Archivio per la categoria ‘Musica’

a small review but at the moment without bench data…

Some months ago I decided to take an amplifier with higher specifications than the “wonderful” CA6, in order to fully kick my bass units, because when used outside, in bridge mode @4Ohm (~1600 Watts), the “small” CA6 appears to be a little undersized, even if it drives 4Ohm bridged without problems. Furthermore I’d like to not “overuse” a power amplifier, so that I carefully look at all the clip leds in order to have them light for few times during the events; I know, and already described, that the limiter circuits do a good job in keeping distortion at low levels when they’re on, but on the other hand there isn’t much more to obtain from an amplifier when it is already telling you that it reached its limit, that’s my point of view… I bought a second hand CC5500 in very good conditions so that it seems just came out of the box.

I read some very negative comments on the various forum .. “it’s crap”, “economical” and so on, but my impression was that many of them were driven by “fanaticism” for other brands, non technical/on the road opinions and assumptions: on the other hand the Crest Pro series is considered to be one of the best sounding line, so why not the CC5500 which has the same schematic as the Pro serie, and the Peavey CS series, with the CC and the CS having a traditional power supply instead of switching? You can also read very good opinions regarding the CS4080 which is CC5500 with higher supply rails and minimum 4Ohm load and, most important “The things I learned while designing the Crest 9200 carried over to your Peavey CS4080Hz. It’s mostly a Crest 9200 output stage with a linear transformer limited to 4 ohm/ch capability. That in turn morphed into the Crest CC5500 with a two ohm rating. Hence the similarity you noted. We would like to keep the two brands uniquely separated, but I’m not going to burn Hartley dollars reinventing technology. When the price point allows, the Crest gets more stuff inside”, forum words of an ex-Crest engineer… point…

In addition to the above I based my choice also on this review and this one  

Currently in this page You will not find bench data like for other units I own, basically for 3 reasons:

  1. my load resistors ( 4 x 2Ohm in series) are rated at 50W each for continuous drive, so 200W total, and a 5x overdrive capability for a duty cycle of 5s ( 5on and 5off). I already use a longer OFF cycle (10s)  and 2 fans blowing on the heat sink, however their life will be at risk with the CC5500, because they already “cried” with the CC4000.
  2. I always use  “real” home plugs in my tests, currently cabled with 1.5mm2 wires from the general switch having a 10A wall outlet, to which I attach a 3m extension (3×2.5mm2) going to the power distributor on the rack. This is far away from regulated bench supplies and almost reflect real usage scenario.
  3. The results of the CC4000 presented on this pages (for the point above) were misunderstood and interpreted on some forums (or from some people) as the amplifier not meeting its specs, and not as the result of the whole power supply line performance. As You can read here the CC4000 fully reached its 8Ohm specs on a bench supply but started suffering mains voltage drops on lower loads.

Che poi non si discosta molto dall’accordatura di uno strumento reale …

Dopo avere condiviso l’ultima versione di soundfont in questa cartella, mi è balenata l’idea di fare una verifica sull’intonazione dei vari strumenti, per verificare che non vi fossero grosse discrepanze di tono nelle varie note, anche se in realtà l’ascolto aveva già confermato una buona omogeneità; alla fine poi si è trattato di un’operazione di rifinitura, gli strumenti accordati erano tutti ben intonati.

(altro…)

My Crest Audio CA6 amp

Pubblicato: 25 giugno 2013 in Elettronica, Musica
Tag:, , ,

A review with some measured data and some modifications to further better this amazing mid-power Pro Amp

I’ve been always fascinated by this line of Pro power amplifiers of the famous brand of Meridian, Mississippi, for several reasons, among which I count

  • Modular construction, there is almost one board for each section: input & and gain, pre/driver & protection, output stage, power supply.
  • “All Transistor” construction, excluding the input like in many Hi-Fi amps, which gives this series a superior sound quality; this is almost an Hi-Fi like amp, and the version with the output binding posts is considered such this way. Moreover there is only 1 ( I say 1) polypropylene capacitor in series with the signal… (I’ll show You later)
  • It uses and advanced (= well engineered ) Modulated Class H output stage, which exhibits no glitches at high frequency during rail switching, also without using RC networks across the switching diode; I simulated the whole circuit with LTSpice and there is always a clean wave and a perfect switch also at 20Khz.
  • Triple Emitter Follower output configuration with a total of 12 output transistors for each channel; this translates into better behavior on lower loads and less distortion, and more reliable operating conditions due to a great number of devices compared to other brands for the same rating, which use typically 8.

(altro…)