luvdunhill

oh, another option would be going from 0.33uF to .47uF, in which case 600V caps are available.

hey, I was wonder if a 400 VDC rated cap would be suitable for replacing the interstage coupling caps in my MPX3 SE? There are 2 caps. I got a tip from Mr. Hansen about a line of capacitors I'd like to try, just don't know how to go about verifying they will work.

What about stainless steel perforated sheets: http://www.onlinemetals.com/merchant.cfm?id=1002&step=2&top_cat=1

maybe that should have been "pink noise >:D"

5AR4 seems much more sane now. If you're using psud2, then checking for current saturation in the choke should be easy. High current is why dual core chokes are often used, like LL1673. I personally think a dual core choke would be more appropriate for the current you're talking about. Concerning the first capacitor, be wary of heavy AC charge current if you're using something larger than 33uF or so. If you push this, both the lifetime of the tube and the cap can suffer. The circuit I was experimenting had problems with hum when the input capacitor go too large. I found that using a series limiting resistor to control peak in-rush current helped. This is usually calculated from the coil resistance of the transformer and then adding a small resistance inline to reach some target value for the rectifier used. Check the datasheet to determine this. Also, the sound was heavily influence by the grounding arrangement. Most important seemed to be the diode connections. Remember, anything connected to them will radiate magnetic field, so keep the wires short and close to the chassis. This really helped the sound, IMHO. This is about the extent of my experience on the matter I'm definitely not an expert, just a tinkerer.

cool. I just went down an almost identical path 6 months ago and wussed out buying the parts for something, when in my mind there were red flags. I didn't really know anyone who was willing to help me with it, so I ditched it.

pink noise?

hey, where are you guys buying those Cardas Sennheiser connectors? I'd like to buy a set from someone/somewhere.

here I thought you were interested in helping me learn ... oh well, you're still a decent guy in my book.

$200 worth of Fairchild IRFP240 and Fairchild IRFP9240 >

thanks for being so understanding Nate

edit: seems to me you're going to have arcing issues with the 5AR4 from exceeding it's PIV and in order to get that choke to work, you'll probably exceed the recommended input cap for the 5AR4 as well. If at all possible, I'd like to learn why this will work

"OTOH, if a pseudo choke I/P filter, with its "fudge factor" cap. is employed, you can safely draw a bit more current" there were more posts I found.. anyways, if there is an open Q&A at some point, I'd be interested to learn more.

yes. I looked at the 193Q and found some people saying that 220mA or so was more reasonable to expect. Here's one such post: http://www.audioasylum.com/cgi/t.mpl?f=tubediy&m=139326 I suppose I lack the experience in this area to weed through random crap on the web and pretty much believe everything I read

check out the EY500. I was going to use this due to the 6.3v heaters and avoiding the additional transformer.

sounds great! I'd be interested to see the actual current capabilities once it gets up and running

I'm assuming the 193Q is the first choke.. no way you're trying to use choke input, so I'm assuming there's a small cap before that. even so, I would be curious if you can actually get 300mA... I went down a similar road and pretty much gave up after simulating with psud2. needless to say, I'm interested to see how this works

seems like a perfect situation for tv damper diodes... Would you mind sharing the choke part number?

so, you have a giant trafo capable of 770 VCT and then tubes with 300v and 400v max plate voltage? where's all that extra voltage going? Assuming you're loosing 50v or so per rectifier...

perhaps a mechanism where you can turn on the heaters independently of the B+ line? I'm going to do this in the amp I'm working on... sorta a manual soft-start.

cool, thanks for the tip

I've come to realize that etch == "good for classical". This has been true 100% of the time for me. Also, etch is not good for "oversampling", and much more conducive to analog and non-oversampling sources.

any reason to turn one of the chokes 90 degrees?

oohh. I misunderstood. I was thinking a "key hole saw"

looks great! so, what's the trick to using a hole saw? Those holes look very nice, considering...