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thxrd a écrit :apres on peut s'amuser a comparer le bruit final avec d'autre amplis de meme puissance ( car comparer des amplis de 20 ou 100 w avec des amplis de 1000w est juste sans signification on a 10 dB ou 16 dB d'ecart de puissance !! ) le ram fera mieux que 99% des concurrents .. A gain egal .. ( Crest / Crown /QSC / ect .. ) beaucoup de foromeurs present ici meme savent tres bien de quoi on parle ..
Here is my use case: I am using the S4044 in active biamp mode, with two channels directly feeding >800Hz frequencies into compression drivers in a custom setup. These are really efficient units (4" beryllium diaphragms, >110dB/2.83v/1m sensitivity) and any residual noise from the amp shows up as a hiss.
Even with inputs unplugged (albeit not short circuited), attenuators at -inf, and gain set at 26dB, I do hear a hiss at a 2m distance.
(The hiss is louder just after the startup, and then rapidly reduces, but stays audible).
I find the hiss much more pronounced than the old Yamaha amps we were using before: http://www2.yamaha.co.jp/manual/pdf/pa/ ... C2002E.pdf
(...)
So far the only solution I found to reduce the hiss was to insert a fixed L-pad after the amp, and I will also try with an autoformer (this looks like a much better solution, as it will multiply the impedance seen by the amp to something like 32 or 64 ohms, effectively reducing the impact of residual voltage, but might also reduce the bandwidth, and saturate at high levels), but I would prefer to connect them directly.
Any solution/advice you could think of?
I understand your matter, but the question is not easy. You are using the amplifier for a very special job, working with a high sensitivity driver, in a monitor placed at 2 meters of your ear!. Perhaps this is the problem, because we have a residual noise of 118uV, which gives a signal to noise ratio of 116dB. But this residual noise is averaged in full range, this is the important matter. Your old Yamaha has a residual noise of 139uV (110dB SNR) , but at 12.47kHz. At this high frequency we have not 110dB of signal to noise ratio, and why? It is very easy: you are comparing two amplifiers which come from different worlds; the Yamaha is a HiFi amplier and the RAM is a high power professional amplifier. In the professional audio amplifier market we have a very low output noise (high SNR), and for the professional audio applications it is a very good performance. But if you want to use it in this particular studio application it can be not enough. I think it can be more than difficult to found an professional high power amplifier in the market which gives you the performance you need.
But, what can be a solution? For us the best option is to reduce the gain system use a L-pad after the amp. It is not a valid solution for low frequencies, but for this high frequencies it can be valid.
thxrd a écrit :Pour le souffle ´ ce n'est pas que "je " trouve qu'il ne souffle pas
Tout les gens et foromeurs qui sont passés chez moi ont pu constater qu'ampli seul avec volume a fond et selecteur sur 26 dB il fallait mettre l'oreille dans la trompe pour savoir si l'ampli etait allumé
thxrd a écrit :La seul question sera .. Le souffle est il audible oui ou non .au point d'ecoute ??
La reponse est non .
Etre obligé de mettre un attenuateur resistif en sortie d'un ampli simplement pour diminuer le bruit est quand meme un comble ( peut etre veulent ils travailler en pseudo generateur de courant ?? Afin de justifier la montagne de points d'EQ utilisés pour obtenir la courbe de reponse montrée .. )
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