ECC33 Mullard round plates, labeled Philips, matched pair, smoke glass > Holy Grail V55 58

365,00

Highlights

  • Mullard UK production 
  • bottom D-getter
  • matched pair
  • smoke glass
  • rounded plates

1 in stock

Description

ECC33 Mullard UK production matched pair !

This is a pair of NOS ECC33 tubes made by Mullard, UK. The properties of this tube are legendary and widely known. I refer to the many threads on the web for more information. 

I was able to obtain a number of these tubes, therefore I could select nice matched pairs. The tubes do have the typical rounded plates and a bottom D-getter with a beautiful flash.They are thoroughly tested.  Both tubes have excellent test values that match the factory specification and balanced systems (see test results below).

The type/date code on the tubes is 5K2 B 3D4; which imples that they are made by Mullard UK. This code is not anymore completely readable on all tubes.

Sonics

Excellent preamp valve, super linear, low noise, very smooth extended highs, very good in phono stages. Open and airy top end.

 > one of the best vintage 6SN7 types ever made.

Test method & results

Tested with:  AVO Mk IV, AVO Valve Data Manual 23rd edition 1981, Utracer 3+, Philips 1532, RFT stabilised power supply, 2x Korad KA3005P programmable power supply and 2x Keithley 2700.  Gas and shorts tested with: AVO Mk IV. Ia & mu are tested with the official factory test setup: Va = 250V and Vg = – 8V. Precision of the test voltages 2%; measurement after 10 minutes stabilization. 

Please read our test notes and shipping policy before buying !

Test results*

Valve 1

V55

Ia (plate current):

Transconductance (Gm):

Gas test, Shorts test:

9,2 /8,7 mA   

 3,6 /3,4 mA/V

OK

=  NOS / Strong

=  NOS / NOS

 

Valve 2

V58

 Ia (plate current):

Transconductance (Gm):

Gas test, Shorts test:

  9,3 /9,7 mA

3,6 /3,7 mA/V

OK

=  NOS / NOS

=  NOS / NOS

 

(Ia new is: 9 mA,  Gm: New is 2,5-2,7 mA/v)

  *  For test methods and factory specification read the tube testing page.

 

Short description

Tube type ECC33
Quantity of Tubes One pair
Brand Philips Miniwatt / Mullard
Manufactured in Mullard, UK
Date codes 5K2 B 3D4 (hardly readable)
Construction Rounded plate
Getter Construction Bottom D-getter
Print Condition See pictures
Box included Generic white box
Equivalent tubes:  6SN7, 5692, CV2821, B65, CV3942
General test results  NOS

Additional information

Weight 50 g
Dimensions 15 × 3 × 3 cm