luvdunhill

Any reason a TVC couldn't be used between a preamp and the amplifier itself? Kinda backwards thinking I suppose ... but it solves the SE -> Balanced problem that AVCs have to deal with...

well, feel free to experiment. Since this is a phono stage, input and output connections should be as short as possible and power should be routed away from things and kept as short as possible as well (including connections to toroids, diode bridges, and the like). If possible, it would be nice to separate/shield the toroids more. Perhaps a tuna can or mandarin orange can could help shield them?

Thanks! were the AVCs wired for gain, or were they used passively, or in front of a preamplifier? I cannot seem to find pricing on the Tributes, so I've e-mailed them...

cool!! Here's my basic idea. Assemble the case. Remove the top and the back panel. Point the front of the case away from you. Stick the side of the PCB that accepts power towards the front of the case. Then shove the PCB in the bottom-left corner as far as it will go. The IEC inlet will be on the right and power cables will route down this side. Bolt the toroid(s) onto the front panel. Stick one capacitor clamp in the upper right corner and one in the upper left corner right up against the front panel and the side panel. Then mount the two bridges on the bottom of the case between the capacitors in the middle. Obviously, the front panel will look a bit lame with bolts sticking out of it, and that's where the wood comes into play

I think 2dB inductive attenuation is much finer than resistive attenuation, but I have nothing to back that claim up other than voodoo magic.

Do you know what transformer he uses? Assuming it's the same guy at DiyA, he's a nice guy ..perhaps he'd tell me

My hottest source is 2v. I'd assume that the (mostly) 2dB steps on this baby with a 2v source is different "feeling" than having a 5v source... I'm surprised there aren't more TVC/AVC proponents around here

for me, it depends on how the steps are spaced, not necessarily the number of steps... ~2dB may not be enough resolution, granted. check out the back of the pic posted.

yes, breatfeeding definitely helps the sleep schedule! as long as you don't roll over on the little one while sleeping

I'm sorta intrigued by this unit: anyone know much about it? Also, anyone heard the AVC TVC units from Diy HiFi (i.e. Django, etc.) 50/50% Permalloy Core Autoformer 28 step (Pair) | Diy HiFi Supply Of course there is the S&B, Sowter, and Jensen (and probably Lundahl) .. any others to consider? This would be used in conjunction with an active preamp. What is the general consensus of TVC used in this type of situation?

why don't you read all the project pages at headwize and see if anything fits the bill? Even if you don't find something suitable, the time spent reading will be well worth it.

I just sent out PayPal request for the remaining parts and the shipping. I have the kits in the car ready to mail. Please make sure you send your current shipping address, so I can verify it with the one that PayPal has on file. I didn't get around to matching the Toshiba semiconductors, but will soon. They'll come in a second shipping in a ESD bag, inside a Jiffy envelope. There "may or may not" be a few "d'ohs" in the BOM... we can discuss when everyone gets their parts. For those using the case I purchased, things are tight. I have sent a case to swt61 and instructions and perhaps he can post pictures when he's done mounting things. I'm notoriously bad at judging spatial relationships in cases, so it's nice to know a few more sets of eyes will be looking at the case layout aspect of the project. If you don't know what a particular part is used for, just ask as everything should have a use At the moment, the only missing parts not included that I know of are #4-40 screws for the heat sinks (you need 3 per) and hook-up wire. Please let me know if you find something else It's a very nice kit, and should be a very straightforward build. Thanks again guys!

yeah, stock idle heat dissipation is around 62 watts stereo. I have one channel running now on my bench and that's almost exactly what I got. I'm at around 22 C temperate rise above ambient. Once you get it, I can help you measure it and you can figure out exactly how it's biased and what it's output is and when it leaves class A. I'd personally turn it on for 12 hours or so and measure the DC offset voltage before I hooked it up, but that's just me being paranoid. Nelson recommends a few weeks burn in before being sure the DC offset is in spec, and somehow I doubt the builder did this... Another thing about buying on the "DIY-market" is that you really need a distortion analyzer to tune this amplifer, according to Nelson... that's the only way you'll get the specs posted, as he's been quite candid about that.

yup, 0.6 C/W per transistor hence the pair. Trust me, this builder had to of lowered the rails or this could be another example of epic fail. Also, everyone over specs what Papa recommends, as those strangely configured, non-conventional heat sinks he uses seem to have magical properties.

F5 puts out 50 stereo watts... my guess is those heatsinks can do 20-30W total.. welcome to class A. From the article: "Heat Sinking At 1.3 amps per channel, you will see idle heat dissipation of 62 watts. To keep the temperature rise of the heat sink to 20 deg C. above the ambient temperature, you will want a heat sink rated at about .6 deg C./watt for each transistor. An example of this would be a chunk of finned aluminum, with a series of 2” fins attached to an 8” by 6” base. You will need two per channel. The output devices need to be intimately attached to the heat sink. The mounting surface on the heat sink should be at least

I wanna go so bad... perhaps I can get you guys to snag some freebies for me

He must of really lowered the power output on that to get away with those heat sinks... or it's going to cook. Ask swt61 about the heat sinks I'm using.

point being: A.) buying black market DIY stuff is lame.. I wonder why he removed the Audiogon listing so quick... B.) the reason he charges less than the MSRP is because there is not much to it when you don't have to design the circuit just copy someone else's ideas.

NP will be offering the boards only for the basic schematic, not the more advanced balanced versions that people are building. The kit I'm referring to can be bought at tech-diy from Jack: Tech DIY Company Store

yes, there are 2 people doing dual transformers.. me with the ghetto ones from surplus sales that are posted in this thread (still haven't figured out which set of wires is the primary and which is the secondary) and swt61, assuming he can shoe-horn 2 donuts in the case somewhere trick mods? hm.. you could look at lowering the JFET degeneration resistors and playing with bias points... perhaps add a choke in the power supply somewhere... uh, I dunno...

yeah... you get my point though. It's a very simple amp, as all the first watt designs are. Add in $80 or so for a Plitron toroid, $50 for binding posts, $10 for IEC inlet, $12 for XLR jacks, and $200 for a chassis and you're still well under $500.

yup, the battery is used as a reference.

so, I've been playing around with some diodes on a power supply and found some I like, but I think I'm cutting it too close with the current rating. The transformer is 82VCT 50VA R-core and I have a 300mA fuse on each rail after the main supply capacitance, which is around 3000uF per rail. I wouldn't expect any more than 300mA per rail, hence the fuse choice. That being said, there is in-rush and the like to consider, and blowing a bridge isn't too exciting in my book. So, without admitting how stupid I was, and how low I went... in your opinion, what's a good rule of thumb?

hm, I don't know. I had most of the parts on hand. Probably $20 or so, plus the power strip? Here's the chassis I recently saw that would work really well: Odio Power Stripe Box Main

easy, look at the part cost You can get a kit for $26 per channel.