NYD 1B PSU related Questions

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mac

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Jun 5, 2009
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Location
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morning everyone.

I am planning to use the Gyraf g9 PSU to power my first attempt at a 1B NYD pre. Question: why did Dave design the PSU to produce a B+ of 300v but then the first thing the B+ hits in the one bottle is R13 which is a 1watt 10k resistor and c6 to drop the voltage to around 235V.

I am assuming if I build the G9 PSU stock (B+ 245V) I can simply omit R13 on the 1B yes??  Or is it best to reduce the values used on the G9 PSU to try to up the voltage to 300V??

mac
 
good old fashioned RC filtering.

on the g9 psu, the HV is RC filtered, regulated, then filtered again before going to the preamp. So yes, you can remove theRC network going into the 1b.
 
Thanks for your response Rodney,
Yes perhaps I should have worded that a little differently.

I understand the RCRC network on the G9 PSU (which I am wanting to retain), but is the RC (R13 and C6) on the one bottle also only there in the circuit as an RC filter?

If I understand this correctly then I can probably just use the G9 PSU stock, remove R13 and C6 from the one bottle and run it at 245v.

Mac
 
> is the RC (R13 and C6) on the one bottle also only there in the circuit as an RC filter?

NYD apparently assumed you could have a very crappy power supply.

In fact you don't NEED any fancy supply. Go 220VAC, 100uFd, 5K 5W, 100uFd, then on to NYD's 10K dropper. Millions of hit records were made with gear like this.

The 65V drop allows a LOT of filtering with a modest cap. It also gives a place where you can trim to use a non-300V supply. If you find some 400V handy, change the 10K to 20K or 30K.

OTOH, if you have a pretty-clean 240V supply, reduce the 10K to 1K. I like to have "some" on-board filter, to final-scrub the power, and reference it to local signal/power common, and reject junk coming from other amps on the same power supply.

If you have a very fine well-designed audio power supply, you may not need the R-C filter.

The internal supply voltage is NOT critical. IIRC, down around 200V the maximum output is kinda lame by some standard. Up above 300V you better re-check all the dissipations. You can use fatter resistors but plate dissipatrion is set by tube type. You can run 100% even 110% of rating (the other half runs cool), but don't go near 150% of rating for more than a minute (i.e. smoke-check, measure V and I, shut-down, calculate). Between these extremes, it's all good.
 
Thanks PRR,
Yes i think i will leave it all in place and see what happens. Ultimately I might drop the value of R13.

Also, i am powering two channels - so Andrew you may have a point there too!!

this unit should be great - I am reusing an old ABC radio switcher chassis and having some fun with it - taking my time and reusing what I have lying around.

thanks again guys,
Mac  :D
 
Hi all,

I'm interested in this thread as I am just about to build a 2 channel slowblow pre based on the Don Hicks schematic. http://www.hicksorganservice.net/misc/stuff.html

This will be my first point to point build and wanted something fairly easy to start with as I am a neewb.

I planned to use as above the G9 power supply for b+ and 12v. (I don't need the 48v supply) simply because I don't fancy building a supply fro scratch and I have the spare pcb for this from G9 builds.

I have two queries:-

1 - it suggests a B+ of 320v but from an earlier thread I read that it will work fine on G9 supply. Is this correct and if so will it have any great effect on the sound.

2. I also read on another thread that on this design it is best to bias the heater voltage up 50-60v from ground. Is this a must or will the normal 12v form the G9 work ok. If a must has anyone done this using the G9 supplies or how do I go about doing this?

Many thanks - any help greatly appreciated.

 

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