Aguilar TH 500 High pass filtering

[ale29]

It is known that some new-ish micro amps such as the Genz Benz Streamliner have a built in high pass filter (set at 30hz in this case) to prevent cone overexcursion trying to reproduce subsonics. This feature is appealing me more and more since I'm using a 2x10 cab (berg HS 210) as stand alone and I want to protect it and maximize headroom if possible.
Other amps have no HPF at all, or a bland roll off (the latter happens in my current GK 700RBII for example).
I'd like to know if someone has ever scoped the Aguilar TH 500 or knows about the presence of a built in high pass filter which would make an external one redundant. I've heard on this forum that the Drive knob acts as a variable HPF/LPF in order to achieve a vintage-ier sound. Any more info about this?
Thanks

 

[CL400Peavey]

Even at 30 hz, that is not really high enough to protect the excursion limits of a 210. I would recommend you take a look at the fdeck HPF-3. You are probably going to want that HPF somewhere in the 50-80 hz range.

 

[Eublet]

I've scoped it. The TH does roll off lows, but not to the extent that the Genz heads do when their LPF is disengaged. I personally love the Genz approach of giving you the option of controlling that extension, particularly on the models that have the variable knob.

The TH does tighten up the bottom more as you roll up the drive control. It's still not in the neighborhood of being considered a 4th order HPF like the Thumpinator of Fdeck pre, but it does help eliminate boom and rumble, making the head have a more vintage low end, while also attenuating the highs to give that more glassy vintage tone in that range.

So it depends on how much sub-low elimination you want to achieve. The Genz heads are really one of the few out there that really do this in such a way that you should never need an external HPF regardless. The TH is more open down low, even a bit into that sub-low range, so if you really want it tight then the Fdeck pre is the way to fix that since it is variable and allows you to customize it.

 

[Eublet]

If it helps, here's the post were I showed some graphs of the TH.

http://www.talkbass.com/forum/f15/a...w-thread-2-a-837421/index41.html#post13429692

 

[ale29]

Thanks, would you have a pic of the curve by any chance?
Or could you quantify (more or less) the amount of the roll-off? On the Genz from some pics I've seen it would be something like 24 or 30dB/octave starting from 30hz.
On GK 1001/700RB from 30 to 20hz there's just a 4dB roll off, 8dB from 30 to 15hz then it becomes more substantial.
http://johnkvintageguitars.homestead.com/GBST900/1001RBII12oclockwandw-o5stringsw.jpg

EDIT: just saw your link, seems like there's very little roll off going on unless you push the Drive really.
I assume the pedal has the same exact pre as the head?

EDIT2: It's not like I'm pushing my cab past its limits currently. It's just nice to know having this feature, just in case, and every little bit helps when using a smallish rig

 

[Eublet]

Thanks, would you have a pic of the curve by any chance?
Or could you quantify (more or less) the amount of the roll-off? On the Genz from some pics I've seen it would be something like 24 or 30dB/octave starting from 30hz.
On GK 1001/700RB from 30 to 20hz there's just a 4dB roll off, 8dB from 30 to 15hz then it becomes more substantial.
http://johnkvintageguitars.homestead.com/GBST900/1001RBII12oclockwandw-o5stringsw.jpg

EDIT: just saw your link, seems like there's very little roll off going on unless you push the Drive really.

You are right. Even with the drive fully engaged, it's nowhere near the 4th order style HPF in the Genz heads. It's more of an EQ control to attain that vintage tone than anything else.

In practice, if you really want this kind of control then I'd just get the Thumpinator for ease of use, or the Fdeck pre if you want to be able to use it more like a tonal control, and then pick whatever head you want to combine it with. I don't know of anyone out there that implements this type of HPF like Genz does, which is a crying shame.

 

[KJung]

It is known that some new-ish micro amps such as the Genz Benz Streamliner have a built in high pass filter (set at 30hz in this case) to prevent cone overexcursion trying to reproduce subsonics. This feature is appealing me more and more since I'm using a 2x10 cab (berg HS 210) as stand alone and I want to protect it and maximize headroom if possible.
Other amps have no HPF at all, or a bland roll off (the latter happens in my current GK 700RBII for example).
I'd like to know if someone has ever scoped the Aguilar TH 500 or knows about the presence of a built in high pass filter which would make an external one redundant. I've heard on this forum that the Drive knob acts as a variable HPF/LPF in order to achieve a vintage-ier sound. Any more info about this?
Thanks

I believe most amps have hi pass filtering way down low for sub bass. However, some have additional 'tightening' at much higher frequencies, like the Genz amps that you use as an example.

The Aguilar TH500 falls right in the middle. Big, but well controlled low end. I feel absolutely no need to use an additional external hi pass with mine, and your Berg 210 can EASILY handle the low end that the TH500 puts out at full volume.

There are only a hand full of amps in my experience that can really benefit from an external hi pass filter... some of the Mesa heads, some of the EA heads, and some of the early SWR heads. Most other heads, unless you are using really lower end cabs, or have a tonal reason for really chopping of significant low end (i.e., emulating a sealed cab sort of vibe), are fine as they are.

That being said, the drive control does a nice job of tonally tightening up that head if you want to go 'sealed sounding old school' with it. You have to carefully balance the gain/mids/drive settings if you want to keep the amp relatively clean, but this is pretty easy to achieve with a bit of experimentation.

 

[CL400Peavey]

I don't know of anyone out there that implements this type of HPF like Genz does, which is a crying shame.

+1

I would love to see a variable HPF on the front of an amp, ala fdeck. You would think manufacturers would be using some sort of filtering at 35hz or so, just to preserve the headroom of the amp. Even at 35 hz, you notice the increased head room and you might not even notice the change in the low end.

 

[Eublet]

+1

I would love to see a variable HPF on the front of an amp, ala fdeck. You would think manufacturers would be using some sort of filtering at 35hz or so, just to preserve the headroom of the amp. Even at 35 hz, you notice the increased head room and you might not even notice the change in the low end.

This is my perspective on this. I agree with Ken's perspective above in a sense...i've never felt a need for an HPF with most any head I own, but I have noticed a lot of difference in overhead and punch when doing so. It can really allow you to push the head and your cab harder, get more usable volume before clipping, and clean up that boomy, vibrating mess. The tonal difference is minimal in a controlled environment perhaps, though I've found it definitely helps in poor enviroments.

So IMHO, there is little reason not to have it in there, as it can provide little difference in some cases, and make all the difference in other cases. Fortunately the Fdeck pre and Thumpinator let you have this type of control regardless of the head you use, even if it is one more piece of gear to have to put in your signal chain.

One more quick note on HPF's like this. I've had nothing but super positive feedback from FOH folks when using one of these. It eliminates a ton of rumble in the house, especially when combined with a bunch of 18" subs. Many sound engineers who don't have the equipment or experience to properly adjust the bass channel to eliminate that sub-low on their own benefit from something like this. I've seen engineers like that instead use the HPF on the boards in an effort to control low end rumble, which usually is set way too high for bass guitar (80 hz or 100hz), or they have to cut lows on the EQ, which really doesn't go deep enough either without removing important content that needs to stay.

So it's not essential, but it can really be worthwhile IME.

 

[KJung]

This is my perspective on this. I agree with Ken's perspective above in a sense...i've never felt a need for an HPF with most any head I own, but I have noticed a lot of difference in overhead and punch when doing so. It can really allow you to push the head and your cab harder, get more usable volume before clipping, and clean up that boomy, vibrating mess. The tonal difference is minimal in a controlled environment perhaps, though I've found it definitely helps in poor enviroments.

So IMHO, there is little reason not to have it in there, as it can provide little difference in some cases, and make all the difference in other cases. Fortunately the Fdeck pre and Thumpinator let you have this type of control regardless of the head you use, even if it is one more piece of gear to have to put in your signal chain.

One more quick note on HPF's like this. I've had nothing but super positive feedback from FOH folks when using one of these. It eliminates a ton of rumble in the house, especially when combined with a bunch of 18" subs. Many sound engineers who don't have the equipment or experience to properly adjust the bass channel to eliminate that sub-low on their own benefit from something like this. I've seen engineers like that instead use the HPF on the boards in an effort to control low end rumble, which usually is set way too high for bass guitar (80 hz or 100hz), or they have to cut lows on the EQ, which really doesn't go deep enough either without removing important content that needs to stay.

So it's not essential, but it can really be worthwhile IME.

+1 Can be, in some cases, really impactful. In others, no negatives to using it, and maybe a bit more headroom.

 

[ale29]

I agree with all of you. It's a shame this function is effectively adopted only on few amps.
Anyway after further research I finally realized the Drive knob on the TH is nothing like an actual "overdrive" knob, it just acts as a variable filter. This is making me more confindent about the TH considering it also doesn't have a baked in "goosed" low end as my GK. It would be nice to know what's happening below 30hz on the TH, too!
I've sent an email to aguilar about this subject.
How would you compare the output vs the 700RB II, especially at 8ohm operation?

 

[Eublet]

I agree with all of you. It's a shame this function is effectively adopted only on few amps.
Anyway after further research I finally realized the Drive knob on the TH is nothing like an actual "overdrive" knob, it just acts as a variable filter.

I'm not sure this is accurate either. Adding gain with the drive control fully counter-clockwise doesn't add overdrive. It'll just drive the head into a clipping state. You have to dial up the "Drive" knob and then adjust gain to get it to overdrive and start providing some harmonic warmth and glassy presence. So there is more going on in this knob than just some bandpass filtering.

This is making me more confindent about the TH considering it also doesn't have a baked in "goosed" low end as my GK. It would be nice to know what's happening below 30hz on the TH, too!
I've sent an email to aguilar about this subject.
How would you compare the output vs the 700RB II, especially at 8ohm operation?

Yes, you can see on my graphs that the inherent voicing of the TH is a bit more mid-centric compared to a flat preamp. There's some thickining in the low mids (centered around 300 hz, an ever so slight mid scoop, and then some upper-mid articulation, followed by a slightly relaxed uppter treble response to provide some "sweetening" of the highs if you will. Of course you can boost lows and highs to give that classic smiley face EQ on the graph, and then use the mid control to do other things. It's a very good sounding preamp IMHO, right out of the box. I find turning it on and setting it flat, even with many of my active basses, instantly makes the tone just sit better in a mix. The active EQ controls on the TH are very powerful and their ability to boost/cut, so IME a little dab will do ya, at least if the Drive control is off.

With the Drive engaged, you are effectively "narrowing" the voice of the instrument, more like a vintage head does, so I've found that I have to be more liberal with boosting lows/highs, combined with a more aggressive scooping of the mids (around 700 hz for me) which can push the thing more into the Sansamp/Ampeg territory.

I no longer have my TH500 head, but the TH pedal has and will continue to be a go-to preamp/DI for me. The really aggressive overdrive/fuzz tones are unique, but I seldom push it that hard. I prefer just a little warming of the tones when I use the AGS circuit, but I would say that the Tone Hammer preamp is one of the most versatile preamps I've ever used given my "modern meets retro" tone goals. There are times when another preamp might do a bit better toward achieving a particular goal than the TH, but I've never had a situation where the TH didn't get me at least 95% of the way there and pass each test with fantastic results. I really can't speak more highly of the pedal. It's a must-have for me.