Help with Kit 34 amp

[jiten]

Dear All,
Sorry for the delay in further information but I have been away for a couple of weeks. the amplifier sounds better and better as it is running in. The slightly forward sound does not detract and is in fact nice when listening to some Indian classical music.
One question - the heater voltage now reads 5.8 v instead of 6.3 v on all valves. There is no problem with performance. Should it be a concern or do I live with it and enjoy?
Kind regards and once again a big thank you for all the help. Jiten.

[Richard]

Hi Jiten,

5.8V should be fine as it's within 10% of 6.3V nominal but check from the 2 grey and 1 blue TX heater wires onwards to make sure all connections are good and correct.

When Kit34 came out it was in the 240V rather than 230V mains era and a lowering of mains voltage will reduce heater voltage by a similar percentage. (Mains voltages around our area have dropped over the last few years and we often see 234V whereas it could sometimes be 246V in the old days.)

Depending on the amount you use it 2 years could be a reasonable life for the EL34s, they are not particularly long-lived, reckon on about 2000 hours when run near full rating as they are in this amp.

Going back to your post #3. C17 is a cathode bypass capacitor and the missing link you describe meant that valve was running without its cathode bypass capacitor. It would (did) run fine but output on that valve would have been affected. It wouldn't have shown in DC voltage checks and the amp may still have sounded good.

It shouldn't have done any damage but I would encourage you to carefully recheck the output stages in the light of this info and against the circuit to be sure all 4 valves have the correct connections. In particular check that those cathode bypass caps are in the right way round marked negative to ground as that would be a reason for them to fail.

[jiten]

Dear Richard,
I have built new tag boards with new components and connections, barring the error that I initially made which caused the very high voltages, it should all be well connected. Now all voltages are correct. The heater voltage of 5.8 does not seem to affect the performance.
My usage must be pretty low as the last EL 34s lasted almost 10 years!
In any event, the sound is great,and getting better every day so I am happy listening to it.
By the way, I must also compliment Nick and team at HiFi Collective who were very helpful with component selection and speed of delivery.
Kind regards, Jiten.

[Richard]

Hi Jiten,
Good to hear and sounds like you should be fine then