Have a 35L6GT slot replaced with a 50L6GT. Tube cross reference here says a substition for both is a 70A(C). Thus, should'nt a 35L6 and a 50L6 also be interchangable, or am I missing something?

A 35L6 is a 35 volt heater. A 50L6 is a 50 volt heater. They are not interchangeable because of the heater voltage.

Hi Paul,
Warren is right. Placing a 50L6GT in place of a 35L6GT will cause all the tubes to operate with filaments that are too cool. Low emission will exist on all the tubes in the set. It will be like having a radio full of weak tubes. The result will likely be weak performance and perhaps humm.
I am assuming series filament, typical with a 35L6GT.

Best Regards,

Bill Grimm

:Hi Paul,
: Warren is right. Placing a 50L6GT in place of a 35L6GT will cause all the tubes to operate with filaments that are too cool. Low emission will exist on all the tubes in the set. It will be like having a radio full of weak tubes. The result will likely be weak performance and perhaps humm.
: I am assuming series filament, typical with a 35L6GT.
:
:Best Regards,
:
:Bill Grimm
:
Lewis

Hi Paul

I see nothing wrong with using a 50L6 in place of 35L6. Yes filament voltage is higher but this averages out over all tubes in the string. With higher line voltage using a 50L6 in place of 35L6 would be preferred.

Radios were designed in the days of 110-117 line voltage. Voltage today is closer to 120-125 volts.

Norm

::Hi Paul,
:: Warren is right. Placing a 50L6GT in place of a 35L6GT will cause all the tubes to operate with filaments that are too cool. Low emission will exist on all the tubes in the set. It will be like having a radio full of weak tubes. The result will likely be weak performance and perhaps humm.
:: I am assuming series filament, typical with a 35L6GT.
::
::Best Regards,
::
::Bill Grimm
::
:
:
:
:For test purposes, you might get by with that swap to see if you have any other problems, but I wouldn't count on it. And, I sure would not let it leave my bench that way.
:Lewis
:

Norm is right. There is no real difference with using a 50L6 for a 35L6. Tubes take longer to warm, and glow slightly dimmer, but performance is just about the same. Furthermore, there is no increase in hum. I don't know why anyone would even think of that. A decrease in cathode temperature isn't going to increase hum.

T.

Things like this hum increase and too cool filament business are thought of because a lot of "contributors" to this and other forums have no idea what they are doing. Luckily others do.

:Norm is right. There is no real difference with using a 50L6 for a 35L6. Tubes take longer to warm, and glow slightly dimmer, but performance is just about the same. Furthermore, there is no increase in hum. I don't know why anyone would even think of that. A decrease in cathode temperature isn't going to increase hum.
:
:T.
:

Hi Thomas,
I had a radio in here that had a significant hum and a 50C5 where a 35C5 should have been. I replaced it with a 35C5 and the hum was gone!
The 50C5 had a significant H-K short of course. I remember the hum, but not always the H-K short. I retract the posibility of hum.

As for general replacement of 35 volt tubes with 50 I tend not to do it. If the 35 volt replacement is not around then I am OK with it. My preference is for orginality and even now a proper replacement gets one closer to the proper 150 miliamperes through the filaments.
Keep in mind, removal of dropping resistors and replacement with a 50 volt tube carries the risk of heat damage to the case as noted below.

Best Regards,

Bill Grimm

Paul,

I absolutely agree with Norm. I have a Granco 610FM radio that had a 35c5 for its output, with a 19T8, 12AT7, and 3-12BA6's. With 4 0.5W resistors in the filament string, it was looking for 110.3 volts total. I removed the 35C5 and put in a 50C5 and bypassed the 4 resistors. Filament string now needs 119.3 volts. Only problem I thought of was a 50C5 gets hotter than a 35C5 and may concentrate heat on the top of the case. No problems so far with over 3 years of use. Just add up the filament voltages. If you fall in the 120-125 volt range, I'd say you're golden.

Anthony

Another sub I like for both tubes is the 50C6G, but it doesn't always fit where these tubes fit. It's an ST14 bulb. It has more bass and power than an XXL6 tube, though, but also, due to the increase in bass, there'll be an ever so slight increase in hum.

T.

Right Norm, as usual. It will not only do no harm but will also extend tube life. Another good sub is a 45Z5 for a 35Z5.

:Hi Paul
:
: I see nothing wrong with using a 50L6 in place of 35L6. Yes filament voltage is higher but this averages out over all tubes in the string. With higher line voltage using a 50L6 in place of 35L6 would be preferred.
:
: Radios were designed in the days of 110-117 line voltage. Voltage today is closer to 120-125 volts.
:
:Norm
:
:::Hi Paul,
::: Warren is right. Placing a 50L6GT in place of a 35L6GT will cause all the tubes to operate with filaments that are too cool. Low emission will exist on all the tubes in the set. It will be like having a radio full of weak tubes. The result will likely be weak performance and perhaps humm.
::: I am assuming series filament, typical with a 35L6GT.
:::
:::Best Regards,
:::
:::Bill Grimm
:::
::
::
::
::For test purposes, you might get by with that swap to see if you have any other problems, but I wouldn't count on it. And, I sure would not let it leave my bench that way.
::Lewis
::
:

Actually with today's higher average line voltage the substitution might make good sense. If you are getting 120-125 volts and the set was designed for 110, things are going to be just fine.

:Right Norm, as usual. It will not only do no harm but will also extend tube life. Another good sub is a 45Z5 for a 35Z5.
:
::Hi Paul
::
:: I see nothing wrong with using a 50L6 in place of 35L6. Yes filament voltage is higher but this averages out over all tubes in the string. With higher line voltage using a 50L6 in place of 35L6 would be preferred.
::
:: Radios were designed in the days of 110-117 line voltage. Voltage today is closer to 120-125 volts.
::
::Norm
::
::::Hi Paul,
:::: Warren is right. Placing a 50L6GT in place of a 35L6GT will cause all the tubes to operate with filaments that are too cool. Low emission will exist on all the tubes in the set. It will be like having a radio full of weak tubes. The result will likely be weak performance and perhaps humm.
:::: I am assuming series filament, typical with a 35L6GT.
::::
::::Best Regards,
::::
::::Bill Grimm
::::
:::
:::
:::
:::For test purposes, you might get by with that swap to see if you have any other problems, but I wouldn't count on it. And, I sure would not let it leave my bench that way.
:::Lewis
:::
::
:

A typical 6 tube with 2 35 volt tubes is designed for a mean voltage of 118. A typical AA5, with a 50 volt and a 35 volt is designed for a mean voltage of 121. None of these sets is designed for 110 volt use, though they will function at 110 volts, and subbing a 50 or a 45 for a 35 will extend the life of the filaments, and possibly the cathodes, too, at 121 volts. If you live in Mexico, you should especially consider this, because there the voltage is around 127 volts.

T.

:A typical 6 tube with 2 35 volt tubes is designed for a mean voltage of 118. A typical AA5, with a 50 volt and a 35 volt is designed for a mean voltage of 121. None of these sets is designed for 110 volt use, though they will function at 110 volts, and subbing a 50 or a 45 for a 35 will extend the life of the filaments, and possibly the cathodes, too, at 121 volts. If you live in Mexico, you should especially consider this, because there the voltage is around 127 volts.
:
:T.
:

PS: A 50L6 is indeed listed as a sub for a 35L6 with acceptable performance in the CISINS tube replacement guide.

Lou

:Have a 35L6GT slot replaced with a 50L6GT. Tube cross reference here says a substition for both is a 70A(C). Thus, should'nt a 35L6 and a 50L6 also be interchangable, or am I missing something?
: