Nice black color scheme =D

Yes - A bit like Hichhiker's Guide "Every time I press one of these black controls, labelled in black on a black background, a little black light lights up black to let me know I've done it. " The only relief is the glow of the tubes and the awesome lignum vitae knob

Kevin I can help you get them. I'll send a PM tomorrow. They are not cheap. These are the devices in the new Pass amps and the cute ones with his logo are custom devices, if you've seen them. He says they are the best output devices he has seen, ever.

After doing 20 chassis and board sets... cheap really is not in my vocabulary.

I very much doubt that even ti khan put $30k pretty much all at once into

a multi year project that ended up loosing money

For what nelson is doing, these are clearly great devices, regardless of cost.

I like the new devices that Dan is using better, they are bipolar obviously, but

can't handle the voltages.

I definitely want to test at the voltages and currents we need.

One of the depletion mode fets as the current source, one of the enhancement

mode fets as the grounded grid output amplifier, and then probably a 2sj79 or something

similar as the cathode drive should make a great output stage, if it does not oscillate or do stupid

things at low currents. The active battery is good as is, and the toshiba part will replace the

2sc3675 with a bit of tweeking, and the ultra stable voltage reference now used in the kgsshv power

supply is also a great idea. So it seems that the 2sj79 and 2sk216 will have to stay, as far as

i know they are still in production.

Congratulations Craig! It's been an education just following your build. It's also been a little bit like watching someone climb Mt. Everest. I admire not only your skills but your unfazed coolness and dedication in the face of repeated problems and frustration. I really appreciate the way you've extensively documented the journey. Nothing like victory in the end. Enjoy!

Here's something interesting. The BH seems to take quite a while after turning on to come on song - around an hour or maybe more. But the T2 wakes up very fast - a minute or two after the HT relay clicks in and it struts its stuff.

Have any of the others with completed beasts noticed this?

Here's something interesting. The BH seems to take quite a while after turning on to come on song - around an hour or maybe more. But the T2 wakes up very fast - a minute or two after the HT relay clicks in and it struts its stuff.

Have any of the others with completed beasts noticed this?

With and Without servo

With and Without servo

Interesting comment, Inu. Could you expand on that please?

One design has a servo, the other doesn't so that would make sense to me a least, Craig... Or maybe I don't quite understand all the Britishisms in your post? or are you referring to the time it takes for the CCS to come up in the BH?

I think he was saying it takes a short time after startup for the T2 to sound brilliant, quicker than the BH.

That's how I parsed it too.

I think the designs of the servo's are such that the amp reaches and maintains the correct dc voltage

very fast, certainly less than 5 minutes. On original BH's, it usually takes about 20 minutes for

stability. BHSE is probably a bit quicker at 10 minutes.

The tightly regulated power supplies also make a significant difference.

Edit: What KG said

I bet the BHSE is slower than the original BH

That's how I parsed it too.

How would you parse "godisnowhere" ?

ok, I need someone to unconfuse me.

I went to a power coating place here in Austin to look around and get some pieces done (not for the T2, but I wanted to see how good of a job they would do).

Most of their work looked like the front of the BHSE, more like clear coat, which they said was a single step application process.

My question is, what do I have to ask for to get the finish that's on the rest of the BHSE, and something that makes sense for application to a heat sink? I forgot to ask, and next time I go back I'll bring a piece with me, but I just wanted to make sure I was a bit more informed.

In general, how think are the power coat layers, around 1 mil?

They didn't seem to know anything about polishing. They said that they scratch up the surface to help with adhesion anyways...

I don't think you can get matte powder coating to look like the back of the BHSE. The small Lundahl box is powder coating without the clear coating. First time I used that place and I didn't realize I had to ask for it...

ask for textured black and you'll get what you want. the coating on mine is pretty thick, probably 4 mils

In general, how think are the power coat layers, around 1 mil?

Whatever you do, ask them about masking the areas where the fixing bolts go so all the chassis components electrically connect together. You really need that for safety, and at the very least not to feel that tell-tale tingling feeling when you touch a floating piece of chassis. You *can* remove the coating where the screws are afterwards (Dremel), but any coating worth a damn is tough, and this is a pain in the ass given how many fixing bolts there are.

They may ask you to do this, in which case you need to find out what sort of tape they recommend to do the masking.

I discovered this gotcha decades ago after I bought a second had copper vapour laser (at work). All the laser head chassis components were thick powder coated, and not electrically connected. There was so much high power interference getting out the chassis seams that I got an rf burn. I was not impressed.

yes, they'll do the masking at the tune of $25/hr. They have a specific 3M (I believe) material that looks sorta like blue-greenish cellophane that they use. I suppose I could do it myself, I didn't think about asking that. We'll see what the project I gave them comes back looking like and go from there. Also, they'll plug up holes that have threads, like the big stainless knob I sent them. I'm curious to see how that turned out.

Justin, thanks for the advice. On say the Pico, do you also have the heads of the screws powder coated with a clear coat? 4 mils on the heat sinks seems like a lot, just to be clear, that's the same thing that you do on the top and bottom panels, and the heat sinks?

Here's a couple of pics with the T2 where it lives in the corner of our bedroom (and that was an interesting conversation, trust me ).

[ATTACH=CONFIG]4217[/ATTACH]

[ATTACH=CONFIG]4216[/ATTACH]

Also measured the amp heatsink temperature after 8 hours = 48C (118F). The power supply was quite a bit cooler than that.

kerry came up with this one... a BHSE with the servo's from a T2.

http://gilmore.chem.northwestern.edu/BlueHawaii-T2-Servo-v1-2.zip

opens with ltspice.

yes, they'll do the masking at the tune of $25/hr. They have a specific 3M (I believe) material that looks sorta like blue-greenish cellophane that they use. I suppose I could do it myself, I didn't think about asking that. We'll see what the project I gave them comes back looking like and go from there. Also, they'll plug up holes that have threads, like the big stainless knob I sent them. I'm curious to see how that turned out.

Justin, thanks for the advice. On say the Pico, do you also have the heads of the screws powder coated with a clear coat? 4 mils on the heat sinks seems like a lot, just to be clear, that's the same thing that you do on the top and bottom panels, and the heat sinks?

pico screws powdercoated with a clear coat? what? the silver screws on the Pico are stainless steel. the black screws are usually black oxide, sometimes painted, depending on where I get them. both suck as the black doesn't last forever, and sometimes they rust. i don't know what the solution is for this. I'd like to just use black anodized screws if i can find the right #2-56 ones. for the Pico Slim, the screws are #0-80, and I haven't found aluminum screws probably for good reason.

yes, it is on the top/bottom/back/heatsinks. the threads are not coated, neither is the mounting surface of the heatsink or areas where I want electrical contact.

amazing thread...

This place offered to powder coat the screws with a clear coat. They say they do this all the time, just the heads not the threads. I'm not sure what it will look like, but I guess we'll see. Thanks again!

I am interested to see how your stuff turns out, and how you like it. Especially the clear stuff. Does this place have anything to see online?

I can't remember from where you were talking about it, but on the translucent plexiglass thing, have you maybe thought about sandwiching two pieces, with the frosted/translucent side captured in the middle? The edges could then be welded and then fired with a torch to smooth them out.... or not.