7s. It's no slouch, though a little noisier than I would like -- certainly not enough to intrude on the music, but there's a bit of hum with it turned up to full listening volume without the music on.
OTH, I can turn the HTMCPS up all the way and it's just dead quiet. I live very near a large radio transmitter, so I built my HTMCPS in a steel box for max shielding, and it is completely impervious to interference. I kept the input runs short, about an inch, and twisted the pairs. More than just being quiet though, the sound is excellent. I did a direct comparison with the Dynaco phono stage and the HTMCPS, and the HypnoToad has more clarity and is more detailed than the Dynaco. I was worried that a solid state stage would suffer in areas of presence and musicality that I associate with tubes, but that is not the case.
So once again: nice job! Next up, a LOMC, probably an AT-OC9II.
OTH, I can turn the HTMCPS up all the way and it's just dead quiet. I live very near a large radio transmitter, so I built my HTMCPS in a steel box for max shielding, and it is completely impervious to interference. I kept the input runs short, about an inch, and twisted the pairs. More than just being quiet though, the sound is excellent. I did a direct comparison with the Dynaco phono stage and the HTMCPS, and the HypnoToad has more clarity and is more detailed than the Dynaco. I was worried that a solid state stage would suffer in areas of presence and musicality that I associate with tubes, but that is not the case.
So once again: nice job! Next up, a LOMC, probably an AT-OC9II.
GreatTone
Super Member
We like pics
Regards,
Sachin
I'll try to take some tonight.
sachu888
Spare the tigers, kill me
GreatTone
Super Member
Thanks...this reminds me of a question I have about loading. It seems like on other phono stages you can alter the input resistive load and change the sonic character, like boosting the treble etc. Does it work the same way with the HPMCPS?
Kappaholic
Active Member
Isn't the cartridge loading only applicable to MM carts?
With the HTMCPS, you cannot and don't need to alter anything to do with loading, it's impervious to that.
You can change the sonic character by rolling in different op amps, be aware though that the input stage is very particular about op amps and some won't even work at all.
sachu888
Spare the tigers, kill me
GreatTone
Super Member
Well, at least I took some photos of the outside. When I get my new AT-33EV I'll have to open it up to change the resistors, so I'll take a shot of the insides then.
I mounted the batteries on the outside for easy monitoring and changing. I may try lantern batteries next, depending on how long the 9Vs last.
I mounted the batteries on the outside for easy monitoring and changing. I may try lantern batteries next, depending on how long the 9Vs last.
Your build looks great.
You're not imagining it, capacitors, op amps and most electrical components sound better with use, I say it usually takes at least a couple of weeks of use for it to really sound it's best.
You will notice a fuzziness to the sound when the batteries get low, definitely switch over to the 4 x 6v lantern batteries, they will save you a fortune for a start. Besides the benefit of having 12volts per side instead of 9volts.
I get the RayoVac twin packs from the camping section at Walmart for around $5.00 a pair and they will last a year or more.
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GreatTone
Super Member
Yeah, I'll score some lantern batteries soon.
So how come this thing sounds so dang good? I thought opamps were supposed to sound bad. It seems like most well-regarded phono stages are either tube or discrete transistors. But I'm blown away by this thing. It's both musical and detailed. Like, a lot.
So how come this thing sounds so dang good? I thought opamps were supposed to sound bad. It seems like most well-regarded phono stages are either tube or discrete transistors. But I'm blown away by this thing. It's both musical and detailed. Like, a lot.