DHT OTL Linestage - Tram 2

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Tram2 is on!

Dear all. The reported bad resistro wasnt such. My apologizes to all of you and to Kiwame. There were a false contact in one of the CCS modules.
Well, my Tram2 is now on, installed and sounding just BeautyFull !!! :note::note::note:
The middle frequencies, voices and strings are the best I have heard in my system.
However I noticed that cymbals and brasses (metalic instruments) sound now mellowed, middle bass is as well softer.
Is it normal during the first hours of operation? or is it how the Tram sounds? What could I do/change in order to get more metallic sound? Id appreciate any suggestions coming from you.

Dont take me wrong please, the Tram sounds wonderful. It is a matter of taste.
MB
 
Good that you tracked down the problem :) Your description of a mellow sound certainly does not match my Tram II..! Actually I would say it's the most dynamic and live-sounding preamp I have ever had in my system. So I guess it's either a matter of break-in, or that something else is wrong with your preamp...!?
 
Hi Morten
by no means there s something wrong with the Tram. As mentioned before the voices and strings are the "sweetest thing ever". I am listening now to Concha Buika via Linn Majik, and for the first time ever I felt Buika was in my room. I dont know if thats good or bad because Buika is as sexy as her voice and having her without having her...;)
I have read in some websites that though neutral the SCRs tend to the soft side. I remember that youre using now the Duelund caps in your Tram. Do you remember the soudn with the SCRs before that?
By the way, the RC regulators arrived today. I really cannot imagine the voice of Buika sounding more real. But I will try anyway.
 
We used different words when describing sound, so one should be careful with the interpretations of course. My reason for asking if you are sure there is not something wrong with your preamp is, that words I would never use to describe the Tram II is mellow and sweet... But again, I don't know your reference for using those words... Personally I would use totally different words: Bold, dynamic, transparent, natural and with that live-feeling that so few products manage to achieve...

If you go back in this thread you can read my evaluation of the Duelund CAST as input caps compared with the original Obbligato teflon caps. The short answer to your question: NO, actually the opposite. Duelund has a very natural and coherent sound whereas all teflon caps that I know of has more highlight of the details. This can make them more impressive, where as the Duelund just dissapear. So if I was forced to call one of them mellow (again a word I would not use for either cap) it would be the Duelund.

I know this does not exactly help you to understand what you hear, but again: I can't really relate to your sonic impressions. They are very different from mine...

Regarding the Rod Coleman DHT regulators they are the biggest sonical difference on the Tram II, and as I have mentioned before: I believe the regulators makes a bigger difference than all other mods combined. Hearing is believing :)
 
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Hi marybety
I will say the same As Desmo about the sound---do you use 45 tube,,im my system they were a bit more sweat or mellow...I will say that the output caps give more to the sound that input caps,,,but not near so much as the Coleman regulator
Tubes is the first place to start ,if you want a different sound.
Best Bjarne
 
I totally agree with Bjarne :) The upgrade of the output caps to 6 x 2,2uF obbligato tinfoil gives quite a lot, and is a bigger improvement than replacing the input caps. However, the Rod Coleman regulators is the most essential of the upgrades...

Regarding tubes: YES, the 45's are less dynamic, more intimate, more mellow...
 
Thanks a lot for your answers Morten and Bjarne.
And yes Morten, you r right. We use different terms for describing the wonderful sound of the Tram. It wasnt my intention to misinterpret your words.

I will let the Tram break in for a couple of weeks before proceeding with the tunings. I will let you now about my impressions.

My next challenge is to find a reference class powerful tube amp (100W) in the diy community for honoring the Tram. Any suggestion is welcome.

For anyone of you reading this thread and still thinking about buying the Tram :scratch1:. Just DO IT!! You will be very happy at the end.:yes:

Regards

MB
 
Hi, has anoyone tried to move the Tram output voltage divider (the relevant part of the resistor network at the output RCAs) to the input of your power amplifier.

My belief is that this would lower the Tram's output (DC) impedance so that the capacitance of the following RCA signal cable to the poweramp does not shape the tonal balance. Please protest if I've got it wrong.

I find that I only use the -12dB output of the Tram and it should be easy to move these four resistors in total to the poweramp input.

I've heard that SET tubes might get broken if they do not see any load (might only be applicable for poweramps with transformer on output). The Tram is decoupled with output capacitors so my belief is that the removal of an output load at the RCA outputs should not hurt the preamp.

Any knowledge on this?

Geir :)
 
Yess, finally installed the the Rod Colemans heaters too.
First impressions:
1. Lower noise floor
2. Increased transparency
3. Expanded soundstage
4. Somewhat drier base/lower mids

The drier sound might well also be due to some exchange of the output resistors.

Overall, well worth the work.
Thank you Rod for offering this technical advance :-D

Geir
 
An update on the above post;
The sound is even better today. Yesterday I could only get the heater voltages up to 2.4V but today managed to get exactly 2.5V on the heater voltages by fiddling (reducing) the resistor values on the Colemans heaters out. Also swapped back to my old resistors (Dale) on the pre outlet.

The dryness in the sound is gone now and it is all music :-D
 
Thanks Geir, Pleased to hear that you like them!

The Current-Sense resistors do need some running-in time, and probably the same for the capacitor C3. These are also the parts that Morten and Bjarne have switched to more exotic parts, to good effect. It should be worth trying them on any Tram with the Filament Regulator upgrade.
 
Thanks Rod, I'll already contacted Morten earlier to get info on the suppliers in northern Europe of these parts.

Currently my current :) sense resistance inserted is very low as I had to put some 1 Ohm and 2,2 Ohm resistors in parallel with the resistors supplies in your kit. Is there any danger that too much current is flowing then?

The heat of the regulators are OK since I simply glued them onto the chassis.

Geir
 
Hi Geir, it's OK provided the dc input voltage does not vary too much.

If the current range is a little too low, increasing the supply voltage slightly will be effective in increasing the range slightly. A lower value for the resistor (between C1 & C2 in the raw supply) will allow this.

This method will probably give better sound.

Setting the filament voltage within the range 2,44V .. 2,50V (measured at the socket) will be good in all cases.
 
Some very interesting information regarding the sound of 45 and 2A3 NOS tubes. This is quoted from Steve Garland from the Killerdac forum in Austrlia:

45 type tubes. These are usually ST shape 1940s. The more in demand 1930 Globe types have the numbers, 145/Arcturus. UX245 /RCA. UX345/ Cunningham. 445/Deforest.

These are in my opinion the next best sounding tube ever made of American design. A Great Naturally real sounding tube. The best timbre of any tube worldwide. These tubes where made for the bread and butter radios of the day.

They have a 2.5 filament voltage and will take 275V. Output is about 2 watts

I do run them hard, 200-250v (around 2 watts).

There are 2 that stand out.

Rogers 245 long plate globe 1930s. Made in Canada. This valve is a very pretty sounding tube, clean clear and so sweet, smooth upper frequencies, can be bright if not carefull with tuning the System, does not have the timbre of the RCAs, they sound more like some 250 globes than a 45, very opposed (sound wise) to the 245 RCA version below. Great on classical.

RCA 245 Globe, This tube type is dark sounding. Can be a little rough and ragged in the upper frequencies, and is also not the cleanest 45 tube around, but it has the best timbre you will hear out of any tube, so real, so solid, real flesh on bone, Great on male vocals, guitar, not white or bright at all. . There are many 45 varieties, and you must get the right one. The black charcoal plate, circle plate globe (1930s) they have the inch long glass piece hanging from the filament support rods . The best 45 ever made along with the Rogers 45 long plate. You can see in the picture, these are the right ones, The blacker the charcoal plate the better, like the one on the left, only buy RCA 245s that have this identical construction.


Most later 1940 ST 45 shape tubes are very good, and cheap more on these and others later

and for 2A3 tubes:

2A3s. The supposed best in the 2A3s range are the monoplates. These 2a3s where made in the 1930-to 1933 as a elite audio or radio tube. Some say they stopped making them because of the cost of manufacture.

They use 2.5 filament voltage and will take 250 Volts

Be careful, many RCA 2a3 monoplates are branded RCA but where made by Sylvania. these usually have a number under the base between the pins, like J39

I find 2A3s monoplates to be overrated sound-wise, very clean clear, big soundstage, To me they sound somewhat sterile and harmonically threadbare. They sound more like a modern tube design, (Mid 1930s on) they are not as musical or involving as the 50 tubes.

Another good 2A3 monoplate is the FIVRE made in ITALY. Very nice tube, better that the genuine RCA monoplate. I have had many of these, including two that where the sort after earlier model with the side support rods (new in box).

The best ones i have ever heard are the Radiotron 2A3 mono plates, made in England, These tubes are very very good but imposable to find, i did have two mint ones a few years ago.

I like the National union 2A3 monoplates, they sound more like a 245 valve. Rich darker full, but a little ragged.

Of the 2A3 dual plates, the best is the black plate, 1940s with spring filament support.

Next is the RCA dual black plate without spring supports.

2A3s dual plates (grey or even black) generally are industrial or military, not really intended for audio use.

An exception to the rule, some people say the FIVRE dual plate is the best 2a3, (i have not heard these)
 
Thanks for the updates :)

@Geir... Could you show pictures of your implementation of the Rod Coleman regulators? It's good to share our experiences and the solutions we make (I believe)... Also: The dry sound you describe is not something I have heard with these regulators, but it appears that it's gone now so all must be good...

@ptashton... Thanks for the tube info. When I bought the Tram I was reading all I could find on all kinds of NOS 45's and 2A3's, from what I was reading the 45's should -generally speaking- be the better tubes. However, of all the tubes I have now tried in the Tram I find the 2A3's superior sounding. In the beginning I also thought that NOS tubes would sound better than new production tubes, and I have bought my share of NOS tubes for the Tram. No I have stopped rolling tubes because the best tubes I have heard for the Tram are the ones I use now... And hey, they are current production tubes, and from China :) Hearing is believing :)
 
Yes, funny you asked because I just thought about it!
I've been on vacation at our "cottage" in Rio, so sorry about late reply.

Anyway, hopefully the photos shows below.

Geir
 

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And the sound is not "dry" anymore. the shift in tonal balance was due to a too low heater voltage at a time before I manged to raise the voltage by reducing the resistance.
As I've been surfing away at Ipanema, I still have to adjust/reduce the resistance in the power supply so to give a higher supply voltage for the Colemans regulators.

Geir
 
Hi Geir,

It sounds like you've been having a great time!

2 things...

1) how are the transistors attached to the chassis. I don't see any bolts.

2) you should be ok to remove the capacitors across the heater socket pins.

I like the apporach of using the chassis as the heatsink, it frees up a lot of space for the power supply filter section.
 
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