I have OCD!
Just realized that there exist a 3. party PSU upgrade for my new TT.
https://www.mcru.co.uk/product/mcru...ac-miracord-series-turntables/?v=dd65ef9a5579
So "TonyEE" was right about this.......
Good to hear about the matched FETs!
Just realized that there exist a 3. party PSU upgrade for my new TT.
https://www.mcru.co.uk/product/mcru...ac-miracord-series-turntables/?v=dd65ef9a5579
So "TonyEE" was right about this.......
Good to hear about the matched FETs!
Looking forward to measurements and listening tests against the Pearl 2. I just upgraded my Pearl 2 with Sparko's regulators and a custom faceplate, so not really looking for an upgrade, but if this one is really better...
Some questions: what is the 1k - 1nF option on the input for? Selectable Zobel network in case of RF interference?
In the Pearl 2 there were some problems with voltages around the ZTX 450 (Q3) when you had 2SK170's with somewhat higher Idss (7-9 mA). Is this still the case with this design (ZTX851 Q5)?
Some questions: what is the 1k - 1nF option on the input for? Selectable Zobel network in case of RF interference?
In the Pearl 2 there were some problems with voltages around the ZTX 450 (Q3) when you had 2SK170's with somewhat higher Idss (7-9 mA). Is this still the case with this design (ZTX851 Q5)?
Dont buy the upgrade PSU. Just Build a even better one yourself.
1. More fun. 🎺🙂🎸
2. All really Cool dudes builds really good stuff.😎
3. Exactly right and personalized top notch performance.🙂👍
1. More fun. 🎺🙂🎸
2. All really Cool dudes builds really good stuff.😎
3. Exactly right and personalized top notch performance.🙂👍
Yes, but I need to limit no. of DIY-projects 🙂
I like to see some "move forward"......relative fast.
Also when this PSU is only about £300-400 a DIY will end up about same amount......I think......or close.
For the P3 I will save a lot compared to Passlabs XS-phono preamp......and I assume P3 is at same level......or better 🙂
I like to see some "move forward"......relative fast.
Also when this PSU is only about £300-400 a DIY will end up about same amount......I think......or close.
For the P3 I will save a lot compared to Passlabs XS-phono preamp......and I assume P3 is at same level......or better 🙂
It could be used for that, but its intent is to address some cartridges (usually high-output moving coil) that react to the input capacitance. It’s not common, but does happen. It’s an easy and simple thing to address. 95% of users will never need it.
There is a number of suitable transistors that will work in this position, the ZTX450 is still an excellent choice. Although the front-end is mostly the same in this compared to Pearl 1 and 2, there is a large difference in that it’s now the first stage of a composite amplifier, and it operates with feedback, which should keep those strangeness controlled.
And the beauty of it is that the K209 are consistent enough off the reel that they can go right in and work nicely. (And of course, there’s 10ohm in the sources…)
It sounds fantastic.
I also see that the large capacitors that were present in the Pearl 2 (10k uF and 3k3 uF) have been replaced with much smaller values. Does the input stage of the P3 not benefit from larger capacitance anymore?
The Pearl 3 board is a lot smaller than the previous Pearls. If you want more capacitance, can always place it in the raw supply.
That said, you are welcome to put as much as you can fit near the regulators.
That said, you are welcome to put as much as you can fit near the regulators.
The powers supply is mostly off the board and several excellent variations are available.
Hello PEARL 3 - builders,
I've got my pcbs (selfmade) today and started to stuff them. Last few days I matched an octett of ONSEMI 2SK2394 (super low noise JFets, high Yfs; small Ciss). I needed around 70 JFets to find this octett.
I also matched two pairs of ZETEX FZT851 (Q5/Q8) for left/right channel equality... On my boards I have the possibility to use through hole- and SMD-
BJTs in the Q5/Q8-position. Necessary? - No!
I used the well proven 'adhesive-tape-technology' to solder the SMD-transistors. I think 6L6 showed this technic as the first?
Waiting for a lot of parts. Will continue slowly, but continously. 🤔
If available, I will also buy a pair of original boards from the store.
And I will also try a version with TOSHIBA 2SK209 GR -JFets. Seems to become a project?
Have fun!
Thanks, Wayne!
Cheers
Dirk 🙂
I've got my pcbs (selfmade) today and started to stuff them. Last few days I matched an octett of ONSEMI 2SK2394 (super low noise JFets, high Yfs; small Ciss). I needed around 70 JFets to find this octett.
I also matched two pairs of ZETEX FZT851 (Q5/Q8) for left/right channel equality... On my boards I have the possibility to use through hole- and SMD-
BJTs in the Q5/Q8-position. Necessary? - No!
I used the well proven 'adhesive-tape-technology' to solder the SMD-transistors. I think 6L6 showed this technic as the first?
Waiting for a lot of parts. Will continue slowly, but continously. 🤔
If available, I will also buy a pair of original boards from the store.
And I will also try a version with TOSHIBA 2SK209 GR -JFets. Seems to become a project?
Have fun!
Thanks, Wayne!
Cheers
Dirk 🙂
Attachments
The Zobel is for very high inductance cartridges. I saw one oscillating years ago. This circuit is effective and seems to have no negative sonic effects. It may help a bit with rf but ferrite beads work well on input wires.
The voltages will fluctuate with high Idss devices. You will start to pull current through the base emitter junction of the cascade.
I don’t really know if that is a problem or not, it doesn’t seem to show up in measurements.
I looked up what I have of dual op amps. I have some LM4562. It looks quite similar in specs as the LME49720 which is mentioned as one that has been tested. So LM4562 will probably work.......
For the P3 I will not do "opamp rolling" but find a nice one to just solder in place.
When people build their P3's it will be interesting to hear about the dual opamp having the best performance (noise, THD).
For the P3 I will not do "opamp rolling" but find a nice one to just solder in place.
When people build their P3's it will be interesting to hear about the dual opamp having the best performance (noise, THD).
I plan on running the Burson v6 opamps. Classic and later Vivid. I also got the v5...
No plans on measuring here... just listening. My front end is already very quiet, I can't hear the lead in/out grooves anymore when running the 90db/w speakers...
No plans on measuring here... just listening. My front end is already very quiet, I can't hear the lead in/out grooves anymore when running the 90db/w speakers...
Knit 2 Pearl3,
I placed an order for OPA 1656 Op-Amps. Also checked my supply of solder wick to clean up excess solder after attaching op-amps to the PCB solder pads.
After looking at the discussion of power supplies over at P2 I am not installing the regulators on the P3 PCB. There is a good chance that the power supply will be cleaner than the LMxxx regulators.
To start with I will be using the Keysight E36312A power supply on the bench.
Yes @tonyEE I will be making measurements.
I am in the camp that thinks that you can measure things that you can't hear and to a lesser extent the other way around.
Thanks DT
I placed an order for OPA 1656 Op-Amps. Also checked my supply of solder wick to clean up excess solder after attaching op-amps to the PCB solder pads.
After looking at the discussion of power supplies over at P2 I am not installing the regulators on the P3 PCB. There is a good chance that the power supply will be cleaner than the LMxxx regulators.
To start with I will be using the Keysight E36312A power supply on the bench.
Yes @tonyEE I will be making measurements.
I am in the camp that thinks that you can measure things that you can't hear and to a lesser extent the other way around.
Thanks DT
Hoo, Hoo,
I have matched 2 pairs of TOSHIBA TTA/TTC 004 B for the outputstage of the PEARL 3. 😵
Still waiting for some parts...
I will use my CRCRC - filtered PSU followed by LT1085/ LT1033- regulators. But I am also watching
Mark Johnsons efforts on a clean PSU (post #253).
Boards are not cleaned yet...
Good night, sleep well! 😴
Dirk
I have matched 2 pairs of TOSHIBA TTA/TTC 004 B for the outputstage of the PEARL 3. 😵
Still waiting for some parts...
I will use my CRCRC - filtered PSU followed by LT1085/ LT1033- regulators. But I am also watching
Mark Johnsons efforts on a clean PSU (post #253).
Boards are not cleaned yet...
Good night, sleep well! 😴
Dirk
Attachments
Hello @6L6 and All,
Final is such a big word. Do not know yet.
Many of you have been through this power supply conversation before with P2. I missed that one.
I have purchased and or fabricated power supplies for other projects including the Super Regulator. I could end up with that one.
The noise specification for the LMxxx regulators does spook me a little bit.
For the Dr. Marsh headphone amplifier I used a a CZH-LABS A-2007 regulator that included two stages of regulation; Lm317 / LT1963A and LM337 / LT3015. The Dr. Marsh amplifier with this power supply measured and sounded nice to me.
I am going to start with my new Keysight E36312A bench supply then add a couple of layers of CR filtering with remote sensing to see how it does.
Last time around I built a home made injection transformer to see how the power supplies reacted to modulation of the amplifier output.
Things are looking good!
Remember that Mark’s filter is only a filter (and looks to be incredible, I’m looking forward to trying it) but has no regulators.
Just a bit of seasonal humor , you know with a bit of pumpkin spice.
The ZTX851 transistors are there to lower noise.
The Jfets are doubled to reduce noise.
24 volt regulators were changed out to 15 volt to reduce noise.
There are iterative changes lining up to improve the performance, I think.
Thanks DT