kit 34

[Richard]

Great stuff, thanks for letting us know and good listening

[jiten]

Further questions.
Now that the amp is working well, there is a sibilance (?) in the treble ( right channel) on my Tannoys (611) and my B&W ( CDM1) seem to sound very muffled) indeed.I have checked the wiring and it is all in phase etc.
The Tannoys generally sound very good. Both sets of speakers are getting on.
Question is do I change valves? Watford valves has several EL34s at varying costs or change the speakers - at even greater cost?
If valves, which ones? The EL 34s vary from about £15 to £34 each and the ecf 80 from £15 to £30 each?
I have the Mullard ECF 80 and I think the original Tesla EL34.
Given that I do this sort of thing on relatively infrequent occasions, I dont mind spending on the valves and speakers as appropriate though not about to go overboard either.
Thank you for your help.
Jiten.

[Richard]

Hi, that's an easy one, get a new set of valves as even if you don't need them now you will at some stage. Plus they will be there as a reference for you to check your existing ones against. Otherwise it is very difficult to know when they are ready for changing.

I'd get the Svet winged C EL34 and Telefunken ECF80 if it were me.

[jiten]

Yes I see the logic of that. The valves get rarer and more expensive with time.

Jiten.

[Richard]

Yes indeed, Svet are great sounding, open and smooth and one of my favourites. I must have heard at least 6 makes.

Those Telefunken are no longer made so will be gone eventually. They were one of the best old factories and have a great sound and consistent electrical performance. They also last a long time, for several sets of output valves, so aren't really very expensive.

Plus, going for valves first will be the cheapest option to check out what may be wrong with the sound, more so than swapping speakers anyway.

[jiten]

Hi, changed all the valves including the power supply and got the telefunken. Music does sound quite incredible. Interesting to compare the 2 speakers. with the Tannoy 611, you can virtually hear every note being played but there is possibly a slight fault in the right speaker as there is sometimes a mild sibilence. The B&W still sound muffled as if there is a towel in front of it.
so still thinking of changing speakers - perhaps to the new DC6T SE.
I see the cost of valve amps is expensive but would building a 300B add to the sound quality? I would like to build one just for something to do, Does it then need a pre amplifier and power supply unit as well?
Just a thought - or I could sit back and listen to the newly energised Kit 34.
Happy to consider ideas.
Jiten.

[jiten]

Hi, I seem to be back when I have problems. The Kit 34 right channel produces little sound till it has warmed up thoroughly and after a click which happens at some time between 15 and 25 minutes, starts to sound great.
Any idea where the connection might be bad?
Further to the previous emails, I now have it connected to Monitor Audio GX 200 speakers and a REL sub woofer. The sound is quite breathtaking.

[Richard]

Hi Jiten,

If it's doing this on both channels I'd suspect a power supply component common to both channels. If it does this every time I'd up-end it and check the voltages along the HT line against the circuit values, at first switch on before it comes good, and see the point at which voltages are bad/low.

I'd suspect,
1. failing rect valve
2. a bad solder joint
3. L1 choke, put a probe either side to check voltage drop is only in the 10V to 20V region
4. any of C1 - C5. They take quite a hammering and are probably due for changing after 10 years
5. R5 R6

It's probably not related, as they would only affect separate channels, but I would consider replacing all the electrolytics if it has been used regularly. Common ones to fail are the EL34 cathode bypass and they can take the valve or even the OPTX if you are unlucky. Also the output stage coupling caps if they are a paper in oil type but if plastic film they should be fine.

[jiten]

Thank you. It is always only the right channel and as you will recall there was at one point what sounded like sibilance in the right channel.
I will check the voltages and other components you have suggested.
Will get back to you.
thank you again.
Jiten.

[jiten]

Originally Posted by Richard

Hi Jiten,

If it's doing this on both channels I'd suspect a power supply component common to both channels. If it does this every time I'd up-end it and check the voltages along the HT line against the circuit values, at first switch on before it comes good, and see the point at which voltages are bad/low.

I'd suspect,
1. failing rect valve so the question . which is the rectifier valve? C5 or C6?
2. a bad solder joint I resoldered whatever looked weak I note that one of the tags on the central tag board was almost ready to break off so have resoldered that. as a result the right channel comes on but still has a thunk in the right channel as the music starts . This can still be on switch on or 5 to 10 minutes later and sounds like a relay cutting in.. It does not recur when warm.
3. L1 choke, put a probe either side to check voltage drop is only in the 10V to 20V region. Sorry but what component is the choke? Do you mean the 2.5 H choke?
4. any of C1 - C5. They take quite a hammering and are probably due for changing after 10 years. OK happy to change these but am now confused about the ones to replace with. There seems to be a huge choice and in case everything has changed, the values in microfarads seem to be different from those listed in the parts. Am I missing something? And please excuse the ignorance here!
5. R5 R6 I can do that but again there is a huge variety of resisitors. What would you use? I tried looking at the HIfi Collective website.

It's probably not related, as they would only affect separate channels, but I would consider replacing all the electrolytics if it has been used regularly. Common ones to fail are the EL34 cathode bypass and they can take the valve or even the OPTX if you are unlucky. Also the output stage coupling caps if they are a paper in oil type but if plastic film they should be fine.

Do you mean C15 and C 16? or C21 and C22? And if they are to be replaced, what with?

Once again apologies fr the ignorance but looking at the box suddenly seems to be a daunting task!!

It is all the more difficult because when working I am still amazed at the incredible sound quality and detail.

Many thanks for your help.
Jiten