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Old 4th May 2013, 10:08 PM   #721
Desmo is offline Desmo  Denmark
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But... IF you can live with the +6dB gain (I can't use it... Way to much gain/microphonics), and IF you don't hear the sound degrading from not loading the output with the resistor network, then you can do like SJS; remove the resistor network, use 1M ohm to ground, use a small output cap and still have a low corner freq, provided that the input impedance is relatively high on the amp.

With a 1 uF output cap and 100k ohm input impedance on the amp the corner freq will be 1.8hz... If the input impedance on the amp is -for instance- 22K ohm the corner freq will be 7,2hz (that's too high meaning a larger cap would be needed)
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Last edited by Desmo; 4th May 2013 at 10:31 PM.
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Old 5th May 2013, 11:28 AM   #722
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Morten, I will lay down on my sword and say that the Philips 5R4GYS is a fantastic sounding tube. It even kills the GEC U52 tube. The Philips tube has an extremely full sweet life like sound as though you are listening to the musicians in front of you. The sound stage fills the whole room. I am using Brimar (USA made) 45 tubes and National Electron 6AS7. A very nice toe tapping sound indeed.

Peter
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Old 5th May 2013, 01:16 PM   #723
Desmo is offline Desmo  Denmark
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Thanks for the update Peter, I'm glad that you like the Philips This is really a nice rectifier - and at a price that is much lower than ''the so called big ones''...
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Old 8th May 2013, 11:31 AM   #724
kazap is offline kazap  Australia
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Default GZ33 rectifier

Has anyone got a GZ33 they can try?

I got a GZ33 off eBay and just listened versus the Philips 5R4GYS thanks to Peter who very kindly cannibalised his own Tram2 to fix mine.

The ridiculously early impression before either rectifier has been run in is that the Mullard is better. The dynamics are more powerful, the imaging layering more precise and cymbals less tizzy. Of course that could all change in a few weeks.

The GZ33 has some robust specs, has a reputation for long life but apparently drops voltage more over the plates. Does that matter?
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Old 11th May 2013, 12:23 AM   #725
kazap is offline kazap  Australia
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Default Remote code

If anyone needs to reprogram a learning remote for the Tram2 and has a Marantz System Remote handy it works using: TUNER with CHANNEL/SKIP or MAIN VOL.
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Old 12th May 2013, 10:06 AM   #726
Desmo is offline Desmo  Denmark
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I'm looking into Mu tubes... The Chatham Electronics 6AS7G are very nice sounding, and should be some of the best 6AS7G types. Then I read that 5998 can be replaced for 6AS7G, and to make it even more complicated, then 5998 is sometimes labeled 2399 - like the Chatham Electronic I just bought. The 5998 / 2399 has totally different internal construction than 6AS7G, so I was a bit skeptical when installing in my Tram II yesterday, but there is music Time to burn in the tube, it will be interesting if it works even better than the Chatham Electronics 6AS7G

PS...Interesting with the GZ33 rectifiers, let us know what you think of the sound as they (and the Philips) burn in. In my experience the Philips changes quite a lot, maybe the same goes for the GZ33...Tizzy cymbals is not something I hear with the Philips, actually quite the opposite. What I like so much with the Philips is it's very natural and coherent sound where nothing ''stands out''...
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Last edited by Desmo; 12th May 2013 at 10:09 AM.
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Old 12th May 2013, 10:26 AM   #727
kazap is offline kazap  Australia
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Quote:
Originally Posted by Desmo View Post
I read that 5998 can be replaced for 6AS7G....
The 5998 has a different mu rating to the 6AS7G.

6AS7G Mu = 2 Gm = 7000, Rplate = 280 ohms
5998 Mu = 5.4 Gm = 15500, Rplate = 350 ohms,

6080 Mu = 2, Gm = 6500-7000, Rplate = 280-300 ohms
6520 Mu = 2 (1.9-2.4) Gm 6400 - 7600
6H13C Mu=2.4 ?????
7236 Mu = 4.8 Gm = 12500, Rplate = 350 ohms

Does that matter in its use as a mu tube?
I was too ignorant of the circuit to try it so I'm fascinated to follow your findings. Thanks again.

PS I using the Philips 5R4GYS at the moment and its sublime.

Last edited by kazap; 12th May 2013 at 10:30 AM.
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Old 12th May 2013, 10:30 AM   #728
Desmo is offline Desmo  Denmark
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Yes, I know it's not identical to the 6AS7G, but ''comparable'' or what ever the word is... Hearing is believing, so if it sounds better it stays, if not then the Chatham Electronics 6AS7G goes back in.
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Old 12th May 2013, 11:56 AM   #729
rab28 is offline rab28  Australia
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Quote:
Originally Posted by kazap View Post
If anyone needs to reprogram a learning remote for the Tram2 and has a Marantz System Remote handy it works using: TUNER with CHANNEL/SKIP or MAIN VOL.
Aha! Can you please post the Marantz model number(s)? A couple of months ago i made a post in another thread about getting a Logitech Harmony Remote to work on the Tram2 by selecting a Marantz amplifier. Volume works a treat, but I don't yet have the input switching working. If you can post the model number of the Marantz amplifier, then anyone should be able to use that to get their Logitech Harmony Remote to work (assuming that the amplifier model is in the Logitech database).
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Old 12th May 2013, 12:14 PM   #730
gregdee is offline gregdee  United Kingdom
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Hi Morten

I am reading this thread quite a while. Congratulations on your mods , every single time executed neat and skillful. Great ideas here and fantastic atmosphere of sharing knowledge about this design. Regarding your 2399 ,it actually looks more like 5998 any brand inside than 6AS7G itself. Never tried those you have got ,by the way ,but they look pretty intriguing.

Regarding rectifiers shout out I would agree with your opinion about Mullard vs. Phillips having both long time and using in different amplifiers . It is more the matter of taste and getting balance in sound with particular electronics one is using than the class , where both are at its own. Going for GZ 37 for example will push tonal balance even more further into bass direction and give more meaty presentation , but sacrifice some dynamics , so it is always courses for horses and the matter of taste. I would like to recommend one more and not so expensive to buy for trying :
Chatham JAN-CAHG 5R4WGA rectifier. [ mine are all dated 5/ 1956 ]

Click the image to open in full size.

I found them to be very interesting alternative if compared against those mentioned above , and they always seemed to be most powerful of all if it comes to micro dynamics and speed. But again , I have never tried them in TRAM design , as I do not own it, BUT ... things might change soon as I had been offered to buy one and I am very looking forward to give it a run in my own rig. It belongs there as my amplification is dominated by 45 and 2A3 valves - among my favorites, hence an interest in this long time and excellent thread . All the best to all others who contributed into quality of this writing here , with greatest respect , Txs Gents

Last edited by gregdee; 12th May 2013 at 12:18 PM.
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