Yes @rhthatcher I have the fuse in the IEC block and currently put in a 500mA fuse as that is what I had in stock for testing. Ground post I forgot to put the provision but I need to provision that later but their is not any on my DIY TT to connect to it. Even my present Schiit phonostage too I did not connect that and no issue of hum/hiss.
I only grounded the PSU mounting pad to the chassis and then to the IEC ground. The umbilical cord to the psu output wiring is not grounded to the chassis. I wanted to try this way as I have done the same in my earlier phonostage builds so let me test and see if I get any issues. If I get into issues I have to get some 4 pin aviation plugs and connect the psu chassis to the umbilical chord. But looking at the @6L6 build notes it is mentioned that even though the chassis is connected on the psu box the same can either be connected on the amp box or you can leave it open. So I went with the open option for now. This is how I made the wiring on the psu box, Purple wire from IEC earth to the psu chassis and then next to it I have used a metal screw to the mounting pad of the psu. So the mounting pad becomes the star ground in the psu box.
Last edited:
Cheers, they do indeed add to the cost, am playing with something here https://www.diyaudio.com/community/threads/pearl-x-mc-mm-phono-preamplifier.410767/
@manniraj
I think Jim's advice was predicated on the signal boards being connected to the ground post and the signal chassis.
if I understand it correctly you've done neither so the signal chassis is essentially floating.
again if you encounter hum you might try connecting the two chasses with a separate wire (which -- if that works/helps you can incorporate in the umbilical as a conductor or shield connected at both ends to the respective chassis.
incidentally, I would not call the chassis ground in the PSU a "star" ground though the signal ground on the other side of the bridge might be wired as such.
I think Jim's advice was predicated on the signal boards being connected to the ground post and the signal chassis.
if I understand it correctly you've done neither so the signal chassis is essentially floating.
again if you encounter hum you might try connecting the two chasses with a separate wire (which -- if that works/helps you can incorporate in the umbilical as a conductor or shield connected at both ends to the respective chassis.
incidentally, I would not call the chassis ground in the PSU a "star" ground though the signal ground on the other side of the bridge might be wired as such.
@Gianluca - re order id 27098...
Chassis arrived one day ahead of FedEx estimate, in perfect condition. Many thanks.
We've seen a number of lovely examples of Gianluca's chassis here; this is one of the reasons - great packing.
Yup, that is my pearl3 (in progress).
Within six hours of placing my order, the chassis were in FedEx tender care, and at my door five days later. Excellent service !
Chassis arrived one day ahead of FedEx estimate, in perfect condition. Many thanks.
We've seen a number of lovely examples of Gianluca's chassis here; this is one of the reasons - great packing.
Yup, that is my pearl3 (in progress).
Within six hours of placing my order, the chassis were in FedEx tender care, and at my door five days later. Excellent service !
https://www.mouser.com/ProductDetail/Hammond-Manufacturing/CS10104?qs=k6dkFvHqcvB18iqqzi2d6A==
I like this enclosure to test the P-3 on the bench.
You can also use it for cookies.
I like this enclosure to test the P-3 on the bench.
You can also use it for cookies.
Update on Pearl 3 playground. Yes, Wayne made a wonderful playground for us audio-nuts. I broke out my experience in a few parts.
Part one - Opamp swapping: I went through all the dual opamps I have in house. NE5532, LM833N, TL072, TL082, M5812AL, OPA1642, LME49720. The LME49720 is what I started with. I rotated all though them and by sound preference, I came back to the LME49720. Some of the opamps 'may' have struggled with current demand. Again, the LME49720 seemed to be fuller and faster in the bass region. The NE5532 was really nice and more refined in the upper frequencies but to me it was slightly too detailed which was not quite as natural sounding. It was my second pick of the opamps.
Second part - I have AT-VM95E, ML and C cartridges. The C didn't work out so well. It was missing a lot of information, a little muddy and not as good at imaging. The VM95E sounds very good to me and the Pearl 3 handled it well. No clipping noted by Audacity analysis. The VM95ML has more detail and more refined.
I also have a Denon DL-110 and that is a level above the VM95ML but similar in detail. Bass is more controlled with the DL-110.
Third part - This was a real surprise - I am elated. I was able to get a Denon DL-103 MC yesterday. I moved the jumper for the gain, kept 100pF for the capacitance. Ended up running 249 ohms on the load R. I tested 1k ohms but imaging and the sound was more open and natural at 249 ohms. Vocals and saxophones are REALLY really good, sometimes eery to hear on a live recording. For a spherical diamond and the lower MC output, it is like the DL-103 is made for the Pearl 3.
Sharing my experience, as a first time Colburn build. I can't express enough thanks for him sharing this design. Thanks Wayne - home run!!
Part one - Opamp swapping: I went through all the dual opamps I have in house. NE5532, LM833N, TL072, TL082, M5812AL, OPA1642, LME49720. The LME49720 is what I started with. I rotated all though them and by sound preference, I came back to the LME49720. Some of the opamps 'may' have struggled with current demand. Again, the LME49720 seemed to be fuller and faster in the bass region. The NE5532 was really nice and more refined in the upper frequencies but to me it was slightly too detailed which was not quite as natural sounding. It was my second pick of the opamps.
Second part - I have AT-VM95E, ML and C cartridges. The C didn't work out so well. It was missing a lot of information, a little muddy and not as good at imaging. The VM95E sounds very good to me and the Pearl 3 handled it well. No clipping noted by Audacity analysis. The VM95ML has more detail and more refined.
I also have a Denon DL-110 and that is a level above the VM95ML but similar in detail. Bass is more controlled with the DL-110.
Third part - This was a real surprise - I am elated. I was able to get a Denon DL-103 MC yesterday. I moved the jumper for the gain, kept 100pF for the capacitance. Ended up running 249 ohms on the load R. I tested 1k ohms but imaging and the sound was more open and natural at 249 ohms. Vocals and saxophones are REALLY really good, sometimes eery to hear on a live recording. For a spherical diamond and the lower MC output, it is like the DL-103 is made for the Pearl 3.
Sharing my experience, as a first time Colburn build. I can't express enough thanks for him sharing this design. Thanks Wayne - home run!!
Yes. I can’t tell a difference in sound quality. (Which was always the point…)
Remember the nifty trick that you can simultaneously use the RCA and the XLR… the balanced line driver does it’s job without affecting the SE output in any way, and also does it’s job in a way totally self-contained, I.E., it doesn’t care what’s going on and just smiles.
Of course, the output of the DRV135 is going to be 6db higher than the RCA out, so an invisible A/B isn’t possible, but who cares.
Remember the nifty trick that you can simultaneously use the RCA and the XLR… the balanced line driver does it’s job without affecting the SE output in any way, and also does it’s job in a way totally self-contained, I.E., it doesn’t care what’s going on and just smiles.
Of course, the output of the DRV135 is going to be 6db higher than the RCA out, so an invisible A/B isn’t possible, but who cares.
Last edited: