Neo driver issues.

[73jbass]

I just noticed something a few weeks ago at a gig with my speaker cabs.Both my 4x10 and 2x12 have neo drivers that sound great,but after a copuple of sets,I noticed that my tone was changing a bit as the night went on. My tone starts to get a bit nasaly,for lack of a better term.I gigged the 2x12 by itself Friday,and it did the same as the 410. Both cabs are 8 ohm,driven by a Thunderfunk head and never pushed hard.Am I hearing things,or is something going on here?

 

[KJung]

I'm sure you are hearing what you hear, but it has nothing to do with the neo drivers IMO and IME. Often, as the night goes on, and the band inching up in volume results in a combination of ear fatigue, a changing impact of room acoustics, and possibly pushing an underpowered rig into a slightly more compressed tone profile (by that, I mean that the band might inch into a volume level that is too much for a given rig, resulting in a combination of the amp reaching its safety limiting threshold... this can EASILY happen when playing aggressively with a moderate powered head like a TF550b at 8ohms..... and speakers pushing toward that 'overextension' thing that results in a loss of deep low end and a bit of grit in the upper mids which can be described as 'nasally') .

Edit: My guess is, assuming you are using a TF550, that you are hearing that amp compress a bit when pushed at 8ohms due to it hitting the 'power amp safety limiting'.

 

[73jbass]

I'm lucky in the fact that this isn't a loud band.We get our levels at sound check,and leave them alone. My TF is typically set with the gain at about 9 or 10 o'clock,depending on the bass,and the master at no more than 12 o'clock.There isn't enough gain to kick in the compressor.So I hardly think I'm pushing it too hard.

 

[KJung]

I'm lucky in the fact that this isn't a loud band.We get our levels at sound check,and leave them alone. My TF is typically set with the gain at about 9 or 10 o'clock,depending on the bass,and the master at no more than 12 o'clock.There isn't enough gain to kick in the compressor.So I hardly think I'm pushing it too hard.

The compressor on the gain is a totally different issue versus the power amp limiter clamping. Depending on how hot your bass output is, that setting could easily drive that amp to full power (especially at 8ohms) as you start to dig in later in the evening. I don't think I ever had my TF master past 12. With the gain at the optimum setting (i.e., where the limiter light flashes only at the loudest, lowest hits), that master setting would be almost maxing that amp out, given the taper design of that master pot (again IMO and IME).

If you typically use only one cab, I would highly recommend getting a reasonably high SPL 4ohm cab like the Berg AE410, the Epi310UL, or two smaller 8ohm cabs that you can always use together, like the Aguilar DB112's, etc. Getting an amp of that power running at its maximum designed output can really make a difference IMO and IME.

However, you aren't hurting anything, and if you just notice this compression on only your loudest gigs later in the evening, you can just live with it if it doesn't drive you crazy.

 

[dnarock]

how long have you had your cabs ? maybe the speakers are just breaking in ?!

 

[greenboy]

Driver power compression? Changing tone due to running harder and further into the excursion, with increasing driver distortion? Hear that a lot at other people's gigs.

 

[Rick Auricchio]

Ask someone with good ears to listen from the audience for a different perspective. You may be suffering from ear fatigue onstage.

 

[will33]

Ask someone with good ears to listen from the audience for a different perspective. You may be suffering from ear fatigue onstage.

Ear fatigue has as much or more to do with it than any of your gear. Yes things change as voice coils warm up, the room has more or less people in it, etc. But your ears change too, they will give some natural compression and damping of the sound, this is your body protecting itself.

I hear this a lot at concerts, the mix starts a little rough for the first couple songs, then the soundguy gets it to sounding good, that's when they should just walk away from the board but they don't. They're ears change after being exposed to the volume for that long and they keep tweaking things and it gets progressively worse.

 

[WingKL]

KJung, I curious about this ''power amp safety limiting''. Is this a phrase you've heard from Dave to describe the current limited power supply in the TF or does it refer to something else?

 

[Petebass]

I tend to agree with those who suspect it's a combination of ear fatigue, power compression, warmer voice coils, and the band volume creeping up which bringing the room acoustics into play more.

Note this is not a "Neo's only" thing. All speakers do it. Poor Neo's, they get blamed for everything!

 

[JimmyM]

Yeah, happens to everybody. I mostly blame it on ear fatigue, though other factors can also play into it.. Even if you play at low levels, you're still going to get some ear fatigue.

 

[B-string]

NEO's are just more acurate than ceramics, everything stands out better/ or worse. Okay I'm going to bed before the missiles are launched

 

[KJung]

KJung, I curious about this ''power amp safety limiting''. Is this a phrase you've heard from Dave to describe the current limited power supply in the TF or does it refer to something else?

I think every solid state amp has this, and it came to my attention through many posts on talkbass concerning the fact that some amps, like the Markbass LMI and the TF550b, can 'quash' a little bit at 8ohms when really pushed. This is actually a good thing in a way, because having your output limited to you don't get into distortion is a good thing. The bad thing is, if you are using a 300 watt amp at 8ohms with a cab with moderate SPL and really pushing it, you can run out of headroom (especially if slapping), and you can hear some 'compression' in your low end and upper treble on occasion.

I think most of the posts above kind of summarize the three issues I raised in the first post: The OP's issue is probably a combination of the band getting a bit louder as the night goes on, and what he is hearing is most probably due to:

1) Ear fatigue
2) His amp coming up against the power amp limiter at 8ohms
and
3) Possibly some overextension of the drivers

Issue one results in losing a bit of top end clarity, issues 2 and 3 result in the low end compression. All combined result in the rig sounding more midrangey (or nasal) as the night goes on. The only fix for 1 is to put in those plugs by the 3rd set. Issues 2 and 3 can be fixed by running that head at 4ohms into either two high quality smaller 8ohm cabs, or a big high quality 4ohm cab.

My best guess is his issue is a combination of 1 and 2.
IMO and IME.

 

[B-string]

Gallien-Krueger does not use output limiters, Mr Gallien designed it not to use output limiters.

 

[KJung]

Gallien-Krueger does not use output limiters, Mr Gallien designed it not to use output limiters.

That would probably not be a positive Seriously though, the GK power amp protection circuitry is called 'intelligent protection logic' or something like that, and my guess is, it performs the same function as a power amp limiter.

If you run these solid state amps as they are designed (i.e., for most of them, maximum power into 4ohms), you will rarely, if ever run into power amp limiting. If you do regularly, you need a bigger amp.

 

[()smoke()]

this explanation seems to describe just what i was experiencing running my TF-420 into a pair of 12s--not that the TF is anything but a coincidence, it was a great amp--just not enough power for what i was trying to do...it was worse when i used one 8ohm cabinet, as expected--and my volume was just a nudge past 12:00 when i would hear this, similar to the OP

i ended up going with a more powerful amp, and the issue went away...i was right on the edge of needing more power with the 420 though, it was a surprisingly loud amp through a pair of 12s given it's rating...from my understanding, i could've perhaps added more speaker area or a more efficient SPL cab for similar results

That would probably not be a positive Seriously though, the GK power amp protection circuitry is called 'intelligent protection logic' or something like that, and my guess is, it performs the same function as a power amp limiter.

If you run these solid state amps as they are designed (i.e., for most of them, maximum power into 4ohms), you will rarely, if ever run into power amp limiting. If you do regularly, you need a bigger amp.

 

[B-string]

That would probably not be a positive Seriously though, the GK power amp protection circuitry is called 'intelligent protection logic' or something like that, and my guess is, it performs the same function as a power amp limiter.

If you run these solid state amps as they are designed (i.e., for most of them, maximum power into 4ohms), you will rarely, if ever run into power amp limiting. If you do regularly, you need a bigger amp.

The G-K's are designed to ride the power supply rails, if excessive current is detected (over 50 ms if I remember correctly) the amp goes into protect mode. It is all part of the powerful mistique and growl from G-K amps (also overbuilt power supplies). Weak speakers need not apply for G-K outputs if you like to push it?

 

[KJung]

The G-K's are designed to ride the power supply rails, if excessive current is detected (over 50 ms if I remember correctly) the amp goes into protect mode. It is all part of the powerful mistique and growl from G-K amps (also overbuilt power supplies). Weak speakers need not apply for G-K outputs if you like to push it?

I never really found GK amps particularly loud for their wattage ratings. The older ones 800/400rb were quite loud, but at the expense of low end. The newer ones seem fairly rated, and typical of other amps with similar power specs.

I do like the growl and grit that comes out of the older 800 and 400rb though. I don't hear much of that in the newer models (700/1001/2001). Nice though, especially at the price point.

I have not heard the Fusion though, and that sounds like it's a KILLER head from the reviews.

 

[73jbass]

I think every solid state amp has this, and it came to my attention through many posts on talkbass concerning the fact that some amps, like the Markbass LMI and the TF550b, can 'quash' a little bit at 8ohms when really pushed. This is actually a good thing in a way, because having your output limited to you don't get into distortion is a good thing. The bad thing is, if you are using a 300 watt amp at 8ohms with a cab with moderate SPL and really pushing it, you can run out of headroom (especially if slapping), and you can hear some 'compression' in your low end and upper treble on occasion.

I think most of the posts above kind of summarize the three issues I raised in the first post: The OP's issue is probably a combination of the band getting a bit louder as the night goes on, and what he is hearing is most probably due to:

1) Ear fatigue
2) His amp coming up against the power amp limiter at 8ohms
and
3) Possibly some overextension of the drivers

Issue one results in losing a bit of top end clarity, issues 2 and 3 result in the low end compression. All combined result in the rig sounding more midrangey (or nasal) as the night goes on. The only fix for 1 is to put in those plugs by the 3rd set. Issues 2 and 3 can be fixed by running that head at 4ohms into either two high quality smaller 8ohm cabs, or a big high quality 4ohm cab.

My best guess is his issue is a combination of 1 and 2.
IMO and IME.

Like I said before,we don't play loud,definitely not enough to wear plugs,and we defintely don't turn up as the night goes on.The singer sometimes goes into the audience and finds some poor guy to sing to,and if one of us is too loud,she'll tell us the first chance she gets! So,we keep the stage volume in check.That's why I "think" I'm not pushing the amp too hard.Might be.I am going to try a different setup next gig and see what happens.Got an Ashly BP-41 I've been wanting to try out anyway,so good time to do it. I don't doubt your statements, it's that this is the first time I've run into this,so I'm try to put together the possible reasons. I do appreciate everyones input! I got as lot more response than I expected.

 

[Bassmec]

Driver power compression? Changing tone due to running harder and further into the excursion, with increasing driver distortion? Hear that a lot at other people's gigs.

You might also be getting a very small amount of thermal flux loss,
Neos are not as thermally flux stable as some other magnet types.