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Old 8th June 2013, 10:51 AM   #821
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Location: Karalee, Queensland
Quote:
Originally Posted by ptashton View Post
From: DHT OTL Linestage - Tram 2

All members who want to use the "holy grail" audio resistor,

the TX2575 Naked Z-Foil,

could order it direct from Arbie Lopez at Texas Components.

alopez@texascomponents.com


That´s the cheapest way to get it IMO.

They have also great Trimpots with Bulk Metal Foil Technologie.

Peter
Better still, go to this link:


TX2575 (the Z-Foil upgrade to the TX2352)

Peter
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Old 14th June 2013, 05:38 AM   #822
kazap is offline kazap  Australia
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Matching the Tram2 Gain to a Power Amp

Could the 4 Power Buffer be the perfect current follower type power amp to match the Tram2 gain, free of the output attenuation resister network?
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Old 24th July 2013, 10:14 PM   #823
sjs is offline sjs  United Kingdom
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Work is finally complete, and I can only commend Desmo for backing the Rod Coleman regs as the way forward.

I published a picture of my heat spreader earlier in the link, here is one of the regs now ready to install:
Click the image to open in full size.

I built the raw dc supply with BHC ALS10 caps, as the ALS range have always been amongst my favourites. It has worked out quite nicely and fits well within the tight Tram2 case:
Click the image to open in full size.

As for the sound, it has been a massive step up.

Compared to my usual line of idht triode line stage preamps my original Tram2 was something of a disappointment. It was big and easy, true, but it was also somewhat mechanical and congested at the same time.

It is now a genuinely good line stage. It manages big tone, easy, relaxed and an amazing sense of depth and soundstage. I am still a little unsure about the absolute bottom octave and a slightly mechanical feel across the midband, which may be the HT supply compared to the passive LCLC I am used to, but even with that caveat it really is something rather special.

The Rod Coleman regs are an absolute must imho, as they help the Tram2 to finally deliver on its promise, and massively reduce the noise floor of the amp.

The resistors are all Tant film, and I use the shunt mod with a 270K resistor to reduce overall gain in order to counteract the worst excess of my high output AN DAC.

If you haven't done the Coleman regs yet, I commend them!
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Old 25th July 2013, 08:33 AM   #824
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Top flight implementation, Simon!

I like the ALS series too, especially for high-voltage circuits (though for the filament circuits I have only used ordinary types). For a power amp these Kemet/BHC ALC or ALS are a real premium choice.

I'm glad to hear the TRAM is sounding good!
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Old 26th July 2013, 03:16 AM   #825
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Simon, can you please take a picture of the Rod Coleman regulator in the Tram2. The picture you posted looks like there is another circuit board below the Rod Coleman board. Just for clarification. Did you use thermal paste between the spreader and Tram2 chassis.

Thanks

Peter
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Old 26th July 2013, 03:29 AM   #826
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hi Peter, the Regulators can be seen on the last picture. They are vertically mounted, at the extreme left & right of the picture.
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Old 26th July 2013, 06:23 AM   #827
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Rod, their is only one vertical circuit board either side??? It just looks like there are two boards either side.

Also, have a read of the e-mail below from another friend who was at the same audio listening session last night. We were listening to some very good audio equipment, but there was something wrong. Have a read. Could you explain the interaction between the inverter and the mains power with the sound of the music.

The e-mail:

Hi Guys

Here’s a little tale from last night, four Queensland Audio Club guys got together as they do, myself being one of them! Now I’d been to this member’s house about 6-8 weeks earlier and he has a both musical and dynamic setup. Now we were pulling bit in and out so the sound was obviously going to fluctuate but from memory the whole first 2-3 hours just didn’t hit the highs of my previous visit.

Now our host isn’t a man to accept average or even good and he was quietly getting irate at this dilemma. The topic came up and the other guys were saying “well it’s not as good a sound as our last visit three weeks ago” … so the question was raised “so what’s different/changed since then”. Well in fact the main system hadn’t actually been switched on since then. But hey, we’d already been running 2-3 hours so everything would have been warmed up by then? Our host left the room and we continued talking – zap – listen to that. Hey, slowly over a minute or so – whoosh – everything came into focus – the magic had reappeared in the audio – beautiful.

Our host returned – hey - sit down and listen to this! A smile appeared on his face – “okay – what did you just do …” Well, the one thing that had happened over the last three week was the installation of a solar panel system on the roof. Although it wouldn’t have been working at 11:00 pm and would have been sat “off-line” it was still on. He’d simply turned off the inverter – doh.

So, although not “ticking over” the inverter must have been turning out a hell of a lot of “hash/interference” through the power supply blah, blah blah – no we couldn’t really come up with a positive reason. But back and forth we went – inverter on – crap sound – inverter off – magic sound – off – crap – on – magic.

So for those with solar, it might be worth a try. Play a few of your favourite tracks – go turn your solar off – come back and replay then. It’d be interesting to “hear” if you get a similar improvement J

Cheers

It was a very strange experience that was resolved.

Last edited by ptashton; 26th July 2013 at 06:27 AM.
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Old 26th July 2013, 08:16 AM   #828
sjs is offline sjs  United Kingdom
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Peter
there is only one circuit board mounted on each heat spreader, what you see in the picture is a reflection of the underside of the board in the aluminium spreader. Yes there is thermal paste between spreader and chassis.
Simon
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Old 26th July 2013, 09:55 AM   #829
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Thanks Simon. Morten had the big Electro Caps on the inside on the side chassis. I see you did not use these.

That is the output black cap you are using that is retained by zip ties.

Thanks

Peter
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Old 26th July 2013, 11:39 AM   #830
sjs is offline sjs  United Kingdom
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The raw dc supply for the Coleman regs has been built using BHC/KEMET ALC10 series caps, 10,000uF 63V for the first one after the bridge rec, and 10,000uF 40V for the second one after the dropper resistors, they are the black caps on the circuit boards in the centre. I used these instead of the large white Rifa electrolytics shown in other solutions.

For the audio output, as discussed earlier in the thread, I have removed the resistor network and have a single 1M0 resistor across the output, and currently use a 1uF 400V SuperCap Robert Hovland Series cap as the output. In hand I also have a Intertechnik Audyn True Copper Cap and an old Audio Note Tin Foil PIO to try out. Whichever gives the best overall balance will remain in place. I would really like to use Dueland VSF or Cast but cannot justify the cost.

After the Tram2 I have a low gain system using valve power amps with high input impedance. I don't need the gain reduction provided by the resistor network, as the Tram2 is now v quiet with the Coleman boards and Herbie's dampers on the 2A3s, so I have used it as an opportunity to put a more regular output cap/resistor pairing.
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