Search the Community

I took my HD500 back into the lab to measure the frequency response of the various amps and pre's and have attached the procedure and results below in the message. If you want all 450k of data you can find it here. My goal is to measure the Cab DEP parameters but first I need to find a flat, neutral amp/pre to use. From the data I've collected it looks like the Class A-15 full may be a nice first try. A couple of interesting things to note: The "No Amp" measurement shows just how wideband and flat the raw HD500 is. Very nice. You can clearly see the amps that have most of their gain in the preamp stages vs the output stages. For example, looking at the 3 Solo-100 models you'll see that the full model has about the same gain thruout while the pre model gain increases as you go from clean -> crunch -> overdrive. But something like the Brit-45 has lots of gain in the power amp stages. All the tone control knobs were set to 50% which, after looking at these responses, is probably not the ideal setting for what I was looking for. The "lumpiness" of some of the responses is most likely due to too much bass and treble (not saying it sounds good or bad, but just that it's not very flat). In many of the amps, the MID control is a midrange cut, not boost. Pre's can have a substantially different response than the full model. For example, the Divide 9/15 Pre could make a pretty good bass amp. Actually, it would make a pretty good acoustic amp as well. Don;t discount the pre's. They provide a whole 'nother set of sounds. Quite a few of them have their own "thump" responance in the 80-100 Hz region (to let those low open E-G notes ring out). I also indirectly measured the distortion of the models by looking at how small the signal needed to be, or how high the Drive control could be set before hitting 1% THD. I arbitrarily used that as a threshold to indicate a "linear system" so that frequency response could be easily measured. Using that metric I grouped the amps/pre's into categories of low, medium, and high gain. The results are probably no surprised to most of you. Note, however, the word "gain" is used to signify the amount of distortion, not gain per se. An amp can have more gain and stay linear (and therefore louder) than an amp that heavily distorts the signal. It's all a matter of headroom. But I'll use the word "gain" here to mean more gain = more heavily distorted as is common amongst guitar folks. I will start another thread showing the frequency response of the various cabs with an amp. Then another showing the various mics with a cab and amp. Then another showing what the cab DEP parameters are doing. it'll take a little while so be patient. In the meantime, enjoy. ------------------------------------ Sorry, the PDF file slightly too big to attach. You'll find it here. 25May 2017: Edited to update Dropbox links