• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

New Guy w/my Foreplay

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Variable mu valves

EC8010 said:


I'm not quite sure what the variable-mu ECC189 is doing in your list,
Nor am I, but I've seen it (and others) in use.

Remembering the way these valves were used:
The RF amp variable mu valves were only required to adjust the gain by a few dB or so, to avoid overload.
The main gain control was normally done in the first IF stage, by an EF183.
My point is, that it's probably a better choice than an EF183.

Also, I remember that before custom var-mu's, AGC was applied to valves like EF80's.

Cheers,
 
beyond the bickering....

that is one fab looking foreplay! Verrrry nice.

...puts mine to shame. The top plate looks very
cooly minimalistic... just two glowing tubes.

makes me want to redo my Foreplay.


---------------------
don't get sentimental
it only ends up drivel
-------------------
 
You mean like these. ;)
 

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For what it's worth, a reply from another board:

The CV 4003 and the ECC82 are not the same. The ECC was manufactured specifically for audio application. This doesn't mean the CV 4003 is crap, just not manufactured to the same exacting standards that the ECC series. The CV 4003 is a "box plate" whereas the ECC series used "long plate" construction. The CV 491 from the late 50's is much better preferred to the CV 4003 and has "long plate" construction. The CV 4003 were manufactured from the early 60's into the 70's, the ECC began production in the 50's.
 
diyAudio Senior Member
Joined 2002
12AU7A

Hi,

You mean like these.

Yes,Sir..that's the ones.

The CV 4003 and the ECC82 are not the same.

I've never been too impressed with the Mullard range of ECC's boxed,long plate (and that's Philips for you and me).

Numero uno to me has always been TFK,than Philips and all its' subsidiaries.
If you need a list of those subsidiaries,I can provide it but it really goes global beyond anyone's imagination so expect an arm long of brands.

Cheers,;)
 
dhaen said:
Hmm,

But, just because a valve was not designed for an audio application in the first place, does not necessarily mean it'll be no good for audio.

Cheers,

This of course is absolutely correct. My recent work tells me that the 6DN7 (line osc/output dual triode) should make (and apparently does make) a very good valve for audio.

Unfortunately ECC82/12AU7/5963/6198 etc, does not.

7N7
 
Wardsweb said:
For what it's worth, a reply from another board:

The CV 4003 and the ECC82 are not the same. The ECC was manufactured specifically for audio application. This doesn't mean the CV 4003 is crap, just not manufactured to the same exacting standards that the ECC series.

This is not true.

CV4003 was made to very exacting standards; also known as Mullard's M8136, it was manufactured to meet a military specification. CV4xxx series valves are ruggedised and had to meet a number of stringent tests in this regard (cf the American "W" suffix). All the Mullard "M" series valves were special quality, which is why they received thier special nomenclature. Brimar's "T" ("trustworthy") range was another example of the same thing.

Your average ECC82/CV491 was turned out by the million, and was probably very good - within its metier, which was TV sets, instrumentation, guitar amplifiers etc.

Not in my amplifiers though (and neither is CV4003/M8136).

7N7
 
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