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  #1  
Old 10th November 2020, 10:19 AM
John Caswell John Caswell is offline
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Default 5U4G substitution

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
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  #2  
Old 10th November 2020, 12:51 PM
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Greg. Greg. is offline
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Default Re: 5U4G substitution

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
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Old 10th November 2020, 01:42 PM
Richard Richard is offline
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Default Re: 5U4G substitution

Yes a great idea as Greg says and if you have a picture of an amp done with them John it would be good
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  #4  
Old 13th November 2020, 12:00 PM
John Caswell John Caswell is offline
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Default Re: 5U4G substitution

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
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  #5  
Old 19th November 2020, 12:38 PM
nneilboss nneilboss is offline
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Default Re: 5U4G substitution

Thanks for offering to do this. Look forward to the write-up
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  #6  
Old 20th November 2020, 06:47 PM
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Greg. Greg. is offline
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Default Re: 5U4G substitution

Iím sure there are many members who may benefit in the future from this rectifier conversion. Iím just a little disappointed that so few of us have posted support for Johnís work on this, as Iím 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 Ďvinylspinnerí as your apprentice so your knowledge will carry on.

Thank you (Dr) John.
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  #7  
Old 20th November 2020, 08:18 PM
A Stuart A Stuart is offline
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Default Re: 5U4G substitution

re "The Apprentice": Good to hear that "the knowledge" is being passed on for posterity.
And I absolutely agree that John deserves our gratitude.

Alastair
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  #8  
Old 21st November 2020, 11:04 AM
vinylspinner vinylspinner is offline
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Default Re: 5U4G substitution

I donít know about the apprentice bit, Iím only there to sweep the floor and make the tea😁 plus the boss is in better shape health wise than I am!
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  #9  
Old 21st November 2020, 01:42 PM
bob orbell bob orbell is offline
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Default Re: 5U4G substitution

Quote:
Originally Posted by Greg. View Post
Iím sure there are many members who may benefit in the future from this rectifier conversion. Iím just a little disappointed that so few of us have posted support for Johnís work on this, as Iím 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 Ďvinylspinnerí as your apprentice so your knowledge will carry on.

Thank you (Dr) John.
I am a little puzzled about this comment from Greg, I am sure members will be interested in Johns conversion, but he has not yet posted it, so why Gregs post , also, I looked for 5U4G, still plenty about, 6D22S, very few or am I missing something. Bob
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  #10  
Old 21st November 2020, 02:01 PM
John Caswell John Caswell is offline
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Default Re: 5U4G substitution

Hi all,Well this modification is to help out people who find the 5U4G expensive, as the audiophools have got it into their heads that they are the dogs ********. GZ34 and GZ37 ditto. Someone is advertising a "matched pair" of GZ34 for £550.00. Will someone far more intelligent than I please explain how you match rectifiers
I ask you £362 for a U52/5U4G on eBay!!!!! Its only a b****y rectifier
Whereas the 6D22S £3.80 for a pair plus bases and top caps - still lower cost.
As for not posting it yet Matthew and I can only do so much in a given day. We have other things to attend too. It is in hand and should be up on the forum within two or so weeks.

John
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