2359glenn

Sko0byDoo · Sep 12, 2015 at 6:14 PM

2359glenn said:
I still think it was the amps they were in blowing these tubes. Khragon I haven't tried them in my amps yet because the amps don't have regulated filament
voltage. The first amp I will put them in will be Tony's I know they will be safe with regulated filament voltage. And this amp will be the same as yours.
I don't want to put them in a amp that the voltage can go over 5 if the line voltage is hot when I put them in.

Got mine to climb over 6V (turned off immediately so not sure what's the max) at a setting when others (EML/Black Treasures) were just perfect at 5V. I think the filament resistance was a little bit off.

Mine running at 5V so far so good, at ~800 hrs. I noticed that they do take time (`30 min) to reach full steady state/max current draw.

Much better than the Black Treasures and EML300B XLS, but am interesting to hear Glenn's take versus WE/SE/TA.

2359glenn · Sep 12, 2015 at 7:18 PM

Scoob you hit it right on the nose.
In a circuit that just uses resistors and capacitors for the 300B filament the resistors drop the voltage
according to the current draw of the 300B filament. If the filament is higher resistance it will draw less
current and the resistors will drop less voltage. Making over voltage on the filament.

Not so easy to measure this has to be done with a hot filament. I will do this when I have time put a resistor
in series set the filament to 5 volts measure the voltage drop across the resistor and calculate the resistance.
I will do this with the Elrog and other 300Bs and compare the resistance readings.

By the way how does the Elrog sound ???? Normally I think throated tungsten tubes sound great.

Khragon · Sep 12, 2015 at 7:26 PM

Elrog sounded very smooth when I had it running on WA5, I would say better than WE300B, however it's a tad bass light, I don't have a problem with that though, not a bass head by any mean, most of my tracks are folks vocal songs.

Elrog tested really weird on my TV-7 tester using 300B settings, but I think that's just the way thoriated filament test.

2359glenn · Sep 12, 2015 at 8:49 PM

I am going to do the resistance measurement on the Elrogs to find out if there resistance is higher then other 300Bs.
That way we will know if it is the amps blowing these tubes. Even though nobody will want to know there expensive
amps are blowing these tubes.
I think a amp running them on AC off a dedicated 5 volt winding off the power transformer they will be OK.
The 5 volts will stay the same regardless of the current draw in this type circuit.
But all these amps will be for speakers running them on AC will have to much hum for headphones.

Maybe your new Elrogs will match other 300Bs and that is the fix?

Khragon · Sep 12, 2015 at 8:56 PM

Thanks Glenn, that will be valuable data for the community.

Sfox7076 · Sep 12, 2015 at 9:25 PM

That is an interesting question. Should they change the resistance to "normalize" their tube? I think they would have to as they will sell a lot fewer tubes if they only work in select amps.

Glenn, where can you find the queue for a build from you? I just wonder how deep the list is.

2359glenn · Sep 12, 2015 at 9:47 PM

sfox7076 said:
That is an interesting question. Should they change the resistance to "normalize" their tube? I think they would have to as they will sell a lot fewer tubes if they only work in select amps.

Glenn, where can you find the queue for a build from you? I just wonder how deep the list is.

If they are selling it as a 300B it should have the specs of a 300B!!!!!!!!!!!!!!!!!!

But a amp that supposed to have 5 volts at the 300B socket should have 5 volts. There can be inconsistency in
the manufacture of any of these tubes that are direct heated.
The only tubes with exact filament resistance were the ones made to be in series string in line operated TVs
and radios.

The list is pretty deep at this point

Sko0byDoo · Sep 12, 2015 at 10:14 PM

The only tubes with exact filament resistance were the ones made to be in series string in line operated TVs
and radios.

Interesting, like those 0.1% resistors, cost an arm and a leg...

On the spec sheet, ER tubes get rated same as WE300B (5V+/-5%, 1.2A). Though, +20% over-spec (what I experienced) is kinda too much for manufacturing variations.

AC heater is simplest but with hum noise, regulated DC is good but the cathode AC low freq signal will get "regulated" too, so SQ degrades. High freq AC heater is best but complicated circuit, can't buy it pre-built.

2359glenn · Sep 12, 2015 at 10:33 PM

sko0bydoo said:
The only tubes with exact filament resistance were the ones made to be in series string in line operated TVs
and radios.

Click to expand...

Interesting, like those 0.1% resistors, cost an arm and a leg...

On the spec sheet, ER tubes get rated same as WE300B (5V+/-5%, 1.2A). Though, +20% over-spec (what I experienced) is kinda too much for manufacturing variations.

AC heater is simplest but with hum noise, regulated DC is good but the cathode AC low freq signal will get "regulated" too, so SQ degrades. High freq AC heater is best but complicated circuit, can't buy it pre-built.

Just hook the regulator to the heater and take the cathode off one side of the heater. The signal does not go through
the regulator. I ground one side through a milliamp meter to read cathode current and to set the bias.
I am not one to use a cathode resistor bypassed with a electrolytic capacitor. Sounds better with fixed bias and
leaving that nasty sounding stuff out.

Sko0byDoo · Sep 12, 2015 at 10:48 PM

I haven't tried regulated DC with fixed-bias yet; always have done the bypass cap and all that nasty sounding stuffs

Well, I have only 1 amp like this, too lazy to convert to fixed-bias.

With fixed regulated DC, you shouldn't have any problem with the ER then, I would imagine. The regulator will keep the output voltage at 5V regardless of the current draw.

Sfox7076 · Sep 13, 2015 at 12:57 PM

I don't mind a deep line. I have waited a long time for stuff in the past. Can I confirm I am on the list though?

As to the Elrogs, I think that it is a business point. If they fail in many amps, Elrog would be better served to change them so they don't have to deal with warranty claims. Unless they are going to have a certified amp list and no warranty claims honored unless the failure happens in a certified amp. It would just be too costly.