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ptashton 15th August 2011 10:51 PM

Tram2 6AS7 and 5U4 alternate tubes
I have just purchased a Tram2 kit and would like your recommendations on the differnt types of 6AS7 and 5U4 tubes that you have used in you Tram2. I hear that the GEC or Genalex U52 rectifier tube is the holy grail for 5U4 tubes. Is that true.

bronal 16th August 2011 08:06 AM

I've settled on the GE green base 6AS7 and the Australian AWA Radiotron 5U4G (5AS4).

Both are GT-shaped (straight-sided). They are therefore less microphonic than ST or globe types (but not as sexy) and the Radiotron in particular emits no RF interference. This is important with the Tram as the rectifier is right next to the 45s/2A3s.

GE 6AS7s are as cheap as chips and the Radiotron 5U4Gs can be had locally for about A$40 NOS.

No doubt someone will post singing the praises of some valves costing $$$s but I am sceptical of whether they would be an improvement.

ptashton 16th August 2011 11:36 AM

I have been try to track down a 5AS4 around Brisbane and I ended up getting a Rogers 5AS4 with ST sides from Canada. When I was in Hong Kong two weeks ago, I picked up from WiWi Tubes the last two Fullmusic 45s with ST sides. They were dated Dec 2005. I also picked up the Tram2 kit from Simon at DIY Hifi Supply in Hong Kong. I have not started the kit as some of the major parts were on back ordered and are being sent. Can not wait to start.

ptashton 16th August 2011 11:58 AM

Has anyone tried GZ37 Rectifier tubes as a substitute for the 5U4G tubes. Is is possible.

ptashton 25th August 2011 07:43 AM

So, everyone who owns at Tram2 pre-amp are using chinese 5U4 and 6AS7 tubes. There must be some of you using other brand of tubes. Please post your selection of tube brands.

clivetjm 25th August 2011 09:07 AM

I suspect everyone is so pleased with the sounds they are getting that they are listening to music! The main decision to make is 45 or 2A3, after that for me it's music but maybe I'm missing out by not rolling the other tubes.

D_arionj 26th August 2011 03:26 PM

Rolling in the Tram
My experience with the Tram has included a few rolls of each of the tubes. I've settled on 2 radiotron 45's a sylvania 6as7, and Rca 5u4g. The choice of output tubes had to include solid plate structures. Anything suspended or mesh was way too noisy and microphonic. The shuguang solid plate 2a3 worked well and is inexpensive. My preference for the 45 is based on that tube's slight detail improvement. They all sizzle a bit with the solid plates keeping it to a minimum.
As for the 6as7/5u4 I can't sense any real differences there. I never had RF problems or noise from any combination so I've kept them constant.
The final choice of output tubes is really based on what blends well with the rest of the system. The changes come in the finer points of HF details and noise. Some tubes I would avoid are the TJ 2a3 mesh. I can't get them quiet enough to enjoy regardless of the dampers used. You'll be happy with most choices as the Tram is a great front end. The decision to stay with one set of tubes really is based on fewest faults vs. detail and there are too many variables to pick a clear winning combination.
I recently changed my main speakers back to Horns with Heil AMT's. The tweeters are so detailed that I had to swap Tram tubes. Minor sizzle in one set became loud crackling with the Heils. I took a chance on the "NOS" 45's and they are perfect for this combination. They are just mellow enough to blend nicely. All this tube rolling is fun and the Tram makes it worthwhile. The differences are clear between sets and some work, others don't. To avoid wasting money, solid plates are a big plus, Nos can be risky but you may find a set that sounds good and is quiet. I have tried many combinations and solid choices are the Sovteks and plain vanilla Shuguangs.

ptashton 27th August 2011 08:47 AM

Thanks D_arionj for your experience with the tubes for your Tram2. That is the sort of information necessary to try and get things right the first time. I am still waiting on parts from Simon at DIY Hifi Supply to start building the pre-amp. I bought two Full Music 45/N ST bottle shaped 2005 vintage tubes from WiWi Tubes in Hong Kong. I am going to use Sylvania 5AS4 tube and United Electron 6AS7. I have the Herbie Audio Guitar rings for the 45 tube.

D_arionj 27th August 2011 02:30 PM

Tram hints
Simon and Thorsten have been very helpful in support of those of us who choose to build the Tram. I'll admit to being frustrated at times with some issues but they have all been solved with patience and good communicating. The time difference has been the largest problem with builders in the US and getting help from HK. I think I've figured it out,, now that I'm done.

As for building advice, the screw terminals can be very tricky to get a strong secure connection. I understand the modular nature of the boards but with hindsight I should have removed them and soldered. My concern was damaging board traces with heat but a poor connection due to a twisting loose wire is much worse. Tinning the wires before tightening would help keeping them solid.
I had a bad filament supply (instantly replaced by DIYHIFI) and the screw terminals made the swap easy so there are some advantages to keeping them. Just be aware of this.

Secondly, final troubleshooting and voltage measurements need to be taken once the circuit settles down. This can take quite a while as the whole circuit takes time to stabilize. Trying to set 120v while things are still changing can be frustrating. Be patient. Good support under the transformer housing is critical to keeping things stable while you wait and measure so I'd suggest finding a nice thick book to keep things steady. The tubes are tall and the bases are weak so not putting any pressure on them will save $$$.
Clip leads are essential to monitor anode voltage safely during this process, and remember that the output caps carry a nice jolt for quite a while.

All the threads about potential heat problems made me concerned about the boards' longevity. I tried a flat laptop cooler under the chassis and it works like a charm and is reasonably quiet. The metal perforations allow for great airflow and the box stays cool. I thank other forum members for the idea.

That's about it. Remember to tighten the screws, pull on the wire and check again! I am, by no means, an expert on this but I have done it while making mistakes and learning from them so if I can do it...


ptashton 28th August 2011 01:32 AM

Thanks D_arionj. I will definitely take on your advice. Cross the fingers, all goes well.


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