Elrog 300B vs Takatsuki 300B tubes

10-25-15: Charles1dad
Hi Al,
Good point, but interestingly Wyan001 and Germanboxers use the same DAC with superb results.

Thanks for pointing that out, Charles. In looking at the Lampi site, though, I see that Dracule's GG is described as having a choke (i.e., an inductor) as the plate/anode load for the output tube, while the Big 7 which the other two gentlemen have been using is described as using a resistor. I don't know if that might account for any difference in how the Elrog performs in the two designs, but it suggests that it could conceivably be a possibility.

10-26-15: Dracule1
System synergy is a possibility. I use a Tortuga Audio passive LDR preamp. May there's an impedance mismatch? Tortuga has a new software upgrade so you can vary the impedance of the preamp, which I don't have. May its time to upgrade and see if this will improve the sound.

There isn't enough information at the Lampi site to be able to say for sure, such as an output impedance spec, but I'd be surprised if there was an impedance compatibility issue here. It appears that all of the currently produced Tortuga passive preamps have input impedances of around 20K or more, regardless of the attenuation setting, which, given that it uses LDRs, figures to be essentially constant as a function of frequency. I'd be surprised if the Lampi's performance would be compromised by such a load. And while the input impedance of your amplifier will reduce the 20K somewhat, depending on the attenuation setting, since you are using a passive preamp I assume the input impedance of the amp is high and will therefore not have a large effect on the impedance seen "looking into" the preamp.

On the other hand, though, it appears that the 300B or other output tube that may be used in the GG & Big 7 is used in an anode follower/plate follower configuration, which leaves me a little bit less certain about impedance compatibility than I would be if it were a cathode follower that would undoubtedly have low output impedance.

Best regards,
-- Al

first time poster here....
I own a Lite7 since a few months. I had the 101d WE and more recently the Elroy 300b. the elrogs were my preference ... much fuller sound!
two weeks ago one of the elrogs failed ... I sent them back and now the dealer is hesitant to send me a replacement pair as long as he doesn't know what's going on. he would prefer to give me the money back ...

so here are a few questions for those of you who experienced failures with elrog tubes:

were there any problems with replacement tubes?
any replacements died?
any known causes that lead to failure?
date of production of the replacement tubes?

any information welcome
cheers!
stefan

Stefan,
So far my replacement Elrogs are working fine(few months) in my amplifier. More time is needed to make any declarations regarding longevity/reliability. I'm hopeful.

My amp has input impedance of 100 kOms and has built in stepped attenuator. I'm going to try hooking my GG DAC directly into the amp bypassing my passive preamp. In some situations, this can dramatically improve the sound. I also spoke toe George a TubesUSA. He recommended trying different types of rectifier tubes including 5R4, 5R4GY, GZ34 and GZ37. He told me to stay away from 5AR4 which draws 4 amps and is too much. I'm currently using the Psvane 274B replica. I also have the EML 5UG that came with DAC which I haven't tried with the Elrogs. I also have a Brimar 5Z4GY coming soon. It was recommended by a fellow Audiogoner who used it in the Lampizator.

While I'm hesitant to question George's recommendations, FWIW I don't understand some of them. According to my documentation and my understanding, the 5AR4 (which he advises against) is two-way interchangeable with, and therefore very similar to, the GZ34 and the GZ37 (which he suggests trying). Also, the filament current drawn by the 5AR4, at least in its vintage incarnations, is 1.9 amps, not 4 amps as stated. 1.9 amps being substantially LESS than the draw of the EML versions of the 5U4 and 274B that are supplied by Lampi according to its website, as well as the filament draw of the vintage versions of those tubes. It is also slightly less than the 2.0 amp filament draw of the 5Z4 and 5R4.

Although if the filament current drawn by the tube is too low, as well as too high, problems can result. If it is significantly too low relative to what was anticipated in the design it could conceivably result in the filament voltage that is applied to the tube being high enough to shorten its life.

If it were me, without an ok from Lampi, either directly or via some indication on its website, I would be hesitant to use a rectifier whose filament current is significantly outside of the range of 2.4 to 3.0 amps, those being the ratings of the EML tubes the Lampi site indicates they supply. Are 1.9 and 2.0 amps "significantly outside" of that range? Not having knowledge of the specifics of the design, I don't know.

Good luck. Regards,
-- Al