Here It Is: The All Singing All Dancing HTMCPS
- Thread starter HypnoToad
- Start date
You're welcome.
A low parts count, easy to build and sounds great even if I say so myself.
Qwin
Active Member
Project Started
Well I've ordered my PCB!
I'm working on a 12v+ 12v- battery solution and have ordered two 12v 1.2Ah sealed lead acid batteries.
There is a Yuasa 24v 300mA charger that will work with these when in series and take about 10hrs to charge (overnight)
The charger is an intelligent three step device finishing in a trickle charge with all kinds of safety devices built in.
I will have an AC isolating switch so the charger will not affect DC performance when playing.
Also I plan on coupling an Automotive LED volt meter to each battery; these can also be taken out of circuit.
These meters are the type that plug into the cigarette lighter, but I will be panel mounting them. They will allow me to see the voltage available from each battery and also the voltage being received in charge mode as it goes through its cycle.
Everything to be mounted in one off the shelf vented case.
I completed a basic layout for the front panel (121 x 89mm) as per picture below.
Well I've ordered my PCB!
I'm working on a 12v+ 12v- battery solution and have ordered two 12v 1.2Ah sealed lead acid batteries.
There is a Yuasa 24v 300mA charger that will work with these when in series and take about 10hrs to charge (overnight)
The charger is an intelligent three step device finishing in a trickle charge with all kinds of safety devices built in.
I will have an AC isolating switch so the charger will not affect DC performance when playing.
Also I plan on coupling an Automotive LED volt meter to each battery; these can also be taken out of circuit.
These meters are the type that plug into the cigarette lighter, but I will be panel mounting them. They will allow me to see the voltage available from each battery and also the voltage being received in charge mode as it goes through its cycle.
Everything to be mounted in one off the shelf vented case.
I completed a basic layout for the front panel (121 x 89mm) as per picture below.
Attachments
cairns4me
Active Member
Sounds a bit biased to me....anyone would think you "consider yourself its Daddy".....You're welcome.
A low parts count, easy to build and sounds great even if I say so myself.
Kappaholic
Active Member
Are the parts on the BOM identical to the ones shown in the pix on page 2?
There are some updates to the BOM: based on the latest PCB batch.
The R3,4,11 &12 have been updated from 390 to 470 ohm resistors as well as R8 & R16 have been updated from 75k to 200k ohms, and finally the C5&C19 caps have been updated from 1.5uF to 2.2 uF.
bearchuck
Active Member
Hey all
I assembled my HTMCPS last week, and with much help from AKers Big Bill and Macd23, I finished the project on Saturday. Felt damn good, especially since I had purchased a sweet Denon DL-103D a couple months ago that had been sitting unused on my desk, just begging to be played.
And as luck would have it, Sunday happened to be one of those super-rare days where I had the opportunity to spin records for eight hours straight. Is that what they call "good AudioKarma?" It sure felt like it.
I'll post some pics and my impressions later, but overall I'm very pleased. I could use some troubleshooting help though as I'd hardly call the phono stage quiet. At moderate to normal volumes it's not bad. In fact, I can get pretty loud and it doesn't really hinder my listening experience (that much). Still, there's definitely some noise there, which is not what I expected based on everyone else's experiences. Here's what I can tell you ...
1. There's way too much gain. Of course, somehow I totally missed the change from the 390 to 470ohm resistors, so once I get those switched out, that should help. Is it worth playing around with the resistors in the first stage as well?
2. I've never really had RF issues, but when the preamp is anywhere near my amp, it squawks and hums like crazy. Fortunately it's easy for me to place the HTMCPS a few feet away, but it still has me thinking that maybe I didn't ground it correctly. Any thoughts? It's in a steel / aluminum box and I'm using nice Blue Jeans cables.
I also just remembered that my grounding post arrived late and hasn't been installed yet. My turntable is grounded internally though and I was under the impression that I didn't necessarily need it. Does that make a difference?
Anyway, I saw the post about putting capacitors across the inputs, so I might experiment with that to help tame the noise. Please let me know if you have any other suggestions though. This thread has been an awesome help and I'm always thankful for all you people who are much smarter than I. Smarter than me? Smarter than I. Me fail english.
Oh, I can't forget to thank Sachin for the board and of course HypnoToad for inventing this wonderful, affordable phono stage! You guys rock!
I assembled my HTMCPS last week, and with much help from AKers Big Bill and Macd23, I finished the project on Saturday. Felt damn good, especially since I had purchased a sweet Denon DL-103D a couple months ago that had been sitting unused on my desk, just begging to be played.
And as luck would have it, Sunday happened to be one of those super-rare days where I had the opportunity to spin records for eight hours straight. Is that what they call "good AudioKarma?" It sure felt like it.
I'll post some pics and my impressions later, but overall I'm very pleased. I could use some troubleshooting help though as I'd hardly call the phono stage quiet. At moderate to normal volumes it's not bad. In fact, I can get pretty loud and it doesn't really hinder my listening experience (that much). Still, there's definitely some noise there, which is not what I expected based on everyone else's experiences. Here's what I can tell you ...
1. There's way too much gain. Of course, somehow I totally missed the change from the 390 to 470ohm resistors, so once I get those switched out, that should help. Is it worth playing around with the resistors in the first stage as well?
2. I've never really had RF issues, but when the preamp is anywhere near my amp, it squawks and hums like crazy. Fortunately it's easy for me to place the HTMCPS a few feet away, but it still has me thinking that maybe I didn't ground it correctly. Any thoughts? It's in a steel / aluminum box and I'm using nice Blue Jeans cables.
I also just remembered that my grounding post arrived late and hasn't been installed yet. My turntable is grounded internally though and I was under the impression that I didn't necessarily need it. Does that make a difference?
Anyway, I saw the post about putting capacitors across the inputs, so I might experiment with that to help tame the noise. Please let me know if you have any other suggestions though. This thread has been an awesome help and I'm always thankful for all you people who are much smarter than I. Smarter than me? Smarter than I. Me fail english.
Oh, I can't forget to thank Sachin for the board and of course HypnoToad for inventing this wonderful, affordable phono stage! You guys rock!
Big Bill
Summertime Rolls.....
You're quite welcome. :yes:
I'd have used an all steel container for maximum RF shielding had this been my build .
The ground lead of your turntable is summed to the negative right channel lead at the plinth mounted RCA jacks. This shouldn't be a factor.
kardus
New Member
Are the parts on the BOM identical to the ones shown in the pix on page 2?
Do you have a mouser number or search query for these RCA jacks? I typically use neutrik jacks in my projects but the ~$9 for the jack and matching gasket plus their large size is becoming troublesome.
macd23
New Member
Chuck,
you mention that there is way to much gain. This could be making your noise floor more apparent and would also explain the feedback problems that you describe. What type of noise are you hearing, is it a low hum or just lack of clarity?
My advice is to first lower the gain and see if that doesnt fix the problem. It was nice meeting you the other day man!
bearchuck
Active Member
Hey Darren
I definitely think that the gain is the biggest part of the problem. At moderately high volume levels (not ear-splitting / earth-shaking levels, mind you), there's a very noticeable amount of white noise, and also an underlying hum.
Right now the HTMCPS is sitting about 3 feet away from the amp and there's not any feedback. the closer it gets to the amp though, the worse it is. When it's sitting directly above the amp, the hum / feedback is crazy loud. I think that I'm going to take Bill's advice and get a heavy-duty steel chassis. That's what we used for a Hagerman Bugle he helped me with and I have zero issues with that.
I wouldn't say that it affects clarity though. If I'm just listening to records casually at moderate levels, I don't notice anything at all and the music sounds fantastic. Again, I'm super stoked on this preamp and I think it just needs some tweaking. All part of the fun!
Great meeting you too, Darren. Thanks again for all your help. I couldn't have done it without you!
Steve, check your gmail account, I sent the latest BOM. :yes:
1. You can lower the values of resistors R2/R10 if you have too much gain. Recheck the calculations with the resistor calculator just to make sure.
The R2/R10 for the Denon DL-103D are 990 ohms and R1/R9 should be 33 ohms.
The change from 390r to 470r will not make that much difference. The gain at the moment should be the same as a Cd player.
2. You need to have the grounding lead from your turntable connected to the ground on the HTMCPS. Especially if you are using a PSU and not batteries.
3. You shouldn't need those capacitors, I am sure if everything was done correctly that grounding it to the turntable will cure your problems.
Last edited:
Big Bill
Summertime Rolls.....
His turntable ground lead is summed to the right channel negative signal lead which means the turntable is grounded to the board itself. However he did not ground his board to his pre chassis as far as I know.