Tan Ultrasound Build

talbany · Post by **talbany** » Sat Jun 16, 2018 2:03 pm

Hey Guy's
Here is my latest effort just getting started I thought I would post my progress here for those who want to watch the build.
The inspiration behind this one has been the sound clips of the famous Tan Ultrasound Music Man amp.I am trying to stick as close to the original as possible with the exception of a few parts I am partial too. I do prefer the Classic power supply loaded with TVA's instead of the more modern Precision PS and added some extra filtering o keep the amp tight at high volumes!
Will try to post more shots as the build progresses.So far it's been fairly slow given my work schedule and time on the road. It's been over a year since my last ODS build so hopefully this will go smoothly.Let me know if you have any questions!
BTW.Thanks to Charlie Wilson and Stelligan for the donors!
Enjoy
Tony

norburybrook · Post by **norburybrook** » Sat Jun 16, 2018 5:06 pm

very nice

What are the power tube sockets? not seen those before.

some interesting resistors and caps on your board. Are they MEPCO metal films on the plates? that's what I used on my current build.

looking forwars to seeing this take shape.

M

Matt J · Post by **Matt J** » Sat Jun 16, 2018 5:58 pm

Looks cool!

I can't wait to see how this turns out, especially considering all the things I've heard over the years about that particular tan ODS.

Has anyone ever gone into detail on the circuitry differences between the tan ODS and ODS #183?

- Matt J.

talbany · Post by **talbany** » Sat Jun 16, 2018 9:06 pm

norburybrook wrote: ↑Sat Jun 16, 2018 5:06 pm very nice

What are the power tube sockets? not seen those before.

some interesting resistors and caps on your board. Are they MEPCO metal films on the plates? that's what I used on my current build.

looking forwars to seeing this take shape.

M

Marcus
The MF's are Rodderstien MK'3 on the plates.Dumble used these resistors in amps like 183/124/192 and many other 5th generation amps.The lighter Blue MF's are NTE WH's again another resistor Dumble used allot in both plates and path!
The tan CF's are Draloric's, These are basically the same (composition) type resistor as the Q-lines Dumble used in again many of his builds (Especially 3rd 4th generation's). The Red ones are of coarse Pihers these were used mostly in the very early 2nd generation amps. Mine is really kind of an amalgamation of all the different types of resistors Dumble used in many of his ODS's over several generations. I prefer to use primarily CF's in the signal path of my low plate amps

.For me, High plate amps don't seem as picky as which type of resistor used in the signal path.
The brown precision resistors used in the original U.S amp are of the earlier ceramic composition RN series and are extremely rare and impossible to find!..
Not really sure of the brand tube socket I bought them from Mojotone. I figured it might be a good idea to use these in an amp with 700V on the plates given that the pins are nice and spread out to help minimize any arching that might happen.

Here is what I believe to be the Ultrasound amp..

BTW.The only Mepco in the amp are the bypass caps for V2

Tony

talbany · Post by **talbany** » Sat Jun 16, 2018 9:13 pm

Matt J wrote: ↑Sat Jun 16, 2018 5:58 pm Looks cool!

I can't wait to see how this turns out, especially considering all the things I've heard over the years about that particular tan ODS.

Has anyone ever gone into detail on the circuitry differences between the tan ODS and ODS #183?

- Matt J.

Matt
183 is a High plate Skyliner no LNFB V1B
The Ultra amp is a Low plate Skyliner w/LNFB V1B using Music Man Iron.Both amps are loaded with EL-34's
That's basically it

Tony

talbany · Post by **talbany** » Fri Jun 22, 2018 6:37 am

Moving along nicely!.Output section sockets wired, Bias board and Relay boards wired and installed.Next are filter caps/Preamp board Stack and filaments.So far I am really enjoying the build..Will shoot some better shots closer to the completion so you can have a better idea how thing are wired

Thanks for looking

Tony

talbany · Post by **talbany** » Fri Jun 22, 2018 6:42 am

Front

M Fowler · Post by **M Fowler** » Fri Jun 22, 2018 11:59 am

Great looking build Tony.

Mark

Post by **pompeiisneaks** » Fri Jun 22, 2018 4:24 pm

Looks great! Couple of questions.

1. where do you get new Sprague Atoms that are yellow like that? Or are those NOS caps. As for NOS caps I though electrolytics, if sitting on the shelf that long were very suspect? How do you ensure they're going to last?
2. I see those screen resistors (I think they're screen) on the power tubes up and connected to a couple long leads of thick gauge copper wire. How do you make sure those won't vibrate and break over time? Does that get connected into something more solid later in the build?

Love learning new tricks so gotta ask

~Phil

AtomCap · Post by **AtomCap** » Sat Jun 23, 2018 7:59 am

date codes of 1979 and 83 on those caps, fwiw - pushing your luck.. just sayin, nice build tho!

talbany · Post by **talbany** » Sat Jun 23, 2018 2:14 pm

pompeiisneaks wrote: ↑Fri Jun 22, 2018 4:24 pm Looks great! Couple of questions.

1. where do you get new Sprague Atoms that are yellow like that? Or are those NOS caps. As for NOS caps I though electrolytics, if sitting on the shelf that long were very suspect? How do you ensure they're going to last?
2. I see those screen resistors (I think they're screen) on the power tubes up and connected to a couple long leads of thick gauge copper wire. How do you make sure those won't vibrate and break over time? Does that get connected into something more solid later in the build?

Love learning new tricks so gotta ask

~Phil

The Caps are NOS surplus have been reformed and leak tested as well as tested under load for several days.
As far as cap shelf life and reforming it depends on several factors as well as the quality of the cap.
Here is a good paper on it.

The resistors you are talking about are the grid resistors. The screen resistors are the 1K ceramics on the sockets. These are generally flown in Dumble (and many other amps) since there are no more empty pins available on the sockets.If you don't want to fly them you can mount them on terminal strips.

Hope this helps!

pushing your luck

Thanks for the warning

Tony

dorrisant · Post by **dorrisant** » Sat Jun 23, 2018 2:54 pm

Pulling up a chair....

Post by **pompeiisneaks** » Sat Jun 23, 2018 5:04 pm

Cool thanks, I guess I've been told in the past that leaving them hanging was a recipe for vibrations to cause them to snap, I've done something similar in past builds, and just shrink tubed around the open areas so they don't have a chance of arcing somewhere. Good to know the risk is a bit overblown

Looks outstanding though, thanks for the amp porn!

~Phil

talbany · Post by **talbany** » Sat Jun 23, 2018 8:16 pm

AtomCap wrote: ↑Sat Jun 23, 2018 7:59 am date codes of 1979 and 83 on those caps, fwiw - pushing your luck.. just sayin, nice build tho!

1983's/85's loaded in my Bluesmaster 2 years ago.

Hey I get using old caps in a Musicman might seem risky and hey for all I know they might get hot

and need to come out!..You never know?? (I've had new caps go).. I like the old TVA's and want to give them a shot...If they don't work out? out they will come..

The advantages of building your own amps and trying some things you might not normally do selling and building for the general public.

If it breaks I can fix it

Tony

stelligan · Post by **stelligan** » Mon Jun 25, 2018 4:37 pm

Fun thread. When we gonna hear it?

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