pfsmith0

Yes, that is one of the uses for this information.

Hi toneman, I would answer with a simple yes/no but I don't understand your statement "you use the to set the output..." I think a very important word is left out between "the" and "to". Would you please repeat the question?

I attached a PDF file to the original post the lists the Frequency (in Hz) represented by Parametric EQ Freq (in %).

After seeing the interest expressed in my EQ frequency responses, I decided to take the HD500 back into the lab to measure gain. How much gain is there from the various inputs? How much gain thru the various EQ (my previous post lists some of that)? Perhaps look at gain thru some of the FX? Or maybe I shouldn't look at gain. I am soliciting other ideas to look at while I have it in the lab. Do any of you have any ideas?

IFRC, there were only a few a ribbon cables but they all disconnect easily. There was a little finagling required but nothing too undaunting. The buttons have a snug fit but can unexpectedly pop off when you, um, don't expect it. The menu control buttons fall out - nothing holds them to the pcb. Be sure you find ALL the screws before you pull too hard. There are screws on the back panel as well as the bottom panel. The first time I did it the knobs went flying off when I pulled the PCB loose, so 1) take them off first, or 2) get a 2nd pair of eyes to watch for flying parts, or 3) don't do this over carpeting. Good luck. If you've tinkered much with electronics you shouldn't have too much trouble. If you HAVEN'T tinkered much then this unit isn't unusually difficult. It may be a good place to learn, albeit it's somewhat expensive to replace. You don't really have a choice, right? You've got to fix the power plug. As I said before, I'd go ahead and replace the USB connector as well while you're in there.

I removed the whole PCB to get access to the top and bottom layers. I had to suck solder off both sides of the thru-hole USB connector to get it out without tearing up any traces.

I've replaced the USB connnector and didn't have any particular difficulty. The USB connector was thru-hole, which was a hassle, and I expect the power connector to be the same. In fact, while you're in there you should replace the USB connector as well. It'll break on you one of these days and it seems the replacement units you can get are much more sturdy.

Please note that I attached frequency response graphs for the Q Filter in the first post of this thread. Also, I identified the Left channel as having the odd frequency response in the Hi Freq portion of the 4 Band Shift EQ. The giant ZIP file containing all the data has been updated with this new information and can still be found in the Dropbox link shown in the first post. Enjoy!

Yes, that's what I'd do.

Hi Rob, You will need 2 instances of the parametric EQ to adjust 300 Hz and 1500 Hz. I often use 3-4 instances to EQ my acoustic intruments to keep them from feeding back at various frequencies. The parametric EQ has basically 3 frequency bands; Low, Variable, and High. Low: as you can see from the graphs, it only cuts or boosts frequencies below 200 Hz. The FREQ control has no affect here. Variable: use the FREQ control to set which frequency to center the affect (43 to 4500 Hz). Use GAIN to set the boost/cut at that frequency (-12dB to +12dB). Use Q to set how many frequencies around the center to affect. For feedback control I usually have to set GAIN = min and Q = max (this gives a very deep but narrow cut). High: as you can see from the graphs, this only cuts/boosts frequencies above 2kHz. FREQ has no affect here. There is more discussion at http://line6.com/support/topic/335-frequency-response-graphs-for-hd500-eqs/

I don't disagree with you, but I do see an advantage for using % instead of absolute numbers. With % they can always update or fine tune the frequencies to make them more useful thru future software updates. That being said, I don't find % very useful, although they're better than nothing. The whole reason I started this work was because I DIDN'T fine % useful. I needed the absolute frequencies so I could 1) understand what they do and 2) use them in a more direct manner instead of experimenting around (too time-consuming). But, I'm glad you're finding these graphs as useful as I do.

Nice write-up meambobbo. I did not realize I maybe should have included the Q-filter. If/when I get the unit back into the lab I'll measure that as well - and determine which channel (left/right) has the messed up 4-band shift EQ high freq response. Also, please note that the Excel data file has the parametric peak frequencies for 1% adjustments. The graphs only show 5% so you may want to download the whole zip file from the link in the first post and include a 1% table in your write-up. I can't attach it here due to size constraints.

Certainly! Use this on your site as you see fit. If you have a more permanent place to store the files then I am interested in that as well!

In the process of trying to figure out what a 4 Band Shift EQ is, I put my HD500 on the test bench and measured the frequency response of ALL the EQs in the HD500. I thought you'd find it useful so I'm sharing the results here. For example, what does a 100% shift mean? What does 0% Q mean? And just where is Freq = 38% in the Parametric EQ? Did you know when you set 2.2kHz of the Graphic EQ to -12dB you'll get a +12dB boost (!) at 1kHz before it dips down at 2.2kHz? No wonder it didn't work very well to eliminate a pesky feedback problem, but caused another one instead. Using these can give you insight into which EQ you really want to use. I've attached the most pertinent pictures here (zipped together to make it easy). The only potential problem is the 4 Band Shift Hi Freq which has mismatched L/R channels (~3dB at 1kHz)! Every other EQ and every other setting has perfect L/R balance (less than .1dB mismatch) but this one does not. I've contacted Line 6 support before submitting this here but they see nothing out of the ordinary (i.e., it sounds fine, which may be true, but there's still a mismatch, big enough to be called a bug in my opinion). I've labeled those two graphs channel 1 & 2 because that's what my test equipment calls them. Unfortunately I didn't have the forsight to find out which was left and which was right before I tore down the setup. But the fact of a mismatch remains. Some things you need to know to properly interpret these: An Audio Precision APx525 was used to generate the sound source and measure frequency response. Output = S/PDIF Input 1 = Mic. Input 2 = same. Mic level on back adjusted to give -20dBFS output with the Graphic EQ Unless otherwise indicated, the gain of all the other EQs were set to nominally give -20dBFS. The gains were recorded so you can see which EQs have built-in gain or loss compared to the Graphic EQ. There were no other FX or amps in the signal chain. Sample rate = 44.1kHz (factory default) I have more complete files that contain the actual data (not just pictures) as well as more settings than shown in these few pictures attached here. Until I can find a better place to put it, you can download the entire 160M set of Excel files from: https://dl.dropboxusercontent.com/u/56306778/HD500%20Measurements.zip. I am open to ideas of where to put this on a more permanent basis. Enjoy! I hope you find these as useful as I have. ---------------------------- I took the HD500 back into the lab and verified that it's the Left Channel that has the odd frequency response in the Hi Freq portion of the 4 Band Shift EQ. I re-uploaded the Excel files to indicate this and re-uploaded the new 4 Band Shift EQ figures here. ---------------------------- I measured the frequency response of the Q Filter (per meambobbo's post) and attached it here. I also updated the giant zip of Excel files. I think this could emulate a pretty Morley wah if you make toe = hi Freq/hi Q/hi Gain and heel = low Freq/low Q/ low Gain. Also, mix attempts to add the filtered signal to the straight signal, which it does. But the filtered signal has some processing delay so the mix includes some notches in the 4k-8kHz region you may not be expecting. You can see this in the attached graphs. For the signal levels I was using (-20dBFS thru the Graphic Equalizer) you can also see some gain compression with the Q filter. So if you want it clean, stick to the lower Gain levels. ----------------------------- Added a PDF file that lists the frequencies (in Hz) represented by the Parametric Frequency (in %). Updated links to ALL my measurement files: Amp Frequency Response Pre and Full (Excel) Cab DEP Parameters (Excel) Cabs with 121 Ribbon (Excel) Gains (Excel) Mic Frequency Response (Excel) Amp Tone Controls (pdf) Amp-Pre Frequency Response (pdf) Cab Frequency Response (pdf) FX Gain (pdf) Model Pak Frequency Response (pdf) Global EQ (zip) Huge 185M EQ frequency response file (zip) This last one was the original subject matter of this thread.