valve amp reliability
- Thread starter Brian S
- Start date
Tony L
Administrator
Ah, but the USSR-era valves are far more highly regarded than the current Putin-era tubes!
PS No difference anywhere else really, the best valves were made back when they were a standard device.
Many thanks for all replies which have reduced my paranoia considerably. I have been using a 300b valve amp for about 18 months, and am well pleased with it. However, I had to move it a week ago and realised it was 50 years since I carried hundredweight bags of cement on my shoulders. The weight of it came as something of a shock, and I don't have a crate for it. So to know components are likely to be easily come by, and that there are engineers around who can deal with repairs is very good news. It was an ex-demo purchse so fairly new but it gets 3 to 5 hours a day usage.
I did have a rectifier go which blew a fuse - easily replaced externally. Also a Psvane Black Bottle 300b valve failed, after a month - replaced under warrranty.
Thanks everyone, again.
I did have a rectifier go which blew a fuse - easily replaced externally. Also a Psvane Black Bottle 300b valve failed, after a month - replaced under warrranty.
Thanks everyone, again.
Arkless Electronics
Trade: Amp design and repairs.
I would put the best USSR 70's and 80's era Russian valves up there with Brimar, Mullard etc. Even they are getting rarer now though and fakes can be seen.... "OTK" markings added to non mil approved valves etc.
Tony L
Administrator
I have what I am 99% sure is a NOS set of 1964 yellow-print Mullard EL84s and I actually prefer the 6P14P-ER I linked to upthread! The same doesn’t go for the small signal ECCxx tubes though, 1950s-70s GB, EU or US manufacture valves sound nicer to my ears, and as for GZ34s etc nothing matches a Mullard.
PS By saying that certain early Tesla ECC83s are stunningly good, up there with my favourites and no one should ever confuse them with the current JJ versions.
Arkless Electronics
Trade: Amp design and repairs.
I also use virtually the same output valves, 6P14P-EB Voskhod made and OTK marked. Interestingly I was comparing input and phase splitter valves in my ST20 last night and soon came to the same conclusion I did last time I tried this... I vastly prefer Russian Sovtek ECC83's to Mullard or Brimar. They are considerably tighter in the bass, have more grip and pace and sound more "in focus". With the UK valves it sounds like a valve amp, a bit soft focus and slightly bloaty bass, but this goes and you would have trouble saying if it's a valve or SS amp unsighted with the Sovteks. I didn't notice any "cons" to detract from the "pros" with the Sovteks.
Tony L
Administrator
The long-plate Sovtek 83 is pretty decent, and certainly good in the bass, but it doesn’t even approach the soundstage and natural string/piano timbre of a good Mullard. It needs to be noted that not all Mullard ECC83s are equal though, I don’t really rate any later than about 1965-6 that much. The early f92 long-plates are very good and anything but soft focus, the I61 first gen short plates just beautiful and what I run, and the early versions of the final I63 construction that still have copper rods rather than nickel are very similar. The mushy and soft sound is the later variants IME. All I63s with the later logo design (nickel rods) I’ve heard sound very soft and compressed to me.
It also needs to be mentioned that I’m voicing my amp for my nearfield positioned JR149s which are just stunning in the mid-band and soundstaging areas but a tad lean in the bass being a small sealed mini-monitor. They like a warm valve set as their bass is very tight and fast, but ultimately not that extended. If I was voicing for the huge Lockwoods downstairs I'd maybe choose my valves differently. I view the Leak/149 rig as primarily a classical & jazz system so go all out for tonality and imaging. It still sounds very good on rock/pop, but my priority is the absolute best string quartet, solo piano, sax or whatever I can get out of it! It also needs pointing out that bar the Russian military 6P14P-ER I’ve actually ended up with exactly the valve set it would have left Leak with in 1961!
It also needs to be mentioned that I’m voicing my amp for my nearfield positioned JR149s which are just stunning in the mid-band and soundstaging areas but a tad lean in the bass being a small sealed mini-monitor. They like a warm valve set as their bass is very tight and fast, but ultimately not that extended. If I was voicing for the huge Lockwoods downstairs I'd maybe choose my valves differently. I view the Leak/149 rig as primarily a classical & jazz system so go all out for tonality and imaging. It still sounds very good on rock/pop, but my priority is the absolute best string quartet, solo piano, sax or whatever I can get out of it! It also needs pointing out that bar the Russian military 6P14P-ER I’ve actually ended up with exactly the valve set it would have left Leak with in 1961!
Arkless Electronics
Trade: Amp design and repairs.
These are short anode Sovteks I'm using here and I can't tell any difference between Sovtek, Mullard and Brimar in the mid range. There is no down side to the Sovteks here.
Even in this case it can be done. I bought a Chinese EL34 amp, second hand and cheap, and used it for 5 years. The power supply transformer eventually went down because it was designed for 220V primary and running it on 240V UK meant that it ran hot, cooked everything and eventually died. No manufacturer original was available and even if it had been it would have been 220V primary so no better. I got my repairer to spec a replacement trafo and had it made by Demeter Transformers of Chelmsford for £90, posted. 5 years further on again it's as sound as a pound.
Arkless Electronics
Trade: Amp design and repairs.
Yes I am of course aware that this is a possibility and have had to do this a few times myself.. last time I had a transformer made to order for a customer was actually for a vintage Ampeg "flip top" bass guitar amp... Problem is that depending on size and spec it could be £200... and then there's my time in speccing it, dealing with the transformer manufacturer etc so it can often be financially prohibitive unless for a pretty high end amp.
Output transformers are another kettle of fish and unless it's a famous enough model to mean some companies sell an off the shelf replacement TX, such as in the case of a Quad II, Dynaco Stereo 70 or maybe some Leak amps, it would not be possible to sort it unless money was no object.
Arkless Electronics
Trade: Amp design and repairs.
Well a 6550 is a beam tetrode output valve, similar to a KT88... and a 6080 is a rare thyratron... with a 21 Amp heater supply requirement... it can be used in phase controlled rectification in a similar manner to a modern SCR/thyristor... would have been used for applications requiring a few KW generally...
Solid state rectifiers are not only ideal but for all intents and purposes perfect (unless you want to rectify < a couple of volts or so). There can be no argument between SS and valve when it comes to rectifiers as SS is better in every way. The only good thing about them is they can give a slow start by allowing the HT to build up gradually as they warm up... if they are indirectly heated that is... Valve rectifiers are inefficient, have large forward resistance and in any competently designed amplifier don't effect the sound. Why are they used in so many modern valve amps? A gimmick to appease those who believe SS is "sand" etc and only valves are for them...
Tony L
Administrator
Where are you based? If in the UK our voltage is stated as “230” to match with some EU regulation, but has a hefty +/- percentage with more on the + side. If I measure mine it is frequently around the 240-246V level. That will very likely cook a typical 220V Chinese tube amp.
PS Edit: UK mains voltage is 230V AC +10% to -6%, i.e. can be up to 253V.
Arkless Electronics
Trade: Amp design and repairs.
IF you are in Europe and your supply is 230V you should be OK. UK mains is 240V and often more like 246V in many areas and can overcook things if the amp is already running the output valves hard or the caps are specced with no voltage margin.
Arkless Electronics
Trade: Amp design and repairs.
Tony L
Administrator
If the amp has a 230V tap it is well worth using, your valves and capacitors etc will have a longer service life. Assuming it is an official feature I’d certainly do it.
Arkless Electronics
Trade: Amp design and repairs.
+1
The EU regulation thing was to bring everything in line. France has had 220V since forever, along with most of the EU, UK 240. Passing an EU reg that made it 230V +10%, -5% brought everyone in line without anyone having to rewire substations costing thousands of pounds. I've seen 254 on UK mains, no wonder my Chines amp with220V primary went pop.