Hi Andrew
I'll be very interested in how you get to 0,1 mv AC noise , and how do you measured it with accuracy .
it will help me a lot ( i am working to get such low noise )
.
Hi 6L6, added CL-60 & and a T1.2A fuse in series with Live primary...it's not tripping my MCB, delayed on/off is working fine, however if I try and switch a bit fast, around a sec or so, it blows the fuse. CL-60 is not hot even after a hour of operation, the hummm on toroid has disappeared after I removed the output snubber resistor and capacitor....why I need to test the restarts is that in India power is not guaranteed, the load moves over to DG power and then back once power is restored...this will case issues ...updated pic
Sent from my iPhone using Tapatalk Pro
Rapid power cycling is an extremely difficult load. Remember that the CL-60 would be hot in that situation and not offer any inrush protection. Increase the fuse to T1.5A or maybe even T2A, and have a supply nearby once the amp is built.
What is the value of your bleeder resistor? You might want to increase it so it discharges the cap bank more slowly.
What is the value of your bleeder resistor? You might want to increase it so it discharges the cap bank more slowly.
What Value of R to use in the UPSU for a Pearl II ?
I've collected nearly all the parts for my Pearl II and the rest should be here next week.
Only waiting on some Mundorf caps which were supposed to be in stock but turns out were not.
I am using an Antek 5022 transformer with the Universal PSU board from the DIY store.
The DIY UPSU is a CRC supply and I am trying to properly size the R in the CRC
Does anyone know how much current the Pearl draws from a +/- 22Vac supply ?
I recall seeing 50 mA somewhere but can't seem to find it again.
Also, does anyone know how to pick an optimum R value for the DIY UPSU.
I read the build thread but the build was based on a power amp build not a phono preamp.
I ran some simulations using PSU designer but it does not seem to be able to show me how the variation in R changes the ripple on the output (input to the regulators).
I've collected nearly all the parts for my Pearl II and the rest should be here next week.
Only waiting on some Mundorf caps which were supposed to be in stock but turns out were not.
I am using an Antek 5022 transformer with the Universal PSU board from the DIY store.
The DIY UPSU is a CRC supply and I am trying to properly size the R in the CRC
Does anyone know how much current the Pearl draws from a +/- 22Vac supply ?
I recall seeing 50 mA somewhere but can't seem to find it again.
Also, does anyone know how to pick an optimum R value for the DIY UPSU.
I read the build thread but the build was based on a power amp build not a phono preamp.
I ran some simulations using PSU designer but it does not seem to be able to show me how the variation in R changes the ripple on the output (input to the regulators).
Can I ask why you recommended the 50v caps? By way of context, I'm making the VFET amp and I'm looking at using 35v caps in the PS. I'm thinking they should be ok because that's more than the supply voltage, or am I missing something?
35v will work quite well in the Vfet, and it's certainly not a 'wrong' choice.
Using a higher voltage rating will give longer life due to the derating, (which is the biggest argument for them) and any power-on surges will be better contained well within the parameters of the cap. Do you need 50V caps? No.
Using a higher voltage rating will give longer life due to the derating, (which is the biggest argument for them) and any power-on surges will be better contained well within the parameters of the cap. Do you need 50V caps? No.
Just got my replacement transformer through.
Ive bought a toroidy audio supreme TS400VA.
Its a bit different. It has a thin grn/yellow wire coming out of it. I think this is for the electrostatic shield (or similar). Its labelled "0".
Does this go to star ground?
It also has a steel casing. This isnt connected to the "0" wire.
As its metal I think this needs to be Earthed. Presumably because it doesnt go through the torroid its not going to cause a short by doing this.
Any ideas on the best way of connecting to earth.
I do have the toroidy mounting plate. Although they were maybe a bit stingy with the supplied screws.
Thanks
Ive bought a toroidy audio supreme TS400VA.
Its a bit different. It has a thin grn/yellow wire coming out of it. I think this is for the electrostatic shield (or similar). Its labelled "0".
Does this go to star ground?
It also has a steel casing. This isnt connected to the "0" wire.
As its metal I think this needs to be Earthed. Presumably because it doesnt go through the torroid its not going to cause a short by doing this.
Any ideas on the best way of connecting to earth.
I do have the toroidy mounting plate. Although they were maybe a bit stingy with the supplied screws.
Thanks
Check using a continuity meter that the Grn/Yel is NOT connected to any other tapping. Once you have proved this, it is safe to assume it is the electrostatic screen wire.
NO !!!! the electrostatic screen diverts interference to the enclosure. It should use the enclosure as it's sink for that interference. The connection MUST be very low impedance at all interference frequencies. This demands a very short connection to the Chassis/Enclosure right next to where the Grn/Yel comes out of the insulation. Do NOT use the long wire provided by the manufacturer. Cut it down to <60mm long and connect direct to enclosure. No where else.
This external (but insulated) conductor is referred to as a "belly bad" or "Guass band" It is insulated so that it does not make any electrical connection to any other electrical part. There should be no wire from it.
DO NOT connect to Earth. It should be completely insulated from any tampering by you.
Did Toroidy give you a link to the data and/or assembly instructions? If not, then get back to him and ask !!!!
Last edited:
Thanks andewT. I'll double check when back at home and with torroidy.
The green wire didnt have continuity with any of the other wires or chassis. I'm pretty sure these have electrostatic screens.
So you think the outside of the gauss band should be varnished or similar, I'd better check that.
The green wire didnt have continuity with any of the other wires or chassis. I'm pretty sure these have electrostatic screens.
So you think the outside of the gauss band should be varnished or similar, I'd better check that.
