[triod750]

"Of course various tubes sound different due to being used outside of their design specifications; the Little Dots have fixed parameters that mean they will sound different."

Spot on, and this is why you can find excellent synergy where input and output tubes compensate for the deficiances in each other and in the recordings you are listening to.
Simple.

 

[Cognomen]

So has my understanding. I expected someone to tell me I'm wrong. I just wrote what I have been told. I have asked previously if it is possible to use the pentodes EL41 and EL42 triodestrapped in pairs as output tubes and the answer was no.

Because of their ic internal connection pins? I glanced at an EL41 datasheet on frank.pocnet.net and it had data for triode connections and triodes in push-pull. I have 6AM5 tubes that a datasheet specified had an ic pin 6: do not connect anything to it. When I looked closely at the tube I noticed nothing was connected to that pin on my Amperex 6AM5. So I ran it in EF91/EF92 mode without chopping off pin 6 and it ran well. Another datasheet, however, was more accurate and specified pin 6 was nc not connected to anything in the tube..

 

[triod750]

Because of their ic internal connection pins? I glanced at an EL41 datasheet on frank.pocnet.net and it had data for triode connections and triodes in push-pull. I have 6AM5 tubes that a datasheet specified had an ic pin 6: do not connect anything to it. When I looked closely at the tube I noticed nothing was connected to that pin on my Amperex 6AM5. So I ran it in EF91/EF92 mode without chopping off pin 6 and it ran well. Another datasheet, however, was more accurate and specified pin 6 was nc not connected to anything in the tube..

I can't answer this since I don't speak electric. I have just used EL42 as input tubes in Little Dot and briefly tried EL41 for this duty too, these with external heater PSU. Tonight I use EL42 'Sakuma style' as both input and output tubes, four of them, in an amp with output transformers. This is just an experiment to hear their tone this way.

 

[Scooter64]

New LD MKIII user here so please bear with me if this has already been covered…….theres a huge number of pages here to digest.
I’m moving the jumpers to change EF91 tubes to EF95. I get that I have to move the jumpers from pins 2 & 3 to 1 & 2 but am I right in saying that pin numbers are 1, 2, 3 from left to right when the amp is upside down and the front is facing me?
I know it’s sounds like a pretty obvious question but doing it for the first time, I do want to make sure I’ve got exactly right.
Thanks

 

[Cognomen]

New LD MKIII user here so please bear with me if this has already been covered…….theres a huge number of pages here to digest.
I’m moving the jumpers to change EF91 tubes to EF95. I get that I have to move the jumpers from pins 2 & 3 to 1 & 2 but am I right in saying that pin numbers are 1, 2, 3 from left to right when the amp is upside down and the front is facing me?
I know it’s sounds like a pretty obvious question but doing it for the first time, I do want to make sure I’ve got exactly right.
Thanks

(When installing or removing jumpers, the amp should have been off and cooled down which makes it possible the electricity harboring capacitors have discharged. IF you shut off the amp with music playing, it will continue playing music while the capacitors are discharging.)

It seems you are probably on the right track for moving the jumpers.

When I turn my version of the MKIII upside down (removing the tubes makes the job easier for me)
with the volume knob pointed toward me, both jumpers should be connecting the two pins to the left for EF95 mode and vice versa for EF91/EF92 mode. When I look with a flashlight, 5654 i.e. EF95 appears near the Leftmost jumper pins and EF91 or EF92 near the rightmost jumper pins.

There are different versions of the MKIII. They do not all look the same when it comes to jumpers. With a flashlight, one can probably find the version number by looking through the housing holes when it's upside down. If you don't already have a manual knowing the version might help if you opt to look online.

It is common for people to lose hold of a jumper when trying to install it. Turning the unit upright and shaking can get it to fall out. Having spares can be good. Some people have bought aftermarket long-handled jumpers. I install the standard tiny jumpers using cotter pin pliers which are like a needle nose plier but much, much narrower, even narrower than tweezers, and not stout.

(IF the jumpers are installed for EF91/EF92 and one powers up the unit with EF95 tubes, the amp will not work and should be quickly turned off because one is shorting the EF95 tubes and probably risking other problems if left on. It is a somewhat common error and people have shut it off soon enough to avoid damage. IF the jumpers are set for EF95 and one powers up with an EF91 or EF92 tubes, another somewhat common goof, the amp is likely to work well but may risk being unstable with some tubes due to an unconnected grid in the tubes. In addition when running EF95 tubes in my MKIII, per my user manual, it makes no difference whether the jumpers are installed for EF95 or completely pulled out of the unit. I think of installing them in EF 95 mode as a good way of storing them and avoiding losing them.)

 

[Scooter64]

(When installing or removing jumpers, the amp should have been off and cooled down which makes it possible the electricity harboring capacitors have discharged. IF you shut off the amp with music playing, it will continue playing music while the capacitors are discharging.)

It seems you are probably on the right track for moving the jumpers.

When I turn my version of the MKIII upside down (removing the tubes makes the job easier for me)
with the volume knob pointed toward me, both jumpers should be connecting the two pins to the left for EF95 mode and vice versa for EF91/EF92 mode. When I look with a flashlight, 5654 i.e. EF95 appears near the Leftmost jumper pins and EF91 or EF92 near the rightmost jumper pins.

There are different versions of the MKIII. They do not all look the same when it comes to jumpers. With a flashlight, one can probably find the version number by looking through the housing holes when it's upside down. If you don't already have a manual knowing the version might help if you opt to look online.

It is common for people to lose hold of a jumper when trying to install it. Turning the unit upright and shaking can get it to fall out. Having spares can be good. Some people have bought aftermarket long-handled jumpers. I install the standard tiny jumpers using cotter pin pliers which are like a needle nose plier but much, much narrower, even narrower than tweezers, and not stout.

(IF the jumpers are installed for EF91/EF92 and one powers up the unit with EF95 tubes, the amp will not work and should be quickly turned off because one is shorting the EF95 tubes and probably risking other problems if left on. It is a somewhat common error and people have shut it off soon enough to avoid damage. IF the jumpers are set for EF95 and one powers up with an EF91 or EF92 tubes, another somewhat common goof, the amp is likely to work well but may risk being unstable with some tubes due to an unconnected grid in the tubes. In addition when running EF95 tubes in my MKIII, per my user manual, it makes no difference whether the jumpers are installed for EF95 or completely pulled out of the unit. I think of installing them in EF 95 mode as a good way of storing them and avoiding losing them.)

Thank you for a comprehensive response - that’s really useful and gives me the confidence I have done it right.
I did do it with the unit off, and it had been overnight. I also used modelling long nose spring loaded tweezers so grabbing hold of the jumpers, and keeping them firm, was pretty straightforward.
I have a got a manual but it’s only a generic one I found on the internet so not specific to the model I have, although from what it says about jumpers and gain control, I think it does cover my unit.
Thanks again

 

[Scooter64]

Jumpers changed, tubes changed from Mullard 8161 EF91s to Voshkod 6ZH1P-EV EF95s and listening on my DT770 Pros……well impressed with the difference