Old Valves

littlemac1980

I came across a big heap of old valves which were my fathers, he was a radio engineer in the 70's and kept them, I'm sure they are working and I think they are marked "low voltage pre-amp valves". I'm guessing they are worth a bit of cash, anyone know where I'd find out. Thanks.

Fuzzy Clam

Hi littlemac, could you post up a few of the valve numbers.

As a job lot of assorted valves, value would be quite low. Some are still quite sought after though and selling them single or in pairs may be best.

watty

An EF80 is 50c, A PX4 €400 an EF86 maybe €4

It depends what they are. Almost no-one wants "job lots" unless a bargain basement price.


Most people are buying 1 to 6 valves.

Plenty vintage advice http://vintagetvandradio.myfreeforum.org/index.php

What are they?
See http://www.r-type.org
and http://www.radiomuseum.org

Most valves are pretty common. Some are not and some are expensive due to Audiophules.

littlemac1980

Ok thanks Guys, I'll go through them now and post up the numbers of them.

littlemac1980

Right a long list so

Most of the boxes are a bit, well old looking I suppose, not off the shelf condition if you know what I mean

The list of those that are boxed are as follows

Boxed:

Philips “Miniwatt” Electron Valve
6SJ7GT
ECC85
EF91 (X3)
EF92 (X2)
EF95
UBF80
12AT7

Siemens Rohre
EF93 6BA6

Valvo
E88CC

Telefunken
UF85 (X2)

GE Electronic Tube
5763

Tungsram Radio
ECC83 (X2)

6 MONATE RSD
UF85 1430

Raytheon
12AT7WA

MAZDA RADIO
EF80 6BX6

Teonex Electronic Valve
VR/105 OC3 (X2)

RCA Electron Tube
12AX7A ECC83 (X2)
0C3
6CB6A/6CF6

BRIMAR Thermionic Valve
807 (X2)
ECC81
EF91 (X3)

BRIMAR Radio Valve
6BH6 (X4)
6AK6

Mullard
EF184 (X3)
PL81
PCL83
QQV03/10
ECC81 (X4)
EF85
ECC91
ECH81
E88CC

Chelmer Valve
OD3 (X2)


There are others then that are not boxed, all appear intact, but some are cleaner looking than others.

Unboxed:

Philips
EF95

Brimar
6K8G

Mullard
EAA91
EF95
EF50 (X2)
EF183

Mazda
TP25

ARP35 (??? That's all it says)

COSSOR
63-SPT
5Z4GT

Cetron
4B32

Tronix
8D3

Tungsram
6BE6


Also:

One that says Made in Great Britain
And the number I can barely make out but I think it says
162 62D4

I also have 3 that are cased in aluminium with no visible markings.

Well I'll check those links you posted, and sure if you recognise any of those I posted as being particularly good in the meantime, I'd appreciate if you let me know.

Funnily enough, I had recently been considering attempting to construct a Valve Amp for my guitar, so If any of those above are what you'd consider appropriate, then I'd appreciate the advice.

Thanks.

watty

The transformers are the expensive bit for a decent guitar amp. If you avoid "fashionable" valves they are cheap enough.

The 1950s designs are best. Some of the "new" designs are by people that are clueless.

Those are a mix of Radio valves and a few TV types. The 807 is an old WWII era transmitter valve sometimes used as valve amp output stage today (fashion rather than common sense as these were very cheaply available after WWII but quality designers preferred things like EL34).

You can use Triodes or "Triodise" a Tetrode, Beam Tetrode or Pentode. Compared with Pentode that increases the power, reduces gain and makes the O/P more susceptible to HT line hum. But "fashion" at the minute is Triode O/P stages. On a well designed amplifier it won't sound different.

A 0D3 I didn't recognise. It's a Gas Regulator
http://www.radiomuseum.org/tubes/tube_0d3.html

The QQV03/10 is Mobile Radio Transmitter valve, not much power so no good for a guitar amp
http://www.radiomuseum.org/tubes/tube_qqv03-10.html



Quite a mixture.

EF = Mostly RF/IF (preamps might use EF86 though)
ECH = Radio frequency changer (Triode/Hexode)
EC = Triode
ECC = Dual triode

E prefix = 6.3V heater
U instead of E means 100mA Series tubes, can be any voltage. For sets without transformer
P is 300mA series usually TVs

EF183 & EF184 pretty late types used really only TV

EF92 etc, "9" in 1st digit means miniature 7 pin, "8" means 9 pin

Z in a part usually means mains rectifier.

USA and Mazda parts start with digits that can be the rounded down heater voltage.
1 = 1.4V
12 = 12.6V
6 = 6.3V
etc

littlemac1980

Thanks very much for the analysis and advice watty.

I have checked up a bit on the internet last night, and found that the E88CC's are supposed to be particularly good, and the RCA 12AX7A's are also supposed to be a bit special, so I'm gonna scour around to see if I can find a project suitable to use those.

It'll be a while before I get started on anything though, I really don't have the first clue about how they operate, I did some electronics in college and my soldering is fairly good thanks to a couple of years of technical work, but attempting to build a complex circuit board from scratch is a good ways ahead of me and I'll have to do a lot of reading.

In the meantime I'll keep an eye out for some suitable transformers, I could probably take one out of an old fender amp I have which had given some trouble a number of years back, and had been sitting in a corner of the shed since, though I'd prefer to have a go at repairing that first.

There are a couple of professional guitarists/Techheads I know so I might see what their interest in what I have is, and weigh up my options then.

Thanks again.

watty

An E88CC is essentially a selected ECC88 military version for reliability and more repeatability. There is no advantage at all in an Audio amp. An EF86 is probably the best ever Audio preamp and the EL34 good output tubes.

No point in stripping the Fender. You need specific transformers for specific designs. Fix up the Fender makes more sense.

Also you need to decide if you want a Rock Electric guitar sound or HiFi. Fender, Marshall and all amps for Rock style electric guitar are designed for loudness and certain kind of distortion. The most ordinary ECC82 are best and what ever output tubes for the power.

HiFi designs are completely different. They give less power for same tubes, always use Pentodes and Tapped Audio Transformers that feed about 10% to the Screen Grids (g2). Any Guitar amp transformer would be useless. They are designed to impart no "sound" at all, just pure undistorted amplification. "Ultra Linear" is the name of the technique using taps on Audio output transformer to Screen Grids.

1) Decide what kind of amp.
2) Source the parts.
3) Bash the chassis.

Wiring layout and earthing points is a critical part of Valve amp designs that don't use a PCB.