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Posts posted by gckelloch

  1. First, you need to determine where the signals are being picked up. 


    Do you hear them through headphones plugged directly into the Pod?  If not, it's probably a bad ground on a cable coming out of the Pod to your monitoring system. 


    If you do hear them through the phones, does it happen with other guitar cables?  If not, it's a bad guitar cable. 


    If it only happens with a certain guitar, it's something in the guitar, like maybe a bad jack. 


    If you do discover that it is definitely the Pod, then see if it happens when all inputs are muted.  If not, it might be a bad input jack.  Try switching inputs to see if it makes a difference. 


    Is the FX loop active?  Disable it.  If that solves it, It might be the FX return or send jack or the cables connected to it. Remove the cables.


    If you have isolated each jack and that's not the issue and it's something internal, it would need servicing.

  2. I just thought of a better way of explaining the reason for the default mixer pan settings. It is effectively dealing with the same situation that a mono fx block has in the PRE path. Summing two inputs and producing one output. The mono fx block is hard coded to sum and then attenuate so you get half the output signal. The mixer default settings essentially do the same. It has two paths coming in and only one going out so the default mixer settings mute half of the input signals. For a standard mono patch that is the correct logic to apply to maintain the same signal level throughout. Obviously we can adjust the balance of the two stereo paths in the mixer according to taste and what amps and fx we have deployed in the patch.



    But I'm saying the mixer appears to sum but not attenuate both channels according to perapera's block diagram (schematics include electronic component values).


    You're not really limited regarding stereo FX in each path, because you can set the "pans" for each path any way you want.  Some settings might produce louder results than others depending on what is in each path.  Just lower the levels to compensate when needed.

  3. Are you saying that the signal level is the same when you mute one path with both pans in the middle?  The signal should double when both paths are engaged and they have identical signals.  If not, the mixer attenuates when it sums, like a mono FX block does with the inputs.  I don't think the mixer block does that.

  4. Great!  Can't help you with finding replacement switches, but the guy in the video says they are pretty standard.  Do some research until you locate some.  They shouldn't be too hard to find.  Radio Shack might have them, but something better quality would probably be worth it.  They should be momentary contact switches.  Good luck!

  5. Wait now.  First we need to delineate between dual mono and stereo in this context to avoid confusion.  When I say dual mono, I mean the signal on the L & R channel is identical.  Stereo means they are not identical.  Summed identical channel signals are simply 6dB louder.  The total signal level rises exponentially to +6dB as pans A & B are set closer together.  If  they are panned differently, there is an averaging that would be the same as using one pan, only louder depending on how closely they are set. 


    If the signals on any of the 4 channels on paths A & B are not identical,  then you would need to set the pan for the path/s with the different signals to something other then extreme L or R to get some signal from all the channels.  At that point, it would be just a matter of using your ears to use both pans to focus the stereo energy where you want it.


    There's no way Line 6 could have designed it to cover all scenarios without some being louder than others, or without possibly loosing unique channel content if panned a certain way.  That's why there are levels for each path. 

  6. I hear a lot about how people find their direct monitored digital modeled amp tones sound too brittle or harsh. Some background in analogue guitar tech might be of use.


    Most guitar amp tone stacks are designed so that the bass and treble are boosted and midrange cut by ~6dB when set flat. This was originally done to compensate for the average inherent high end losses in hand-wound Hi-Z pickups, and somewhat for the large speaker beaming affect on stage. A 12" speaker only disperses to ~1kHz. The bass was boosted because early low powered amps and open back speaker cabs did not produce much bass on stage. The mid cut just averaged out the spectrum rather than have a sharper 12dB boost in the bass/treble. It's actually all a poor solution for problems that have been solved in better ways.


    Eventually, we became accustomed to the classic scooped Fender Twin type clean sound. As higher gain sounds became popular in the 60's, the tone stack bass boost was no longer evident as the amp compresses it anyway. Depending on the musical style, it can be very appealing. I know I really dig the thunderous boom of a cranked KT66-based Marshall. Of course, the effect can get muddy if your pickups don't produce a clear fundamental.


    That's why I'm a big Wilde pickups fan. Bill Lawrence knew all about this stuff. He was there working with the major industry pros in the 50's up to his recent passing to help guitarists get their sounds just right. Several other designers now produce consistent quality pickups as well. Consistency was always an issue with pickups in the past...especially with hand-winding. Stretched wire and/or cracked isolation created EM shorts, which in turn causes magnetic eddy-currents that cancel out higher frequencies. Also, typically large Hi-Z coils reduce overall clarity and fundamental note strength. We may see more designers using thinner wire as CNC winding machines become more prevalent.


    Tone stack adjustments are generally required to produce similar results at different gain settings, but you might find that for a clean Fender Twin tone, engaging the bright switch, boosting the mids right up to ~8, cutting the treble down to roughly 3 and maybe the bass just a little will produce a sweeter clearer tone with quality low inductance (~1.5 - 4H) pickups. I also highly recommend a low ~200pF total capacitance cable. The same type of settings with the presence at ~3 works for a classic creamy Marshal sound, but I find the bass can generally be set a bit higher or left flat for the desired compression effect. It of course depends on the pickups.


    The problem with the designed in ~6db treble boost is that quality lower H pickups don't need it, so it often ends up causing high end harshness and hash in the 5kHz region. Metal players often rely on higher H pickups through low pass filtered hi gain preamp channels where all the upper harmonics are artificially generated in the preamp. Said harmonics tend to be more uniform, so there is more leeway when mixing them in without it turning to hash. Active eq knobs are also tuned for specific results for some brightness without harshness.


    Beyond all those factors, a broad cut in the ~2.5 - 3.5kHz region will reduce that piercing "ice pick" affect -- it being the center of the critical hearing range. It depends again on the pickups and their position on the guitar -- the bridge often sounding more shrill. Perhaps the increased hearing sensitivity is an evolutionary result stemming from the sound of breaking bones or branches, or falling rocks? There was also a study that showed people from different regions of the earth have different hearing biases. It may be no surprise to know that people of Asian origin hear more bass, and those of African origin hear more highs, with Caucasian being in between. Such biases might be purely a result of regional temperature averages i.e. higher pressure/warmer air decreases higher frequency transmission.


    To get the specifics of Tone stack configurations, you can get a PC app that has adjustable TS graphs for several popular amps here:


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  7. I thought we were talking strictly about the affect of centering the pans of two identical dual mono signals, rather than altering the width of a stereo signal.  Regardless of total channels, a mono signal has no stereo width.  I don't see how the energy distribution of identical mono signals in the center of a stereo field could possibly be affected unless there were some other factor canceling or boosting the center portion of signal.  For such a result, M/S processing would be required. 

  8. As well as setting the internal output to Combo Front & Stack Front, you need to set the "1/4" Out" switch on the HD500 surface to "Amp" when plugging into Hi-Z guitar amp inputs.  I'm not sure how much you need to adjust the internal or amp tone stack set afterwards, but just use either set so it's not confusing.

  9. The only thing you gain by setting the balances for A and B to 0 with the amp in the pre position is a 6dB boost from the exact same A and B signals summing, which might even clip the D/A.  The mojo is imagined.

  10. You can just use the tone stack on your amp in put to achieve the same thing.  When set flat, most guitar amp tone stacks have a ~6dB bass/treble boost and midrange cut as compensation for the nature of Hi-Z electronics and the older open back guitar speaker cabs.  It's certainly less than an ideal solution.

  11. That's a good example.  If you set the threshold on a compressor very low, it will boost the signal a lot when you aren't playing.  It might be boosted over 10dB depending on the threshold setting.  Since the signal is boosted so much, and nothing but a read ahead "brickwall" limiter (which can't be used in realtime) can catch 100% of the initial transient, the first transient after you haven't played for a second or so will pass through and possibly clip something after it.  You should only use low threshold settings before an amp that breaks up somewhat smoothly.  You definitely can't rely on a compressor for protection from D/A clipping after the amp, so you should only use one after the amp to even out the signal a little via ducking the higher transients.  You may need to use a much higher threshold (or lower drive knob setting) on the compressor to avoid any post amp clipping.  You also may need to keep your amp outputs or any post amp outputs lower than expected, because the initial  transients will still get through no matter what.

  12. It makes sense that at least the Soldano would have a higher 3rd harmonic level when the front is pushed harder than from within the preamp with the Drive knob after the first gain stage.  The models of older amps may not have included that aspect in the modeling, or the volume knobs on those amps simply drive from the first preamp stage.


    I'm surprised the Mesa does, though.  I'm not sure running a 1kHz tone through the amp really tells the whole story.  I think you'd need to run some sort of noise impulses at different levels to do an accurate response test.  The preamp might recover differently with various transients depending on how it's driven.  There may be impulse sets specifically for this type of test that you can download somewhere.  You'd also want the amp DEP Master as low as possible so it doesn't alter the results, and no speaker cab, mic or FX.  Ether way, thanks for checking it out pera.

  13. I actually don't know the specifics of amp circuit design. I have tried to limit my use of technical jargon only to how it affects the sound -- as opposed to an electrical engineer who might explain what happens within the circuitry and not explain how it affects the sound. You'll notice I use the word "sound" rather than "tone". It's important to delineate between tone and timbre: both of which fall under the rubric of "sound". It is common amongst guitar players to proclaim that "tone is in the fingers". That's actually not quite correct. Timbre is in the fingers. Tone is in the guitar and the gear it connects to...more on this below.


    It's also common that guitar players aren't aware of the physics and terminology involved in the characteristics of sound. We resort to using subjective terms that aren't really reliable in conveying our meaning -- some terms being more universally understood than others. There is still much I don't know, but I have cleared up some essential things for myself. I think it makes more sense to offer up the "tools" to understanding a guitar sound, rather than just make pat recommendations based on subjective terms which can often describe texture more than sound. In other words: "Give a man a fish..." It might also make sense that, given the amp/cab customizing DEP features in the POD HD series, we would want to utilize them ASAP to tailor the sound without having to resort to adding pedals which take up FX blocks and often compromise sensitivity and nuance.


    Tone has to do with how frequency ranges are equalized along the spectrum. The guitar itself is a sort of equalizer filter -- in that inherent resonances fall into certain ranges regardless of the notes played on it. The same is also true for a guitar speaker, and for resonances in certain amp components (including the tubes), and possibly from eddy currents in output transformers. Those resonances do involve harmonics, but the frequencies of those harmonics are static. i.e. they do not stem from the pitch of the guitar notes, but are merely reinforced when guitar harmonics are the same frequencies.


    When I use the word timbre with regard to exciting a guitar string, I refer to the portion of the definition where finger/pick technique is used to alter the string's harmonic content -- not the tone. That harmonic content relates to the fundamental note. Its not the same as equalizing a spectrum range, because the harmonic series changes for each note and string. Apply the same pick technique on the low E string as for the E on the D string and the harmonic series will of course be roughly an octave higher. Therefore, distortion generators (like tubes) alter the timbre, because the generated harmonics are based on note pitch.


    Like I mentioned above, tubes can also have resonances that become more apparent as they are pushed, so they might also affect the guitar tone. I'm not quite sure of that, but tubes do exhibit some capacitance, and capacitance creates a resonance. Perhaps it's why certain tubes might sound more 'glassy" and others more "velvety"...or whatever other subjective descriptors seem right.


    I also mentioned output transformers. One cool thing about them is that they generally only produce harmonics up to ~500Hz (depending on construction), which means they will compress and add "warmth" or "meat" without the high end hash. Hiwatt amps were known for having very good transformers. I remember mine sounded like a big diesel train when cranked. I had the Sylvania 6CA7 beam tetrode tubes in it, so I guess they produced less 3rd harmonics than EL34's. They were still pretty crunchy though...with a big bold driven sound and massive bass. Line 6 doesn't mention their Hiway model using 6CA7's, but I suspect it does.


    Smooth clean with a little dirt does hint more at something with 6V6, KT66 or 5881 tubes. Another thing about the Divide 9/13 amp model is that the 5879 preamp tubes produce a fatter sound than those used in most amps. Still, driving the power amp will be more dynamic. You should get more sustain for the same grit with the Amp DEP Master at 100%.  Leave either or both Drive knobs set not too gritty (~50%?) with the Channel Output maybe 50-70% and experiment with driving the first preamp stage with an eq in an FX block right before the amp to see if it affects the attack character. Once you have that sounding as you want, adjust the Drives to the right grit level. You may have to go back and forth with the Drive knobs and eq output to get the attack character the way you want for the amount of grit, or it may not make any difference with this model.  Finally, the passive tone stacks adjust only the amp tone and distortion. They do not affect the preamp section.


    Lastly, the stock Divide cab might be just fine, but something with 2x12" might be better. Celestions generally have more presence than Jensens. The Fanes should actually have more high end extension than anything else there without being harsh. Describing the sound of all the cabs and mics would be too much even for long-winded old me ;) Your best bet in learning how the cabs really sound is to use one of the ribbon mics. For this application, the soft highs of the 67 Cond might be just what you want. Several of the other mics boost the highs and some roll off bass, so be aware of that. The 57 Off Xs would have a flatter high end than On Xs, but still some bass roll off. Look up FR graphs of the various mics to see what's what.

  14. Good suggestions here.  Some things to listen for regarding the upper mids and highs are that amps with ELxx power tubes tend to have a more crunchy gnarly  distortion.  Those with Pentode ELxx power tubes generate only odd harmonics in class AB (push pull) mode.  Even harmonics are canceled in class AB.  Class A (single-ended) operation adds even harminics, as can be achieved by turning the Amp DEP Bias up all the way into full class A mode for any amp.  Both the even and odd harmonics present in the string vibrations are still however accentuated as tubes compress.  The following beam tetrode type tubes generate much less 3rd harmonic distortion than pentodes, leaving complex chords sounding clearer. The Soldano and Bassman 5881 tubes seem to have a glassy compression effect compared to the 6L6's in the Fender Twin and other amps, which to me have that glassy crunch favored by many modern metal players.  KTxx tubes generally have a more open sound with an smooth breakup producing a bubbly sizzling distortion.  The KT88's in the Brit 75 are more crunchy than KT66's, but have the biggest bass sound of all.  6V6 tubes seem close to KT66 and 5881 to me with equally huge bass, but a more velvety breakup.


    In short, if you want less 3rd harmonics for clearer chords in your amp distortion derived crunch, go for something with beam tetrodes.  Then, if you want to add even harmonics for a richer amp crunch that will not further muddy chords, turn up the Amp DEP Bias for the Class AB models.  Transformer distortion will add both types of harmonics as well, so it's really a matter of how hard the amp is pushed.  Any amp will get muddy in the bass when pushed hard enough, but I don't think you'll be pushing the amp that hard for this type of sound. 


    Tube preamps are normally wired in class A, so driving them generally generates the whole harmonic series.  Some preamps use mutiple cascading preamp tubes.  They produce more sustain/less crunch than those with just two.  I think the Divided by 13 amp allows you to mix the smooth 6V6 distortion and EL84 crunch, so it might be a good one to try out.  If you get too much crunch, you could try switching the IN-Z feature to 230k or lower to roll off some highs before the amp.  It will have less affect with higher inductance pickups.  Running a compressor before the amp can be really helpful, but it's kinda cool if you don't have to do that.  Turning up the Amp DEP Bias X might make that completely unnecessary.  Don't be afraid to turn the tone stack presence, treble and even the bass down, and boost the mids.  The presence tames amp crunch.  At 12 O'clock in most guitar amp tone stacks, the bass and treble are boosted and mids are cut.  Sweet and creamy tones can be had by evening the curve out a bit. 

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  15. He was talking about a TV series with David Duchovny of X-Files fame.  Me, I never got over the loss of Hillel Slovak, but Frusciante is an original for sure. 


    As far as the TV series: I got hooked on that for a while until a friend pointed out how cliched the premise and cheap the writing is.  I started to become disenchanted and the spell of my Duchovny man crush (us X-Files fans all had that) was finally broken.  Same thing happened with Entourage.  Pivens just couldn't carry it for me anymore.  Seriously, it all wasn't going anywhere and I was sort of offended by both series after while.  I did however watch the entire UK Shameless.  It was much funnier, and more poignant in some ways.  I don't think I got one good laugh out of Californication when I think about it.  Too many shows, so little time.

  16. Good catch, rad.  I just read about that yesterday.  I was going to suggest using one of them on each path if you run them post amp, but I thought it might use up too much DSP.  They really should add a phase feature to the mixer.  You would of course compare each path soloed and then adjust the phase to match what you think the high end should sound like when combined.  Actually getting the phase aligned can be a difficult task.  Perhaps an auto phase feature will be added at some point.  There is a software plugin with such a capability that aligns audio tracks recorded with different mics, so it can be done.

  17. Hardly believe I forgot to mention this and it may seem obvious to some: as a general rule, you can use some kind of limiting FX after your clean amp tones to trim ~6dB off the transients without it being obvious.  Not only will it guard against clipping, but you could gain about that much back on the Pod output S/N ratio as the overall loudness is raised up ~6dB compared with the noise.  You might not gain much loudness with high gain tones, but it might help keep resonances under control.  The point is to set the threshold so it doesn't compress the average loudness...just the peaks.  It really needs to completely limit the peaks and not let through the first few ms like compressors do.  I think the Vintage Mic Pre is the only one that can do something close to that because it's not a compressor   Such "brickwall" compression requires some latency to "read ahead" and catch the peaks before they are limited. 

  18. Thanks, hurgh.  People should really experiment with those preamp gain nuances before complaining that the amp sound is either too brittle or whimpy.  Of course, it's not really like using the guitar volume with passive pickups, because unless you have a specifically designed "treble" bleed circuit in accordance with the external capacitance load, the highs will in most cases be attenuated as you turn down the guitar volume.

  19. Solid work radatas.  Clear versions of perapera's block diagram of the HD500/X signal path are here and further on in the thread: 




    The question still remains whether driving the amp models with the output of an FX block sounds any different than turning up the amp gain.  I suspect it does...but maybe not for certain models of amps with actual master volumes?  Line 6 should fill us all in on this...unless maybe they figure answer is obvious?

  20. Assuming you know that to compare the sound you need to set the 1/4" output switch on the front to Line and the internal out to Studio Direct when going to a PA, you won't hear the full range sound coming out of your guitar cabs unless they are pointed directly at your head.  12" speakers don't disperse much above ~1kHz.  4x12" cabs are even more notorious for a "beaming" affect. 


    What you miss in the Studio Direct sound is the added compression and subtle complex smoothing resonances of the real guitar speakers.  PA speakers (particularly the tweeters) have a much higher damping factor and better transient response to better convey everything going into them.  I don't think the Pod models include natural guitar speaker compression.  There should be a Drive Cab DEP knob if they did.  They also may not really capture the complex high end smoothing resonances, which can be somewhat comped by increasing the Cab DEP Res, Thump and/or Decay (damping factor). 


    With a tube amp as you monitor amp, you also get some transformer, rectifier and/or PSU sag along with fattening tube compression, depending of how much you drive the amp.  The Vintage Mic Pre or Tube Compressor run after the amp models might cover that aspect, as well as keep the the cab resonances under control, evening out the level and sustain. You might like the tone more with the IN-Z set to 230k (essentially the same as turning the guitar tone knob down a bit), as there will be less preamp hash.


    In order to really hear what is going into a mixing board from the Pod, you need to monitor with accurate full range studio monitors when you set up your presets.  You could also use quality full range headphones if you have a studio monitor simulation device.  There are some apps available for PC, but I've seen a headphone amp with such a feature.   Of course, make sure you aren't getting any internal Pod clipping or driving your PA into clipping.  


    To hear what can be achieved direct to a mixer, listen to the sweet fat tones in this guy's video demo.

  21. Good to have this info in one place.  The inputs must be before the dual A/D converter, right?  Yes, many factors influence guitar output, but setting the inputs the same shouldn't make a difference to the A/D, because each side of the converter gets the same signal level.  So, if you are not clipping the inputs, retaining unity gain throughout should not cause internal clipping. 


    It should be noted that centering the Mixer block "pans" with identical signals on both input paths does boost the signal by 6dB, and could clip the D/A converters.  Even setting model block outputs up too high might clip the D/A.  That's why it's important to achieve unity gain throughout the entire path.  It makes sense to start with a clean uncompressed and full sounding preset - making sure it never clips the D/A - as a reference to adjust loudness levels for all other presets.  Make sense to everyone?

  22. If you want to run multiple quality FX with dual amps, you'll need the 500X.  Tape echos, the Vintage Mic Pre, reverbs, and other deep rich emulations take a lot of DSP.  It's a shame the 500 didn't have that essential extra 20% DSP to begin with.

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