Help me understand this circuit. Aragon 47k/Acurus P10 Phono Stage

Hi Rick,
Yes, I forgot to mention that. I'm using Mogami W2497 which is very low capacitance aprox 67pf/meter(Kimber PBJ is even lower and very nice) I think I calculated around 80pf for the TT, arm, and cable, and then 270pf for the loading so around 350-380pf total.
 
Hi,

congrats to the successful tweak!
And if you clean the PCB from soldering residues You will notice an even greater increase in dynamics and resolution 'lol'

"Look, if you think your few NE55xx stuffed in an Altoids box with some disk caps is all your ears and time is worth then go live the dream.
Big mouth words for someone who couldn't analyze that simple little circuit in first place.
At least those experienced guys You barked up against with Your I-know-better attitude can easily design circuits with or without NE55xx from scratch! Yes, we can! Can You?

jauu
Calvin
 
Hi 6L6.

Thank you for your thoughtful response. You bring up an aspect I had not considered before regarding C1. At first, I considered constructing some kind of pad with selectable capacitance to address this issue. Ideally, I wanted to use some kind of pin header that would accept the cap leads thus making it plug-in/switchable but I couldn't find a solution.

A buck ninety-two. 40 pins. break off as many as you need.
https://www.digikey.com/en/products/detail/adam-tech/SMC-1-40-1-GT/9831942


I use mostly a MM Nagaoka MP-110 body with a NP-200 boron stylus, (killer budget setup by the way) and sometimes a AT OC9II MC. The Nagaoka carries a rather unusually large inductance of 810mH which when I calculate shows a very nice flat response across the band with no LC peak utilizing the 47k's, 47k loading and 270pf capacitance. This also matches what I hear.

It's a Moving Iron. As your calculations confirm, because of the large inductance it's not going to need low capacitance to be flat in the audio band. And the OC9II is MC, obviously, so it might want additional capacitance.

But, you do bring up a good point that would indeed need to be addressed to insure broader MM cartridge comparability.

Which is why I suggested removing it entirely. Particularly as the input wiring of the 47k has ferrite beads to deal with the RF stuff. (which is awesome, btw) Your idea of pins to make it something you can change is a good one. When you get your loading C down really low, the MM Audio-Technica cartridges become incredible sounding.

I do wish the 47k came with selectable capacitance loading. Given that I now have a broader understanding of the impact of capacitance loading I question when people give a poor review to a phono preamp utilizing a MM cartridge. I think I just happened to stumble on a good match with the 47k/Nagaoka combo.

That's not so much the combination of the the two components but more that the Nagaoka is unperturbed by C loading.

I also took your advice and picked up a Mega328 thank you!

Nifty little widget, isn't it? 🙂


I'm using Mogami W2497 which is very low capacitance aprox 67pf/meter(Kimber PBJ is even lower and very nice) I think I calculated around 80pf for the TT, arm, and cable, and then 270pf for the loading so around 350-380pf total.

W2497 is great stuff, fantastic for phono for the exact reason you are using it. PBJ is unshielded and therefore completely unsuited for phono, as these are the smallest signals anywhere in the entire audio chain. But it has low capacitance, which is not all bad, and it is very pretty.
 
Hi 6l6,

Yes, my mistake it is a MI. I got so use to seeing it listed under MM in mags etc. I got programed into calling it a MM. I did try those exact pin headers but they are rather long/tall and ran into clearance issues with the lid/chassis is rather low. I thought I could modify an 8 pin dip socket but the cap legs are too large for the socket to accept. Idk, I might go back and try the single pin headers again at some point.
Question, which MM Audio-Technica cartridge do you like/prefer?
 
Hi,

congrats to the successful tweak!
And if you clean the PCB from soldering residues You will notice an even greater increase in dynamics and resolution 'lol'

"Look, if you think your few NE55xx stuffed in an Altoids box with some disk caps is all your ears and time is worth then go live the dream.
Big mouth words for someone who couldn't analyze that simple little circuit in first place.
At least those experienced guys You barked up against with Your I-know-better attitude can easily design circuits with or without NE55xx from scratch! Yes, we can! Can You?

jauu
Calvin
Oh. So, first it was my poor and futile choices in parts selection and now its my attitude? I see you've had a lot of practice in shifting goal posts. I have a good understanding of circuit design and functionality after spending years in the EDA industry. I also know there are peeps with far more knowledge than I which is why I started this post. I requested feedback and confirmation for my thoughts. Seems the exact opposite of a "know it all." It's clear, that you, and couple other trolls, have nothing constructive to add and simply want to bully users. That's really unfortunate.
 
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Just want to say this thread and Diginoob inspired me to have Kevin Chambers (Mondialfan) upgrade my 47K. It's got lots of fancy boutique parts which I am sure will annoy some here, but it measures better than the original Aragon specs and has an upgraded and custom linear power supply made by Kevin.

Not sure if cross-forum posting is allowed, but it's now up on Audiokarma in the DIY section. (don't want to post a link in case that violates forum rules).
 
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Ok, thanks!

I have cut and pasted the post and included pics 🙂

POST:
Okay, I am not a DIY'er but I know someone who is and I figured people may be interested in seeing what the esteemed Kevin Chambers has done to my unit. And apologies to @mondialfan ahead of time if I have lost something in translation. I'm sure he'll point out my mistake(s).
:)


This particular unit was not operating, and I picked it up for cheap ($175 IIRC) which gave me some headroom to add fancy parts. Had the seller ship directly to KC.

Turns out the original plastic Aragon power supply was kaput in one channel, so I had Kevin work up a custom unit to pair with the 47K (Bonus: This can work with any Aragon unit that used the 3-pin XLR power connector, including all Aragon preamps).

Kevin's custom supply uses a 30VA transformer and we went with premium Nichicon KG audio caps in the PS since this is basically an "all-in" build.

While the 47K comes with really good 1% Dale resistors, a way to raise the bar was using Z-Foils, which we (he) did in many places. We upgraded the coupling caps and most everything in the preamp (except for the RIAA stage, which Aragon spec'd pretty nicely).

Now I am still learning about turntables and cartridge loading, but the original 47K design as a single 270pF capacitor. Kevin mentioned that he thought he could come up with something more precise, so here's what he came up with...

He decided on a 2 terminal mounting block (the blue colored ones in attached pics) for the cartridge loading capacitor. The original 270pF mica caps are loaded in the terminal blocks for now. The blocks will allow me to take off the cover and, using a small screwdriver, loosen and change the loading capacitor out to any value I choose or remove it altogether to run a cartridge unloaded with only the wiring capacitance as a load capacitor. (It's hard to see the Z-foils but they're all in there).

As far as the rest of the upgrade work (In addition to all of the capacitors and resistors we used), Kevin ended up installing higher performance transistors into the voltage regulator circuit and adding additional film bypass capacitance to the regulator circuit as well to improve its performance. He also used a set of his current source boards for the differential input circuitry and had to customize them for the higher current used in the 47k phono.

Overall, Kevin felt like it should make for a very nice unit. Based on the new specs and how it measures compared to the original factory specs, he is 100% right. Measured signal-to-noise ratio has been improved 12dB! This paired with my very quiet Performance DC turntable (90+ dB manufacturer specs) should hopefully make for some incredibly black backgrounds.

Kevin has now massaged my 24K SP, my Aragon 4004 (brought to better than Mark ii specs), and this 47K. The preamp was so good I sold my Schitt Freya+ with NOS tubes. Can't wait to pick up my amp and phono preamp and get listening to some vinyl
:)
 

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@atlvalet Congratulations! Wonderful to see another maxed out 47K! I'm confident you will enjoy it immensely and find it puts many current much more expensive phono stages to shame. KC did wonderful work & I love your capacitance solution using the small terminal block. It address the height/clearance issue by mounting them horizontally. I may go back and implement the same mod myself. The 24k SP sounds very exciting a perfect match to the 47k and you will have that incredible Penny & Giles Vol/potentiometer!

 
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Just to be clear, that was Kevin's solution. I didn't even know it was possible (or a potential roadblock for carts) until he mentioned it. And if I hadn't seen your YouTube vids, I wouldn't have been inspired.

BTW, all in I think I'm at about $1000. $175 for the "broken" 47K, roughly $300 for parts and labor on the custom LPS, $300 for parts for the 47K, and probably $200-ish in labor.

Only thing I really added to this was suggesting a green LED in the center of the LPS. Kevin figured out a way to do it with a flush LED and liked it so much he did it to his unit too lol
 
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For those curious, here is the fancy parts list for the 47K (not including LPS). There are other parts that Kevin upgraded that you'll see on the board (Nichicon green caps, I think Nichicon Gold under the black plate the the left), but those weren't in the list of "fancy" that I asked for:

4 - 47R Ohm Takman Resistor 0.25W REY Series
4 - 27R Ohm Takman Resistor 0.25W REY Series
2 - 24R Ohm Takman Resistor 0.25W REY Series
6 - Audio Note 2,200uF 25Vdc Standard Electrolytic Capacitor
2 - Auricap Capacitor 10uF 160Vdc XO Series
2 - ZFoil 51.1k ohms - custom
4 - ZFoil 47.5k ohms - custom (invoice said 4.75K, but I think that's a typo)
2 - Zfoil 47k ohms
2 - Zfoil 1.0k ohms
2 - Zfoil 470 ohms
2 - Zfoil 100 ohms
 
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Not to rip up an old thread, but thought I wanted to share my build of a restored P10 and might inspire others🙂
In this unit I replaced the 1A diodes with 2A ultra-fast soft-recovery in the PSU and skipped the 5VA transformer in favour or a 10VA. This is the maximum that'll fit beneath the internal metal lid and require some drilling to the PCB.
The 3.300uf e.caps are replaced with 105°C 4.700uf Vishay MAL-series. All 1000uf's has been changed to the better spec'ed Chemi-Con KNZ.
I've used Dale RN55D/RN60D throughout in the circuit, only resistors that's still untouched is the 2 watters..
I've pulled the foilcap and replaced with Nichocon Muse and a 0.22u Wilma MKP10 in parallel. This was due to the internal PSU, and I wanted as low distortion as possible in a sensitive circuit, so the big yellow had to go. Sound wise I cannot hear the difference between the 10u/.22u vs the foilcap.
Looking at the Aragon preamp-series they all have a zobel filter at the output and anti-parallel diodes at the ground lift witch non of the Acurus (or Aragon 47K) had. I added both in this unit.
On top I skipped the R15/R16 and replaced them with constant current sources to the diff-section.

Its an excellent sounding unit.

Best regards
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Good looking work.

Was using 10 uf Solens which was a nice boost in performance.

Upgraded to Solen Silver caps, Wow. I'm still in disbelief at the massive level of improvement.

Audio Technica AT-OC9XML > Pure Silver tonearm wires > Pure Silver interconnects > Peerless 4722 SUT > Acurus P-10 > 6DJ8 tube preamplifier > Ashly XR4001 4 way crossover > 8 amplifier channels 1,800 watts > JBL Altec EV speakers.

Tritium table platter 1.png

4 Way 1,800 watt Speakers Sept 2023.jpg
 
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@hcpower have you compared your unit with any other phono pre? Just curious, because I just dropped my unit in with my two other Aragon components.

Also, those blue caps are new I assume? That's in the RIAA network, right? If new, what did they replace? I think the ones in my unit stayed the same, unless Kevin replaced them (he may have, but I'm still a newb).