[highstream]

Thanks. Good to have another potential source. With the Lampi TRP dac, no known gain issue with KT66 (or 77 or 88) or EL34 (6CA7) or EL51

 

[leftside]

Thanks. Good to have another potential source. With the Lampi TRP dac, no known gain issue with KT66 (or 77 or 88) or EL34 (6CA7) or EL51

I think you misunderstood me. There are no "issues", but the different gain of the various tubes can be deceptive when doing listening comparisons. Ours ears often equate "louder" to "better".

 

[highstream]

True enough. The Tesla EL51 seems to either hit a volume level or excites the room in a way that feels overloaded at a lower preamp volume setting than, say, a GEC KT66.

 

[JonathanKlein]

@highstream @leftside @Monsterzero

I have some newbie tube questions. I've done some general internet searching prior to posting this, but getting input from those with the Lampi DACs will likely steer me in the best direction. So with that, please bear with me...

1. Is the GA TRP 2 auto-biasing so that it will adjust for different spec tubes? In other words, as long as I insert a tube with matching pinout, is it safe to assume that it won't cause damage to the DAC?
2. How important is to use matching quad tubes? For example, the holy grail tubes for this DAC per whatsbestforum, is the Tesla EL51. I was able to obtain two NOS sets of matching pairs, but the sets aren’t matched with each other. Is there an optimal left vs. right side installation order I should follow?
3. Do I need to use four power tubes if I’m only using the SE output (as opposed to balanced output) or will two suffice?

Thanks in advance.

 

[highstream]

Good questions to ask at TRP thread, where more TRP users.

 

[Monsterzero]

I only have SE,so only two power tubes for mine. As far as L/R, IDK,I just put them in. I do not notice any difference from R/L. Perhaps @Gopher can advise better.

 

[leftside]

@highstream @leftside @Monsterzero

I have some newbie tube questions. I've done some general internet searching prior to posting this, but getting input from those with the Lampi DACs will likely steer me in the best direction. So with that, please bear with me...

1. Is the GA TRP 2 auto-biasing so that it will adjust for different spec tubes? In other words, as long as I insert a tube with matching pinout, is it safe to assume that it won't cause damage to the DAC?
2. How important is to use matching quad tubes? For example, the holy grail tubes for this DAC per whatsbestforum, is the Tesla EL51. I was able to obtain two NOS sets of matching pairs, but the sets aren’t matched with each other. Is there an optimal left vs. right side installation order I should follow?
3. Do I need to use four power tubes if I’m only using the SE output (as opposed to balanced output) or will two suffice?

Thanks in advance.

1a. The TRP is self biasing, I think by using a second cathode resistor. "In theory" you shouldn't notice too many differences in the tubes rolled apart from gain, but the design will allow you to roll many different tubes. Now, I say "in theory" as many people are reporting hearing differences with various tubes (and not just gain). I also think I'm hearing differences with EL3N, EL11 and EL12 tubes that I've been using. These appear to be warmer than the KT66, EL35 and EL37 I've tried. More listening required
1b. Don't assume because a tube has a matching pinout it will work. This might end up being a very expensive assumption.
2) With the "tube buffer" design I highly doubt needing perfectly matching tubes.
3) Don't know. I deliberately avoided the balanced DAC this time around (my GA is balanced) as I know the prices of some of the more desirable tubes that this DAC takes.

 

[JonathanKlein]

@leftside Very helpful! Thank you

 

[Crashem]

@highstream @leftside @Monsterzero

I have some newbie tube questions. I've done some general internet searching prior to posting this, but getting input from those with the Lampi DACs will likely steer me in the best direction. So with that, please bear with me...

1. Is the GA TRP 2 auto-biasing so that it will adjust for different spec tubes? In other words, as long as I insert a tube with matching pinout, is it safe to assume that it won't cause damage to the DAC?
2. How important is to use matching quad tubes? For example, the holy grail tubes for this DAC per whatsbestforum, is the Tesla EL51. I was able to obtain two NOS sets of matching pairs, but the sets aren’t matched with each other. Is there an optimal left vs. right side installation order I should follow?
3. Do I need to use four power tubes if I’m only using the SE output (as opposed to balanced output) or will two suffice?

Thanks in advance.

I have had both the balanced GG and now SE Pacific so my answers are based on my experience with them:

1. Great question. On the GG and Pacific, you would have to change the setting which affected the heater setting depending on which general type of tube being used. Additionally, both the GG and Pacific could run tubes out of spec. I assume you can do the same with the TRP. It is doubtful that the DAC will be harmed assuming the tubes are working, but you could blow or compromise life of tube. The BIG caveat would be that the pinout of the tubes match the lampi so make sure they match.

2) Matching pairs should be fine. one tube from each matching pair on left and right side. Not matching pair solely on left or right side.

3) On the balanced GG, I could run the DAC SE and put pair of tubes in back sockets. TRP should be similar is my guess. I would doublecheck with Lampi where to put them on TRP.

 

[JonathanKlein]

@Crashem Thanks for the info. That will save me some coin not needing quad tubes while I'm running in SE (for now). I'll double check with Lukasz on the TRP specifics.

 

[JonathanKlein]

The following is direct from Lukasz, basically confirming everything that @Crashem stated above.

1. Is the GA TRP 2 auto-biasing so that it will adjust for different spec tubes? In other words, as long as I insert a tube with matching pinout, it won’t cause damage to the DAC? YES, EXACTLY. ANY PENTODE OR TERODE WITH SAME PINOUT WILL WORK JUST FINE
2. How important is to use matching quad tubes vs two sets of matched pairs vs all unmatched? Is there a specific left vs right side that I should install them if they aren’t matched? EACH TUBE HAS THE PARAMETERS SET INDIVIDUALLY, SO THEORETICALLY THERE IS NOTHING WRONG WITH USING 4 RADICALLY DIFFERENT TUBES. THE LEFT - RIGHT WORK AS “SEEN” AND REAR ROW IS BALANCED NEGATIVE, FRONT ROW IS SE AND XLR POSITIVE. WHEN YOU LISTEN TO SE YOU CAN USE ONLY FRONT ROW OF TUBES.

 

[Gopher]

I only have SE,so only two power tubes for mine. As far as L/R, IDK,I just put them in. I do not notice any difference from R/L. Perhaps @Gopher can advise better.

You will be fine as long as you are using supported pentode tubes.

It is not required that a pair (or quad) of tubes be matched.

In our new generation DHT DACs you are able to use just 2 tubes given the voltages are digitally regulated rather than the result of a formula taking 4 into consideration. I'm honestly not sure if the same is applicable for the pentode dacs, but will double check with Lukasz.

 

[attilahun]

New TRP owner, started with some RCA tubes: 6L6 and 5R4.
Looking forward to trying some more tubes.

 

[highstream]

Congrats.Be sure to head over to the What’s Best TRP forum for a more model focused discussion.

 

[leftside]

New TRP owner, stated with some RCA tubes: 6L6 and 5R4.
Looking forward to trying some more tubes.

Sweet looking setup. Like the shelves as well. I've also have on order some 1948 RCA 6L6G tubes.

I've been snowed under with work this week, but it's a long weekend here coming up, and I'll be trying quite a few more tubes if it's raining outside. So far, I'm liking all tubes EL11/EL12/EL3N seem to add a touch of warmth, and might be suited to some recordings.