QB 5/1750

Greg · Post by **Greg** » Thu Mar 10, 2011 8:33 pm

Picked this up from the Hi-Fi World website. It's a Nat 'Transmitter' Valve 100W SE Class A Monoblock Amp using the QB 5/1750 transmitter valve.

Data sheet here. http://tdsl.duncanamps.com/pdf/vm271.pdf

Apparently it has 1500V on the anode. UK price is £16,420 but I'm not sure if that is the price per pair or for a single monoblock.

Any DIY thoughts?

pre65 · Post by **pre65** » Thu Mar 10, 2011 8:40 pm

Have a chat with Philip Ramsey at Bluebell if you want single ended power like that.

He is very enthusiastic about 833a like wot I am doing, but my effort is rather "bargain basement" and I don't need the full monty watts wise.

Steve Cresswell was going to use a big transmitter tube, I don't know if he still has them.

Whatever you do, it should cost one hellava lot less than £16K

Here's a link to the Wavac 833a amp @ $350,000 although I think they do a bit cheaper version as well.

http://www.stereophile.com/tubepoweramps/704wavac/

Greg · Post by **Greg** » Thu Mar 10, 2011 9:21 pm

Yep, I'm certainly not signing up to the callenge in any way. I just wanted to explore the thoughts of you and others on the topic. There are others here much into transmission valves and no doubt they have some knowledge to contribute on this. I was hoping to open up some discussion on the viability of this QB 5/1750 transmitter valve for audio use.

pre65 · Post by **pre65** » Thu Mar 10, 2011 9:28 pm

Well if they can make one, it certainly is possible.

But practical ?

If I had not had so many of the bits already to hand for my 833a project it would have been quite expensive.

Actually, the one I had on test the other day did not get as hot as I thought, but it is being run at quite a low level.

Hopefully it will be at Owston so you can have a dekko.

Andrew · Post by **Andrew** » Thu Mar 10, 2011 9:28 pm

pre65 wrote:Have a chat with Philip Ramsey at Bluebell if you want single ended power like that.

What's wrong with push-pull, if you want power

andrew Ivimey · Post by **andrew Ivimey** » Thu Mar 10, 2011 9:39 pm

Right now I'm finding it difficult to accomodate EL34PPs in triode mode. It sjust so Effffing LOUD.

there's nowt wrong with 1 watt!

Lee S · Post by **Lee S** » Thu Mar 10, 2011 9:58 pm

I went to Bristol and heard those playing through some large £17k ESL's. It sounded.... errrr..... alright I suppose.... Nothing to write home about though and IMHO, certainly nowhere near worth the cost.....

Post by **Nick** » Thu Mar 10, 2011 10:15 pm

Yep I saw that picture, the curves don't look that exciting, 1k5 @ 250ma would work, but it doesn't look very linear. As always its the cost of the iron that pushes the price up with these amps. Driving +ve grids is a known problem, with good solutions. If I had the funds based on the 100Th results I got, I would pick a eimac 304Th instead of that tetrode.

Dave the bass · Post by **Dave the bass** » Fri Mar 11, 2011 8:05 am

Greg wrote:Yep, I'm certainly not signing up to the callenge in any way.

You're not?

Ban him!

DTB

audio-talk

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