Question about tubes

[Martin_T]

Hi everyone

I'm new to this forum, as well as to the world of DIY.
Since I live in Argentina, I might have some trouble trying to find some parts.
My question is regarding tubes. So far, I found these tubes being sold in my country: RSD, Orion, Haltron, Toshiba, Heinz & Kaufman, and some military ones.
They are all 12au7s and ecc82s.
I might find some RCAs, GEs or Philips. But I think it's going to be a little harder.
I just want to know if you have any comments on them regarding quality.
I attempt to build the g9 mic preamp, and since I don't have any backgrounds in vacuum tubes, I thought you could give me some advice.
Thanks very much in advance.

Martin

 

[adamasd]

I can not say anything on those brands, but I would recomend building it with what ever tubes you have at hand. Get it all working and then buy some new tubes if you feel it needs them. There a numorous suppliers online selling both NOS and new tubes that will ship internationaly.

adam

 

[toby]

i would agree with martin, and say get stuff working with whatever, then put nicer tubes in once stufff is working.

don't forget as well its pretty easy to get stuff from abroad. i'm in the UK where there are loads of stuff around, but i still buy from america and germany. ebay is good for this.

 

[Martin_T]

Guys:

Thanks very much for your advice.
What you suggest is what I thought since the beginning, but I wanted to know if anybody knew anything about those tubes.
I guess I?ll have to start building.
I?ll let you know when I have something to show.

Martin

 

[PRR]

> if anybody knew anything about those tubes... being sold in my country: RSD, Orion, Haltron, Toshiba, Heinz & Kaufman

Toshiba made a LOT of tubes 1950s-1970s, including many tubes sold under other brands. But, like most tube companies, they made high-quality stuff and low-quality stuff, whatever the customer was willing to pay for. Some of the TV makers squeezed for every last penny, since the TV warranty generally did not cover tube failures. The Japanese know how to do cheap. Some industrial and military customers demanded, got, and paid for very high quality, and the Japanese can do that very well too. Toshiba is probably a good bet, even their cheap tubes are not sloppily made; but you could be unlucky and get a batch originally made for a low-bid contract to a cheap TV maker.

I've heard of Orion but I think it existed as a brand-name that sold various tubes by various makers at whatever quality. Never heard of the others. They may be local to Argentina, and may be locally produced or imported from Japan, US, Europe with the local brand put on.

Generally, a tube will work, unless it is defective. Build your amp, get several tubes, and try them. Let the circuit and each tube cook for a few hours, especially if they have been in storage for years. All tubes of the same type in the same circuit should bias up to the same plate and grid voltage +/-20%. Any tube that is obviously "off" should be returned for replacement or discarded. Of the others, some will be noisy: most tubes were not tested for noise so you have to weed out the hissy ones for use in high-level stages. Some will make horrible sounds when you tap them, "microphonic", and should not be used in low-level stages or near loud speakers (guitar amp cabinets). Some tubes will have dirty pins.

A 12AU7 isn't a very fussy design and most 12AU7s that light-up will work fine. High-gain tubes and power tubes are more likely to give trouble.

thetubestore.com has most tube types, clean and functional, good price, ships quick, even to europe. See if they ship to your town.

 

[punk]

some sources for tubes and parts for the g9:

www.tubesandmore.com

www.mouser.com

www.alliedelec.com

I believe they all ship Internationally.

I don't have any specific info on the manufacturers you mentioned. I have collected a lot of tubes over the years and I agree with PRR. In my area, there are 'hamfests' which are good places to find old electronics. Find where ham radio operators gather in your area.

I have experience with a wide range of tubes from genereic brands to Telefunken. IHMO, I don't believe the very high prices attached to Telefunken tubes and the like are worth the extra money.

Also, IMHO, I find the transformers make a greater difference in the 'colour' of a circuit. And, IMHO, economical transformers sometimes sound 'better' for my subjective purposes.

In my G9 I used the OEP xformers.

byron

 

[toby]

i would add aswell that a well designed circuit, like the gyraf pre, will sound pretty good even with really cheap tubes in, and although putting stuff like NOS telefunkens in stuff makes a difference the pre will still be good without them.

 

[CJ]

I bet you want cheap considering the state of the Argentianian economy and since your a beginner. Everything said above and go for the military stuff first, as it is supposed to be tested and built a litle better. You only need a couple of tubes for he G9, so don't get too stressed.
The iron and caps you use will probably make more diference than which tube type, but yes, tweaking a box by trying different tubes is always done at my place.

 

[Martin_T]

Hi guys.
Once again, thanks for your replies.
I have one final question about tubes: Can I build the G9 using 12ax7's instead of 12au7's?
I ask this because I've been offered a couple of Sylvanias 5751 for a really good price, and I wanted to know if that would make a difference.
Thanks very much for your feedback.

Martin.

 

[gyraf]

Martin,

You could probably use 12AX7's for the first gain stage in the G9 - but it would behave much different. You'll probably loose some top end at high gains.

For the output tube you need to use 12AU7/ECC82/5814 because it has to drive a quite low impedance.

Jakob E.

 

[CJ]

Martin, I have tons of extra tubes, but live in the US.
I could try to mail you some, but it might take weeks to get there!
They would be free of course, so if you have the time...
cj

 

[tony dB]

[quote author="gyraf"]Martin,

You could probably use 12AX7's for the first gain stage in the G9 - but it would behave much different. You'll probably loose some top end at high gains.

For the output tube you need to use 12AU7/ECC82/5814 because it has to drive a quite low impedance.

Jakob E.[/quote]

Jakob,

What would be the most interesting option here?
Having seen some ECC82 in gear and gtramps i guess this is a well available tube with good characteristics, but is it superior to the others you mentioned?

Cheers,

Tony

 

[gyraf]

yep, the G9 is designed around ECC82's - so these will work best here...

 

[tony dB]

ECC82's yummie

Thanks Jakob.

 

[toby]

if you really wanted to use ecc83s as a front end the tubetech pre on jacobs site has 83s up front, so have a look how this differs from the G9.



i can't really see why you would want to use 83s, cos they are about twice the price of ecc82s and i personally prefer ecc82 for studio gear.



toby

 

[alk509]

[quote author="toby"]i can't really see why you would want to use 83s[/quote]

Because that's all that's available to him.

Peace,
Al.