Engineering vs tube rolling

[disco]

I had not heard before that this was intended to be an 'EL84'.

This dealer has quite some stock to sell There's no hard data to support his claim of excellency.

 

[DF96]

Billington has been trying to shift EL821's for years.

 

[316a]

Billington has been trying to shift EL821's for years.

They probably still have 100,000 or so , I think the only type they have more of is EB91

316a

 

[billshurv]

So if the EL821 is no better than an EL84 why are they trying to shift them for nearly the same price? Do they not understand supply and demand?

 

[JMFahey]

Yes they do, and act accordingly.
When you have a ton of anything and you can't sell it, you *create* demand for it, it's called "advertising", either direct (Ads) or indirect (posting in Forums, Net pages, etc.)

Business 101

 

[billshurv]

They don't seem to be doing very well at it then...

 

[Wavebourn]

It looks like a pretty good tube. However, 6P15P is better.

http://istok2.com/scan/600_1.gif
http://www.r-type.org/pdfs/6ch6.pdf

 

[disco]

It looks like a pretty good tube. However, 6P15P is better.

Way better I'd say.

An externally hosted image should be here but it was not working when we last tested it.

 

[fredeb]

Just to quickly re-necro this thread for anyone potentially wanting to use some EL821's ....

Look here : https://www.avforums.co.za/index.php/topic,17235.msg225716.html#msg225716

I am now the proud owner of this little amp which happily drives my DM12's ( not in the least efficient ) as desktop monitors , and quite quietly at that .


More info here : http://www.tube-and-valve-electronics.co.uk/product_information/6CHC_Electron_Tube_Circuit_Idea.asp

 

[trobbins]

With today's ease in making distortion measurements for pretty much any DIYer it is very easy to roll through one's stash of a particular valve in a particular amp and select for better 'technical' performance, especially with say NFB disconnected. . That process avoids the doubt of buying 'matched' or premium valves that were tested in other than the final circuit configuration and operating levels. It can also allow any performance tweaking to be done at nominal output signal levels, by say output stage bias set up. It also confirms that there is no hidden dodgy valve.

 

[TonyTecson]

6LU8 for just a pair to tubes per channel...http://www.diyaudio.com/forums/tubes-valves/183193-tonys-6lu8-push-pull-power-amp-build.html