5U4G substitution

[John Caswell]

Hi all,
Various people have asked regarding the replacement of 5U4G valves with 6D22S in the WAD amplifiers. The main advantages are a slow warm up of about 30-40 seconds and much lower cost.
This will will work very well with the amplifiers that use 2 off 5U4G but is not easily implemented in single full wave valve rectifier amplifiers. You can however use the 6D22S in place of the GZ37 in the 300B p-p with just a simple valve base change and a serious saving in cost

To give you an idea, you will require the following -
2 off 6D22Ss valves
2 off B9D valve bases, ceramic preferably, (NOT B9A) top or bottom chassis mount
2 off 1/4" valve top cap connectors
A short length of wire about 12"-18" - preferably PTFE/Teflon
A 1/4" or 6mm rubber grommet
The ability to drill or get drilled a 1/4" or 6mm hole in the chassis.
If there is enough interest I will draw and write up the necessary blurb, pass it to the other moderators for modification/correction and get it placed in the FAQ

John

[Greg.]

I think it would be a great addition in the FAQ. After all, once it is there, it is available for anyone needing the conversion now and for anyone at anytime in the future. Great idea

[Richard]

Yes a great idea as Greg says and if you have a picture of an amp done with them John it would be good

[John Caswell]

Hi all,
This is now in hand - Matthew has a 6550 so we are going to modify his. He will take all the piccys and I will write the blurb. Measurements will also be included.
The WAD 330B stereo, not the monoblocks, is a bit more difficult as I said, due to the small rectifier PCB. But for those who are more DIY oriented it can be done using a valve base and tagboard. I will dream up some modifications accordingly.

John

[nneilboss]

Thanks for offering to do this. Look forward to the write-up

[Greg.]

I’m sure there are many members who may benefit in the future from this rectifier conversion. I’m just a little disappointed that so few of us have posted support for John’s work on this, as I’m sure over the passage of time it will be gratefully appreciated by many.

So, just as a bit of encouragement, Dr John, please keep at it. Your knowledge and work is much appreciated. We are very lucky to have you here and we also appreciate that you have ‘vinylspinner’ as your apprentice so your knowledge will carry on.

Thank you (Dr) John.

[bob orbell]

Very well laid out Richard, I am sure this mod will be a good move, one thing to add though, you do not mention KAT 6550 ( power amp ) the mod will of course apply to this model also. Bob