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Old 4th August 2013, 11:30 AM   #881
kazap is offline kazap  Australia
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Thanks Rod for that very interesting advice.

It might be tempting to experiment ...The Tube CAD Journal: Voltage regulators for the 2A3

I used an under-volted computer fan below my Tram2 just for cooling the old regulators and the fan was silent from 40cm or so. It didnt cool the toroid cover down - predictable with it sited on top but running the Tram2 on 220V did. I dont think the internals of the Tram2 run that hot after shooting temps with an infra-red thermometer and I have no plan to go back to using a fan.
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Old 4th August 2013, 12:05 PM   #882
rab28 is offline rab28  Australia
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Quote:
Originally Posted by beardman View Post
From ground to DHT Anode there should be 120v,,,if this volt is not right,you will have a good deal of noise..
Hi Bjarne, you were right on the money: today i measured the anode voltages as 147V (!) and 129V. I adjusted both to 120.0+-0.1V, and the noise completely disappeared. Thank you!

However - and i could be imagining things here - in the admittedly fairly brief listen i had after reinstalling the Tram2 into my system, although the noise had gone, i had the feeling that the sound was a bit less 'alive' than usual... I'll see how that goes when i get a chance to listen again (my system is in the living room of our small home (with 2 young boys), so my listening sessions are sadly all too rare).

Also I was asked to post a picture of my Coleman regulator installation, so here it is:
Click the image to open in full size.

Apart from my cat sticking his nose in at the left, you might notice there are small fans mounted to the heatsinks at either end of the copper bar. I have not heard any fan noise, but at least when i had the Tram2 open, it was not hot enough to start them running after about an hour.

You might also notice the paralleled Obbligato output caps (thanks Morten!), and Duelund Alexander input caps. The resistors in the signal path have been replaced with Shinkoh tantalums.

- richard
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Old 4th August 2013, 12:45 PM   #883
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To rab28
You have right when you say that the sound is different with the change in anode volt--
i can hear it when i adjust mine Tram...when the volt is under 120, there is one sound (typical more bass and warm sound)..i am not sure what happen with volt over 120...
but with 120v much lower noise.but also a bit colder more hard sound ..a little funny ^^
Best Bjarne
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Old 4th August 2013, 12:49 PM   #884
Desmo is offline Desmo  Denmark
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Originally Posted by rab28 View Post
anode voltages as 147V (!) and 129V. I adjusted both to 120.0+-0.1V

- richard
Drifting anode voltage is a pain with the CCS as they are designed / delivered (bad design around the trimmers), that's why I installed the fixed resistors. I recommend to do something about this (might also cure the noise you have in one channel). Remember to let the Tram II warm up for around half an hour before adjusting the voltage. And then check and re-adjust around 15 minutes after your first adjustment. Keep repeating this until you see no change in voltage.

Cool (in more than one way) integration of the small fans at the heatsinks..! And I see that you're Tram II is getting to peak-fitness-condition (name of a song from a Danish band, also works here). Nice implementation... Have you made the layout and circuit board for the raw supply yourself? Or did you find a suitable circuit board online somewhere?

My only small concern is the -relatively- long wires from the rectifiers to the first cap (I assume the Kemet / Rifa's are the first caps like in my implementation) on the raw supply for the Rod Coleman regulators. You have high peak currents running in those wires so they can radiate some noise. You could screen those and connect the screens to chassis ground.
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Last edited by Desmo; 4th August 2013 at 12:53 PM.
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Old 6th August 2013, 12:00 PM   #885
rab28 is offline rab28  Australia
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Quote:
Originally Posted by Desmo View Post
Have you made the layout and circuit board for the raw supply yourself? Or did you find a suitable circuit board online somewhere?
The supply board was made (and installed) by Lucas Cant, aka Black Art Audio here in Melbourne.

Quote:
Originally Posted by Desmo View Post
My only small concern is the -relatively- long wires from the rectifiers to the ... You could screen those and connect the screens to chassis ground.
Thanks for the tip, although it doesn't seem to be an issue...

-richard
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Old 6th August 2013, 09:10 PM   #886
Desmo is offline Desmo  Denmark
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Quote:
Originally Posted by rab28 View Post
The supply board was made (and installed) by Lucas Cant, aka Black Art Audio here in Melbourne.



Thanks for the tip, although it doesn't seem to be an issue...

-richard
Cool with the small circuit board

Issue, or no issue... Those wires do radiate noise, since they carry high pulse current, and noise does not always show up as ''noise'', I mean noise you end up hearing through the speakers. It can show up as smearing of the sound....

Those wires are the most critical ones in the preamp to keep short. When they are a bit longer like here the simple solution is to twist them really tight, then the ''ground'' act as a simple shield. Or they could be both twisted and shielded, with a ground connected to chassis. Good thing in your installation is, that the wires are at a distance from the circuit.

I'm not saying that it will make a sonic difference, because I don't know how sensitive the Tram II circuit is to radiated noise. What I'm saying is, that I would twist/shield.
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Old 7th August 2013, 10:13 AM   #887
reggie is offline reggie  Australia
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Hello once again. I am wondering if anyone can give me some final piece(s) of advice please. I have received my Coleman regulators and am taking them to the same place rab28 took his TRAM to have them installed (Lucas Cant). However, because I don't have a lot to money to spend Lucas has suggested that I mount the Coleman regulators in a separate enclosure outside the TRAM. So my questions are: (a) is this an ok option and (b) if I should have one more inexpensive upgrade to the TRAM done at the same time, what should it be?
Also, for the last few days I have been monitoring the voltage coming into the house. The lowest has been 232v and the highest 259v. Assuming my little Digitech QM1523 is reasonably accurate are these voltages something to worry about? I contacted the manufacturer of step down transformers and they suggested that maybe a voltage regulator might be better for me? Can someone advise me please.
Reggie
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Old 7th August 2013, 03:42 PM   #888
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It's best to mount the Regulator modules close to the tube sockets. This is only a noise pickup consideration; the Regulators are stable with any cable length.

But since the Filament trasformer winding is already in the TRAM, and the Regulators are very small, it should be possible to mount them internally. If not, the performance might be degraded a little but if this saves you cost.... you must decide the balance of values!

One thing to avoid for sure: please don't mount the rectifier/capacitors far from the trafo. This will cause radiated noise from the rectifier to get everywhere.

259V is a definite challenge for a 220V specified trafo. May even get some saturation. The internal temperature of the TRAM is most important - why not measure it. A thermocouple DMM or IR gun-type will be perfect to measure.

The neighbourhood of any electrolytic caps should not exceed 70 deg C (preferaby 50).
The power tube glass should nowhere exceed about 175 deg C.
The power trafo should be restricted to 70 deg C.

If any of these are exceeded, a fan or other cooling improvement is needed.
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Old 8th August 2013, 06:22 AM   #889
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Hi Guys,
I am getting into the TRAM game and have ordered Rod regs, Desmo, what value and voltage Alexanders and Deulands are you using. I intend to use a higher rated transformer to try and avoid some of the heat issues experienced.

Any advice on a ground up and custom FCUPS build would be greatly appreciated.
Perhaps we could get our own upgraded FCUPS boards made?

I will probably go down the TJ 2A3 road.Thank you for your time and help.
Let the journey begin.

Cheers
Greg
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Last edited by PixelPlay; 8th August 2013 at 06:40 AM.
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Old 8th August 2013, 07:10 AM   #890
Desmo is offline Desmo  Denmark
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First: There is no heat issue with the transformer. It performes well within specs and is placed on top of the chassis so there is plenty of air/cooling. On a hot summer day it get's warm to the thouch - nothing more. Using a larger transformer changes little to nothing.......

(If there is one thing that I could wish for in the discussions on this preamp is that all those ''heat issues'' and ''melt down fears'' would stop). Again: Consider the Tram II as a small Class A power amp, it get's hot as a Class A amp, because it is a Class A amp. Class A amps can run for 20 or 30 years before electrolytics in the power supply are dry. This is the normal ''problem'' with a hot chassis. And since the power supply in the Tram II is all made up of polypropylene caps, there is not even caps to dry out.

So if you can't accept to have a Class A power amp as your preamp = buy another preamp, that is much better than to tear the construction apart and making all kinds of solutions to make it run cold. It will never run cold, it uses 120W and every one of them ends up as dissapated heat. Nearly every preamp on the planet uses much less power than the 120W that the Tram II uses. Meaning = nearly every preamp on the planet runs colder.

My Duelund CAST input caps are 100nF and I believe they are 200V (look back in the thread to find pics if you need the voltage rating).
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