DHT OTL Linestage - Tram 2

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Hi Clive,
My mounting of the regulator boards may be a bit dramatic; I simply glued them with 'super-glue' to the chassis sides. The regulators have electrically non-conducting packing that avoids short-circuiting.
If I had done it over again I would have soldered the regulators on the upper side of the boards so that are domewhat easier to remove/replace in event of failure.

Thank you about the tip to remove capasitor over the filament pins.

Geir
 
Hi Geir,

Thanks for the pictures, it's always cool to see other implementations :)

The epoxy coating of the chassis is quite bad at dissipating heat, meaning that the junction temperature inside the transistors will be very high in your set-up. Don't expect the transistors to have a long life...

Also: You MUST remove the capacitors on the the filament pins, otherwise they will both color the sound and work as filters that alter the freq response. With those caps in place I understand why you heard a mellow bass, basically the cut off the bass range when used with the Rod Coleman regs.
 
Thank you Morten,
I was about to get a second opinion about removing the caps over the filament pins.
Now I'll open the chassis and just remove them.

Not so sure about the heat build-up though as the regulators are not so very hot to the touch. But thanks for your advices anyway.

Geur
 
That helped,
More air around the instruments :-D

Just bought a 'vintage' reel-to-reel tapedeck, a Revox B77 with new heads.
My oh my, I've never believed that this machine from mid-seventies could be so transparent and seemingly uncoloured!

I'm a happy guy :)
And it's Friday

Geir
 
What is a ''regulator plate''..? Do you mean the housing of the transistors? If you have 40deg celcious on the transistor housing then all is fine. I think it will be higher though, as your test with the fingers also indicate. If you can hold your finger on the transistor for a few seconds, then that indicate a temperature on around 60 deg celcious - and that is fine, especially if it's with 2A3 tubes...
 
Yes, that's right - 40 to 60 deg C is OK.

70 deg C is the maximum temperature for the transistor case, or the heatsink (near the transistor).

Must be a good heatsink!

He is not using a heatsink..! The transistors are just super-glued to the epoxy painted chassis. I'm a bit surprised if the temp is this low since a thick layer of epoxy paint + super glue between the transistor and the aluminium chassis could be a serious barrier for heat transfer... But apparently it works...
 
Id like to buy a used Tram2 - please PM me if you know of one sitting on a back shelf.

Otherwise I wonder if anyone could build a two box version for me with the power and heater regulation in its own chassis to keep the tubed chassis cooler?
The chassis doesn't get to hot, the air flows out past the sub-chassis and out via the tube sockets. The rev 1 heater supply heater sinks are too small for 2A3 use but ok for 45s. Rev 2 are marginal for 2A3s and rev 3 are fine.

Maybe you want to say which country you are if you hope for a rare 2nd hand Tram.
 
The chassis doesn't get to hot, the air flows out past the sub-chassis and out via the tube sockets. The rev 1 heater supply heater sinks are too small for 2A3 use but ok for 45s. Rev 2 are marginal for 2A3s and rev 3 are fine.

Maybe you want to say which country you are if you hope for a rare 2nd hand Tram.

Thanks for setting me straight on the heat dispersal in the standard Tram2 chassis design. I guess a two box design might still be a good idea for the best isolation of induced currents? I would also ideally like the tubes to be as cool as possible too. I live in Brisbane, Australia and summers are warmish. Id rather the tubes suck up room temperature air then preheated air.

As for buying a used Tram2 Id be happy to buy one from anywhere.

I was treated to hearing a Tram2 in my home today and I'm converted :eek:
 
Personally I believe a two box solution as you describe will be a compromised design that will not sound as good as the one box solution. You will have long wires between the boxes on critical places in the signal path (supplies that are as considered in the signal path, especially the DHT supplies). As Clive mentions there is no heat issue, so I can't really think of reasons why one would compromise the design / sound to get two boxes and -maybe- a lower temperature...

I do however understand that people who has not yet had any hands on experience with the Tram II can be a bit freaked out and think there are heat issues because there has been so much debate on the topic. But as Clive say: It's was because if too small heat sinks for the DHT regulators. With larger heat sinks all is good.

You should consider the Tram II as a small integrated Class A tube amp, because basically that is what it is. So it get's quite warm, but not hot hot...

EDIT... Ahh, notice in your last post, that you have actually heard one now :)


Thanks for setting me straight on the heat dispersal in the standard Tram2 chassis design. I guess a two box design might still be a good idea for the best isolation of induced currents? I would also ideally like the tubes to be as cool as possible too. I live in Brisbane, Australia and summers are warmish. Id rather the tubes suck up room temperature air then preheated air.

As for buying a used Tram2 Id be happy to buy one from anywhere.

I was treated to hearing a Tram2 in my home today and I'm converted :eek:
 
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Personally I believe a two box solution as you describe will be a compromised design .......

Thanks for sharing your expert opinion. As a result I've promptly given up the two chassis idea. This will have the added benefit that it will be much easier for me to get a Tram2.

Having heard one today I'm ruined. The system sounds pedantic without it. The only thing my SS state gear does better is a lower noise floor. Are there any build mods e.g. with different capacitors you can recommend that might reduce the Tram2 noise floor?
 
Thanks for sharing your expert opinion. As a result I've promptly given up the two chassis idea. This will have the added benefit that it will be much easier for me to get a Tram2.

Having heard one today I'm ruined. The system sounds pedantic without it. The only thing my SS state gear does better is a lower noise floor. Are there any build mods e.g. with different capacitors you can recommend that might reduce the Tram2 noise floor?

You're welcome... And it's always a matter of choice and the compromises you feel are the best. Me, I prefer to have my electronics compact and with short wiring, this can be achieved with the one box solution. Others might have other preferences...

Installing the Rod Coleman DHT regulators will give you BOTH quite a big improvement in sound AND a much lower noise floor. Go back some pages in this thread and see my installation of this regulator...
 
Hi Peter,

Ahhh... It's a small world ;) Then it's time for you to get the Rod Coleman regulators installed...!

The Full Music 2A3SE are amazing tubes. Expensive, but worth the money. They are clearer, more dynamic, more coherent and less microphonic than any other tubes I have tried in the Tram. Very nice :)
 
Morten and everyone else, it's Christmas eve evening down under. Hope Santa brings you lots of audio tube or solid state presents. My wish list includes a pair of Full Music 2A3SE tubes and a pair fantastic sounding loadspeakers. You only get Santa presents if you are nice. Anyway, to quote Santa "HO HO HO" and

"Happy Christmas to all. And to all a good night".
 
Those are the Full Music 2A3 / C, mine are the 2A3 / SE and unfortunately they are even more expensive... Full Music 2A3/SE Electric Tube, Matched Pair

Yes, it's a lot of money..! But it's cheaper than to buy 5+ other pairs of tube hoping to find a cheaper short cut to the best sound ;) And with the excellent design in the Tram II where the auto bias makes a gentle start-up of the tubes, these should have a life on 2000 - 5000 hours. Not too bad...
 
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