[jdkJake]

Soon, soon.

I have a BUNCH of tubes coming. Enough to keep me busy for quite some time. I will pop in a pair of the RCA 12FM6, they are in the mix I ordered.

I am listening to the Grados with the 12AE6 set right now. Too early to comment. I need to re-adjust to the Grado sound to give it a fair comment.

As I have said in other forums, I enjoy the Grado's best straight out of my iPod touch lounging in my backyard enjoying an adult beverage and taking in the beauty of my surroundings.

Of course, the heat in Florida is just going from bake to broil, so, time to move inside and enjoy the miniMAX!

jk

 

[jdkJake]

Quote:

Originally Posted by jdkJake /img/forum/go_quote.gif Exciting night tonight! I went ahead and put in a large tube order at Beezar in order to get a good selection of tubes to try out. Tom set me up with a great selection that is currently on it's way. I AM SO PSYCHED!! In the meantime, I also had Craig at Whiplash send me a set of the Matsushiita 12AE6 that GradoFan2 mentioned above. Photos are attached below. Based upon what I have already read (and Tom has taught us), these might actually be Tung-Sol. But, I do not know for sure as I have never seen one to compare. In any case, I rolled them into the miniMAX, biased them up and went for a listen! They stabilized fairly quickly (within an hour). It was a very straightforward process, but, necessary as the FM6 settings were greater than 20V with the AE6! Anyway, they need a ton of more hours on them, but, right off, the are quite different. Very smooth. Even smoother than the Sylvania FM6. They have lot's of slam and dynamics. And BASS! Let me tell you, these are NOT bass shy. Far deeper and more of it than the Sylvania FM6 ever had. As far as extension goes, the Sylvania FM6 have a sweeter, more forward and more extended top end. The soundstage is a bit smaller with the AE6 as well. Must be all that extra bass coming through. Man, it this bass was paired with the treble/soundstage of the Sylvania FM6, well, let me tell you, that would be the sound to rule them all! I will live with these a while until the others start to show up. It will be interesting to hear how they "age". This is so, so cool! Being able to completely change the character of your amp for a few bucks is most rewarding. I cannot wait for the "Beezar Box of Goodness" to show up. jk

I confirmed these are indeed Tung-Sol. They look exactly like the set I received from Beezar. Same marking, construction and getter placement.

jk

 

[tomb]

Quote:

Originally Posted by jdkJake /img/forum/go_quote.gif I confirmed these are indeed Tung-Sol. They look exactly like the set I received from Beezar. Same marking, construction and getter placement. jk

Thanks for confirming, but I suspected as much: it sounds like Matsush*ta imported them from Tung-Sol. Tung-Sol actually invented the "space-charge" tube and were the first to design and manufacture these low-voltage tubes. GE, RCA, and Sylvania were the other mfrs, but the brands painted on the tubes and on the boxes are as numerous as with any other tube - perhaps more so.

Jeff Duntemann has an excellent article on space-charge tubes that gives a little wider perspective than you'll find on the MAX/MiniMAX website tube pages:
Space Charge and Other Low-Voltage Tubes
Be careful if you look at it right now. I've sent Jeff an e-mail about it, but it's obviously been hacked pretty bad. Still, if you can get past the hacked links, the rest of the info is still there.

The Internet is getting to be a tough place these days ...

 

[xodeuce]

Is there any difference b/t the mini-max and the regular max other than the board layout and power supply circuit?

 

[tomb]

Quote:

Originally Posted by xodeuce /img/forum/go_quote.gif Is there any difference b/t the mini-max and the regular max other than the board layout and power supply circuit?

The regulated power supply circuit on the MiniMAX was much improved over the regular MAX. That resulted in more detail, tighter bass, etc. Whether the difference is striking vs. incremental depends on your listening experience with the Millett Hybrid. I would say that the MiniMAX is as good as a Millett Hybrid with Diamond BJT buffers can be, period - it's that refined.

The new V1.2 MAX board incorporates the same power supply as the MiniMAX, but it's not quite available, yet. Glass Jar Audio should have kits when it is, though. The biggest difference between the two amps is that the regular MAX can be built with a Diamond-MOSFET-buffer. As far as we know, a Diamond-MOSFET-buffer is unique in DIY and commercial amps (guess I'll find out after saying that

).

 

[Gradofan2]

Quote:

Originally Posted by tomb /img/forum/go_quote.gif The regulated power supply circuit on the MiniMAX was much improved over the regular MAX. That resulted in more detail, tighter bass, etc. Whether the difference is striking vs. incremental depends on your listening experience with the Millett Hybrid. I would say that the MiniMAX is as good as a Millett Hybrid with Diamond BJT buffers can be, period - it's that refined. The new V1.2 MAX board incorporates the same power supply as the MiniMAX, but it's not quite available, yet. Glass Jar Audio should have kits when it is, though. The biggest difference between the two amps is that the regular MAX can be built with a Diamond-MOSFET-buffer. As far as we know, a Diamond-MOSFET-buffer is unique in DIY and commercial amps (guess I'll find out after saying that ).

And... larger VQ output caps???

Anyway... what's the benefit of the Diamond-MOSFET-buffer vs the Diamond-BJT-buffer in the MiniMax???

 

[tomb]

Quote:

Originally Posted by Gradofan2 /img/forum/go_quote.gif And... larger VQ output caps??? Anyway... what's the benefit of the Diamond-MOSFET-buffer vs the Diamond-BJT-buffer in the MiniMax???

I should've also said the biggest difference is that the MAX V1.2 has an onboard BantamDAC, too.

Anyway, the biggest difference electronically is that the MiniMAX BJT Diamond buffer tops out at 50ma Class A bias (BJT's don't improve much beyond that, anyway). The MOSFET Diamond buffer can run at 120ma - I've had it as high as 150ma.

As for the differences in sound with the MOSFETs, I think SACD-Lover has expressed some opinions in the past. I also know what my opinion is, but I'll have to let some others build the new versions, first, and see if they agree.

Again, both are quality amps, IMHO, and each will have their niche. The MOSFET-MAX will necessarily be much bigger, more expensive, and will probably not lend itself to much outside of DIY, but we'll see ...

 

[jdkJake]

So what does 120ma of bias bring to the table?

I take it you are are pleased with the sound of the new design?

jk

 

[ecclesand]

Quote:

Originally Posted by jdkJake /img/forum/go_quote.gif So what does 120ma of bias bring to the table? I take it you are are pleased with the sound of the new design? jk

So how do your Grados sound with the 12AE6?

My MiniMax is on it's way and I can't wait to try it with my RS2. One of the reasons I haven't tried tubes until now is because of the heat they generate. Does the MiniMax generate a lot of heat?

 

[tomb]

Quote:

Originally Posted by jdkJake /img/forum/go_quote.gif So what does 120ma of bias bring to the table? I take it you are are pleased with the sound of the new design? jk

Yes.

 

[tomb]

Quote:

Originally Posted by ecclesand /img/forum/go_quote.gif So how do your Grados sound with the 12AE6? My MiniMax is on it's way and I can't wait to try it with my RS2. One of the reasons I haven't tried tubes until now is because of the heat they generate. Does the MiniMax generate a lot of heat?

Class A design dictates that an amp runs hot. That's not because of the tubes, but because of the transistors.

The transistors are biased so that the constant current is more than most headphones will ever need. That keeps the transistors from having to switch on and off in response to the signal, which increases distortion due to the switching components. So, the current is always turned on. That means the transistors generate heat and there are heat sinks and cooling slots in the amp to keep things cool.

This is the ultimate style of design for headphone amps and is incorporated in almost all DIY designs, including the PPAV2, the M3, the Dynahi/Dynamite and the B22. Note that none of those designs mentioned use tubes.

I think you'll find that the cooling capability of the MiniMAX custom-machined case is pretty good, however, and will stay pretty cool, relatively speaking. The tubes, too, since they are essentially running at ~13.5V, are relatively cooler compared to some of the high-voltage stuff.


P.S. As a matter of fact, the design of the MiniMAX case is such that the amp actually runs cooler with the case than running as a bare, exposed PCB without case.

 

[Gradofan2]

Quote:

Originally Posted by ecclesand /img/forum/go_quote.gif So how do your Grados sound with the 12AE6? My MiniMax is on it's way and I can't wait to try it with my RS2. One of the reasons I haven't tried tubes until now is because of the heat they generate. Does the MiniMax generate a lot of heat?

It does generate a bit of heat - I wouldn't call it a lot - not anywhere as much as my DV332 did. But... the amp does feel warm if you place your hand on it - though, not warm enough to burn you, or feel very uncomfortable. It has good ventilation, and allows the heat to escape to prevent it from becoming too warm.

 

[ecclesand]

Quote:

Originally Posted by tomb /img/forum/go_quote.gif Class A design dictates that an amp runs hot. That's not because of the tubes, but because of the transistors. The transistors are biased so that the constant current is more than most headphones will ever need. That keeps the transistors from having to switch on and off in response to the signal, which increases distortion due to the switching components. So, the current is always turned on. That means the transistors generate heat and there are heat sinks and cooling slots in the amp to keep things cool. This is the ultimate style of design for headphone amps and is incorporated in almost all DIY designs, including the PPAV2, the M3, the Dynahi/Dynamite and the B22. Note that none of those designs mentioned use tubes. I think you'll find that the cooling capability of the MiniMAX custom-machined case is pretty good, however, and will stay pretty cool, relatively speaking. The tubes, too, since they are essentially running at ~13.5V, are relatively cooler compared to some of the high-voltage stuff. P.S. As a matter of fact, the design of the MiniMAX case is such that the amp actually runs cooler with the case than running as a bare, exposed PCB without case.

Quote:

Originally Posted by Gradofan2 /img/forum/go_quote.gif It does generate a bit of heat - I wouldn't call it a lot - not anywhere as much as my DV332 did. But... the amp does feel warm if you place your hand on it - though, not warm enough to burn you, or feel very uncomfortable. It has good ventilation, and allows the heat to escape to prevent it from becoming too warm.

Very good information...thank you for that. This is my first tube amp and I'm just learning what a getter is and what biasing tubes means and what each type of tube offers and how to roll tubes..and...and...and...

I can see where the MiniMax enclosure itself acts as a heatsink.

 

[jdkJake]

TomB,

I am still curious as to what the extra bias available with the new MOSFET MAX brings to the table (120mA vice the 50mA of the miniMAX).

Is it just more available current or is it more than that?

Thanks

jk

 

[jdkJake]

Quote:

Originally Posted by ecclesand /img/forum/go_quote.gif So how do your Grados sound with the 12AE6? My MiniMax is on it's way and I can't wait to try it with my RS2. One of the reasons I haven't tried tubes until now is because of the heat they generate. Does the MiniMax generate a lot of heat?

Well, I have tried the SR225i with a set of Tung-Sol 12AE6 tubes. They sounded really nice with that tube. It was a very fun listen, typical Grado! I found the Tung-Sol has a big, extended bass that I think helps the Grados. They also take a slight bit off the top without really effecting the mids, which, with Grado's I think helps the sound a lot. I need more time to get a better impression, but, what I did hear I liked very much.

I am currently using a Sylvania 12AE6 which, has a sound characteristic closer to the Sylvania 12FM6 I have on hand. I have yet to use the Grados with that tube, but, with the HD650's, it is very, very impressive. Better bass than the Sylvania 12FM6 with far better dynamics and presence. While the bass is not a big and extended as the Tung-Sol, the mids and highs are heavenly. I really like the Sylvania highs on both the 12FM6 and 12AE6. I think (and others agree) the high gain of the 12AE6 is a better match for the HD650 and really makes it shine. I only have a dozen or so hours on them, but, I can't imagine them getting much better. Probably the most balanced sound I have heard so far. Very sweet indeed.

I have some Tung-Sol 12FK6's to try as well. These are low gain tubes better suited for low impedance phones like the grado. I will try to get to those soon, but, right now, the Sylvania 12AE6/HD650 combo is very, VERY hard to put down!!

jk