Curious about these DHTs. Hard to find any information on either but they are in Franks with curves. Anyone used them and can comment?
https://frank.pocnet.net/sheets/060/l/LP2.pdf
https://frank.pocnet.net/sheets/060/l/LP2.pdf
Yes, used both and many other British 2v types - advantage over 01a etc is higher mu which is obviously useful in two stage SE amps. Sonically of course a matter of taste - VR21 is good but my favorite is the VT-45 (mentioned previously) able to take 300v anode volts - but expensive .
Thanks - if I'm right I just emailed you yesterday.
Could you get the P2 hum-free? Could the sound quality rival the 26 or 47 which are my current choices? Grateful for feedback on this.
Could you get the P2 hum-free? Could the sound quality rival the 26 or 47 which are my current choices? Grateful for feedback on this.
I've been looking up these British 2V DHTs. Several VR types like VR19, VR21, VR22, VR27 etc. interesting little things, quite rare.
It's tempting to play around with them.........
It's tempting to play around with them.........
I was lucky to pick up an item of1940's test gear that had 5 VR21's and a P2 very cheaply - could be something to look out for as they probably had little use. The P2 makes a useful driver......and the VR21 as mentioned has good sensitivity.
I'm now listening to a newly put together P2 stage. Actually CV1246, courtesy of Langrex. Schematic attached.
First observation - these valves are microphonic. Bump the chassis and you get a merry tune. Leave the chassis alone and they're OK. My chassis is 4mm aluminium and I don't usually have problems with microphony, but a lighter chassis might.
Sound quality. My usual stage is a 26 lately, rotating with a type 47. These are the driver stages for my EL12n 2 stage SE amp. These two DHTs have a fair bit of filament current going through them - 1A and 1.75A. This seems to add weight - and bass impact - to the sound. Sounds like a simplistic observation but that's what it sounds like. But from the upper bass upwards the P2 is very nice - clear, clean, neutral with plenty of nice treble detail and no edge to the sound. It brings back memories of the Type 30 I used years ago, but I'd say it was better than that.
So yes, I like the sound and I'm enjoying a variety of music - voices are nice, orchestral music has good timbre, tone and detail. Piano is nice. Plenty to like. I'll leave it in my system for the rest of the evening and see how it goes. I miss the fullness and weight in the bass I get with 26 and 47 - it's a rather lighter sound overall, but for what it is, it's very clear and pleasant. So a qualified approval. I expect I'll go back to my 26, but I'm in no hurry. I'm enjoying the clarity the P2 brings. I didn't have issues with microphony when in use, but others might. If you can deal with the microphony I'd suggest this is an interesting choice of valve for the upper part of a 2 way active speaker.
First observation - these valves are microphonic. Bump the chassis and you get a merry tune. Leave the chassis alone and they're OK. My chassis is 4mm aluminium and I don't usually have problems with microphony, but a lighter chassis might.
Sound quality. My usual stage is a 26 lately, rotating with a type 47. These are the driver stages for my EL12n 2 stage SE amp. These two DHTs have a fair bit of filament current going through them - 1A and 1.75A. This seems to add weight - and bass impact - to the sound. Sounds like a simplistic observation but that's what it sounds like. But from the upper bass upwards the P2 is very nice - clear, clean, neutral with plenty of nice treble detail and no edge to the sound. It brings back memories of the Type 30 I used years ago, but I'd say it was better than that.
So yes, I like the sound and I'm enjoying a variety of music - voices are nice, orchestral music has good timbre, tone and detail. Piano is nice. Plenty to like. I'll leave it in my system for the rest of the evening and see how it goes. I miss the fullness and weight in the bass I get with 26 and 47 - it's a rather lighter sound overall, but for what it is, it's very clear and pleasant. So a qualified approval. I expect I'll go back to my 26, but I'm in no hurry. I'm enjoying the clarity the P2 brings. I didn't have issues with microphony when in use, but others might. If you can deal with the microphony I'd suggest this is an interesting choice of valve for the upper part of a 2 way active speaker.
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"This seems to add weight - and bass impact - to the sound"
What speakers do you have andyjevans?
What's the low frequency bandwidth in particular...
Cheers
What speakers do you have andyjevans?
What's the low frequency bandwidth in particular...
Cheers
Hello pl802. Speakers are Mission 761. I can't measure FR. There's more bass with the 26 or 47 in a straight A-B comparison. It's a very nice sounding valve with that observation, very clear and transparent.
I won't be using the P2 long term, so my pair is for sale + sockets at a discount from the new price, only 3hrs on them. PM me if interested.
I won't be using the P2 long term, so my pair is for sale + sockets at a discount from the new price, only 3hrs on them. PM me if interested.
While I'm on the subject of B4 bases, can anyone recommend any other DHT tubes with B4 bases that have greater filament current than 200mA?
There must have been several types made with this base. Many like the VR21 had even less filament current, like 100mA. So which had more?
There must have been several types made with this base. Many like the VR21 had even less filament current, like 100mA. So which had more?
Andy, the only one I know is the VT45 which requires 440mA filament current and is happy with 300v ht - a rare item!
They are at Langrex at £50 so expensive BUT work well as drivers and within their power limit work well as outputs. They occasionally come up on eBay - I've been watching for them for some years - they are very rare. Their original use seems unknown but they work well as above.
I think I did mention these here a while ago.
Good luck!
They are at Langrex at £50 so expensive BUT work well as drivers and within their power limit work well as outputs. They occasionally come up on eBay - I've been watching for them for some years - they are very rare. Their original use seems unknown but they work well as above.
I think I did mention these here a while ago.
Good luck!
Yes - the VT45 looks very nice, but expensive. So are PX4 and all the 4xxx series, 4606, 4613, 4609, 4630, 4617. All very rare and silly money.
There must be more tubes with B4 bases, but I can't think of any apart from the low current filament types like VR19, VR21, HL2, VT50
There must be more tubes with B4 bases, but I can't think of any apart from the low current filament types like VR19, VR21, HL2, VT50
I have searched for just that for many years without success, that's not to say there isn't anything but if so I believe likely to be intended for industrial or military use much as I expect the VT45 is.
Low current radio valves were of course prized for their economy, the lower the better for their designed use.
atb
David.
Low current radio valves were of course prized for their economy, the lower the better for their designed use.
atb
David.
Well, the P2 stage is still in my system a few days later. It rings a little if I cough near it but that's all, and it goes away very quickly. The tone is really nice and apart from the rather light bass response it's all good. Very nice high end and a true DHT sound. Not for everyone but what it does, it does really well.
Maybe I should put more current through it and lower the value of the anode resistor. Data shows up to 17mA.
Maybe I should put more current through it and lower the value of the anode resistor. Data shows up to 17mA.
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At the end, I did put together a headphone SET amp with P2 tubes - single stage with one P2 tube for each channel, driven by a dac through a passive transformer volume control.
Yes, P2 is more microphonic than likes of 71a and 45, but this can be dealt with.
No issue with bass in my case - the output transformers I used have enough primary inductance to handle tubes with up to 5k output impedance. Reflected load with my headphone is more than 10k.
Very nice sounding with my Senn headphones.
An excellent solution with just one stage if your source has adequate output level.
Yes, P2 is more microphonic than likes of 71a and 45, but this can be dealt with.
No issue with bass in my case - the output transformers I used have enough primary inductance to handle tubes with up to 5k output impedance. Reflected load with my headphone is more than 10k.
Very nice sounding with my Senn headphones.
An excellent solution with just one stage if your source has adequate output level.
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