Junction
Well-known member
Has anybody come across a tube based VU meter buffer design or schematic? I've got some tube pre's and want to install a VU meter/buffer, hanging off the tube power supply.
Cheers
Michael
Cheers
Michael
A Vu meter buffer relies on a rather low output impedance since the meter is supposed to see a total source impedance of about 4k. So if you don't need voltage gain you could use a cath follower, but if you need gain, you must have gain from a common cathode stage followed by a cath follower, or a step-down transformer. Most of the times, in vintage (or not so vintage) equipment, VU meters are driven off a transformer - and very often from the unit's output.Junction said:Has anybody come across a tube based VU meter buffer design or schematic? I've got some tube pre's and want to install a VU meter/buffer, hanging off the tube power supply.
Cheers
Michael
Yes I could but a VU meter across the audio path can introduce distortion into the audio, I dont want to mess with the audio, a buffer seems the best way to tackle it.MagnetoSound said:Can you just tap it onto (one of) the output stage cathode(s)?
Yeah good suggestion, however I am going overboard on the tube/iron thing, this sucker has or will have soon, 4 audio trannys, a choke and 2 power trannys (as the original pre was 110V and I am on 240V supply), so only the right think to do it put another tube in there, there is already a spare 7 pin socket on the chassis, so I was thinking of using a 6AU6, not actually that much more work in wiring up a tube that a transistor.volker said:Why waste a tube for such a mundane task? One or two high voltage MOSFETs will do the job perfectly. Without hurting your glass sound .
Brian Roth said:In principle, you could power an opamp from the filament power supply.
Yeah fair call lasso, I have been researching several vintage tube mixer schemos and they all run their meter off the secondary of the OT. The vintage VU meters that I have hardly even blink when connected to the output, might be worth tweaking the internal resistor, there is one in there along side the germanium bridge. Definitely worth a try.lassoharp said:What abbey road said. Unless your tube pres do not use an output transformer, just connect it from the OT secondary with an appropriate pad/divider network in front and you're done.
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