DHT OTL Linestage - Tram 2

[ptashton]

Originally Posted by Desmo

That is done Peter...

I use a very, very nice sounding Cunningham tube at the Mu position. It sounds and also look amazing because the glow of the heater is so strong and visible through the internal structure.

At this point I can't really think of anything else that can be improved on my Tram II... And it sounds amazing..!

Morten, that is what I thought when I used an earily RCA 5U4G. I also tried the Tungsol 5U4G. Non of them compared to the refined sound of the GEC U52. It's like comparing an Opal to a Rolls Royce.

Peter

[Desmo]

Originally Posted by ptashton

Morten, I wish it was Thorsten Lösch. Thorsten use to be very active on this forum and solved may problems straight away. I just did not get the feeling it was Thorsten in the e-mail correspondence with Simon.

Peter

Obviously I can't say who answers e-mails from them, but previously, when Simon has called upon their technician it has been Thorsten.

...So let me rephrase (second languages can be challenging sometimes getting points 100% clear): If one needs the best qualified technical response when contacting DIYHIFISUPPLY, then ask for a response from Thorsten Lösch. He is the one with the deep understanding of this design...

[ptashton]

Originally Posted by Desmo

Obviously I can't say who answers e-mails from them, but previously, when Simon has called upon their technician it has been Thorsten.

...So let me rephrase (second languages can be challenging sometimes getting points 100% clear): If one needs the best qualified technical response when contacting DIYHIFISUPPLY, then ask for a response from Thorsten Lösch. He is the one with the deep understanding of this design...

Morten, that is an excellent idea of yours.

It is very frustrating when you ask a question to Simon and you do not get a response. Even if he or another member of DIYHIFI send you back a 'CC' to the request to the Technician. I have phoned on several occasions to ensure Simon has received my e-mail regarding Tram 2 voltage discrepancies. There has been some misplaced e-mails.

[Desmo]

Originally Posted by ptashton

Morten, that is what I thought when I used an earily RCA 5U4G. I also tried the Tungsol 5U4G. Non of them compared to the refined sound of the GEC U52. It's like comparing an Opal to a Rolls Royce.

Peter

Thanks. Yes, I get your point (again) on the GEC U52 If I get to borrow one some day I will get the chance to form my own opinion... Some believe it's the holy grail of rectifiers, others that it's good, but too hyped and overprized and that tubes like the Philips 5r4gys are at the same sonic level (for 10-20% of the price). Some also feel, that the GEC U52 is too creamy and too ''soft and tubey'' sounding...

I'm NOT into the ''NOS tube storytelling'', so for me hearing is beliving. If I get to hear a GEC U52, and I think it's noticably better than the Philips 5r4gys or the Brimar 5r4gy from the 1950's, then I will buy a GEC U52. If not, then I will be happy with the much cheaper 5r4 types. One of the reasons that I really like the Tram II is, that it's soo good for a decent amout of money. There are better cost-no-object preamps out there for sure, but I like things that has amazing sound quality for little money. That's why I also consider a cheap and excellent sounding rectifier more interesting, than a very expensive and exellent sounding one...

But that's just me...

To be honest I don't really have an interest in tubes, their history, internal construction details etc etc. For me it's a ''bottle that plugs into a socket''. Some bottles sound different/better than others. I just take advise from a few friends of mine who is into all the stuff about these cool ''bottles'' and I buy what they recommend. I know their systems and what their sonic preferences are, they know me and my system and therefore it's easy for them to point me in a certain direction.

It's more difficult so share recommendations across the globe, like here. For instance, I have never heard your system Peter, so I have no idea what ''natural'' means to you. Maybe we have the same preferences, maybe not... It's hard to know..! The other 2-3 guys I take tube advise from live within an hours drive, and we have listened, compared and shared a lot during the years, so when they say tube X sound in a certain way I know exactly what they mean...

[Desmo]

I found these interesting comments on the 5R4 rectifiers and I can relate to what they both describe...

Read the 11 product reviews: Philips 5R4GYS Made in Holland - Upscale Audio

And this interesting review where the Philips (2) and Brimar (3) are compared. My source mentioned, that there would be little (if any) sonic difference between them. This guy seems to think the Brimar is a step above the Philips. I'm looking forward to compare them in the Tram II in a few days time... REVIEW: Decware Select Zen CSP2 Tube Headphone Amp

[Falck]

Originally Posted by ptashton

Mats, I had trouble with the voltages of my Tram2 and e-mailed Simon. This is his response. The feedback from DIYHIFI is not very good. They need a Technician on hand to respond to the technical questions. Their Technican is off site and it takes time if they do to respond. The questions on this forum are very much the same with voltage readings not matching the Tram2 manual. I asked if they could change the Manual to indicate the correct voltages, but it never happened. See attachment for lights on FCUPS Module after startup has stabilised. You get the different LEDs light up as you say.

From: Simon
Sent: Monday, July 30, 2012 5:11 PM
To: ptashton
Subject: Re: Testing ABS FCUP Tram2 Boards

Hi Peter

The LED is red, it seems to have some issue though the voltage we measured now is correct (-20v to -30v).

We are sending you the modules now. Please let us the result.

regards,
Simon
On 7/27/2012 9:14 AM, ptashton wrote:

What voltage did you get on the FCPSU for the Bias –74 volt. I was getting –118 volts. Are you getting –74 volts at the Bias point.


All the best

Peter

Hi Peter
Thank you for your replay

All LEDs D13, D14 and D15 lights up after about 30 sec. D15 is a bit "weaker" I think. I have measured again and got this result:
"In wall" 230V AC

FCPSU Module
Both "RED" 204V AC to "DLK-"
Bias -174V to GRD (stable)
B+ about 320 V ..... and rising (just before i turned Tram off).
(No tubes)

BIAS module
Bias -174V
Purple cables 9,7V AC

And same as before between ground and grid -163V. After about 10 sec it´s stable. After a while the voltage starts to sink. I desided to turn the Tram of because of the high voltage at the FCPSU so I have not mesured how low it goes.

Best Regards
Mats

[Falck]

Originally Posted by Desmo

Hi Mats,

Welcome to the dark side of DHT preamps

Heater voltage:
Adjusting to 2,7V with no tubes is fine. This is just to get the heater voltage ''about right'' before inserting the tubes. When you have the preamp up and running, with tubes, you should let it warm up for at least half an hour and then make fine adjustment of heater voltage to 2,5V.

Grid voltage:
Check if the wiring and the resistors around the Auto Bias module is correct. When power is on, the auto bias module pulls down the grid to the negative voltage of around -65 volts (+/-) and then the voltage gradually goes up to the operating point over several seconds. This is to make a soft start on the DHT tubes. That your voltage is much lower could indicate something with the wiring or the autobias module. Try to check if the voltage stays at the -163V? Or does it gradually rise..!? Is this in both channels..?

Hi Morten,

Thank you for your replay

I have checked the wiring and resitors and they seems ok. I have also done some more mesasurements which I have just posted.

Best Regards
Mats

[ptashton]

Morten: Some also feel, that the GEC U52 is too creamy and too ''soft and tubey'' sounding...

Answer: I have been told the creamy ones are the Osram made GEC U52 tubes.

Morten: But that's just me...

To be honest I don't really have an interest in tubes, their history, internal construction details etc etc. For me it's a ''bottle that plugs into a socket''. Some bottles sound different/better than others. I just take advise from a few friends of mine who is into all the stuff about these cool ''bottles'' and I buy what they recommend. I know their systems and what their sonic preferences are, they know me and my system and therefore it's easy for them to point me in a certain direction.

Answer: I agree whole heartedly. In my case, I had some NOS GEC KT88, KT66 and EL37 tubes which can be used in my Primuluna Two Amp. I tried then, did not like the sound and ended up with Mullard EL34s. I have tried, Chinese, Russian, USA, English and Dutch tubes in this amp and a Phonodude pre-amp. I mostly find the Dutch tubes sound best in my system.

Morten: It's more difficult so share recommendations across the globe, like here. For instance, I have never heard your system Peter, so I have no idea what ''natural'' means to you. Maybe we have the same preferences, maybe not... It's hard to know..! The other 2-3 guys I take tube advise from live within an hours drive, and we have listened, compared and shared a lot during the years, so when they say tube X sound in a certain way I know exactly what they mean...

Answer: Maybe Hugh can give his opinion as he is getting the Philips 5R4GYS and he is now listening to my GEC U52 tube.

[rab28]

Hi all, just wanted to report that as of this afternoon, I am now the proud owner of a Tram2... indeed, it seems I am the owner of possibly the very last Tram2 (as we know it today) to be sold by DIYaudioSupply... it seems they can't get the HV supply modules and more and the known replacements are too large to fit in the chassis...

Due to various circumstances, i only had a chance to listen to a few tracks tonight... still cold... not run in... with the aircon humming away... speakers too close to wall.... i.e. far from optimum!

The verdict? Sounds a-mazing, so much more life, body - and clarity - than the (non commercial) preamp i had been using, which was no slouch. I am one happy camper !

Can't wait to get the Coleman regulator (heater supply) boards into it. Then down the track, other tweaks... NOS valves...

I have been enjoying the conversations in this thread and I will now be watching it very closely!

[Falck]

Originally Posted by Desmo

Hi Mats,

Welcome to the dark side of DHT preamps

Heater voltage:
Adjusting to 2,7V with no tubes is fine. This is just to get the heater voltage ''about right'' before inserting the tubes. When you have the preamp up and running, with tubes, you should let it warm up for at least half an hour and then make fine adjustment of heater voltage to 2,5V.

Grid voltage:
Check if the wiring and the resistors around the Auto Bias module is correct. When power is on, the auto bias module pulls down the grid to the negative voltage of around -65 volts (+/-) and then the voltage gradually goes up to the operating point over several seconds. This is to make a soft start on the DHT tubes. That your voltage is much lower could indicate something with the wiring or the autobias module. Try to check if the voltage stays at the -163V? Or does it gradually rise..!? Is this in both channels..?

Hi Morten,

I still haven´t found whats wrong with my Tram but I got a question about the jumper J1 and J2 at the FCUPS modul. I got FCUPS version V2. How is your J1 and j2 set? have you got a picture of it?

Best Regards.
Mats