Question for tube gurus

mikeyb128

Picked up a quad of RCA 5814A triple mica black plates from 1960. These are NOS and have been tested. I've been leaving my pre amp on while home to let these burn in. I've noticed my left tower, the tweeter has a noticeable squeal. I've narrowed it down to one tube, and have swapped in another one. So I'm positive it's the tube. Will this dissipate with burn in? Or is it hooped? I have contacted the seller about this, awaiting a reply. No other noises and sounds fine playing music. This in only when no music playing.

mikeyb128

Forgot to mention I did clean the pins, which were black.

Nightfall

Black pins on NOS tubes? Oxidation?

mikeyb128

Nightfall wrote: »

Black pins on NOS tubes? Oxidation?

Definitely, I used some scotch bright (like wool) and deoxit and came out nice and clean. These are almost 70 years old.

F1nut

Will this dissipate with burn in?

No, it's bad.

heiney9

I've had that noise happen when first powered up, but in my few cases it went away and never came back. If you are getting noise after they have been on and stabilized then it's a bad thing. If you've cleaned pins and sockets and also swapped positions I'd say it's the tube. One thing I have done to abate noise if very slightly push on the tube in the socket to get a better/different seat.

Many times tubes are only checked for emission and GM, not for noise and microphonics. On large, rare tube purchases I always ask about noise and microphonics and if they can be returned because of it.

A quad of 1960 RCA 5814's shouldn't have set you back too much. It's part of running tubes sometimes............hopefully the seller will help you out, depends on his sales policy.

H9

mikeyb128

I pulled the top off the pre and tried wiggling it, pushing on it, And didn't make a difference. After being on all night it seems this noise comes and goes, right now it's not here. And yes these weren't that expensive. Still waiting on his response. I will play them for the weekend and see what happens. They sound good though!

What's the burn in time for tubes typically?

ken brydson

this is all all I got on tubes...

https://www.youtube.com/watch?v=fiVNsis2h0M

heiney9

I'd say 50-100 hours for break in if they are in fact NOS. There is a small chance it might go away with more playing time. Those are robust tubes, but again 50+ years old. One of the things that fascinate me about tubes is the fact all these are still around and many are still functioning perfectly after 50, 60,70 years. Way back before the "throw away" market.

H9

BlueMDPicker

Just for grins, try lifting the ground on the preamp power cord with a cheater plug or removable ground pin if so equipped.

mikeyb128

Left my preamp on for the last 24 hours, And absolutely zero noise, No more squeal. Seems these tubes are quite micro phonic... I can hear the relay click through my speakers when switching inputs on my Cary. Popped the hood and tapped them gently, all are the same. The later versions of RCA black plate 2 mica from 1962 are dead quiet.... I guess that's the whole part of this tube hole, Try something different. I'm looking at some Mullard made Valvo from Hamburg Germany as my next adventure. Damn I love tubes.

Nightfall

Amperex made in Holland!

heiney9

mikeyb128, you need a pair or a quad. Getting ready to shed some inventory.

mikeyb128

heiney9 wrote: »

mikeyb128, you need a pair or a quad. Getting ready to shed some inventory.

I need a quad, and I'm interested when the time comes. Let me know, I've heard good things, I've been eyeing some up on eBay.

mikeyb128

Nightfall wrote: »

Amperex made in Holland!

I have some amperex holland bugle boys (1959). tried them and didn't like them, but I only have a pair, I would like to get a quad in there, I don't think I gave them a fair evaluation with only a pair.

heiney9

mikeyb128 wrote: »

I'm looking at some Mullard made Valvo from Hamburg Germany as my next adventure.

Explain? It's rare to have an actual Mullard labeled tube be made in Hamburg. Not saying it can't happen as we all know how Philips cross labeled many, many tubes in the day to satisfy demand all over the world. Doesn't matter what the label says, it's all about the codes.

So you are actually looking at some (12AU7/ECC82's) that are labeled Mullard, but have Hamburg Germany production codes? Valvo Hamburg tubes were only produced from about 1953-1961. After that it seems all Valvo labeled tubes were from other Philips manufacturers, most notably Heerlen Holland and Blackburn England.

mikeyb128 wrote: »

I have some amperex holland bugle boys (1959). tried them and didn't like them, but I only have a pair, I would like to get a quad in there, I don't think I gave them a fair evaluation with only a pair.

Are these long plate or short plate? 1959 was a transition between the two. What didn't you like about them? What characteristics do they have compared to tubes you do like?

I am still sorting but I doubt I'll have any quads to sell, mostly pairs and some singles.

H9

heiney9

I think I have a couple Valvo ECC82 (hamburg) quads to offer up. Still sorting and deciding. I don't sell these normally, but it's ridiculous how many I've accumulated over the years. Simply ridiculous

My favorite tube

H9

mikeyb128

Sorry should have explained better, they are Valvo but made in the Mullard factory. Here is the eBay listing:
https://www.ebay.ca/ulk/itm/282026194849

Looks like the bugle boys are long plates, I don't think I gave them a proper evaluation, I had them paired with some RCA black plate tubes, I would like to try a quad of them before I decide. I didn't hate them, but a little too much emphasis in the upper ranges, I only listened for a day, and in my limited experience with tubes, I'm noticing they seem to settle down after sitting idle in the preamp for 24 hours.

My focals are extremely sensitive to changes upstream, I have to be careful as they can become a little bright. I have had good luck with the RCA 5814 black plates, they are very clean and balanced from top to bottom with a nice soundstage. I don't have many tubes on hand to try, I'm keeping my eye out for those rare ones to try, I'm slowly building a small stash of tubes. I'm fascinated by them, and I love nos tubes in original boxes with nice silk screening, blows me away something this old survives the times, and still looks new.

Tube buying has been tricky with the poor exchange, so have been trying to jump on things when I see them.

heiney9

RCA's 12AU7's in general are warmish and can be a bit bass heavy. Those Valvo's are typical Blackburn Mullards, they are going to be warmish as well, a bit fleshed out in the midrange (vocals) slightly rolled off highs, and a little looser on the bottom but a bit more control than the RCA bp's.

If you can hold tight I do have a couple Valvo Hamburg quads I think need a new home. Not sure what your budget is......

H9

mikeyb128

heiney9 wrote: »

RCA's 12AU7's in general are warmish and can be a bit bass heavy. Those Valvo's are typical Blackburn Mullards, they are going to be warmish as well, a bit fleshed out in the midrange (vocals) slightly rolled off highs, and a little looser on the bottom but a bit more control than the RCA bp's.

If you can hold tight I do have a couple Valvo Hamburg quads I think need a new home. Not sure what your budget is......

H9

I'm not in a hurry, if you decide to shed a quad, let me know as I'm interested. I'm in the process of trying to decide on some tubes for my shanling as well, I'm using some budget ge Jan military tubes in there, which are surprisingly good for the 3.99 price tag. Budget is in the 200ish range plus shipping. I'm liking the warmer tubes that have a nice balance, the Berillium tweeter is a match made in heaven with warmer sounding tubes, makes it super smooth, almost silky, and very accurate. If the Valvo/mullards are like the RCA black plates, then they are right up my alley, I'm liking the sound of these.

heiney9

The Valvo Hamburgs have a stunning amount of "air" in the treble, good extension but very sweet, never harsh. I thought you said the Amperex/RCA combo was too warm? Mullards are warmer than Amperex Hollands.

I will let you know soon, just wanted to give you a heads up in case you were buying something else. I will work with your time table.

H9

Nightfall

I find Mullards to have too forward midrange for my tastes.