tomb
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BMF - drop me a PM if you get no takers. I'll buy them from you.
New Millett Hybrid Maxed Amp
- Thread starter cetoole
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BoilermakerFan
Headphoneus Supremus
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Quote:
Thanks Tom. I'll let you know, but I figure I'd try to help peeps on a tight budget. The $15 savings basically covers a wall wart PSU. Need to formally post them in the for sale forum too.
| Originally Posted by tomb /img/forum/go_quote.gif BMF - drop me a PM if you get no takers. I'll buy them from you.
|
Thanks Tom. I'll let you know, but I figure I'd try to help peeps on a tight budget. The $15 savings basically covers a wall wart PSU. Need to formally post them in the for sale forum too.
abcheng
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Hey guys, I bought the PCBs a while and never got around to build them until now. I'm currently ordering parts to build my
Millett Maxed Amp, but I have a question about the heatsinks listed on the BOM.
Aavid #531002B02500G (1"h.) 4
Aavid #531002B02500G (1-1/2"h.) 4
There are two types of heatsinks listed, and the difference I see is in height. I purchase one or the other, but not both right?
Millett Maxed Amp, but I have a question about the heatsinks listed on the BOM.
Aavid #531002B02500G (1"h.) 4
Aavid #531002B02500G (1-1/2"h.) 4
There are two types of heatsinks listed, and the difference I see is in height. I purchase one or the other, but not both right?
cetoole
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Quote:
Yup, and which one depends on what you want to be able to bias to, and will effect how you case it.
| Originally Posted by abcheng /img/forum/go_quote.gif Hey guys, I bought the PCBs a while and never got around to build them until now. I'm currently ordering parts to build my Millett Maxed Amp, but I have a question about the heatsinks listed on the BOM. Aavid #531002B02500G (1"h.) 4 Aavid #531002B02500G (1-1/2"h.) 4 There are two types of heatsinks listed, and the difference I see is in height. I purchase one or the other, but not both right? |
Yup, and which one depends on what you want to be able to bias to, and will effect how you case it.
MASantos
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Quote:
You say a back panel SPST. I guess this is kind of a dumb question, but can it be wired to the front panel right?
Quote:
Now, will v1.3 have a sigma11???
Seriously now, I could imagine a balanced Millett MAX board with sigma11 power supply, board pads for stepped attenuator, onboard connectors and so on...
the ultimate Millett Hibrid!
| Originally Posted by tomb /img/forum/go_quote.gif cetoole has finished the design on the MAX V1.2: Of course, the primary changes are the incorporation of the superior MiniMAX power supply, and room for the BantamDAC on board. Switching between BantamDAC and "normal" RCA inputs will be controlled with a back panel SPST switch (2-position terminal block) that throws a 24V relay. Since the 24V relay was required because of the limited space back there, we also incorporated it into the headphone delay-relay. |
You say a back panel SPST. I guess this is kind of a dumb question, but can it be wired to the front panel right?
Quote:
| Originally Posted by tomb /img/forum/go_quote.gif Surprise, surprise! With fewer parts and higher voltage, the headphone relay-delay works better than ever. We have sized and tested the parts selection for a Cold-Start delay time of 45 seconds, but the Hot-Start time is still ~30 seconds. Transients on cutoff - if they are there - are too fast to measure with my Fluke. This is an improvement over the existing design and other delay-relays, which throw a few volts of transient offset upon shutoff. Normally, this is trivial with a connected load and only noticeable when measured in a zero-load condition. However, this new circuit appears to have no offset on shut-off at all, load or not. This is of course, a nice benefit to the new circuit, besides the commonality of relays and fewer parts. I have been living with the new relay circuit on a MiniMAX for a few weeks now with no ill effects whatsoever - as stated it works better. |
Now, will v1.3 have a sigma11???
Seriously now, I could imagine a balanced Millett MAX board with sigma11 power supply, board pads for stepped attenuator, onboard connectors and so on...
tomb
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Quote:
If you want to run the leads that far, of course. That's another reason the board is slotted in the back - besides the fact that it takes up the entire length of the Hammond case, now.
Quote:
Talk to Pabbi1. His is pretty close to that.
| Originally Posted by MASantos /img/forum/go_quote.gif You say a back panel SPST. I guess this is kind of a dumb question, but can it be wired to the front panel right? |
If you want to run the leads that far, of course. That's another reason the board is slotted in the back - besides the fact that it takes up the entire length of the Hammond case, now.
Quote:
| Now, will v1.3 have a sigma11???
Seriously now, I could imagine a balanced Millett MAX board with sigma11 power supply, board pads for stepped attenuator, onboard connectors and so on...
|
Talk to Pabbi1. His is pretty close to that.
MASantos
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Thanks tomb!
nocturnalsheet
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Quote:
Hi Tomb,
currently tried a few tubes and currently my configuration is RCA 12AE6A with Slyvania 12AE6A.
thinking of finding few more tubes to try again.
btw how do i tell from observation who is the MFR of the different tubes?
thanks.
| Originally Posted by tomb /img/forum/go_quote.gif I've sort of given up trying to assign sound qualities per brand.
Sylvania generally built the best structure in the tubes - all of them have a channel going across the plates at the top mica spacer. None of the other mfrs used that construction. At the same time, that doesn't necessarily guarantee the best sound. Generally speaking (very generally) ... and this is per MFR, not painted-on "brand": RCA - very good overall neutral sound, sort of clear, but slightly soft highs - similar to the BUF634 sound of a PIMETA, if you've heard that. They are very forgiving for almost any recording. GE - lots of prat, great bass impact and powerful punch, great mids, not as good in the highs as an overall average compared to the others. Tung Sol - very similar to the RCA's, very neutral, but with "sweeter" extended highs, compared to the RCA's soft highs. Sylvania - similar to the others - if you find a good one, the highs are very revealing, which can be good or bad, depending on the recording. All that said, there is much more difference in the sound from type to type: 12AE6 compared to 12FM6 and 12FK6. The 12AE6 has the most impact and is the most dynamic. I would recommend them for high impedance phones in every case. 12FK6 has the best highs and detail, but impact can be lacking except on low impedance phones. 12FM6 is in the middle of the other two. Despite all of this, you'd be better off deciding on which tube type and making sure you have a decent match in construction and output. As noted, the brand name means nothing. Hope that helps ... |
Hi Tomb,
currently tried a few tubes and currently my configuration is RCA 12AE6A with Slyvania 12AE6A.
thinking of finding few more tubes to try again.
btw how do i tell from observation who is the MFR of the different tubes?
thanks.
tomb
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Quote:
Believe it or not, it's pretty simple, really. There were four manufacturers of Millett tubes:
RCA - tell-tale sign is the presence of a dark-gray, etched tube designation on the side near the top of the tube. The designation ("12AE6", "12FK6", etc.) is bordered by an octagon whose sides have been shortened to fit the text. I often refer to it as a "squished octagon." Note that sometimes this feature may be highly worn and almost invisible. It's often a process of deductive elmination - if the other tell-tale signs are not there, then keep looking for the presence of the squished octagon, no matter how light. If you can't find one, or you find a tube designation etched on the side near the top of the tube - without an octagon or any other border - then it's Tung-Sol.
GE - Pretty easy for these. GE used white etching on the sides of the tube. This etching is often large, perhaps covering 1/2 the space of the visible side of a tube. The tube designation is accompanied by a series of white dots beneath. "Size" in this context means the total space of the tube designation text and the dots that are below. The white lettering itself is about twice the size of an RCA or Tung-Sol designation. The dots - about 3 to 5 total, on a couple of rows - are about 1/16" in diameter or slightly smaller.
The lower gain tubes by GE - 12FK6's for instance - also have a very unique appearance. GE stamped one-piece "J" plates with a contiguous outside lip. All the other mfrs would trim the plates on one end, although there are some with better finishes than others on the trimmed edge. However, only GE used the stamped "J" with an outside-bordering lip.
GE's also were the only ones to use "rings" for getters in some of their tubes (not all). These can be side rings - welded sideways to one of the plates at mid-height, or on a rod at the very top - "halo" fashion. These "rings" are more like a thick washer than any sort of bent or curved wire and are much smaller than RCA-style halo getters - around 1/4" diameter or slightly larger.
Sylvania - Very easy to spot these, too. Sylvania actually built their tubes differently than anyone else. Sylvania uses an upside-down channel as additional support at the top of the plates and the top mica spacer. This channel is 90 degrees relative to the parallel plates as you look down at the top of the tube. Every other mfr just used a clear disc at the top of the plates. Sylvania has the clear disc, too, but no one else has this supporting channel that rests on the top mica spacer. Note that the clear disc (1/4" - 3/8" dia) is often not present at all in the other mfrs - the plates are sometimes free-floating at top except for the top mica spacer.
Also, many Sylvanias have a vertical side square getter. No other mfr used side getters except that they were welded to one of the plates sideways (which may be the predominant getter for all tube types). The Sylvanias that used these have a supporting vertical rod and the getter is welded in the middle - as if the getter was going up top but never made it.
Tung-Sol - When you've elminated every other possibility, the chances are the tube is Tung-Sol. The most predominant feature is the lack of features of any of the tubes' mfrs above, along with a tube designation etching at the top of the tube sides - dark gray and without a border. Some Tung-Sol tubes have tube tips that are rounded and "bobbed," instead of pulled up into a pointy tip.
Beyond this, except for the GE "J" plates in their 12FK6's, the mfrs shared plate types with each other to a large degree. There are some that I've only seen on RCA and vice-versa, but the distinguishing feature is not worth mentioning, since often the finish may be the only thing unique, not the shape.
An unfortunate fact is that even after all of this, I've come across tubes that have both a squished octagon tube designator and white etching with dots.
I guess this can be explained by GE's on and off ownership of RCA as a subsidiary. Hope this helps you.
| Originally Posted by nocturnalsheet /img/forum/go_quote.gif Hi Tomb, currently tried a few tubes and currently my configuration is RCA 12AE6A with Slyvania 12AE6A. thinking of finding few more tubes to try again. btw how do i tell from observation who is the MFR of the different tubes? thanks. |
Believe it or not, it's pretty simple, really. There were four manufacturers of Millett tubes:
RCA - tell-tale sign is the presence of a dark-gray, etched tube designation on the side near the top of the tube. The designation ("12AE6", "12FK6", etc.) is bordered by an octagon whose sides have been shortened to fit the text. I often refer to it as a "squished octagon." Note that sometimes this feature may be highly worn and almost invisible. It's often a process of deductive elmination - if the other tell-tale signs are not there, then keep looking for the presence of the squished octagon, no matter how light. If you can't find one, or you find a tube designation etched on the side near the top of the tube - without an octagon or any other border - then it's Tung-Sol.
GE - Pretty easy for these. GE used white etching on the sides of the tube. This etching is often large, perhaps covering 1/2 the space of the visible side of a tube. The tube designation is accompanied by a series of white dots beneath. "Size" in this context means the total space of the tube designation text and the dots that are below. The white lettering itself is about twice the size of an RCA or Tung-Sol designation. The dots - about 3 to 5 total, on a couple of rows - are about 1/16" in diameter or slightly smaller.
The lower gain tubes by GE - 12FK6's for instance - also have a very unique appearance. GE stamped one-piece "J" plates with a contiguous outside lip. All the other mfrs would trim the plates on one end, although there are some with better finishes than others on the trimmed edge. However, only GE used the stamped "J" with an outside-bordering lip.
GE's also were the only ones to use "rings" for getters in some of their tubes (not all). These can be side rings - welded sideways to one of the plates at mid-height, or on a rod at the very top - "halo" fashion. These "rings" are more like a thick washer than any sort of bent or curved wire and are much smaller than RCA-style halo getters - around 1/4" diameter or slightly larger.
Sylvania - Very easy to spot these, too. Sylvania actually built their tubes differently than anyone else. Sylvania uses an upside-down channel as additional support at the top of the plates and the top mica spacer. This channel is 90 degrees relative to the parallel plates as you look down at the top of the tube. Every other mfr just used a clear disc at the top of the plates. Sylvania has the clear disc, too, but no one else has this supporting channel that rests on the top mica spacer. Note that the clear disc (1/4" - 3/8" dia) is often not present at all in the other mfrs - the plates are sometimes free-floating at top except for the top mica spacer.
Also, many Sylvanias have a vertical side square getter. No other mfr used side getters except that they were welded to one of the plates sideways (which may be the predominant getter for all tube types). The Sylvanias that used these have a supporting vertical rod and the getter is welded in the middle - as if the getter was going up top but never made it.
Tung-Sol - When you've elminated every other possibility, the chances are the tube is Tung-Sol. The most predominant feature is the lack of features of any of the tubes' mfrs above, along with a tube designation etching at the top of the tube sides - dark gray and without a border. Some Tung-Sol tubes have tube tips that are rounded and "bobbed," instead of pulled up into a pointy tip.
Beyond this, except for the GE "J" plates in their 12FK6's, the mfrs shared plate types with each other to a large degree. There are some that I've only seen on RCA and vice-versa, but the distinguishing feature is not worth mentioning, since often the finish may be the only thing unique, not the shape.
An unfortunate fact is that even after all of this, I've come across tubes that have both a squished octagon tube designator and white etching with dots.
tomb
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Quote:
You mean I wrote all of that this morning and you didn't care to check back?
| Originally Posted by nocturnalsheet /img/forum/go_quote.gif Hi Tomb, currently tried a few tubes and currently my configuration is RCA 12AE6A with Slyvania 12AE6A. thinking of finding few more tubes to try again. btw how do i tell from observation who is the MFR of the different tubes? thanks. |
You mean I wrote all of that this morning and you didn't care to check back?
nocturnalsheet
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Quote:
Hey Tomb,
I did check back, thanks for your inputs, really appreciate it.
different timezones we are in you know.
i shall wait for the tubes to arrive and try to figure out who are the manufacturers.
| Originally Posted by tomb /img/forum/go_quote.gif You mean I wrote all of that this morning and you didn't care to check back?
|
Hey Tomb,
I did check back, thanks for your inputs, really appreciate it.
different timezones we are in you know.
i shall wait for the tubes to arrive and try to figure out who are the manufacturers.
tomb
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Proto boards have arrived! I'm going to build one and if works out, production boards will be ordered immediately. Thought you might like to see how they turned out (click for full size pics):
Beefy
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Nice! I like the little extra touches, like the silkscreen label for the fuse / no fuse......
ruZZ.il
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The board has really evolved nicely. I'm not sure when I'll get to check one out though.. I've already got a few MAXs
Though, no mosfet one yet, and it'll probably stay nice and cool with those holes. They really keep the miniMAX cool.. hmmm..
abcheng
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Quote:
Thanks for the reply. Will the 1.5" heat sinks fit in the Hammond case in the BOM?
Does anyone have any of these parts available?
RB12L/R 2K ohm Trimmer Pot - Mouser doesn't have any in stock right now.
as well as:
Tube LED's, 3mm ultra-high, 5500 mcd - Blue
I can only seem to find 3600mcd LEDs on Mouser. Is 3600mcd bright enough, or should go with 5500mcd LEDs instead?
Quote:
Wow, the proto boards of the new version are out when I'm about to build the original version of the Millett Max ? I may have to wait until the boards for the new version of the Millett Max are available.
| Originally Posted by cetoole /img/forum/go_quote.gif Yup, and which one depends on what you want to be able to bias to, and will effect how you case it. |
Thanks for the reply. Will the 1.5" heat sinks fit in the Hammond case in the BOM?
Does anyone have any of these parts available?
RB12L/R 2K ohm Trimmer Pot - Mouser doesn't have any in stock right now.
as well as:
Tube LED's, 3mm ultra-high, 5500 mcd - Blue
I can only seem to find 3600mcd LEDs on Mouser. Is 3600mcd bright enough, or should go with 5500mcd LEDs instead?
Quote:
| Originally Posted by tomb /img/forum/go_quote.gif Proto boards have arrived! I'm going to build one and if works out, production boards will be ordered immediately. Thought you might like to see how they turned out (click for full size pics): |
Wow, the proto boards of the new version are out when I'm about to build the original version of the Millett Max ? I may have to wait until the boards for the new version of the Millett Max are available.
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