HY40 Power Triode

[targeteye]

I was digging through my Tube box and found these. Although I knew I had them I've never looked into what they were.

Anyone try them in an amp? I've found no information about them being used by anyone in audio. I did find the spec sheet.

http://tubedata.itchurch.org/sheets/084/h/HY40.pdf

Thanks
Steve

[Vargas]

Kind of reminds me of the T40 or even the TZ40. Maybe this will help http://www.suertenich.com/html/audio...poweramps.html

[Bandersnatch]

hey-Hey!!!,
Mine all have ceramic bases. IMO they've got a bit too much plate resistance for use as a power tube( it is more than the 211 ).
cheers,
Douglas

[kevinkr]

Hey hey Doug,
According to the spec sheet rp if I've interpreted things correctly is just under a couple of K ohms - what have I missed? Seems like transformers suitable for the 211 would be in the ball park?

Power output would be much less however as Pdiss is about 1/3 of that of a 211.. Smaller HV tolerant opt could be used..

Just a guess on my part. What think ye Doug?

[Bandersnatch]

hey-Hey!!!,
By either the curves or data sheets, plate Z is 5 to 6k. Gm of 3.8 mA/V and mu of 25 leaves 6k5( and that is where one realizes the full gm). Plate curves give similar story. Now a small-signal triode( or more realistically, fairly large signal ) with 40W of plate dissipation is of use. I was thinking of LTP on something like 845, with full 8-900V B+ delivered to the amplifier/phase inverter stage. It is a nice tube, I wish I had more, PP leaves me needing *ANY* type of tube in sets of four...
cheers,
Douglas

[targeteye]

Thanks for the input folks. If one was going to go thru all the trouble of brewing an amp sounds like there are better choices out there. Even if these are already in my stock

Steve

[Miles Prower]

Originally posted by targeteye
Thanks for the input folks. If one was going to go thru all the trouble of brewing an amp sounds like there are better choices out there. Even if these are already in my stock

Steve

Since you already have them, then why not use 'em? Just because a particular VT doesn't have an audio "pedigree" didn't stop me.

[Bandersnatch]

Originally posted by Miles Prower


Since you already have them, then why not use 'em? Just because a particular VT doesn't have an audio "pedigree" didn't stop me.

Lack of an audio pedigree is nearly justification in and of itself to use it for audio. I'd differentiate between pedigree and useful properties. Plate Z is one, yes? Get this too high, and a well damped, open loop design isn't possible anymore. Check out the HY51, that has twice the gm, and 50% more dissipation. They're just as hard to get hold of... ( I've got a partial of them too, trade? ).

Now these tubes are not plate gettered, so getting them to some minimum dissipation is not required( like Tantalum anode types, or perhaps the Zirconium doping Svetlana used in the 572's ).
cheers,
Douglas

[Miles Prower]

Originally posted by Bandersnatch
Lack of an audio pedigree is nearly justification in and of itself to use it for audio. I'd differentiate between pedigree and useful properties. Plate Z is one, yes? Get this too high, and a well damped, open loop design isn't possible anymore.

The r(p)=~ 6K isn't all that bad. You can always get the effective r(p) down with local NFB. That's how I'd probably use 'em, though I'd definitely give a listen before deciding whether and what type of NFB was required.

The 811s that get used in lots of Class A2 designs have an even higher r(p).

[Bandersnatch]

Originally posted by Miles Prower


The 811s that get used in lots of Class A2 designs have an even higher r(p).

hey-Hey!!!,
Those tubes are effectively pentodes( and to top it all off there's plenty of pentodes with lower plate Z ). Not that there's anything wrong with pentodes, but the usual triode game of loading being a multiple of plate Z is just not in the cards here.
cheers,
Douglas