Found a NOS Mullard!

olafgarten

nick79 said:

This seems as good a time to ask as any, what were/are 6bw7's used in?

AFAIK, 6BW7 is another name for the EF80 which, in Britain, was used mainly for TV signal amplification in the late 50s. 

RiftAmps

thermionic said:

“Receiving valve” suggests to me that wireless radio sets were what they mainly used for.

Three different valve ‘categories’

- CRTs or other ‘display’ valves (Nixie, Magic Eye etc)

- Transmitting valves, used to process and send signals, usually huge buggers that need many kV to operate 

- Receiving valves, used to process and receive signals, used in TV, Radio, HiFi, Guitar amps. Essentially the ‘anything else not listed above’ category.


The EF86 is just a high-gain audio pre-amplifier designed to be used in the earlier stages of a device (by ‘gain’ we mean voltage amplification, not overdrive). It was popular with designers because it could greatly amplify a signal using a very low HT. Check out the Mullard 3-3 HiFi to see one running in starvation.

I regularly come across the 12.6v heater version, the UF86, in radio sets 

ICBM

Phil_aka_Pip said:

EF86 is a low-power pentode. You find them in Vox AC30s and Radford power amps (amongst other things).

Only very early AC30s with two channels. Almost all use ECC83s instead.

PhilKing

I have a Vox AC4 that was modded to use a 6BR7 instead of an EF86, as the sound is very similar, but they don't have the noise issues.  However, they aren't pin compatable.

ICBM

PhilKing said:

I have a Vox AC4 that was modded to use a 6BR7 instead of an EF86, as the sound is very similar, but they don't have the noise issues.  However, they aren't pin compatable.

If that’s an original AC4, there’s a very simple mod which will give more power and a richer sound, at the slight expense of a little more background hum - move the feed to the OT from the second filter cap to the first.

PhilKing

I wish it was an original, but it is a reissue.  They sound pretty good but use a 12AX7, having the mod done gave it a much bigger voice.

57Deluxe

@rico ;;;;  - you wanna putyour feet up and watch this then...Documentary on Valve production at Blackburn works

DJH83004

great link from 57deluxe, please watch it from start to finish to understand why Mullard, Brimar, Philips etc were the best in the world - for me the greatest thing is the machines that made the valves - top engineers who designed and produced them.