[babbkutz@comcast]

off your short list of headphones (the 650s are great just not as comfortable as the 600s...tight on the head)

 

[tomb]

Quote:

Originally Posted by c0nsumer /img/forum/go_quote.gif Reading through all of this is tempting me to make another MAX, this time in a silver Hammond case with wood ends, 12FK6 tubes, a BJT output stage, and some sort of special caps. Lessons learned from the previous MAX I built should make this one go even more smoothly, and it'd be interesting to A/B them. I just happen to have a spare volume pot, sockets, and two MAX PCBs. I'd just need to snag some parts from Mouser, eBay, Jameco, and Digi-Key... Hmm... If you all were doing this, is there anything special you'd do cap and transistor-wise? I'm thinking just Muse ES caps, 1.5" heatsinks (why not -- it all still fits in the chassis nicely), again no LEDs (saves on power, makes for cooler power supply, etc), maybe a thermistor in series with (or in place of) the fuse... I've got no idea about which pairings of transistors might be best, though. For what it's worth I've got a set of Sennheiser HD570 headphones and the next set will likely either be the 600s or 650s. I personally really prefer over the ear, open ear headphones.

Based on your description, a really nice set of BJT's may be the best improvement. The MJE's are no slouch, but the Toshiba and Sanyo pairs are really superior. The best resource - as always - is Steinchen's original revMH DB website. Scroll down to the bottom of this page and you will see his reviews for the various BJT pairs:

http://www.diamondstar.de/dDB_partslist.html

I have used the 2SC3422/2SA1359 pair many times and can personally vouch for their "rockability" and "slam".

They are very, very nice.

The 2SC3421/2SA1358 I've also used and they have tremendous bass extension - organ pedal deep. They also happen to have been used on the Dynahi and cetoole's first proto. Again, a very good choice - and if asked, I would have to say that the highs are not necessarily "rough" as Steinchen mentions.

The 2SC2238/2SA968 pair became Steinchen's all-time favorite. I have yet to use them, but have no doubt they will be among the best - every other BJT I've tried has tracked Steinchen's reviews pretty well.

About the wood panels - Naamanf had a thread on DIYForums.org where he was selling ready made wooden front and back plates for the Hammond.

 

[slowpogo]

This has been asked before (by myself and others) but at this point, is anyone willing to sell off a board? I thought maybe someone is deciding they don't really need 3 or 4 PCBs after all.

 

[fc911c]

Quote:

Originally Posted by slowpogo /img/forum/go_quote.gif This has been asked before (by myself and others) but at this point, is anyone willing to sell off a board? I thought maybe someone is deciding they don't really need 3 or 4 PCBs after all.

Yes I'd be interested in one as well.

Thanks
Frank

 

[amphead]

Hmmmmmmm..............Ever since I turned RA1L counter-clockwise 20 turns, she is now quite a fuse blower. All trimmers except PS are fully clockwise. The PS trimmer is turned down. The next step is to put a fuse holder/ fuse in my diy power supply and jumper the fuse in the MAX, to see if its inrush or something not so nice.

Sniff test and visual on trannies good.

 

[britishbane]

Quote:

Originally Posted by slowpogo /img/forum/go_quote.gif This has been asked before (by myself and others) but at this point, is anyone willing to sell off a board? I thought maybe someone is deciding they don't really need 3 or 4 PCBs after all.

What they said. Interested as well.

 

[amphead]

Note to self, no more inrush current jokes. Thats probably going to be my problem.

 

[tomb]

I suggest taking the fuse clips out and stomping on them once or twice. You could throw in a couple of the fuses for good measure. Then put your one AC lead in the other terminal block position and forget about it.

OK - a moment of weakness ... Seriously, it sounds like your power supply is supplying a lot of volts that are getting burned off in the PS. If the temperatures are OK and the LM317 doesn't shut down, you can live with it. Go up to my previous post about biasing the DB's and carefully check, measure, wait, measure and then adjust until you get them where you want.

 

[ooeric]

anyone still building these too sell?
ive been looking for one, i cant diy. my hands just cant it do.

 

[c0nsumer]

Quote:

Originally Posted by babbkutz@comcast /img/forum/go_quote.gif off your short list of headphones (the 650s are great just not as comfortable as the 600s...tight on the head)

Hmm... I've never tried AKG headphones... They look quite comfortable, though...

I'm just having a hard time shelling out that much, especially as I happened to get the 570s for about US$36 as a local shop was going out of business and clearancing everything.

 

[c0nsumer]

Quote:

Originally Posted by tomb /img/forum/go_quote.gif Based on your description, a really nice set of BJT's may be the best improvement. The MJE's are no slouch, but the Toshiba and Sanyo pairs are really superior. The best resource - as always - is Steinchen's original revMH DB website. Scroll down to the bottom of this page and you will see his reviews for the various BJT pairs: http://www.diamondstar.de/dDB_partslist.html I have used the 2SC3422/2SA1359 pair many times and can personally vouch for their "rockability" and "slam". They are very, very nice. The 2SC3421/2SA1358 I've also used and they have tremendous bass extension - organ pedal deep. They also happen to have been used on the Dynahi and cetoole's first proto. Again, a very good choice - and if asked, I would have to say that the highs are not necessarily "rough" as Steinchen mentions. The 2SC2238/2SA968 pair became Steinchen's all-time favorite. I have yet to use them, but have no doubt they will be among the best - every other BJT I've tried has tracked Steinchen's reviews pretty well. About the wood panels - Naamanf had a thread on DIYForums.org where he was selling ready made wooden front and back plates for the Hammond.

I had been looking through there, and while I originally was looking at his default recommendations, I don't think it'd be too hard to hook in the 2SC2238/2SA968 set. Hmm.

I found someone who has six 12FK6 tubes for a reasonable price, NOS. I might pick up four of them or so...

I like those wood end panels, but I think I'm going to grab some veneer tomorrow (not sure what sort yet) and attempt to laminate it cleanly on to aluminum. I figure surface hit with some 440 grit or so should do well with contact cement, the veneer, and a decent setup for pressing it all together. We'll see, I'll definitely post about how its done and such.

Right now I'm thinking a light wood, but maybe not zebra... I'll see what Woodcraft has. Oh, and some wipe-on urethane...

 

[amphead]

Ok, so knock on wood it was peak inrush current causing my problem so far. 2A regular blo 250VAC fuse on the primary of my trafo. Jumpered fuse position on the MAX. For now I am just warming my hands by the tubes. After the tubes burn-in for an hour, I will attempt to bias.

 

[amphead]

Tube and DB bias trimmers fully clockwise. DB bias currently at ~29mv. Regulator heat sink very warm 5 second touch maximum. No burned plastic smell, so far. Still not ready to jump in, I'm waiting for the water temp to be just right! Tom, I wonder how much cooler the PS heatsink will be once I get the tube bias to 13.75, assuming that I ever get there? Can't imagine ever putting the lid on, the way it feels now, without moving to Alaska or maybe Sweden.

 

[bperboy]

Quote:

Originally Posted by amphead /img/forum/go_quote.gif Tube and DB bias trimmers fully clockwise. DB bias currently at ~29mv. Regulator heat sink very warm 5 second touch maximum. No burned plastic smell, so far. Still not ready to jump in, I'm waiting for the water temp to be just right! Tom, I wonder how much cooler the PS heatsink will be once I get the tube bias to 13.75, assuming that I ever get there? Can't imagine ever putting the lid on, the way it feels now, without moving to Alaska or maybe Sweden.

Personally, I leave the top off mine all the time. No worries about heat, and no worries about trying to align the tube holes perfectly!

 

[amphead]

Mmmm..Hmmm..., so the consensus is that sinks and tubes will stay quite warm, even at proper bias.