I received your pm. Thank you rab28. I wonder if any reader of this thread can explain to me (please forgive my ignorance) about the TRAM's transformer. When I purchased my Tram it was because I had read on the Troels Gravensen's (Danish DIY speaker builder) web-site that he had built himself a TRAM pre-amp because he thought it was one of the best pieces of equipment he had heard. However, it turned out that his TRAM was the Mark 1 and it had an Output Transformer. So , imagine my surprise when my TRAM arrived and it was a Mark 2 which is Output Transformer Less. I understand that building a good output transformer is expensive so maybe they were trying to cut costs with the TRAM 2. So when you are talking about the TRAM 2's transformer, what is it that you are actually talking about please.
Reggie
Ps I know nuthing
Reggie
Ps I know nuthing
Troels Gravesen is a good friend of mine and lives nearby, we have often talked about comparing our preamps, but have not done so yet... The Tram and the Tram II comes from the same source, and that's the reason for the same name. However they are TOTALLY different designs, only resemblance is, that they are both tube preamps.
There is one transformer in the Tram II, the mains transformer, and that's the one being talked about here.
The ''issue'' (for some) about the Tram II is, that it runs hot due to it's design as a small Class A amp used on preamp level to form a DHT triode preamp running current hungry 45's or 2A3's. Some people are very worried about heat from a preamp and try to come up with solutions to get rid of the heat. My advise on this: If you worry that much, then a Class A, DHT design is not for you, get rid of the preamp and buy something else that runs cooler...
There is one transformer in the Tram II, the mains transformer, and that's the one being talked about here.
The ''issue'' (for some) about the Tram II is, that it runs hot due to it's design as a small Class A amp used on preamp level to form a DHT triode preamp running current hungry 45's or 2A3's. Some people are very worried about heat from a preamp and try to come up with solutions to get rid of the heat. My advise on this: If you worry that much, then a Class A, DHT design is not for you, get rid of the preamp and buy something else that runs cooler...
Hi Reggie
As Morten explained all the talk is about the mains transformer that lives in the top front round enclosure and puts out different voltages for the Tram2 to run on.
The Tram2 has no output transformers that are often needed on tube amps to step down the impedance of the output signal. Transformers are often thought to stamp a certain sound signature on the signal. I understand that sound can be quite sweet but slow. There might be a good reason the Tram2 design was selected. That might have a lot to do with being OTL (output transformer less). The full beauty of the DHT's can be heard with great speed, immediacy and imaging. I reckon your a lucky man having a Tram2.
The Tram2 mains transformer case doesnt get so hot its a worry to me. Im totally happy with the mains trannie even up here in Brisbane.
One thing I have noticed is it runs much cooler using a 240V to 220V step down mains transformer to plug the Tram2 into and the sound is fine.
My mains is usually about 242V. In Australia many homes get 250V. The Tram2 is meant to be good for 220-240V. I guess running it off 220V takes the heat off the trannie literally but the other guys will know much more about that.
As Morten explained all the talk is about the mains transformer that lives in the top front round enclosure and puts out different voltages for the Tram2 to run on.
The Tram2 has no output transformers that are often needed on tube amps to step down the impedance of the output signal. Transformers are often thought to stamp a certain sound signature on the signal. I understand that sound can be quite sweet but slow. There might be a good reason the Tram2 design was selected. That might have a lot to do with being OTL (output transformer less). The full beauty of the DHT's can be heard with great speed, immediacy and imaging. I reckon your a lucky man having a Tram2.
The Tram2 mains transformer case doesnt get so hot its a worry to me. Im totally happy with the mains trannie even up here in Brisbane.
One thing I have noticed is it runs much cooler using a 240V to 220V step down mains transformer to plug the Tram2 into and the sound is fine.
My mains is usually about 242V. In Australia many homes get 250V. The Tram2 is meant to be good for 220-240V. I guess running it off 220V takes the heat off the trannie literally but the other guys will know much more about that.
You will not spend all that money on caps anyway
The Tram II use 125W as I remember the specs. These W has to go somewhere = heat...There are 3 main heat sources: The tubes, the mains transformer and finally the DHT regulators. Since two of them are already outside the box a bigger box will have zero influence on the heat from those two heat sources. With a bigger box you could make larger heatsinks for the DHT regs etc etc... But you still need to dissapate 125W of heat...
Even with a bigger box the the heat build up is the same. Try as an example to put a 60W bulb into a closed metal box, first try with a small box, then a larger (bulb with light in it, that is ;-)). With the small box it will heat up faster, than with the bigger box, but eventually they will reach the same temperature (exept for one or two degrees the bigger box will be colder due to larger surface area).
If you want to move heat, you have to move air. You have to move air over the metal surface that that dissipate the heat (That's why heat sinks are designed the way they are). So basically, there are two options: Forced air with a whisper quite fan. Or large external heat sinks for the DHT regs, that has no direct contact with the chassis. Both will bring down the temp inside the box if that is desired. Larger heatsinks inside a bigger box makes practically no change...
Personally I like compact circuits for short signal paths etc etc (and I consider the power supply wiring as indirect part of the signal path), so I belive the best solution is to force air through the box = whisper quite fan, running very slow, it takes nearly nothing to bring down the temperature quite a lot. But that's just me And with a clever design for routing of the forced air it can be made in a way so air is also forced over the transformer box, so it will also run a bit cooler.
If you want to move heat, you have to move air. You have to move air over the metal surface that that dissipate the heat (That's why heat sinks are designed the way they are). So basically, there are two options: Forced air with a whisper quite fan. Or large external heat sinks for the DHT regs, that has no direct contact with the chassis. Both will bring down the temp inside the box if that is desired. Larger heatsinks inside a bigger box makes practically no change...
Personally I like compact circuits for short signal paths etc etc (and I consider the power supply wiring as indirect part of the signal path), so I belive the best solution is to force air through the box = whisper quite fan, running very slow, it takes nearly nothing to bring down the temperature quite a lot. But that's just me
And with a clever design for routing of the forced air it can be made in a way so air is also forced over the transformer box, so it will also run a bit cooler.
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I can verify using a very quiet fan plummeted the internal temps and let me get away with running 2A3 on MkII heatsinks. But only those heatsinks got hot. The rest of the components were cruising. Im happy with theTram2 chassis.
DIY is fun. I think the Tram2 internals and the mains transformer cover can be passively cooled with a cunning design. Get some copper pipe about 10mm diameter. Flatten the pipe into a crescent moon profile so the concavity fits the outer diameter of the transformer cover. Drill holes around the outside of the transformer case and place the pipe over the holes. Join the pipes vertically to the transformer cover with double sided thermal tape. This design uses the heat of the transformers to creates a convective up-draft in the chimney copper pipes that then exhausts the warm air inside the chassis. The hotter the trannie gets the better the chimney convection works allowing self-regulated cooling. I cant be bothered doing this but I reckon it will work. Maybe.
DIY is fun. I think the Tram2 internals and the mains transformer cover can be passively cooled with a cunning design. Get some copper pipe about 10mm diameter. Flatten the pipe into a crescent moon profile so the concavity fits the outer diameter of the transformer cover. Drill holes around the outside of the transformer case and place the pipe over the holes. Join the pipes vertically to the transformer cover with double sided thermal tape. This design uses the heat of the transformers to creates a convective up-draft in the chimney copper pipes that then exhausts the warm air inside the chassis. The hotter the trannie gets the better the chimney convection works allowing self-regulated cooling. I cant be bothered doing this but I reckon it will work. Maybe.
Exactly, the temperature is not high inside the box, so no problem with component life cycle... In my opinion all this talk about heat is overrated.
I think that the only reason it's even discussed is that it's a preamp that get's hot. And since preamps normally does not run hot, it's unusual and ''a problem''. No one talks of problems when a Class A power amp get hot, because ''that is how it is with that type of amp''... Well, the Tram II is a small Class A amp and should be considered as such.
Thank you all for your response. So, as I understand it, (a) the TRAM runs hot anyway (b) in some areas (like mine) the mains voltage is around the 250 and that exceeds the operating values of the TRAM, then, because the 2A3 valve draws more current and that equals more heat, there is a greater chance of it breaking down. So, if I want to use the 2A3 I can either: (i) take my chances and use the 2A3 anyway (ii) find a way of cooling the TRAM or (iii) use a step down mains transformer like kazap does. Or, if I use the Rod Coleman DHT regulators, can I then use the 2A3's?
Reggie
Reggie
Ive had my Tram2 just a few months more then you but as I understand it:
- run your Tram2 on 220-230 V to take the load of its power transformer
- failures dont come from the Tram2 transformer or general heat issues but from the internal Tram2 regulator version I or II
- dont use 2A3 unless you have the MK3 regulator or the Coleman regulators
- get the Coleman regulators to improve the sound quality
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236 volts ...I wonder if your Tram2 would sound a little sweeter and run a little cooler plugged into a 240V to 220V step-down transformer?
I guess some step-down mains transformers filter some of the noise out of the grid power improving the sound quality a little while unloading the Tram2 toroid that might run just a little cooler like mine? Critical opinions welcome.
I guess some step-down mains transformers filter some of the noise out of the grid power improving the sound quality a little while unloading the Tram2 toroid that might run just a little cooler like mine? Critical opinions welcome.
Hello kazap.
I've just found this Australian based manufacturer of (toroidal) step-down transformers...Tortech Australia's specialist in toroidal and step-down transformers. They specifically mention the step-down of Asian based equipment to Australia's 240v. However, to determine which is the best transformer for it's application they have to know the wattage of the piece of equipment (or, if you know the amperage one can calculate wattage). Can you help me with this please?
Reggie.
PS. I've just taken a reading of our mains voltage. It's 2100hrs here on a Saturday night and it's reading 237v. I'll take an other reading tomorrow.
I've just found this Australian based manufacturer of (toroidal) step-down transformers...Tortech Australia's specialist in toroidal and step-down transformers. They specifically mention the step-down of Asian based equipment to Australia's 240v. However, to determine which is the best transformer for it's application they have to know the wattage of the piece of equipment (or, if you know the amperage one can calculate wattage). Can you help me with this please?
Reggie.
PS. I've just taken a reading of our mains voltage. It's 2100hrs here on a Saturday night and it's reading 237v. I'll take an other reading tomorrow.
Power Consumption: 220-240VAC 50/60hz 120W
Tram2 - DHT OTL Linestage Kit - Level 3 Remote Controllable (price not including tubes) $1495. Order by email. | DIY HiFi Supply
Best to have free overhead. Some say X2. So get 300w 240 - 220 European Stepdown Transformer
Tram2 - DHT OTL Linestage Kit - Level 3 Remote Controllable (price not including tubes) $1495. Order by email. | DIY HiFi Supply
Best to have free overhead. Some say X2. So get 300w 240 - 220 European Stepdown Transformer
Hi Reg,
another consideration is the filament's secondary winding in the TRAM.
According to the manual, it's a 7.5V winding.
7.5V is perfect for the 2A3 Coleman Regulator. It is worth measuring the ac voltage of the Trafo now - if it is near 7.5V it will be difficult to reduce it any further. The 240:220V trafo will reduce the filament tap's voltage too!
On the other hand, if the filament winding measures 8.1V or more, then the TRAM trafo is probably suffering from overvoltage, and the 240:220 will be useful.
I support the idea of a slow-running fan, if possible. A 120mm fan run at low voltage (eg 5V on a 12V fan) makes almost zero noise, but is very helpful for cooling.
another consideration is the filament's secondary winding in the TRAM.
According to the manual, it's a 7.5V winding.
7.5V is perfect for the 2A3 Coleman Regulator. It is worth measuring the ac voltage of the Trafo now - if it is near 7.5V it will be difficult to reduce it any further. The 240:220V trafo will reduce the filament tap's voltage too!
On the other hand, if the filament winding measures 8.1V or more, then the TRAM trafo is probably suffering from overvoltage, and the 240:220 will be useful.
I support the idea of a slow-running fan, if possible. A 120mm fan run at low voltage (eg 5V on a 12V fan) makes almost zero noise, but is very helpful for cooling.
Thanks Rod for the excellent info and suggesting measuring of the regulator supply voltage.
I had just assumed from the Tram2 specs of running on 220-240VAC that this implied it was running within specs at 220v and would therefore be increasingly loaded above 220V.
Thanks Simon for doing the actual measurement.
I understand the life of DHT tubes can be considerably extended running them slightly under-voltage on the heater. With the cost of 2A3 this would be of interest to me if there is no loss of sound quality or even an improvement in sound. Apparently there's an exponential relationship rather then a linear one, between heater temperature and tube life? Anyone know the applicable equation?
From Mick the designer of Supratek who has enormous DHT preamp and poweramp experience "Running DHT tubes at lower currents also helps with microphonics and even decreases distortion, but it's always a fine line , and different tubes have different reactions to it- the 300B has to be run at its exact voltage and current , the 10 or 801A gets quite an advantage from decreasing it's current. But these days any decent preamp is going to have regulated DC heaters, which if designed properly will output proper voltage no matter what the line voltage is. "
Id be grateful for opinions on this please?
Rod - is it possible to set your regulators up to under-volt them in an adjustable way while powered up so as to be able to listen for the sound changes and "tune" the voltage for optimal sound? If so how could we go about it? I think a temporary adjustable circuit to measure the best voltage and then set that voltage permanently would be great?
I had just assumed from the Tram2 specs of running on 220-240VAC that this implied it was running within specs at 220v and would therefore be increasingly loaded above 220V.
Thanks Simon for doing the actual measurement.
I understand the life of DHT tubes can be considerably extended running them slightly under-voltage on the heater. With the cost of 2A3 this would be of interest to me if there is no loss of sound quality or even an improvement in sound. Apparently there's an exponential relationship rather then a linear one, between heater temperature and tube life? Anyone know the applicable equation?
From Mick the designer of Supratek who has enormous DHT preamp and poweramp experience "Running DHT tubes at lower currents also helps with microphonics and even decreases distortion, but it's always a fine line , and different tubes have different reactions to it- the 300B has to be run at its exact voltage and current , the 10 or 801A gets quite an advantage from decreasing it's current. But these days any decent preamp is going to have regulated DC heaters, which if designed properly will output proper voltage no matter what the line voltage is. "
Id be grateful for opinions on this please?
Rod - is it possible to set your regulators up to under-volt them in an adjustable way while powered up so as to be able to listen for the sound changes and "tune" the voltage for optimal sound? If so how could we go about it? I think a temporary adjustable circuit to measure the best voltage and then set that voltage permanently would be great?
The Coleman Regulators have a trimmer, so that you can adjust the filament current within a range of about +/- 15% of nominal 2.5A.
Running expensive 2A3s on reduced voltage is risky, in my view. Reduced terminal voltage means reduced temperature, and reduced emission, which the filament is not designed to support.
EML expressly warn us not to try reducing the operating filament voltage of their 2A3s, and give -5% as the absolute limit. My personal view is that this is an intentional design parameter, and should be respected for any 2A3. I set up my own DHTs to +0% and -2% limits using the Coleman Regulator trimmer.
Having said that, you can trim the filament voltage a little lower or a short while, to listen for changes, but I would think carefully before leaving it low. Make sure you can get to the trimmer when you install the Coleman Regulators inside the TRAM!
Meanwhile, Simon's measured 8.15V for a 7.5V filament winding indicate that the TRAM 2 trafo was designed for 220V. Applying a 240V supply (which could mean up to 257V in practice, allowing for the legally-permitted +10% in the UK, at least) might make it sweat a little.
Unless the trafo core saturates at 240V (look for waveform distortion of the filament tap, using a scope), then the solution is still to apply some gentle cooling, as noted earlier. A low speed (5V on a 12V fan) and choosing quality fans like Sanyo will give good quiet results, I suspect.
Running expensive 2A3s on reduced voltage is risky, in my view. Reduced terminal voltage means reduced temperature, and reduced emission, which the filament is not designed to support.
EML expressly warn us not to try reducing the operating filament voltage of their 2A3s, and give -5% as the absolute limit. My personal view is that this is an intentional design parameter, and should be respected for any 2A3. I set up my own DHTs to +0% and -2% limits using the Coleman Regulator trimmer.
Having said that, you can trim the filament voltage a little lower or a short while, to listen for changes, but I would think carefully before leaving it low. Make sure you can get to the trimmer when you install the Coleman Regulators inside the TRAM!
Meanwhile, Simon's measured 8.15V for a 7.5V filament winding indicate that the TRAM 2 trafo was designed for 220V. Applying a 240V supply (which could mean up to 257V in practice, allowing for the legally-permitted +10% in the UK, at least) might make it sweat a little.
Unless the trafo core saturates at 240V (look for waveform distortion of the filament tap, using a scope), then the solution is still to apply some gentle cooling, as noted earlier. A low speed (5V on a 12V fan) and choosing quality fans like Sanyo will give good quiet results, I suspect.
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