Phono11 - Brain Damage

[buddam]

Greg

what is that Vishay? Is it the gold coloured jobbie?

Adrian

[Greg.]

Hi Adrian,

In the photo they do appear gold. Go to Michael Percy page 12 and you'll find them at the top of the page.

Best wishes,

Greg

[Black Stuart]

Hi Adrian,
if you do decide to order please let me know and we could share costs.

Black Stuart

[Black Stuart]

Hi all,
an update on Phono11 rebuild and a 'word to the wise'.

I finished the rebuild a week ago and have had nothing but problems since I realised the mistake with soldering one of the HT wires to the wrong solder pad.

OK, I put that right and of course voltages from PSU11 were within a volt or two spot on at 249V-252V.However in Phono11 T/Ps' 1/2/4/ & 5 were wrong, not disastrastly wrong but wrong. So of course I went mad with the soldering iron, even though I reckon soldering is not a problem for me.

I just could'nt figure out what was wrong. After working on this brain damage for 3 days, I was lying awake one night and it came to me - like the preverbial light going on. I was using 5751 valves for V2/V3 and they have a lower output than 'standard' 12AX7 valves. So in the morning I changed them for EH 12AX7s' and bingo all these T/Ps were well within the 'desirable voltage range'.

OK, you can say that I should have realised that different signal valves have different outputs but I feel that common sense should have told WAD to include this very important fact in the instructions. So my advice is that if you have a phono stage or pre - do not forget to prep up on output level of the valves you are using - because they will definately determine some of the readings you will get. I have been e-mailing Greg on the problem Phono11 and he has said he tends to get some high readings on his Phono11, once he informed me what valves he is using in his phono - his readings are not high but relate directly to the valves he is using - for all newbies - you have been warned.

So, everything is rosie with my Phono11 yes? - no. Firstly the quality of the copper signal runs/earths and eyelets is definately inferior to the original Phono11 PCB, so for those wanting to build Phono11 - take care if these PCBs come up for sale in the future.

Secondly all signal/earth wire used is solid core - for signal input it is silver CvH gauge and for signal out 0.75mm silver plated copper. All earth wiring is enamelled solid core copper. All wiring is sheathed in teflon tubing, except for the earth wiring which I have coiled round the Teflon tubing, carrying the signal wires and NO this earth wiring touches no other components or casing anywhere.

Once I sorted the voltages out I tried to test the sound - oh oh only signal from right channel, so I used the s/iron on all solder joints around LC signal out. Eventually got this working only to lose RC. Got this working only to lose the LC again. I should say that when I turned the volume up on the integrated KEL34 - I always got that hiss when the pot is turned right up - on both channels. I have changed the i/cs from L to R/ changed i/cs completely. I have used an electrician's screwdriver that has an LED, so I know that juice is going into the integrated amp on both channels - yes I even changed decks to make sure that I don't have a problem with my SL120 or the lead out wires. It's pointless me going on blindly so am working on all the other things I need to do - I have finished rebuilding one KAT88 and I'm now working on modding my original KAT88. I Then have the CF mod to do, so plenty of things to get on with but I just don't understand what the hell is going on in Phono11. as I have had music coming from both channels but not together, the problem cannot be either Resistors or Caps - can it? And as I am using solid core wiring throughout it is easy especially with Teflon tubing to see if the wiring has broken somewhere - a real mystery. Somewhere I have stored a Lehman ss phono stage which I will have to unearth as I don't have many CDs and anyway I much prefer vinyl - even through an inferior ss phono stage.

So to recap all voltages in Phono11 are well within spec; I have had music coming through both channels but not at the same time; I have resoldered virtually all solder joints to the point of nausea; non of the signal wires are broken and most importantly I feel there is current going right through to both speakers but sound from one channel only.

Black Stuart