yawg hat geschrieben:Which other types have you tested before deciding on the Mullards? How would you describe the sonic character of the Mullards compared to their competitors? Resolution, midband, treble, soundstage ....
I have tried these:
GOLDEN DRAGON 12AX7G-E83CC-01 GOLD
PM 12AX7LM
SYLVANIA 12AX7
ELECTRO HARMONIX 12AX7EH
JJ/TESLA ECC83S BALANCED
JJ/TESLA ECC803S BALANCED LONG PLATES
TELEFUNKEN ECC83 "diamond" SMOOTHPLATES MATCHED PAIR
SIEMENS ECC83 MATCHED PAIR
MULLARD CV4004/M8137 BOX PLATE MATCHED PAIR "SHIELD"
AMPEREX 5751 MATCHED PAIR
SOVTEK 12AX7WA
RCA 5751 BLACK PLATE MATCHED PAIR, DOUBLE AND TRIPLE MICA
TELEFUNKEN ECC83 "diamond" MATCHED PAIR OF 1959
GROOVE GT12AX7M
PHILIPS 12AX7 AUDIO BALANCED
5751 JAN GE
SYLVANIA 5751 double mica
12AX7 RTC "BOX PLATES"
yawg hat geschrieben:Are the CV4004 the same type as the 5751 i.e. lower gain than the standard 12AX7?.
CV4004 are 12AX7/E83CC but not ECC83...
12AX7 have a mu=100% while 5751 have a mu=70%. That means transconductance is better, intern resistances lower and it should be a better sound: but it depends, you have to try...
NB: the tubes I talk about are NOT Mullard but RTC made by Mullard. There have the same looking but don't sound the same...
yawg hat geschrieben:In what sort of device do you use them? I found that different tubes have a much greater impact on the sound of my True Blue preamp. Different tubes in my Cayin DAC didn't make such a big difference ....
In Jolida JD-100A, JD-100H and JD-100S CDPs, preamp Cayin SC-6LS...
yawg hat geschrieben:Or perhaps there simply is more difference in quality with the 12AX7 than with the E88CC, meaning there don't exist real bad E88CC?
Not at all, here is the ones I have tried:
Amperex PQ orange label E88CC/6DJ8 made in Holland
Amperex 6922 Buggleboy
Telefunken E88CC "diamond"
Siemens CCa à deux hanses de 1960
Siemens E188CC
Brimar CV2492
Brimar E88CC
Valvo E288CC
Golden Dragon 6922/E88CC Gold pins
mullard e-188cc
russian cryo
e88cc rtc
Otherwise, compared to all others, the timbres are marvellous, the soundstage is nearly excellent -less good than RCA 5751-, the dynamic is perfect and so and so...

CAYIN CDT-17A OAD&TS Full Discret OPA ver.2/VECTEUR L4.2 OAD-->full symetric DIY ampli class A-->Ellis 1801b OAD/JBL PROJECT ARRAY 1400
Headphone Ampli Cayin HA-1A-->headphone Grado Labs SR-325i Gold.