pfsmith0

I made a lot of frequency response and THD measurements of full and pre models (summarized here) and basically they can be treated as any other modeled amp. In many cases they operate substantially differently than their full model counterparts. Don't dismiss the Pre models as something incomplete or somehow only half as good as a full model. They are very usable and give you a whole 'nother set of sounds to play with.

Oh, one more thing. You may want to try the amp gain EXP control with the Divide 9/15 Pre. According to my measurements (summarized here), it has flat frequency response and low THD. It seems to be reasonably transparent, although I have not tried it.

Yes, it would have been nice if they allowed the EXP to control the mixer in some way. Not only would that solve this problem but allow for some pretty effects.

+1 to panaman

If the noise gate improves it then I'm thinking at least some of the noise is coming from the guitar. Does the hum go away when you unplug the guitar?

Latency is just time delay and is independent in my system. If I have a latency of 240 samples at 48kbps then I'll get a latency of 480 samples at 96kbps. It's 5msec of latency either way. My sound card can keep up with that. The bottleneck at 96kbps occurs when my DAW has to do a lot processing of the signal. At 96kbps it has 1/2 the time to do it in compared to 48kbps. If the CPU can't keep up then latency will get longer at higher sample rates, not lower. I guess my point is latency is more than a sound card issue. Still, 48kHz should be good for the HD500.

I would not use 96 kHz. Depending on what you're doing this can bring your computer to it's knees. Regarding 44.1kHz (for CDs) or 48kHz (for video), it probably doesn't make much difference. It's mostly a concern when recording with your DAW. Most sample libraries come at 44.1kHz but modern DAWs can upsample to 48kHz on the fly. Many people seem to favor 48kHz just to give themselves a little more room to process 20kHz signals with less phase shift. If you're only doing music or using older equipment then 44.1kHz is good enough. Whatever you do, choose one and stick with it because it can be a pain keeping track of which recording uses which sample rate. For better future-proofing I've gone to 48kHz.

Hi Duncann, no I did not measure Cab DEP parameters on other cabs/mics. However, it would not surprise me if they changed with each cab. That being said, I believe the effects will be similar. Thump will enhance some high-Q frequency in the 60-100 Hz region while Res Level increases the level over a broader low frequency region.

What in the world does "Thump" mean? Does it go away when "RES LEVEL" goes to zero? And just what is "RES LEVEL"? I took my HD500 into the lab to find out. Since I didn't know what I was getting myself into I wanted to try to find an amp with flat frequency response, a mic with flat frequency response, and a cab with flat frequency response. If not flat then at least smoothly varying. If not over the whole frequency range, then at least over the range where Thump and Res Level do something interesting. So I picked: Class A-15, adjusted for +/-2dB variation over a wide frequency range 121 Ribbon mic 1x12 Blackface 'Lux Cab The results are in the PDF attached here. You can download the entire spreadsheet of data here. I then set Thump = 0% and adjusted Res Level over it's range. You can see it basically acts as a boost below 1 kHz. It especially invokes a resonance at 80 Hz (for this cab at least). I then set Res Level to 50% (the default setting) and adjusted Thump over it's entire range. It has a similar effect but more restricted around the 80 Hz resonance. I suspect different cabs will have different resonance frequencies but the effect will be similar. I then set Res Level to 0 to see what the Thump control does. Although it's effect is less, it does NOT go away. If you want to remove these effects then both Res Level AND Thump need to be set to 0. Note that I did not measure DEP Decay. It is a slow time domain effect and can cause havoc in frequency domain measurements. I would get different measurements as I changed the sweep rate. The decayed signal would mix with the original signal and add constructively/destructively, depending on which frequency I was measuring and how long it took the sweep generator to get there. The measurement artifacts swamped any meaningful frequency response measurements. So, I *think* this ends my adventures into HD500 amp/mic/cab DEP measurements. There should be total of 4 threads on this: Amp/Pre frequency response and THD measurements. Cab frequency response measurements Mic frequency response measurements And this one on Cab DEP measurements Cab DEP Parameters.pdf

This is a great idea. In the meantime I have to go find a rubber band.

I measured the frequency response of the mic available in the HD500 and attached a PDF of the results here. I also have all the data in an excel file here. I used the Class A-15 adjusted for flat frequency response and the 1x12 Blackface 'Lux cab. You can clearly see the extended low frequency response of the ribbon mics and the hi-mid enhancement of the 57. I'll be using these results to measure what the can DEP parameters are doing but thought I'd share my data here in case anyone wants it. ------------------------- Sorry, the PDF file didn't show up so I attached it again. Mic Frequency Response.pdf

In the search for figuring out what the Cab DEP really do, I had to first find an amp with flat frequency response. Then I had to pick the flattest amp and measure it with the cabs to see which ones has the smoothest frequency response (such as it is). That data is given here. Next I will measure the smoothest cab with the various mics to see what will give me the cleanest platform on which to look at the cab DEP parameters. All this because I don't know what to expect from the cab DEP parameters. I picked the 121 Ribbon to test the cabs because according to the mics' technical sheets that one seems to have the widest and flattest frequency response. I picked the Class A-15 because that also gave me a flat frequency response when adjusted. The frequency responses of the cabs can be found in the PDF attached to this message. The Excel sheet containing the data can be found here. What to do with this? Not really sure how helpful it is, but it appears the single driver have flatter frequency response than multi-driver cabs. If you want a brighter sound, go with the single driver cabs. I figured as long as I took the data I may as well share it. ---------------- Edit: the file is too big (241k?). You'll have to download it from here. Edit: corrected the link above (again).

Yes, the left XLR is not mono but I've been doing this at church for years (sending only the left XLR to the sound board) and have not noticed anything unusual. But I do not use obvious stereo effects (ping-pong delay, for example). I think you'll be just fine for more "normal/typical" types of signal chains. You can certainly try it to see if it satisfies. It's worked fine for me. My typical signal chain is compression -> wah -> overdrive -> amp -> mixer (everything centered - the signal is mono at this point) -> delay -> reverb. So the only stereo effects you'd be losing is due to delays and and reverbs.

Well, you have to be armed with some knowledge first. 2nd order distortion terms are warm sounding while 3rd order terms are harsher and more in your face. The list will guide you to pick which ones will give you what you want. In general, power amp gain sounds harsher than preamp gain, so the list can help you pick which amp saturates in which way (by comparing the Full and Pre gain and THD). If you want a bright sound then pick an amp that's naturally bright like the Super O or Class A-30 TB. There are quite amps suitable for bass besides the Flip Top. Try the Divide 9/15 Pre or PhD Motorway Pre. Who would have thought the Hiway 100 Pre is one of the cleanest amps in there? It was enlightening to me to discover the Mid control on the Blackface is a midrange cut. I otherwise wouldn't know how to use it appropriately. You can certainly audition all the amps and pre's until you find one suitable but this list can guide you to focus on the few that lend themselves to what you're looking for. It saves time. It helps reduce the learning curve. That's about all I can think of. Power amp gain vs preamp gain. Knowing which are naturally bright or have an extended frequency response. Which are clean. Which are dirty. Not only that, but they can be ranked as to how dirty they are. It's much more than academic to me. It will help me pick the amp suitable for the occasion without spending an inordinate amount of time sifting thru them all.

I measured the EQs last year. You'll find the info here. The first page of the pdf file describes a little of how I measured it. The APx525 (by Audio Precision) is a piece of high performance audio test equipment. It'll measure all sorts of things - THD, SNR, gain, levels, frequency/phase response, etc. It has balanced analog, unbalanced analog, serial data, AES/SPDIF inputs and outputs. For this I plugged the unbalanced output into the Guitar Input of the HD500 (set to normal) and then fed the SPDIF output of the HD500 back into the test equipment. That way I only go thru one set of converters to get a better idea of the raw performance of the HD500. Inputs are set to Guitar/Variax (to reduce noise) and the mixer is set to everything centered at 0 dB. I can then setup whatever signal chain I want, drive it to whatever frequency/level I want, and measure what's coming out. Fairly simple, but tedious. Measuring amps are a little tricky because distortion, which is desirable for guitar amps, creates problems getting accurate frequency response. So I had to reduce the input to quite a low level to keep the system non-distorting. Then, what level do I set all the knobs? I picked these: Channel Volume = 100% E.R. = 0% (early reflections - reflections can change the response based on how long it takes to sweep the frequency range, which doesn't reflect amp performance at all - better to just turn it off) Tone controls - set all to 50%, mid-level seemed like a good idea at the time Drive - raise it until I got 1% THD Amp DEP - hum = 0% the rest leave at default settings That'd about it.

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

The HD500 is way easier to use than my old Boss GT-6 was.

So, if the default settings reduce the guitar's signal by about 5dB. If you need to largest signal out of the HD500 then use the headphone output. If it's TOO hot then reduce it with the Master Volume.

I've made some measurements you can find here. You'll see that the gain from Guitar(normal) to 1/4"(amp) out is -4.9dB while the gain from Guitar(normal) to XLR is -14.3 dB (and gain from Guitar(normal) to headphone is +10.5dB). In addition, the 1/4"(line) output is 6dB larger than 1/4"(amp).

Yes, the Flip Top is the only modeled bass amp but you can use several others, reducing treble & presence if there's too much hiss in those. The HD500 records really well, in my opinion, especially if you use the SPDIF output, but USB should be similar (although I'm not sure how much latency USB adds). But for practice all you'll need to do is power it up, select a preset, plug in your guitar, and plug in your headphones. By far the most time will be spent tweaking the preset to your liking.

Ooooh, let's make an HD500(x) Wiki page! I don't know how to do it, but I'll contribute.

And just to provide another item that may be of interest, if you need a right angle adapter for the power plug, this one works great: http://www.amazon.com/BiXPower-LC53-Right-Connector-Converter/dp/B004L74PGI/.

+1 to using Channel Volume to match loudness of each patch. +0.5 to using the Mixer if Channel Volume doesn't give you enough range. I doubt you will need this.

If you click on the amazon link and look at "what others searched for" you'll find these as well: http://www.amazon.com/HD500-effects-replacement-supply-adaptor/dp/B00GQWSRXS/ They're running around $18 but are only 2.5A, although users have apparently been using it with the HD500 w/o any issues.

Well, I went and made the measurements but the system crashed while trying to export to Excel (aaargh!!), so I'll have to go back and do it again next weekend. However, I did notice that the RES LEVEL knob controls a narrow high-Q peak in the 100-200 Hz region, depending on which cab's being used. When set to 0 the peak is barely noticeable. When set to 0 the THUMP and DECAY knobs have very little effect. As RES LEVEL is increased, THUMP makes it even larger. Once those frequencies are excited, the DECAY control determines how long it takes for those frequencies to subside. If you don't want that peak, turn all 3 levels down to 0. LOW CUT is just a variable high pass filter. Adjust that to remove any muddiness you don't want. I'll take the unit back in and publish graphs once I get a successful export.