Tan Ultrasound Build

[talbany]

Getting close
Cap & Preamp boards installed. Stack wired and filaments all wired up..Passed the smoke test Voltages look good! including Bias and Relay power supply..I need to finish running some coax and input and Fet board!..Right now I am waiting on a few more parts as well as my glass Hopefully be here in the next day or so..I need to run a few more tests on my caps before firing up to full load..So far no smoke or weird limps
These builds are a test of your patience and focus for sure I completely forgot how demanding these builds can be..Hopefully, this beast will SCREAM!!

BTW.I did add the Zener string on the preamp since these caps are NOS and only 450V rated..

Tony

[talbany]

ONE MORE

[martin manning]

Tony did you try anything special to reform the caps, like temporarily putting a large resistor after the rectifier?

[norburybrook]

Looks fabulous


M

[BarryW]

I love those dual relay boards, I need some of those.

That's really a beaut Tony, great work. Can't wait to hear it!

[talbany]

Tony did you try anything special to reform the caps, like temporarily putting a large resistor after the rectifier?

Exactly! (100k 5W)..The Plate caps and B+2 have already been formed up and check out OK, however the PI and V2 I have to form up check ESR totals and for any leakage. All the caps check out at or slightly above uF ratings before installation, I will be doing this later tonight. Any advice or recommendations are of course always appreciated from you!

Thanks for checking in!
Tony

[talbany]

I love those dual relay boards, I need some of those.

That's really a beaut Tony, great work. Can't wait to hear it!

Barry
The boards are cool we made those when I was still at VVT I only have 1 left or would be glad to send you some!..Thanks for the compliment and can't wait to hear it growl as well.I will pot some clips when it starts breathing.

Looks fabulous

Thanks M

Tony

[martin manning]

Tony did you try anything special to reform the caps, like temporarily putting a large resistor after the rectifier?

Exactly! (100k 5W)..The Plate caps and B+2 have already been formed up and check out OK, however the PI and V2 I have to form up check ESR totals and for any leakage. All the caps check out at or slightly above uF ratings before installation, I will be doing this later tonight. Any advice or recommendations are of course always appreciated from you!

The only thing I might add is to monitor the voltage across that resistor and see if it is dropping or stable, and of course what you are seeing (if there is no load anywhere) is the total leakage current through all the filters.

[telentubes]

Always a pleasure to follow your projects

[talbany]

"IT IS ALIVE"

Apart from a bad new input jack? Amp fired right up worked perfectly Voltages settled out
B+1 695
Screens 345
PI 280/287
V2-223/220
V1-213/214
Voltages on V1 and V2 are a little high if I lift my 10k dropper to around a 12K (like Dumble did) would be about perfect!!
However, I am digging it!
I exchanged out the MK'3 plates for period correct (1981) Dale's like the ones used in the Ultrasound amp was a nice upgrade! (Thanks to CW) The amp sounds good with either LNFB V1b on or off, however, I actually prefer it on when in OD. Unfortunately, one of my new TAD EL-34's didn't light so I am not able to give a full review or do clips until I get the amp with a fresh set and dialed in. I still have to wire up and adjust the FET (I may put that on a relay as well).As soon as I do I will give my full review and let you know what I think.
The main difference between my amp and the original Ultrasound amp are?
Mine has
Classic Power supply w/ 3 150W Zener start-up diodes
50uF more filtering on the plates (To help keep the 34's tighter longer)
25uF more filtering on the screen supply for better regulation on new production EL-34's
Polystyrene .01 OD1 cap instead of the usual PS series for a slightly tighter bass response of OD side
2uF Presence cap instead of a 1Uf ala 102 value.
Apart from the power supply all of the values are just as the Tan Ultrasound Music Man amp.
Hope you enjoy the shots and let me know if you have any questions!

Happy 4th of July.

Tony

[talbany]

A few more

[erwin_ve]

Looks great and clean! After soldering: do you clean with alcohol? I Always get a bit of stripes, yours are completely clean.
Is there any reason you put the cathode bypass caps on top of the resistor?
That shiny cap on v2a, what is that?

With 700v on the plates any precautions with distances between wiring or mounting holes? I mean on the safety side.
Thanks for posting, might try this in the future.

[talbany]

Looks great and clean! After soldering: do you clean with alcohol? I Always get a bit of stripes, yours are completely clean.
Is there any reason you put the cathode bypass caps on top of the resistor?
That shiny cap on v2a, what is that?

With 700v on the plates any precautions with distances between wiring or mounting holes? I mean on the safety side.
Thanks for posting, might try this in the future.

Erwin
I used to use alcohol but always left a slight haze. This is what I use now..The blackboards I use look good however it shows every smudge. The only thing about this flux remover it can remove some paint on the older resistors and markings on the caps so use sparingly..Also, use gloves when you use it as it's toxic as hell!
I updated my post to list the differences between mine and why I made some changes. The clear cap on OD1 is a Sprague .01 600V polystyrene cap..They sound very similar to the PS caps we use, I like to use them in that spot as I have found them to give me a slightly more focused low-end response in OD..Other than that they sound just like a PS cap!
No real reason why I put the cap above the resistor there.The bypass resistors I used were the new smaller Dales and are not very tall.
As far as some HV precautions you may want to use are! The new sockets from Mojotone as they are nice and spread out further than the standard pin ones. Other than that not really other than placing a pair of diodes across the output transformer primaries to help with some flyback arching.
If you go with the classic PS you may want to add a string of Zeners after the 40k PI dropper to keep the voltages down during startup,

Hope this helps!
Tony

[martin manning]

Looks phantasmagorical!

[talbany]

Looks phantasmagorical!

Thanks Martin..I think.

Tony