[tomb]

Quote:

Originally Posted by joneeboi /img/forum/go_quote.gif I was wondering, as I often do when staring at the insides of my MAX, and I thought about what it would be like to have a 3 channel MAX. How would that work? One way would be to populate a board and a half and use one channel as the GND. Does that make sense electrically or pragmatically? We currently use a huge ground plane, so how does that affect the implementation of a 3rd channel? How would input and output grounds be connected to the board? Wouldn't you just wire the input ground to, say, the left channel and take output ground to be the left output? I don't have any balanced sources nor do I plan on having any in the near future, so pulling a pabbi would be so very nice and useless for me. I don't suppose Team Millett wants to focus on a 3CH design anytime soon. What do we allegedly have on tap at the moment? MiniMAX, Super MAX, 12AU7/12AX7 (or whatever) MAX? Is a 3rd channel even worth my internet chat breath?

As for the 3rd channel, I've discussed the possibility with Colin, but the single-ended, negative ground topology presents some problems. The easiest way to do it is to make the buffers into 3 channels using a TLE or a voltage divider of some sort. Sinking lots of current will become an issue that way, so I'm not sure.

Ferrari has built one like that - I'd send him a note and see if he can explain it to you.

As for what's on tap - I'm in the middle of creating two new websites for the MAX. One is projected for mid-March, although that may slip a little due to the IRS.

My intent is to focus on a much more step-by-step set of instructions for building one from the board up - especially for the MOSFETs. Also, I sort of hinted at this earlier, but I'm going to use a couple of new cases that will be detailed as well. Hopefully, the design will also incorporate a method for building and installing an Alien DAC in the case - which will be no bigger than the standard MAX. There are a few tricks that I've come up with to make it work.

Beezar will carry the MOSFETs and JFETs, too.

The MiniMAX is due probably a month later, but we'll be depending on Colin for that one. He's had a little trouble with trace routing around the middle heat sinks. I believe he's been trying to open the distance up between them because on the Mini, the output bypass caps go between the middle two sinks.

Beezar added 12AE6 and 12FK6 tubes tonight, along with a few other trinkets. RK27's are still slated for March 31st.

 

[Ampersand]

Hello,

Just finished my 2nd MAX build and I'm having a bit of a problem. BTW, the first build went flawlessly

.

Tubes and buffers bias fine. I don't hear the relay click like I do in the first MAX. Could the relay be faulty?? Is there a voltage I can check??

In the meantime, I'll double check my resistor values within the Delay circuit.

Thanks,
Mike

 

[joneeboi]

That sounds really great, Tom. It's a bummer to hear about the IRS thing. What do they have a problem with? And thanks for the update on the website stuff. As most newbies would agree, it's always better to have a detailed, step-by-step instruction guide to help through the build. Just for kicks, we could go through the pages of the thread and count the number of times people have accidentally flipped the buffer trannies.

Also, it'll be cool to see how you intend to incorporate the Alien DAC into the MAX. I think we're all aware of how much you enjoy it, so it's good to see how those projects are naturally fusing together through your continued participation on these forums. I'm so glad I got to be part of this chapter in history.

Finally, I'm sure I speak on behalf of everyone on Team Millett MAX when I say, "Thank you, Colin and Tom, for all your incredible and immeasurable contribution and commitment to this project."

 

[chilly]

Hey everyone,

just wanted to let everyone know, another Max lives... I just finished around 4 this afternoon, I did have some minor problems biasing.... but once I figured out how to read a DMM. (This is only my second electronics project, The soha was my first)

The 2 problems I have now, one is that the gain is probably to high ( I am using UE-5c's as my headphones and their really low ohm 24 or so I think.), I'm using the 12ae6's I have just ordered the other 2 sets. So we will see how that goes.

The other problem I have is I have a noisy pot. Not sure what to do about that as its already soldered to the board.

SO my thanks to all of you, and Tomb, as I couldn't have dones this without you and the website.

Thanks

chilly

 

[pabbi1]

Quote:

Originally Posted by joneeboi /img/forum/go_quote.gif I was wondering, as I often do when staring at the insides of my MAX, and I thought about what it would be like to have a 3 channel MAX. How would that work? One way would be to populate a board and a half and use one channel as the GND. Does that make sense electrically or pragmatically? We currently use a huge ground plane, so how does that affect the implementation of a 3rd channel? How would input and output grounds be connected to the board? Wouldn't you just wire the input ground to, say, the left channel and take output ground to be the left output? I don't have any balanced sources nor do I plan on having any in the near future, so pulling a pabbi would be so very nice and useless for me. I don't suppose Team Millett wants to focus on a 3CH design anytime soon. What do we allegedly have on tap at the moment? MiniMAX, Super MAX, 12AU7/12AX7 (or whatever) MAX? Is a 3rd channel even worth my internet chat breath?

Keep in mind I also added in the balanced source (OPUS DAC) into the solution. While I do have a balanced source player as well, my implementation was to also get balanced source with a very modest transport. I am thinking you want something along the lines of Millett output with a m³ or Beta22topology? You might also ping Ti Kan (Amb) about how to do this with two boards, and, if there is any gain, or severe downside.

Now, I am curious about the status of that all tube DAC...

 

[cronic]

Quote:

Originally Posted by ruZZ.il /img/forum/go_quote.gif cronic: Do you mean the tube bias trimmers? They may need quiet a few turns before you see response. They're 20 turn trimmers. most importantly, make sure your db's are biased right. 0.04v like you said above is good to start. Try use the mV scale and get them accurately matched, too.

Yes its the tube bias. I can only get 24 v no matter where the trimmer is set with the 12ae6a tube. I have the db set to 50.02mV. The 12fk6 tb sets the way it should, but with the 12ae6a tubes installed only 24 volts. Is that a sign of bad tubes?

 

[tomb]

Quote:

Originally Posted by cronic /img/forum/go_quote.gif Yes its the tube bias. I can only get 24 v no matter where the trimmer is set with the 12ae6a tube. I have the db set to 50.02mV. The 12fk6 tb sets the way it should, but with the 12ae6a tubes installed only 24 volts. Is that a sign of bad tubes?

I think what Russ is saying is that it doesn't make sense. The chances of having two 12AE6's that won't bias is small to impossible. I'm speaking for him, too, but I think we both suspect that you're not turning the trimmers far enough. Most of the ones spec'd for the MAX and Millett are 25-turn trimmers. The 12AE6 biases at the other end of the trimmers, if I remember correctly - and it may only bias in the last 4 or 5 turns.

I'd try while listening for a click to be sure you don't tear up the trimmers. If you have Murata's (recommended), they won't break. Anyway, leave the tubes up and running for about a half-hour, then try it again.

Like I said, it's almost impossible that they could both be bad and also have your 12FK6's bias fine.

 

[tomb]

Quote:

Originally Posted by chilly /img/forum/go_quote.gif Hey everyone, just wanted to let everyone know, another Max lives... I just finished around 4 this afternoon, I did have some minor problems biasing.... but once I figured out how to read a DMM. (This is only my second electronics project, The soha was my first) The 2 problems I have now, one is that the gain is probably to high ( I am using UE-5c's as my headphones and their really low ohm 24 or so I think.), I'm using the 12ae6's I have just ordered the other 2 sets. So we will see how that goes. The other problem I have is I have a noisy pot. Not sure what to do about that as its already soldered to the board. SO my thanks to all of you, and Tomb, as I couldn't have dones this without you and the website. Thanks chilly

Thanks for the compliment!

I hate to say this, but using IEM's is probably not the best choice with a tube amp, even if it is a hybrid. You may need 100ohm output resistors or more to tame the gain and also the noise.

Most likely, the noise in the pot you're hearing is tube noise. Scratchiness occurs if the tubes aren't completely stable and/or have some less-than-optimum connections on the pins. Try switching the tubes and see if that alters the pot noise slightly. If it's an ALPS, it's probably the tubes plus your IEMs.

 

[tomb]

Quote:

Originally Posted by Ampersand /img/forum/go_quote.gif Hello, Just finished my 2nd MAX build and I'm having a bit of a problem. BTW, the first build went flawlessly . Tubes and buffers bias fine. I don't hear the relay click like I do in the first MAX. Could the relay be faulty?? Is there a voltage I can check?? In the meantime, I'll double check my resistor values within the Delay circuit. Thanks, Mike

The most common cause of this problem with most MAX builders is installing the BD139 backwards. Take a look on the MAX website at Tweaks -> e12 Delay. At the bottom of the page, I included a key plan and detail of how to recognize the proper orientation of the BD139 in the relay circuit.

One good thing is that the BD139 doesn't seem to damage itself in this condition if that's what your problem is. So, just take it out and turn it around.

Let us know if that's it.

 

[cronic]

Quote:

Originally Posted by tomb /img/forum/go_quote.gif I think what Russ is saying is that it doesn't make sense. The chances of having two 12AE6's that won't bias is small to impossible. I'm speaking for him, too, but I think we both suspect that you're not turning the trimmers far enough. Most of the ones spec'd for the MAX and Millett are 25-turn trimmers. The 12AE6 biases at the other end of the trimmers, if I remember correctly - and it may only bias in the last 4 or 5 turns. I'd try while listening for a click to be sure you don't tear up the trimmers. If you have Murata's (recommended), they won't break. Anyway, leave the tubes up and running for about a half-hour, then try it again. Like I said, it's almost impossible that they could both be bad and also have your 12FK6's bias fine.

Yes, I understand what you are saying. I have tried them all the way to either side. Click to click either way I get 24 v. I also noticed that I get no glow at all out of the 12ae6a, whereas the 12fk6 have a nice glow at the tip. The 12ae5a are also dead cold, whereas the 12fk6 get nice and warm after bing on for a while. Bad tubes?

 

[tomb]

Quote:

Originally Posted by joneeboi /img/forum/go_quote.gif <snip>Finally, I'm sure I speak on behalf of everyone on Team Millett MAX when I say, "Thank you, Colin and Tom, for all your incredible and immeasurable contribution and commitment to this project."

Thank you so much for such a complimentary post, Joneeboi! It means a lot from someone like you, who's been with the project for so long.

Not to worry about me and the IRS (I hope, anyway). It's just that it takes me about two solid months of weekends to do my taxes.

 

[Ampersand]

Thanks for the quick response. No, the BD139 is in there correctly. I have the two MAXs side-by-side. All components in the Delay circuit are in the correct orientation.

Any other ideas?

BTW, the tubes I'm using to test this 2nd MAX are the ones I just pulled from the 'working' MAX.

Thanks,
Mike

 

[cetoole]

Quote:

Originally Posted by cronic /img/forum/go_quote.gif Yes, I understand what you are saying. I have tried them all the way to either side. Click to click either way I get 24 v. I also noticed that I get no glow at all out of the 12ae6a, whereas the 12fk6 have a nice glow at the tip. The 12ae5a are also dead cold, whereas the 12fk6 get nice and warm after bing on for a while. Bad tubes?

My money (nickel) says one of your 12AE6A tubes has an open heater. Use your DMM (you have one, right) on continuity, or resistance mode, and test the heater pins on each tube. I bet you will find one that is quite low and one that is infinite resistance. Its rare, but happens, and if you find one like this, you just gotta pony up the few bucks and replace it.

 

[cronic]

Quote:

Originally Posted by cetoole /img/forum/go_quote.gif My money (nickel) says one of your 12AE6A tubes has an open heater. Use your DMM (you have one, right) on continuity, or resistance mode, and test the heater pins on each tube. I bet you will find one that is quite low and one that is infinite resistance. Its rare, but happens, and if you find one like this, you just gotta pony up the few bucks and replace it.

Thanks man, I measured continuity between pin 2 and pin 3 on both tubes. One reads up to 110 ohms and then falls at a constant rate ohms and the other reads 0 ohms. Looks like thats the issue.

 

[Daveze]

Quote:

Originally Posted by joneeboi /img/forum/go_quote.gif I was wondering, as I often do when staring at the insides of my MAX, and I thought about what it would be like to have a 3 channel MAX. How would that work? One way would be to populate a board and a half and use one channel as the GND. Does that make sense electrically or pragmatically? We currently use a huge ground plane, so how does that affect the implementation of a 3rd channel? How would input and output grounds be connected to the board? Wouldn't you just wire the input ground to, say, the left channel and take output ground to be the left output? I don't have any balanced sources nor do I plan on having any in the near future, so pulling a pabbi would be so very nice and useless for me. I don't suppose Team Millett wants to focus on a 3CH design anytime soon. What do we allegedly have on tap at the moment? MiniMAX, Super MAX, 12AU7/12AX7 (or whatever) MAX? Is a 3rd channel even worth my internet chat breath?

I've considered this a wee tad. I was thinking that an original Millet with 3 x JISBOS on the back end might work nicely. Using two tubes for voltage gain, then implementing the 3rd channel just on the current stage.