Tan Music Man

[talbany]

Perhaps we should then add this zener string (In place of the 820K) to the schematic to help protect and extend tube and cap life of the preamp at startup all together!(especially for those that did not stack ). Martin what do you think will this suffice?
BTW.We should also add a pair of diodes across the plates of the OPT Sec. on the sockets to protect from any arching.

Tony

MUSICMAN.GIF

[ToneMerc]

BTW.We should also add a pair of diodes across the plates of the OPT Sec. on the sockets to protect from any arching.

Tony

Yep, I remember that tip from you.......thanks again.

TM

[martin manning]

Perhaps we should then add this zener string (In place of the 820K) to the schematic to help protect and extend tube and cap life of the preamp at startup all together!(especially for those that did not stack ). Martin what do you think will this suffice?

That's another way to do it. Here's what I came up with.

[talbany]

So you are talking about more like that of a precision PS style:D (Doubling up on radials) Thanks Martin!
IMO opinion we should then mark your's Precision Style and mine a Classic. If no one has anything further to add? let's move on.

To All..
So after the think tank process and coming up with 2 supplies that are without a doubt more electrically stable
We should also consider the elephant in the room which is?. Why is it that of all the internal pics (5 now) of MM ODS's that I have seen, none have either of our PS mods in them and yet all of them seem to have their original caps still in an amp that is in some cases 35 years old and still sound wonderful and don't (from what I know) have a bad reputation for chewing through tubes or starting fires.

If I were manufacturing these amps to the general public you bet your ass I would insist these safety measures would be implemented!!.. However as a builder and amp designer (and many others here) who knows the rules and how these operate and don't do things like leaving it on for long periods of time unloaded or ignore using the Stby switch or loading it with crappy cheap caps w/no voltage headroom, there should be no reason why the Dumble method won't give us years of reliable service life! Dumble has already proven his MM amps appear to be very reliable!
So with all that said I think we should have the new MM layout posted exactly the way Dumble did it for historical accuracy and in the description post our 2 modified/updated Classic and Precision supplies (and recommend them highly) for those wanting to build such a M.M style ODS!..Any objections?
Thanks to all for contributing to the schematic I guess I need to get off my ass and finish the layout

BTW. I really would like to make the MM layout a low plate Skyliner since the tan Ultrasound amp is most famous and loved by so many. Like I said I don't know for certain if the pics Aaron and myself posted are of that exact amp?. If anyone here has any info on the Ultrasound please feel free to post it or if you want to remain invisible you can PM me! I know somebody out there knows something..Make the call...Ha Ha!!

Any other comments, questions, discussions, feel free!!

Tony

[Mark]

Martin, why does your power supply not have 270K resistors across the 100uF caps in the doubler circuit as HAD's circuit does?

I thought the resistors are there as a voltage divider to ensure the caps have equal voltage across them.

[talbany]

Mark
He's already told us why

Yeah but dont you still have to balance the 2 series caps?.Wish I could see some traces.

I'm sure that's what those 270k's are there for, but I don't think they are doing anything except wasting power. The upper and lower cap pairs will get charged up to peak AC 30 times per second, which is much faster than the RC time constant with the balance resistors. To do this right, though, I think all of the other caps should be stacked to cover transients and power-up without tubes installed. I'd also put a Zener on the FET filter node to protect it.

[martin manning]

Tony, I agree you should document it as in the original. I think the reason that it worked (works) fine for Dumble is that there was a bit more margin on the voltage limits. Without a load, the filters after the stacked one are seeing 450V+. These days components are designed more precisely (even the high quality ones), and it would be best to respect the stated maximums. That's where I was headed with the schematic I posted. Stacked filters can cover the required voltage capability with inexpensive and available parts. In the original, the voltages will be a little lower due to the 40k/820k divider and the 12k dropper. I'm seeing 355 for B3, 285 for B4 and 275 for B5.

BTW, 700V on the plates with 5k5 Zpri or there about is good from a plate dissipation point of view, but I'm not so sure about the 350V screen. I think something between 250 and 300V would actually be a better match.

[martin manning]

BTW, 700V on the plates with 5k5 Zpri or there about is good from a plate dissipation point of view, but I'm not so sure about the 350V screen. I think something between 250 and 300V would actually be a better match.

If I had one of these to play with I think I would try an 8-10k resistor between the choke and the screen filter to see what the difference is. A 5W would be big enough, dissipating only ~1W at idle.

[talbany]

Tony, I agree you should draw it up as in the original. I think the reason that it worked (works) fine for Dumble is that there was a bit more margin on the voltage limits. Without a load, the filters after the stacked one are seeing 450V+. These days components are designed more precisely (even the high quality ones), and it would be best to respect the stated maximums. That's where I was headed with the schematic I posted. Stacked filters can cover the required voltage capability with inexpensive and available parts. In the original, the voltages will be a little lower due to the 40k/820k divider and the 12k dropper. I'm seeing 355 for B3, 285 for B4 and 275 for B5.

BTW, 700V on the plates with 5k5 Zpri or there about is good from a plate dissipation point of view, but I'm not so sure about the 350V screen. I think something between 250 and 300V would actually be a better match.

Martin
One of the main reasons why I have been hesitant until now to post any layouts of the MM info is due to the higher voltages in this amp I would just feel awful if someone tried to build this amp with my layout without taking the proper precautions or make a slip up that could seriously injure themselves or worse!!..So needless to say this one will be filled with warnings and precautions. Thanks as always for running the numbers for us to help make sure we all build us a safer great sounding amp!!

Will go ahead and specify a 5K5 OPT for the layout then

BTW, 700V on the plates with 5k5 Zpri or there about is good from a plate dissipation point of view, but I'm not so sure about the 350V screen. I think something between 250 and 300V would actually be a better match.

As far as the screens go! Dumble uses 150 ohm 3 watt on the screens of the 6L amp, Music man uses the typical 1K5.(total) My guess would be due to the lower voltages (less protection needed) any other thoughts on why he might have lowered them down that far?

screens.jpg

Tony

[tylerbaster]

FYI this is powersupply of Bruno Super100 with EL34 I have been in.I believe the amp is clone of the Ultra Tan dumble.It was Low plate skyliner,25uf on V1 cathodes.I hope this helps!

[talbany]

Tyler
Yes the S-100 is a clone of the Ultrasound amp...Thanks for the PS schematic and the info that does help we just need the front of the amps pot values namely the OD/Drive and OD volume values as well as the value of the cathode bypass caps on the OD side( my notes have 10uf) and the value of the snubbers on V2 if you have them...I believe I have everything else I need to do that amp!.
Btw..If you have any of the voltages in the preamp that would help as well!
Thanks for the contribution!

Tony

[talbany]

Double

[tylerbaster]

Tony,I couldn't check the pot values and voltages.
Please check the photos.

https://yahoo.jp/box/qA40DP

V2 cathodes are 4.7Uf.
Snubbers are 220p.
NFB resistor is 4k7.

[martin manning]

FYI this is powersupply of Bruno Super100 with EL34...

Thanks for that, Tyler. I guess that's another vote for stacked filters all down the line.

As far as the screens go! Dumble uses 150 ohm 3 watt on the screens of the 6L amp, Music man uses the typical 1K5.(total) My guess would be due to the lower voltages (less protection needed) any other thoughts on why he might have lowered them down that far?

So which is which? I can't make sense of what you wrote there. I thought 470Ω for 6L6 amps ala Fender, and 1k or so for EL34. Above there is mention of 150Ω for the MM power supply.

On screen voltage in general I think it's about getting the load line to pass through the knee, and that is often made to occur dynamically. The 350V static screen voltage puts the load line well below the knee, and that's why I say I would like to see what happens if the screen voltage were lowered.

Does anyone have details on the Musicman power transformer? I would like to know the DC resistance of the HV secondary. I can't believe or don't understand the specs posted above, since the current rating has to be quite high to work with the doubler. Maybe that's DC current listed?

[Aaron]

Does anyone have details on the Musicman power transformer? I would like to know the DC resistance of the HV secondary. I can't believe or don't understand the specs posted above, since the current rating has to be quite high to work with the doubler. Maybe that's DC current listed?

There’s talk here, but whether it’s the correct one?
http://ampgarage.com/forum/viewtopic.php?t=26354

Thanks,
Aaron