[Daveze]

Scy, I like the idea of the huge heatsink on the regulator...mine's running pretty darn hot (52-55 degC) and I imagine anyone with MOSFETs must be in a similar spot.

For anyone interested in mine, I think I've chickened out on swapping my output transistors. I was thinking about it the other night and I remembered just how much of a pain of a job it was the first time. I might change my mind when I get home though...

On the plus side, it has been operating really happily at 176mA for a while now. Its a little bit sensitive to surrounding temps though, when its nice and chilly (I dunno 15-18 degC) it sits happily at about 49-50 deg C but it does get up to ~52 degC on the warmer days (mid 20's). After the fiddling required to get it to measure 176mV, it does sit very comfortably there, no variation. I was thinking of upping it to say 90-100mA (298mV and 220mV) but seeing the sensitivity to surrounding temps has scared me off a bit, particularly because I'll forget when we come back into summer and it gets properly hot.

Tom, I'll make a mental note to check the temp on the PN4392 when I get home.

 

[tomb]

Quote:

Originally Posted by DrizzitT /img/forum/go_quote.gif Another Millett Max (build 2) lives! I'm not much of an audiophile (built for cost of mats for a friend + soldering experience), but it does sound good. One problem though... I got both the 12FK6 and the 12AE6 from beezar.com. The 12AE6's all work fine, one of the 12FK6's hums. The humming gets worse when my hand gets closer and when I tap the tube, I don't "hear" the tap like all the other tubes. Switched channels and the same problem, only on the other side. Is this a tube problem or circuit problem? I'm guessing tubes due to the consistency of the problem over channels but this is my first foray into tubes so...

It's possible that it's a grounding problem through the pins (bad connection). That's usually the case if your hand causes a reaction, I think. You might try going over the pins with a cotton swab and some alcohol. I do that for all that I sell, but it's possible I missed one. There's also the possibility that the poor connection is inside the tube.

Regardless, if you can't get it to work to your satisfaction, please return it and I'll replace it, no charge.

Quote:

Originally Posted by Daveze Tom, I'll make a mental note to check the temp on the PN4392 when I get home.

It's probably OK since we changed to the current multiplier in the diamond buffer, but still - that's the other critical part to worry about getting hot (besides the LM317 and the output transistors). There are a few resistors that could get pretty toasty (heater resistor, voltage adjust resistor on the LM317, and the output transistor power resistors), but they should all be sized at almost twice the needed rating.

 

[BoilermakerFan]

Quote:

Originally Posted by DrizzitT /img/forum/go_quote.gif One problem though... <snip> Switched channels and the same problem, only on the other side. <snip>...

Since the problem follows the tube, and doesn't stay in the same channel, I don't think he has a grounding problem. Plus the AE6As are fine, so it's bad tube. Just swap out the tube with Tom.

 

[soloz2]

I have to get ready for work now, but I've spent the last hour and a half going through parts to see what I really need and already have for my current Max build. I just needed a few parts
I'm getting
a push button switch
filtered IEC input
2" heatsinks instead of the 1.5" ones I currently have

and I missed needing CB8 so I grabbed a couple of those.
I just need to pick out some fuses and then I'm all set, but that will likely have to be tonight

good thing I get orders practically next day!

 

[tomb]

Quote:

Originally Posted by BoilermakerFan /img/forum/go_quote.gif Since the problem follows the tube, and doesn't stay in the same channel, I don't think he has a grounding problem. Plus the AE6As are fine, so it's bad tube. Just swap out the tube with Tom.

Yep - I worded it poorly, but grounding the tube through the pin connections is what I was talking about, not really "grounding" in the sense we normally talk about. Sometimes the pins themselves can get a hairline crack at the entry point into the tube, too. In either case, as you say, it would follow the tube, though.

 

[Scy]

Quote:

Originally Posted by sokece /img/forum/go_quote.gif Really nice case. Do you mind tell us how much you spend for the case?

As you might have guessed, it's not exactly a bargain.
Most of the price is for the parts from fpe.
For the front- and back panels and the acrylic cover, the overall cost was around 90€ including 19% tax and shipping.
The wooden parts cost 25€
then there is the sheet of metal at the bottom, some screws and bolts and the feet for the case. Haven't really thought the cost for those, but it was nothing much I suppose.

 

[srserl]

Scy, your amp looks stunning! I really like the contrast of old-school look of the wood and tubes with the high tech look of the plexiglass (and components), heatsinks, and front panel.
Definitely one of the best looking amps I have seen.

Scott

 

[Daveze]

Quote:

Originally Posted by tomb /img/forum/go_quote.gif It's probably OK since we changed to the current multiplier in the diamond buffer, but still - that's the other critical part to worry about getting hot (besides the LM317 and the output transistors). There are a few resistors that could get pretty toasty (heater resistor, voltage adjust resistor on the LM317, and the output transistor power resistors), but they should all be sized at almost twice the needed rating.

For your interest, the PN4392 hardly breaks a sweat. All the guys around the LM317 do get hot though, some I imagine will be because of the current but I think the proximity to the LM317 heatsink (currently 55 degC) has a bit to do with it. Also, I only have the 1" heatsink on the LM317, which is quite nearsighted of me.

The rectifier diodes are also getting a bit warm too.

 

[DrizzitT]

Quote:

Originally Posted by tomb /img/forum/go_quote.gif Yep - I worded it poorly, but grounding the tube through the pin connections is what I was talking about, not really "grounding" in the sense we normally talk about. Sometimes the pins themselves can get a hairline crack at the entry point into the tube, too. In either case, as you say, it would follow the tube, though.

Hm. I'll give the tube cleaning a try later this week, and if it doesn't work, I'll contact you, tomb, regarding the swapping of tubes.

Also, a question. What gauge wire is being used for casing the power terminal/switches/3.5mm/RCA jacks? I'm thinking of buying some "better" (non-EE hookup wire) wire but am not very familiar with gauge sizes (I'm assuming they aren't quite the same as speaker wire). I currently have 30 gauge, but that looks a bit too thin for this purpose... Probably going to buy from the ebay site listed on the diyMod page. Also, I assume hook-up wire is sufficient for the test points (ie, crappy wire won't affect the overall system). Thanks for the help guys!

 

[ruZZ.il]

Quote:

Originally Posted by DrizzitT /img/forum/go_quote.gif Hm. I'll give the tube cleaning a try later this week, and if it doesn't work, I'll contact you, tomb, regarding the swapping of tubes. Also, a question. What gauge wire is being used for casing the power terminal/switches/3.5mm/RCA jacks? I'm thinking of buying some "better" (non-EE hookup wire) wire but am not very familiar with gauge sizes (I'm assuming they aren't quite the same as speaker wire). I currently have 30 gauge, but that looks a bit too thin for this purpose... Probably going to buy from the ebay site listed on the diyMod page. Also, I assume hook-up wire is sufficient for the test points (ie, crappy wire won't affect the overall system). Thanks for the help guys!

I think 22awg is probably your best all round bet for that kind of stuff. 24awg would be sufficient too, and is what I've used for some headphone re-cabling with great results, so it'll be good for short internal runs. it'll probably be good for all the internal wiring.. JohnsWireShop is where we got a lot of wire from around here, and probably who you were referring to. He doesn't have much 22awg in right now, but if you took what he had, you'd still be able to strip that pair and use the bits. If you only need a foot or 2, I'll gladly send you some, though it'll take a little while to get there.. just let me know. Also, IIRC, he may have gone on vacation for a little while, promising to come back with a bunch of re-stock. It may be worth sending him a message before ordering.
Again, if you don't mind waiting about 2 weeks, I'll send you a little variety pack enough for a build or 2..

 

[tomb]

What a wonderful offer, ruZZ.il! Yes, I am in complete agreement, to0: 22ga teflon SPC is a great way to go - all I ever use.

You have a great suggestion to drop John a note. He's back from his vacation(?) now, apparently, but doesn't have much 22ga except those two twisted pairs last time I looked. I'm getting very low myself and hope that he has more soon.


EDIT: I sent navships (John) a note asking about more 22ga. I'll let you all know what he says.

 

[tomb]

Wow - that was pretty quick! See reply below from John of John's Wire Shop on ebay:

Quote:

Hi, I just got in a lot of 22ga wire. I was hoping to get this listed in my store much sooner, I will start listing these today as soon as I take the pictures of the wire. Some of the colors that I have in 22ga are, white, black, blue, green, gray, red, white/gray/red, white/red/violet, white/blue/orange, white/brown/black, plus many more colors with strips. John - navships

 

[soloz2]

I'm wondering if anyone can help me out. I just realized that I don't have enough standoffs to mount my Max. I hope to bring it to the Toronto meet on Saturday, I should be receiving all the other parts I need and the enclosure and toroids tomorrow or Friday, but I'm short some standoffs to mount the Max board in the enclosure, I don't think I have enough time to order some.

Does anyone have some standoffs? I'll need 5 or so. I'd be more than happy to send some funds via PP

 

[tomb]

Quote:

Originally Posted by soloz2 /img/forum/go_quote.gif I'm wondering if anyone can help me out. I just realized that I don't have enough standoffs to mount my Max. I hope to bring it to the Toronto meet on Saturday, I should be receiving all the other parts I need and the enclosure and toroids tomorrow or Friday, but I'm short some standoffs to mount the Max board in the enclosure, I don't think I have enough time to order some. Does anyone have some standoffs? I'll need 5 or so. I'd be more than happy to send some funds via PP

I can probably spare that many that are either 3/8" or 1/2" - I forget which I have. The mail is going to be pushing it to get it to you in time, though. I may be able to get them in the mail to you this afternoon, but I can't guarantee that for certain - it may be tomorrow morning.

PM me with your address if you're interested. I'm sure I have it somewhere, but that would save me the time from looking it up.

 

[BoilermakerFan]

Also, if Tom can't help you out, couldn't you use PC standoffs in a pinch? I think even Best Buy sells them now. Lowe's will have the small 4-40 pan head screws and cap nuts to secure it temporarily if Tom's don't make it in time.

Worst case, I know Lowe's has nylon spacers that will accept 4-40 screws so you could temp it in that way with a pan head sheet metal screw, nylon spacer, and cap nut. Might require a trip into Buffalo to hit a Lowe's, but Lowe's has a much better small hardware selection than the big orange box store.