New Millett Hybrid Maxed Amp
May 29, 2008 at 6:40 AM Post #4,846 of 6,727
Regarding biasing the DBs:
As has been recommended before, I suggest making sure they're actually biased to their minimum at first power up, and if not, shut down and make the change right away. It has happened (<cough cough>) that I powered up my first max with the BJTs at max and they didn't last too long :p
So, measure their bias first at least, then get the other voltages in the ball park, then get the BJTs.. is what I'd do..
 
May 30, 2008 at 12:07 AM Post #4,847 of 6,727
I just finished casing my millett maxed and I was wondering if the holes in the top (for heat) are necessary?

I'm not too good at case work so I'm sort of hesitant to drill 20+ holes in the top of the case if I don't absolutely have to.

Also, which type of tube gives the best detail? I already have a set of the three different types, but haven't had a chance to compare each against each other.
 
May 30, 2008 at 12:34 AM Post #4,848 of 6,727
Quote:

Originally Posted by MasiveMunkey /img/forum/go_quote.gif
I just finished casing my millett maxed and I was wondering if the holes in the top (for heat) are necessary?

I'm not too good at case work so I'm sort of hesitant to drill 20+ holes in the top of the case if I don't absolutely have to.

Also, which type of tube gives the best detail? I already have a set of the three different types, but haven't had a chance to compare each against each other.



You can use a hole saw or punch to make one big hole over the area and cover it on the inside with screen. Several others have done that.

The 12FK6 tubes are said to have the most detail. The 12AE6s have the most punch. The 12FM6 tubes fall in the middle and are the hardest to find.

Which caps did you use?
 
May 30, 2008 at 12:48 AM Post #4,849 of 6,727
Hmm... I don't remember I put them in such a long time ago.

So heat vents are necessary? My amp does feel kind of hot...
 
May 30, 2008 at 12:52 AM Post #4,850 of 6,727
Quote:

Originally Posted by MasiveMunkey /img/forum/go_quote.gif
Hmm... I don't remember I put them in such a long time ago.

So heat vents are necessary? My amp does feel kind of hot...



you could always run it topless...

edit: on a more constructive note I have some nice wire mesh if you're in need
 
May 30, 2008 at 1:16 AM Post #4,851 of 6,727
Quote:

Originally Posted by MasiveMunkey /img/forum/go_quote.gif
I just finished casing my millett maxed and I was wondering if the holes in the top (for heat) are necessary?

I'm not too good at case work so I'm sort of hesitant to drill 20+ holes in the top of the case if I don't absolutely have to.

Also, which type of tube gives the best detail? I already have a set of the three different types, but haven't had a chance to compare each against each other.



I was thinking about this as well. If you're worried about drilling a lot of holes in the sense that they might not line up perfectly and look nice, you could always drill fewer larger holes. I was also thinking that you could drill holes in the side of the case (above the board level), and that convection would draw cooler air in from these, and you might only need one or two holes in each location. I don't know if anyone has done this.
 
May 30, 2008 at 2:09 AM Post #4,852 of 6,727
Quote:

Originally Posted by soloz2 /img/forum/go_quote.gif
you could always run it topless...

edit: on a more constructive note I have some nice wire mesh if you're in need



I'm interested in it. Send me a PM with the size of the pieces you have left. Did you ever use JB Weld to install it in your MAX? FWIW, I'll be in Buffalo, NY the week of June 23 too.

Quote:

Originally Posted by Iniamyen /img/forum/go_quote.gif
I was thinking about this as well. If you're worried about drilling a lot of holes in the sense that they might not line up perfectly and look nice, you could always drill fewer larger holes. I was also thinking that you could drill holes in the side of the case (above the board level), and that convection would draw cooler air in from these, and you might only need one or two holes in each location. I don't know if anyone has done this.


You still need to vent the top with enough area to enable the convection to occur. Side holes may help, but I think the side holes will be harder to drill nicely than the top holes. I might try holes at the rear to allow more convection flow around the voltage regulator. It also depends on high you biased your BJTs or MOSFETS. If you have the BJTs biased lower around 30mA then you could get away with less holes, but I still think it would be easier for you guyts to buy a Uni-Bit that goes up to 3/4" and make a few 3/4" holes over the DB and V-Reg heatsinks and use black or silver window screen on the inside to keep fingers and small bits out.
 
May 30, 2008 at 2:21 AM Post #4,853 of 6,727
Quote:

Originally Posted by BoilermakerFan /img/forum/go_quote.gif
I'm interested in it. Send me a PM with the size of the pieces you have left. Did you ever use JB Weld to install it in your MAX? FWIW, I'll be in Buffalo, NY the week of June 23 too.




I have some modders mesh from a PC case mod I did a couple years ago... I have almost 1'x2' of that and then I have almost 2'x2' of some wire mesh I bought to use on Grados, and well You don't need a lot for Grado screens
biggrin.gif
 
May 30, 2008 at 2:25 AM Post #4,854 of 6,727
Quote:

Originally Posted by BoilermakerFan /img/forum/go_quote.gif
I'm interested in it. Send me a PM with the size of the pieces you have left. Did you ever use JB Weld to install it in your MAX?


I used JB Qwik to secure my mesh. It worked great. I cut some plywood into the right size, wrapped it in wax paper, then used that as a "weight distribution plate". I put a big 30lb barbell on top of the wood, on top of the mesh w/ jb. The mesh ended up totally flat and secure.
 
May 30, 2008 at 3:04 AM Post #4,855 of 6,727
Quote:

Originally Posted by soloz2 /img/forum/go_quote.gif
I have some modders mesh from a PC case mod I did a couple years ago... I have almost 1'x2' of that and then I have almost 2'x2' of some wire mesh I bought to use on Grados, and well You don't need a lot for Grado screens
biggrin.gif



I sent you a PM.
 
May 30, 2008 at 11:05 AM Post #4,856 of 6,727
Quote:

Originally Posted by MasiveMunkey /img/forum/go_quote.gif
I just finished casing my millett maxed and I was wondering if the holes in the top (for heat) are necessary?

I'm not too good at case work so I'm sort of hesitant to drill 20+ holes in the top of the case if I don't absolutely have to.

Also, which type of tube gives the best detail? I already have a set of the three different types, but haven't had a chance to compare each against each other.



As others have said, topless is fine - many builders have left it at that.

However, three things remove all fear from me:
1. a stepped drill bit,
2. the MAX website drilling templates, and
3. use of a spring-loaded center punch.

In my situation, the template is used mainly as a guide for the spring-loaded punch. Secondarily, the template (when glued down with rubber cement) provides protection to the case finish from any errant metal chips (there are a lot of those). The punch removes any possibility that the drill bit walks. Use of the center punch will allow the use of a hand power drill - as shown in the construction section of the MAX website. You onlly have to eyeball the end of the drill bit with the center-punched indentation - it automatically "walks" to the indentation. Finally, a stepped drill bit ensures that the metal is cut, not ripped. Don't ever try to drill a hole in thin aluminum in one cut with a bit sized for the full size of the hole.

All that said, I can understand why one would be reluctant with the finish at the size of that case lid. Personally, I would never attempt it without a glued-down drill template that covers the entire surface. There's just too much metal spraying around - even if you vacuum it up after every hole.
wink.gif


After the first prototype, I use a Delta tabletop drill press with a Harbor Freight 4" indexing drill vise. The indexer only cost about $30 on sale. It's the smallest one they make, but just barely fits within the vertical travel of the small Delta drill press. (It won't fit on one of the cheaper Harbor Freight table top drill presses.) The holes go very quickly with one of those, but it's only time that it saves - not whether the holes are centered correctly and the finish is undamaged - the drilling template and the center hole punch do that. The drill press does result in finer cut holes - the edges are sharper and look more like a machine cut.

As for the tube holes, there's just nothing like one of those Greenlee punches. Be careful that you are certain of the final hole size, though, if you purchase one. Many of them are made for conduit, which are referenced by ID. The OD can be many fractions of an inch larger. For instance, a "3/4-inch conduit punch" cuts an OD (hole size) of well over 1 inch.
 
Jun 1, 2008 at 5:00 PM Post #4,857 of 6,727
putting together my BOM for my 3rd Max build. the first two were Muse ES/k42 builds. I was happy with the amps, but feel a bit less slam would be desirable so the next build will be blackgates.

Now of course CA2 will be 1000uf 25v NX
CA7 will be 680uf 35v NX
CA8 will likely be vitQ, but I have a case of k42's... so I haven't decided yet...
CA9 will be jumpered

now for the questions:
CA3/CA6 I have both Wilmas and k42's. I'll have enough room to tombstone the k42's so that isn't an issue, which would be better?

CA4/CA5, the original BOM called for 470uf 35v, the updated calls for 1000uf 35v.
first question, is there any sonic benefit to using 1000uf, or is it cosmetic?
second question, would there be any benefit to populating these positions with Blackgate NX caps?
Finally, if it wouldn't be worth populating the positions with Blackgate NX, I do have some Muse ES 470uf 35v caps that I could use
 
Jun 1, 2008 at 7:16 PM Post #4,858 of 6,727
Quote:

Originally Posted by soloz2 /img/forum/go_quote.gif
putting together my BOM for my 3rd Max build. the first two were Muse ES/k42 builds. I was happy with the amps, but feel a bit less slam would be desirable so the next build will be blackgates.

Now of course CA2 will be 1000uf 25v NX
CA7 will be 680uf 35v NX
CA8 will likely be vitQ, but I have a case of k42's... so I haven't decided yet...
CA9 will be jumpered



This will kill my sales of K42's
wink.gif
, but there's no question the VitQ's are better. I would go with the 0.22uf's, though, simply because the capacitance rating of the Black Gates are higher than the typical 470uf. Otherwise, for ES's at 470uf I would use the 0.18uf VitQ's.

Another option is the NX HiQ 0.47uf 50V - they will work well at CA9, too, but you are correct not to put the VitQ's back there.
Quote:

now for the questions:
CA3/CA6 I have both Wilmas and k42's. I'll have enough room to tombstone the k42's so that isn't an issue, which would be better?


Wima's, period - sound is not an issue here and the Wima's are unbeatable in these locations, IMHO.
Quote:

CA4/CA5, the original BOM called for 470uf 35v, the updated calls for 1000uf 35v.
first question, is there any sonic benefit to using 1000uf, or is it cosmetic?


No - getting rid of the tremendous slam will be accomplished by the BG's at CA2 and CA7 (in return for more detail), but you will noticeably lose bass with 470uf's at CA4/5. There is a lot of current to handle after the PS and CA4/CA5 take care of practically all of it.
Quote:

second question, would there be any benefit to populating these positions with Blackgate NX caps?


Panasonic FM's are almost unparalled in their ESR/ripple. That said, sonic improvements might be noticeable with BG FK's (just a guess). I have heard that their ESR is even lower (you'll never find the data published, though), but it will be an expensive experiment.
wink.gif

Quote:

Finally, if it wouldn't be worth populating the positions with Blackgate NX, I do have some Muse ES 470uf 35v caps that I could use


No - 1000uf is best, more than that - I have used 1800uf's on every build except the MiniMAX, where they were 1200uf's.
 
Jun 1, 2008 at 7:37 PM Post #4,859 of 6,727
Quote:

Originally Posted by tomb /img/forum/go_quote.gif
This will kill my sales of K42's
wink.gif
, but there's no question the VitQ's are better. I would go with the 0.22uf's, though, simply because the capacitance rating of the Black Gates are higher than the typical 470uf. Otherwise, for ES's at 470uf I would use the 0.18uf VitQ's.

Another option is the NX HiQ 0.47uf 50V - they will work well at CA9, too, but you are correct not to put the VitQ's back there.



the price for vit q's is about the same as the NX HiQ's anyone tried both?

Quote:

No - getting rid of the tremendous slam will be accomplished by the BG's at CA2 and CA7 (in return for more detail), but you will noticeably lose bass with 470uf's at CA4/5. There is a lot of current to handle after the PS and CA4/CA5 take care of practically all of it.
Panasonic FM's are almost unparalled in their ESR/ripple. That said, sonic improvements might be noticeable with BG FK's (just a guess). I have heard that their ESR is even lower (you'll never find the data published, though), but it will be an expensive experiment.
wink.gif

No - 1000uf is best, more than that - I have used 1800uf's on every build except the MiniMAX, where they were 1200uf's.


hmm... well I guess Panasonic FM it is. $100 is a bit more than I'd like to spend :p
 
Jun 1, 2008 at 8:14 PM Post #4,860 of 6,727
Quote:

Originally Posted by soloz2 /img/forum/go_quote.gif
the price for vit q's is about the same as the NX HiQ's anyone tried both?


Yes, and I preferred VitQs.
 

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