Pars

Yep, Lampizator is the shit... Literally. I've been seeing examples of the quality work this guy puts out for a number of years. Most have been a masterclass in how not to do something. Can't believe how many 'phools buy into this guys crap. Sent from my iPhone using Tapatalk

Just wanted to ask, but due to the Zeners intended on ensuring the opamps come up correctly, I am guessing that it wouldn't be a good idea to bring a GRLV up using a variac the first time it is fired up? Sent from my iPhone using Tapatalk

^that! Sent from my iPhone using Tapatalk

Ray (you know who) used to do that as well, or paint them. Just have Kevin x-ray them

Happy Birthday Gene! Hope you have a great one!

You'll probably have to wire it up so it switches the pot in or bypasses it, so the switch will always be in the signal path. I don't think you would want to wire it so that the switch just shorts out the pot, as the pot would still be in parallel and might have some effect on the sound?

You mean you want to use the switch to bypass the volume pot and go straight in with no attenuation? I wouldn't think the switch would be audible in the signal path. Sent from my iPhone using Tapatalk

Happy Birthday!

Yes, if I wanted to get serious about it I would buy the locky_z kit (read about it on diyaudio as well). Marc (luvdunhill) has one and did some jfet measurements/matching for me. The Tek 575 does look like fun (in a special sort of personal hell way :)), though it always has seemed odd that old tube stuff is probably more supportable that old SS stuff as some of the devices may have been MD'd with no replacements available (Counterpoint MOSFETs come to mind, as well as the one chip in the Tek 2465s). As for the transistors in the Fairchild app note, it looks like 2SD1801 / 2SB1201 are equivalents and available from Mouser.

I was thinking about slapping this together on a breadboard: https://www.fairchildsemi.com/application-notes/AN/AN-6610.pdf The transistors listed (92PU01 / 92PU51) must be ancient as I cannot find them. I ran across somewhat of a datasheet here: http://www.datasheets360.com/part/detail/92pu01/3582415256795608549/?alternatePartManufacturerId=0 It looks like a Fairchild KSD882Y might come close? Or could I use anything capable of a bit of power (such as MPSW06/56)? It would seem that an Ic of 2A on the 92PU01 is pretty high for what might be required here?

^ As mwl168 said, R8 and R9 (the ones you leave alone for voltage changes *) are the ones that terminate at ground plane on one end. * for some voltages, KG used 2K instead of 1.5K for these. I am using this same tactic on a supply for 35V (5K/2K).

For the 15v GRLV, you should have ~21.2 V ((16V * 1.414) - 1.4) raw after the rectifiers with your current 16-0-16 Vac transformer. I would think that would be plenty? Sent from my iPhone using Tapatalk

Very nice Michael! Though I also agree on the connectors. Female only on power out.

A couple of parts questions: 1. The 4.7uf Wima. Anything critical about this value. I have 3.3uf and I believe 10uf in the MKS2XL. Ordering 4.7uf but until I get them wanted to try firing this up. 2. The 47pf ceramic. I have some 33pf mica, would this do until I get the 47pf caps? Sent from my iPhone using Tapatalk

No, was going to use them on a dual GRLV just for testing (with a variac to put it down to 20Vac). I'll buy an Antec 50VA for actual use. I also am going to buy one of Mark's phase dot kits from him just for the hell of it.

Yeah, though I still would have watched another season.

No, I was referring to the Peak Atlas DCA75. I had run across the Lockty7 thing on diyaudio and it looked interesting as well. I'm just looking for the best inexpensive device tester for validating devices. DY294? The Atlas DCA (though it is 4x the price of the 294, and won't do higher voltages).

Yes, watched it. I liked it, but it had its problems. Unfortunately, HBO didn't pick it up for a 2nd season.

So I have this ILP 49783R, 160VA 2x24-26Vac xfrmr. No markings. Single primary, both leads white. From the descriptions I have read online (which jive with what I saw lighting this thing up and ohming), yel-red is one secondary and blue-black is the other. They state that yel-black is 48-52Vac (I would assume with the other leads connected together. So can I assume something like the following drawing, and that the phase dots would be either yellow and blue, or red and black? And don't laugh too hard at my crude drawing

Commenting on ang728's board layout: an additional output connector would be nice when feeding a pair of dynalo/dynahi boards. Provision for other rectifier diodes would also be nice though not a must have. Accommodating 3 bridges worth of those would add some footprint to the board I would think. Sent from my iPhone using Tapatalk

Might confuse the fab though... plate these slots, don't plate those I didn't have any trouble soldering one, and didn't see any tendency to self-wick solder across or anything.

There are some threads on diyaudio regarding this. One in particular is from Russ White (twisted pear audio) from 2006. Sent from my iPhone using Tapatalk

Oops, thought I had the pic in there. It was basically lines between the slot and the pads the arrows are pointing to, which are what you need to be careful about not bridging. Sent from my iPhone using Tapatalk

I don't believe Kevin has posted a schematic, but I think it is similar to Amb's attenuator. Each relay is shunting a resistor to ground. There could be any combination of relays on at a time (8 maximum), for the 256 steps in the attenuator. I guess it depends on how you define "in the signal path". See http://www.amb.org/audio/delta1/ Please correct me if this is wrong.

You mean something like this (blue lines)?