More tube questions

heiney9

What difference in sound can a rectifying tube make in a pre-amp? My Dared pre uses a Chinese 5Z4P rectifying tube and I also received a GZ34 (equivalent) with my purchase.

I'm seeing some pretty pricey GZ34 Mullard, Valvo, Tele, GE, Brimar rectifying tubes. The big question is there enough of a sound difference to invest the money in NOS rectifying tube for a pre-amp? Is rolling the rectifying tube worth the cost at the pre-amp level?

TIA

H9

Face

Minimal in my experience.

heiney9

So if I have a decent rectifying tube I should be alright? I believe he shipped a JJ tube worth about $25, in addition to the 5Z4P Chinese tube.

He also sent me another pair of RFT (12AT7's) tubes and another rectifier tube but I forget what it was.

mhardy6647

According to Jim McShane, current Russian and Chinese 5AR4s are decent; there was a time when they were not too great. The good thing about one of those pricey Mullard GZ34s is that it'll probably last forever.

Sometimes one can find US-branded 5AR4s that are just rebranded Mullards (though this gets less and less common).

heiney9

Keiko wrote: »

I didn't want to start a new thread since heiney got the ball rolling with this one.

Anyway, my tube newb question: How important is it to have a matched pair for the Yaqin I have coming in? Or will it matter as long as they're the same? I've just noticed sellers specifying matched pairs and I'm not sure if this is significant or not. I'm looking to order a pair of 6ak5 and 5654's probably in the next few weeks after I break this in.

Thanks,

Mike

In my experience it's more important to have a matched set for output tubes rather than buffered input tubes. It's always best to get them matched or from the same production run/date/plant, etc if possible. I have not yet been confident enough to buy a single tube at a time simply because of all the various production dates/plants, etc. I buy in pairs and usually they are sold as matching, or closely matching.

Some on-line tube retailers charge a fee to match them, IMO, I wouldn;t pay that fee for the type of use your are using them for.

Just my "green" .02c

H9

mhardy6647

Real performance matching of output tubes (gain/transconductance) is critical when (and only when) the amplifier topology is fixed bias or cathode bias and a pair of (or all 4) tubes share a cathode resistor and capacitor. Push-pull outputs should probably be matched for any bias scheme, though.

For small signal tubes, it's probably a good idea to 'voice' pairs of tubes, but gain/transconductance matching shouldn't be necessary. Noise and microphonics are usually more of the problem with small-signal tubes (i.e., preamp tubes, drivers, and phase splitters).

mhardy6647

:-P Well, I guess what I was trying to say was that sometimes you've gotta match pairs of tubes, sometimes not. I cannot think of a time when it would hurt to have a matched pair if the tubes were being used in some paired way. The only drawback is the incremental cost (or time spent if you have a transconductance-measuring tube tester like a Hickok TV-7 and you do it yourself)!

reeltrouble1

mhardy6647 wrote: »

Real performance matching of output tubes (gain/transconductance) is critical when (and only when) the amplifier topology is fixed bias or cathode bias and a pair of (or all 4) tubes share a cathode resistor and capacitor. Push-pull outputs should probably be matched for any bias scheme, though.

For small signal tubes, it's probably a good idea to 'voice' pairs of tubes, but gain/transconductance matching shouldn't be necessary. Noise and microphonics are usually more of the problem with small-signal tubes (i.e., preamp tubes, drivers, and phase splitters).

agreed.

RT1

mmadden28

Yall just scared me away from tubes a bit.

concealer404

mmadden28 wrote: »

Yall just scared me away from tubes a bit.

Hahaha, yeah....

I just started to feel a bit glazed over. And then i remembered that my buffer will be here tomorrow. Starting to wonder what i've gotten myself into.

mhardy6647

mmadden28 wrote: »

Yall just scared me away from tubes a bit.

Tubes aren't the least bit scary(*) -- 'specially once you hear what they can do. Best of all, even a 70-year old vacuum tube amplifier is still readily reparable -- and often worth repairing.


* - except for that pesky plate voltage... it's the volts that jolt, but the mills [milliamps] that kill

concealer404

Keiko wrote: »

Let us know how you like that little Indeed buffer concealer.

Will do!

Hopefully i'll have time to burn it in and get some solid listening paired with the ERC-1 at the same time.

I don't expect to hear a huge improvement out of it, but if i hear any, then that's enough evidence to me that doing it the "right" way would benefit me a worthwhile amount, and then down the rabbit hole i may go.

mhardy6647

I wouldn't worry about it if there is no sonic consequence.

george daniel

Keiko wrote: »

Question tube gurus....Is it unusual for some tubes to glow brighter than others?

The 2 Raytheon 6AK5W tubes I have in the Yaq now, I notice one is slightly dimmer than the other. Is this normal?

Like mhardy said,, but that reminded me,,I've got an old amperex, that lights up like a lightbulb upon initial power up,, scared the bazookies outta' me the first time,,lol.:)

edit;; I can't begin to tell you that having someone you know and/or trust is very important when it comes to output tubes,,especially if your amp has an "auto bias" such as mine.

mhardy6647

The filament flash on start-up is common in some European tubes (and I first saw it in a Japanese 11BM8; freaked me out).

concealer404

Keiko wrote: »

You may be pleasantly surprised.

I am very pleasantly surprised.

I'll leave my short review here for all to see:

"FAT."

I'll post up the rest once the ERC-1 demo reviews start getting posted. It kindof goes hand in hand with the ERC-1, and i don't want to let the cat out of the bag until it's run it's course.

But we'll say that i'm very impressed and happy with my purchase.

Another convert here, although i don't think i'll make the jump to going tube amp/pre or anything yet. I have more pressing issues to address with my rig, and this buffer has made enough difference to keep me happy for the tim being.

heiney9

Mike, I got your PM will be replying soon. I didn't care for the GZ34 as I believe it output too much voltage. You mentioned a GZ32 that's probably a better choice. The GZ30 is the direct equivalent. They say you can use a 5Y3 but I out one I had in and it started to smell. I had a friend give me a Sovtek 5Y3 and in doing some research this is what I found the Sovtek is indirectly heated vs a std 5Y3 being directly heated. The 5Zp that comes with the Dared is indirectly heated...........not sure what impact using a directly heated rectifier vs. indirectly. The extra PIN is just fine. It's not used.

Here are some links to some equivalents.

http://cgi.ebay.com/Vintage-5Z4-CV1863-Stereo-Tube_W0QQitemZ180390427317QQcmdZViewItemQQptZVintage_Electronics_R2?hash=item2a001b7ab5&_trksid=p3286.c0.m14

http://cgi.ebay.com/5Z4-RCA-long-black-plates-TESTED_W0QQitemZ320393762196QQcmdZViewItemQQptZVintage_Electronics_R2?hash=item4a98f4d594&_trksid=p3286.c0.m14

I'm told these are direct replacements also. I've bought from him before....good seller

http://cgi.ebay.com/5C4S-5C4M-5Z4-CV1863-Russian-TUBE-NOS-QTY-4_W0QQitemZ250379086803QQcmdZViewItemQQptZVintage_Electronics_R2?hash=item3a4bc1abd3&_trksid=p3286.m20.l1116

I just bought a 50's RCA 5V4G which is supposed to be a direct substitute. Haven't put it in yet as I just received it. I'll let you know how it works.

http://cgi.ebay.com/2-Strong-RCA-Gray-Plate-D-Getter-5V4-GA-Rectifier-Tubes_W0QQitemZ120456702974QQcmdZViewItemQQptZVintage_Electronics_R2?hash=item1c0bc76bfe&_trksid=p3286.c0.m14

Got my substitute info from here.

http://www.nostalgiaair.org/tubes/5z4.htm

A friend sent me this straightI have 4 basic variables on rectifying tubes:

5AR - develops 413 volts in .2 seconds - voltage drop : -17 volts @ 225ma

5U4 - develops 357 volts in .44 seconds - voltage drop : -44 volts @ 225ma

5R4 - develops 330 volts in .44 seconds - no data listed

5Y3 - develops 303 volts in .44 seconds - voltage drop : -60 volts @ 125ma

Solid state - about 450 volts in .1 second

Can always put a "larger" rectifier tube in place of a smaller - go down the scale (put a 5AR tube in a unit designed for a 5Y3) - but never a bigger one (a 5Y3 tube in an amp designed for a 5U4) out of a tube book.


Hope this helps...................tubes can be confusing as hell when rolling substitutes.

H9

heiney9

Mike, the GZ32 is a/k/a 5V4 so yes that will work. I just rolled in a 1950 RCA 5V4G and it sounds fantastic. Better than the Shunguang piece of doo doo.

If you end up bidding on some on e-bay let me know so we aren;t bidding against each other. I'm looking at an RCA 5V4GT which is the "coke" bottle shape.

H9

reeltrouble1

The only thing necessary to know about tubes is:

Tubes Rule.

RT1

heiney9

mhardy6647 wrote: »

The filament flash on start-up is common in some European tubes (and I first saw it in a Japanese 11BM8; freaked me out).

I know have a pair of RFT ECC81 where one flashes on power up and also a GE (Mullard Blackburn plant) ECC85 where one flashes on power up. If it's normal I won't worry about it. I was just concerned it might shorten of be an indication of shortened tube life.

I paid a pretty penny (as far as 6AQ8/ECC85 prices go) for the GE's for the Dared MP5 clone. They sound absolutely wonderful and have made in Great Britain stamped on them with date codes showing the Blackburn plant.

Ted..........tubes mostly rule .

H9

megasat16

heiney9 wrote: »

Ted..........tubes mostly rule .

H9

How nice it would be if Pass Makes Tubes Preamp?