NOS buizen 'balanced'

[ptrvnmgn]

Hallo allemaal,

Als ik online NOS voorversterker buizen zoek, kom ik van verschillende types zowel 'gewone' versies als balanced versies tegen. Wat betekent het precies wanneer die NOS buizen balanced zijn? En ik dacht dat daar alleen sprake van hoefde te zijn bij eindversterker buizen?

[tmms]

Er zitten twee trioden in een buisje. Balanced houdt in dat die twee stages ongeveer gelijke specificaties hebben. Eventueel van belang in de fasedraaier positie.

[NRJay]

GENERAL INFO

Dual triode pre-amp valves like the ECC83 12AX7 have two separate valves inside one glass envelope. When the characteristics on each triode are the same it is considered to be a balanced valve. These are generally used in the phase inverter/splitter position (usually the last preamp valve before the power-amp valves).

PHASE INVERTER CIRCUIT

The phase inverter circuit feeds the audio signal into the power-amp valves and in almost all guitar amps is designed unbalanced (not symmetrical) and the components used in the amp circuit will generally have tolerances of 5% and often more in older amps. So by design it is inherently not balanced.

MY HUMBLE OPINION

So what does a balanced valve do in the phase inverter position, it probably just locks in these imbalances. After testing 1,000's of pre-amp valves and doing audible tests on guitar amps with balanced and unbalanced valves we have yet to hear any audible difference by putting these in the phase inverter position. Yes some balanced valves sounded better, but not as a rule just like unbalanced ones sounded good to. One thing we have noticed and only generally is that they are slightly less noisy.

Guitar amps are not hi-fi amps where they are looking to balance the whole circuit. Guitar amps are about tone and their circuits are flawed, but this is what makes them sound so good to our ears. It seems that many ideas have come over from the hi-fi fraternity (and needlessly though) and then perpetuated by valve vendors.

The inherent imbalance produced in the Phase Inverter results in more harmonic complexity (adding 2nd order harmonic overtones), resulting in a sonically pleasing end result. Remove the imperfections and you make your amp sterile.
.

Bron:
http://www.ebay.com/gds/Balanced-Valve-in-Phase-Inverter-Fact-or-Fiction-/10000000027501302/g.html

[tmms]

Dat van die harmonic compexity, interessant. Moet aan de AC30 denken, die PI staat akelig scheef volgens mij.

[nico verduin]

Lang leve de waarheid van het internet:blast:

[tmms]

Zat erop te wachten:D. Dacht altijd dat 100K/82K gewoon was, maar dat van die harmonischen heb ik ook eens zo begrepen uit een verhandeling die vertrouwenwekkend overkwam. Ihkv het niet-opheffen van verschillen in signaal dacht ik.