Thank you Chris; found it.
Looks like for TO-200 I need #6, right?
Keystone Electronics Corp. - Fibre Shoulder Washers
TO-200? Is that one of those new-fangled three-legged fuses? Bah, humbug.
Anything newer than octal sockets is just a fad, like teenage hairstyles!
All good fortunes,
Chris
But seriously, I'm not smart enough to say for sure; you'll have to measure it somehow. All the best.
Hi Anatoliy
You can buy the shoulder-washers separately, but it is often easier to get a "TO-220 mounting kit":
Europe: Farnell 520214
U.S.: Mouser 532-4880SG
these are packed with a Mica insulator for TO-220. You can get kits for TO-3 or TO-218 also.
Hi Bigun,
I can prepare a kit that works as a 6A3. Connect one extra resistor, and it shifts up to the 2A3 range. It has a 25-turn trimmer to fine tune.
You will certainly like the sound it helps to make!
Thanks Rod
Sorry for the typo. My keyboard sometimes swallows keystroke, then I can add a wrong tetter, or in a wrong place. I meant TO-220, of course.
Hi all,
Another Dane in this thread (beardman) gave me the heads-up on the Rod Coleman regulator for use in the Tram II DHT preamp from DIY HIFI SUPPLY...
I just finished the work with the implementation of the regulators, it has been quite some work because there is NO space in this little preamp chassis, and I wanted a large cooling area and furthermore I wanted to used RIFA PEH200 caps as the first ones after the rectifier in the raw-dc supply. These RIFA's can handle 12A ripple so they will last (almost) forever in this application...
I have not listened yet, but the preamp is back in my system and I was eager to check if these regulators are quiet enough for preamp use: YES..! With these regulators the noise floor is much lower than with the original ones from DIY HIFI SUPPLY. Maybe I should mention that I use 2A3 tubes, and that it has been quite difficult to get a low noise floor with these in the Tram II preamp. No problem with the Coleman regulators. If the sonic improvement is as good as the improvement in noise performance I will be one happy Tram II owner
Here are a few pics of the installation and the custom heatsink / chassis arrangement that I made. My heatsink assembly is connected to the inner rubber mounted aluminium sub-chassis so this aluminium plate is also part of the cooling system. It runs hot, but not crazy hot...
I will get back with sonic impressions
Another Dane in this thread (beardman) gave me the heads-up on the Rod Coleman regulator for use in the Tram II DHT preamp from DIY HIFI SUPPLY...
I just finished the work with the implementation of the regulators, it has been quite some work because there is NO space in this little preamp chassis, and I wanted a large cooling area and furthermore I wanted to used RIFA PEH200 caps as the first ones after the rectifier in the raw-dc supply. These RIFA's can handle 12A ripple so they will last (almost) forever in this application...
I have not listened yet, but the preamp is back in my system and I was eager to check if these regulators are quiet enough for preamp use: YES..! With these regulators the noise floor is much lower than with the original ones from DIY HIFI SUPPLY. Maybe I should mention that I use 2A3 tubes, and that it has been quite difficult to get a low noise floor with these in the Tram II preamp. No problem with the Coleman regulators. If the sonic improvement is as good as the improvement in noise performance I will be one happy Tram II owner
Here are a few pics of the installation and the custom heatsink / chassis arrangement that I made. My heatsink assembly is connected to the inner rubber mounted aluminium sub-chassis so this aluminium plate is also part of the cooling system. It runs hot, but not crazy hot...
I will get back with sonic impressions
OK... I have now done two listening sessions with the new Rod Coleman regulators installed.
The much lower noise floor than before is a big relief actually, listening is so much better, when there is no noise in the quite passages and between tracks.
But the lower noise floor is actually just a bonus because the major advantage is the sound that improves quite a lot with these Rod Coleman regulators..! I guess many does not know the DIY HIFI SUPPLY Tram II preamp, but it's a DHT using 2A3 triodes, and it has a very, very natural and dynamic sound. I have always considered the Tram II to be on of the most natural sounding preamps I have ever tried, but when listening with these regulators installed I now realize that a thin ''electronic sounding haze'' has been removed. It was natural sounding before, and even more natural sounding now.
Furthermore ''images float in space'', these words (the Danish version ;-)) just kept popping up in my head when listening with these installed. There is a flow to the music and the images float in a 3 dimensional space in a totally different way than before. It's not that the soundstage is bigger as such, but it's more real, more there, more open, more natural and the music has better flow and a focus that it did not have before. With this thin haze lifted away I also here more details, especially the ones that usually hides deep in the mix. For instance I listened to a jazz LP and during a guitar solo I could hear the guitar player humming his tunes while he was playing them. I have not heard that before on this record..!
These are my first impressions, and a big THANK YOU to you Rod for these regulators and your help
After reading the thread I see that even better sound can be had by a few updates of a resistor and a cap. Components are ordered
The much lower noise floor than before is a big relief actually, listening is so much better, when there is no noise in the quite passages and between tracks.
But the lower noise floor is actually just a bonus because the major advantage is the sound that improves quite a lot with these Rod Coleman regulators..! I guess many does not know the DIY HIFI SUPPLY Tram II preamp, but it's a DHT using 2A3 triodes, and it has a very, very natural and dynamic sound. I have always considered the Tram II to be on of the most natural sounding preamps I have ever tried, but when listening with these regulators installed I now realize that a thin ''electronic sounding haze'' has been removed. It was natural sounding before, and even more natural sounding now.
Furthermore ''images float in space'', these words (the Danish version ;-)) just kept popping up in my head when listening with these installed. There is a flow to the music and the images float in a 3 dimensional space in a totally different way than before. It's not that the soundstage is bigger as such, but it's more real, more there, more open, more natural and the music has better flow and a focus that it did not have before. With this thin haze lifted away I also here more details, especially the ones that usually hides deep in the mix. For instance I listened to a jazz LP and during a guitar solo I could hear the guitar player humming his tunes while he was playing them. I have not heard that before on this record..!
These are my first impressions, and a big THANK YOU to you Rod for these regulators and your help
After reading the thread I see that even better sound can be had by a few updates of a resistor and a cap. Components are ordered
Thank you, Morten, for letting us know! I am pleased that the Regulators have worked well.
It is interesting to note that the TRAM II is 2A3-powered. Many DIYers still believe that the low filament-voltage of the 2A3 means that ac-heating is fine.
In fact, the 2A3 always needs careful filament heating, even in PP power amps, because the real consideration is the anode/plate current. At 60mA dc, and the signal current of 1 .. 10mA (for quiet listening) - you have to take very great care with the design of a 2500mA heating supply or regulator, if the errors/overshoots/noise of the 2500mA is to avoid stamping all over the 10mA! And since the heating current and the anode current flow in the same metal wire, this is what will happen.
It is interesting to note that the TRAM II is 2A3-powered. Many DIYers still believe that the low filament-voltage of the 2A3 means that ac-heating is fine.
In fact, the 2A3 always needs careful filament heating, even in PP power amps, because the real consideration is the anode/plate current. At 60mA dc, and the signal current of 1 .. 10mA (for quiet listening) - you have to take very great care with the design of a 2500mA heating supply or regulator, if the errors/overshoots/noise of the 2500mA is to avoid stamping all over the 10mA! And since the heating current and the anode current flow in the same metal wire, this is what will happen.
I have now updated C3 and R1. For C3 I have choosen Amtrans AMCH mylar caps... Good sound, decent price, not that big so they can actually fit, finally they are spec'ed for high temperatures. For R1 I have choosen 12W Mills wirewound, they sound great and have a big surface area to dissipate the heat from so they don't run so hot.
When not using R2 there is actually decent space for the caps, so the installation can be quite clean as seen here I agree with the previous posters: Upgrading these gives a clear sonic improvement..!
When not using R2 there is actually decent space for the caps, so the installation can be quite clean as seen here
I agree with the previous posters: Upgrading these gives a clear sonic improvement..!
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Thanks Bigun..! It has been quite a lot of work to implement the heaters because the chassis is so small, but I'm really glad that I did the effort because the sound is so much better with these heaters (and noise so much lower).
BTW, I know that carbon resistors is ''the new crome'' these days, but if anyone is interested then give the Mills wirewound a chance, they sound really good..!
BTW, I know that carbon resistors is ''the new crome'' these days, but if anyone is interested then give the Mills wirewound a chance, they sound really good..!
Tram II preamp owners calling Rod Coleman
Since your DHT regulators starts slower than the voltage regulators originally installed in the Tram II preamp we are bit worried about stressing the DHT's, so we consider a delayed start of the anode voltage. The Tram II has one of these ''electronic choke'' supplies that both sends out the +B and the -C supplies as you can see in this schematic. Looking at the best place to have the relays for the delayed start I think this position might be the best solution? (see red markings, upper right hand corner).
Let's say we delay for one minute, then the heater voltage will be strong on the DHT's and also on the rectifier tube when the +B and -C kicks in. The question is, if it's a problem that the +B will then ramp up faster than normal due to the heater voltage on the rectifier tube being on from the beginning..!?
Another option could be to insert the relay directly on the +B at the output of the power supply module, then everything except +B will start up as usual.
Any advise would be appreciated - thanks
Morten
Since your DHT regulators starts slower than the voltage regulators originally installed in the Tram II preamp we are bit worried about stressing the DHT's, so we consider a delayed start of the anode voltage. The Tram II has one of these ''electronic choke'' supplies that both sends out the +B and the -C supplies as you can see in this schematic. Looking at the best place to have the relays for the delayed start I think this position might be the best solution? (see red markings, upper right hand corner).
Let's say we delay for one minute, then the heater voltage will be strong on the DHT's and also on the rectifier tube when the +B and -C kicks in. The question is, if it's a problem that the +B will then ramp up faster than normal due to the heater voltage on the rectifier tube being on from the beginning..!?
Another option could be to insert the relay directly on the +B at the output of the power supply module, then everything except +B will start up as usual.
Any advise would be appreciated - thanks
Morten
An externally hosted image should be here but it was not working when we last tested it.
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Hi Morten,
With any heating method, it is best to switch the HV on, after the filaments have warmed up. The Rise time of the B+ should be a slow ramp. You can put a switch or relay in the Centre-Tap-to-GND wire of the power trafo.
The alternative method: Bias the 2A3s and other fixed-bias tubes to cut-off level (eg -90V).
However, looking at the schematic you posted, the DIYHFS autobias module appears to be present. This module (If I have read correctly) applies a very high negative bias to the 2A3 grid when power is applied, and gradually decreases the bias level until the programmed anode current is achieved.
If this is so, the high negative bias will reduce the electric field around the filament to almost zero. So far as the filament knows, there is no HT applied!
You can check the value of negative bias at switch-ON, and if it is large enough to cut-off the anode current, it is safe.
This solution is better than switching the B+, and so for your preamp, no further action is required.
With any heating method, it is best to switch the HV on, after the filaments have warmed up. The Rise time of the B+ should be a slow ramp. You can put a switch or relay in the Centre-Tap-to-GND wire of the power trafo.
The alternative method: Bias the 2A3s and other fixed-bias tubes to cut-off level (eg -90V).
However, looking at the schematic you posted, the DIYHFS autobias module appears to be present. This module (If I have read correctly) applies a very high negative bias to the 2A3 grid when power is applied, and gradually decreases the bias level until the programmed anode current is achieved.
If this is so, the high negative bias will reduce the electric field around the filament to almost zero. So far as the filament knows, there is no HT applied!
You can check the value of negative bias at switch-ON, and if it is large enough to cut-off the anode current, it is safe.
This solution is better than switching the B+, and so for your preamp, no further action is required.
Hi Rod,
Yes, you are right: The DIYHFS autobias modules is part of the Tram II preamp (it's the circuit board between the DHT's in the pics I have show inside the Tram II), I will try to measure the time it takes for the autobias to decrease negative bias level, compared to the time it takes for your regulator to get up to 2,3 - 2,5V. Based on your comments I suppose all is good even if the +B is applied faster than the heater voltage from your regulator, as long as the autobias decreases the bias even slower than the voltage comes on from your regulator. Correct?
Yes, you are right: The DIYHFS autobias modules is part of the Tram II preamp (it's the circuit board between the DHT's in the pics I have show inside the Tram II), I will try to measure the time it takes for the autobias to decrease negative bias level, compared to the time it takes for your regulator to get up to 2,3 - 2,5V. Based on your comments I suppose all is good even if the +B is applied faster than the heater voltage from your regulator, as long as the autobias decreases the bias even slower than the voltage comes on from your regulator. Correct?
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