A.M.P. BH-420 Enhance Button question??

[JAC77]

Long time user of BH-420, have had and sold several. I always come back to it because I can never find something else that sounds and feels as good. That being said, I became curious about the enhance button. I almost always have the enhance function engaged, only disengage when using certain cabs (typically 1x15s). A few months ago I got curious about the “baked in” tone that button provides and decided to try to mimic that sound with the EQ section only, leaving the enhance disengaged. I can’t replicate it using only EQ. I have more hours than I want to admit sunk into trying to replicate that sound. I have a copy of the schematic of this amp, is there a way to figure out what actual EQ curve is from the schematic? Ultimately it doesn’t matter, but the rabbit hole of curiosity is eating my brain…

 

[gtirard]

Long time user of BH-420, have had and sold several. I always come back to it because I can never find something else that sounds and feels as good. That being said, I became curious about the enhance button. I almost always have the enhance function engaged, only disengage when using certain cabs (typically 1x15s). A few months ago I got curious about the “baked in” tone that button provides and decided to try to mimic that sound with the EQ section only, leaving the enhance disengaged. I can’t replicate it using only EQ. I have more hours than I want to admit sunk into trying to replicate that sound. I have a copy of the schematic of this amp, is there a way to figure out what actual EQ curve is from the schematic? Ultimately it doesn’t matter, but the rabbit hole of curiosity is eating my brain…

Interested - I've also lost time trying to replicate other amp's tone with EQ, and never could get close. So hopefully I might learn things here.
The only difference between you and me is that I never dared asking because I felt stupid and ignorant about it Now I know that I'm not alone.

What method did you try? I've tried using the EQ section of an amp (without 2 parametric mids) in order to replicate the baked in tone of another amp, just intuitively, and it never worked. I've also tried to find a DAW plugin in order to "view" the EQ curve of an amp, but I didn't really find such plugin.

You could try to capture that tone with NAM (Neural Amp Modeler), a free and open source software that lets you make digital models from real amps, using deep learning, and then use it in a DAW plugin or even on NAM player pedal (Dimehead or Darkglass Anagram). That would not tell you what this tone is made of, but you could apply it to any audio source and even share it with the community.

There is already a couple of capture on Tone3000, one with flat EQ and one with… flat EQ and the "enhance" button engaged… Except it's a capture of the AMP BH-260, the smaller version of the BH-420. It should be pretty close to your BH-420 because the power section shouldn't make any difference, or at least if the preamp section of these two amps are really identical. So if you download these models, you should be able to apply the "enhance" switch of the AMP BH amps to any audio track in any DAW, without the amp.

I'm going to try these models for fun (you've piqued my curiosity)

 

[JAC77]

Whoa, I just fiddle with knobs, man. I don’t even know what you’re talkin about.

 

[gtirard]

Interested - I've also lost time trying to replicate other amp's tone with EQ, and never could get close. So hopefully I might learn things here.
The only difference between you and me is that I never dared asking because I felt stupid and ignorant about it Now I know that I'm not alone.

What method did you try? I've tried using the EQ section of an amp (without 2 parametric mids) in order to replicate the baked in tone of another amp, just intuitively, and it never worked. I've also tried to find a DAW plugin in order to "view" the EQ curve of an amp, but I didn't really find such plugin.

You could try to capture that tone with NAM (Neural Amp Modeler), a free and open source software that lets you make digital models from real amps, using deep learning, and then use it in a DAW plugin or even on NAM player pedal (Dimehead or Darkglass Anagram). That would not tell you what this tone is made of, but you could apply it to any audio source and even share it with the community.

There is already a couple of capture on Tone3000, one with flat EQ and one with… flat EQ and the "enhance" button engaged… Except it's a capture of the AMP BH-260, the smaller version of the BH-420. It should be pretty close to your BH-420 because the power section shouldn't make any difference, or at least if the preamp section of these two amps are really identical. So if you download these models, you should be able to apply the "enhance" switch of the AMP BH amps to any audio track in any DAW, without the amp.

I'm going to try these models for fun (you've piqued my curiosity)

View attachment 7220828

I like it!

 

[gtirard]

Whoa, I just fiddle with knobs, man. I don’t even know what you’re talkin about.

Well, if you have a computer and a DAW (I'm using Logic on a Mac but you can use any other equivalent software on Mac or PC), you can download the NAM plugin and a profile of the AMP BH-260, and then apply this enhance tone to any audio track.

This will not tell you what is the EQ equivalent of that enhance filter, but you will be able to apply this tone without having the amp.

 

[gtirard]

Now I'm trying to find the same color using a parametric EQ, I'm not super close yet, but I'm approaching it.
I suppose it's a strong "mid scoop" of some sort (boot the bass frequencies, scoop the mids, and boost in treble), but there are so many parameters and my experience in EQing is limited, so I quickly get lost…

I suppose that someone with better ears than mine could get pretty close.

 

[6thplanet]

@gtirard , have you ever captured an amp with that software?

 

[gtirard]

@gtirard , have you ever captured an amp with that software?

Not yet, but it's funny you ask, because I was just thinking I'd like to try.

There aren't many models for bass, not yet, the overwhelming majority of models are for guitars.

Now with the NAM compatibility of the Darkglass Anagram, the interest of the community for bass amp models may grow. Also the inclusion of NAM in the Anagram kinds of confirms the technology is here to stay.

I think I'm going to give it a try with Jad Freer Sisma first (then maybe the Quilter Bass Block v803, and then a few other amps if it's cool). Too bad I sold my Jule Monique without capturing it.

 

[brianrost]

JAC77,

The enhance on the A.M.P. amps is a fixed scoop. Low boost, low mid cut, treble boost. With all the EQ on the BH420 you could can certainly come close with the four parametric mid bands, but why bother? If you like the sound (I did for a long time) why screw around with the EQ to replicate it?

Wild guess: boost the bass knob to around 3:00. Then set the midrange knob that covers 200Hz to 600Hz to 550Hz and the level to 9:00. Leave the rest of the EQ and the tone balance at 12:00. Then go from there, sweeping the mid EQ band through it’s entire 200-600 range and fine tuning the boost and cut settings of the bass, mid and treble knobs.

For comparison:

Ampeg Ultra Lo is +2dB @ 40Hz, -10dB @ 500Hz No treble boost!
GK Contour is +2db @ 50Hz, -10db @ 500Hz, +3db @ 7kHz, +9db @ 10kHz
Trace Eliott Series 6 boost at 50Hz and the high end between 2kHz to 5kHz, cut at 400Hz (dB levels not specified)

I’d try it myself on my BH-260 but I’m too lazy, I just press the button when I want the scoop My own favorite setting is actually leaving all EQ at 12:00 and using the tone balance to bring up the bass while bringing down the treble. I only touch the mids when playing my DB which needs a cut around 800Hz.

 

[JAC77]

JAC77,

The enhance on the A.M.P. amps is a fixed scoop. Low boost, low mid cut, treble boost. With all the EQ on the BH420 you could can certainly come close with the four parametric mid bands, but why bother? If you like the sound (I did for a long time) why screw around with the EQ to replicate it?

Wild guess: boost the bass knob to around 3:00. Then set the midrange knob that covers 200Hz to 600Hz to 550Hz and the level to 9:00. Leave the rest of the EQ and the tone balance at 12:00. Then go from there, sweeping the mid EQ band through it’s entire 200-600 range and fine tuning the boost and cut settings of the bass, mid and treble knobs.

For comparison:

Ampeg Ultra Lo is +2dB @ 40Hz, -10dB @ 500Hz No treble boost!
GK Contour is +2db @ 50Hz, -10db @ 500Hz, +3db @ 7kHz, +9db @ 10kHz
Trace Eliott Series 6 boost at 50Hz and the high end between 2kHz to 5kHz, cut at 400Hz (dB levels not specified)

I’d try it myself on my BH-260 but I’m too lazy, I just press the button when I want the scoop My own favorite setting is actually leaving all EQ at 12:00 and using the tone balance to bring up the bass while bringing down the treble. I only touch the mids when playing my DB which needs a cut around 800Hz.

Thanks for that. I know it’s a low boost, mid cut, and high boost. I’m curious about specific frequencies mostly so that when I’m playing a gig with provided backline, I can get that tone. That info about Ampeg, GK, and Trace is xcellent food for thought!

 

[Dbassmon]

AMP BH420 is beautifully voiced bass amp. I have owned one since 1987. AMP was on the cutting edge of boutique bass amp builders in the late 80's.
I would still use it as my gigging amp if were smaller and lighter. The tone is beautiful. It sits in my garage as a backup, should I need it.

The tone of the amp (any amp) is the sum of the parts, transformers, and caps used, etc. Replicating that will be a challenge and perhaps requires a IR (impulse response) captured from the AMP BH420, and sophisticated modeling to replicate the impedance and interaction with all aspects of the circuit design, to get a convincing model.

The contour is mid-scoop, bass treble boost, similar to the curve on the example shown above. Even if that curve was 100% accurate, it does not account for what the transformer, caps and power supply are doing to voice the amp.

You can get really accurate models of GK, Eden and Ampeg amps because they are ubiquitous and still popular today. There is a market for digital models of those amps.

AMP was out business long ago, they did not sell anywhere near as well SVTs, or RB800s.

 

[TonH]

The manual can be found here:
Limiter; Enhance Button; Bass Control - AMP BH-420 Owner's Manual [Page 5]

less mid-bass muddiness with "enhance" engaged

and the schematics at page 11:

AMP BH-420 Owner's Manual (Page 11 of 13) | ManualsLib

 

[Admiral Akbar]

Inspired by this thread, I just blasted my 64 Jazz through the A.M.P. 420 and Bergantino NV610T.

Oh my goodness!

The A.M.P. is REALLY great sounding!!

 

[Luther]

Long time user of BH-420, have had and sold several. I always come back to it because I can never find something else that sounds and feels as good. That being said, I became curious about the enhance button. I almost always have the enhance function engaged, only disengage when using certain cabs (typically 1x15s). A few months ago I got curious about the “baked in” tone that button provides and decided to try to mimic that sound with the EQ section only, leaving the enhance disengaged. I can’t replicate it using only EQ. I have more hours than I want to admit sunk into trying to replicate that sound. I have a copy of the schematic of this amp, is there a way to figure out what actual EQ curve is from the schematic? Ultimately it doesn’t matter, but the rabbit hole of curiosity is eating my brain…

I have a successor to the 420, the Gibson GB-440, predecessor to the Thunderfunk. Leave EQ Flat, set the enhance to preferred bass level and set timbre to preferred treble level - Glorious. Paired with an EDEN D-215XLT - Heaven.

 

[JAC77]

JAC77,

The enhance on the A.M.P. amps is a fixed scoop. Low boost, low mid cut, treble boost. With all the EQ on the BH420 you could can certainly come close with the four parametric mid bands, but why bother? If you like the sound (I did for a long time) why screw around with the EQ to replicate it?

Wild guess: boost the bass knob to around 3:00. Then set the midrange knob that covers 200Hz to 600Hz to 550Hz and the level to 9:00. Leave the rest of the EQ and the tone balance at 12:00. Then go from there, sweeping the mid EQ band through it’s entire 200-600 range and fine tuning the boost and cut settings of the bass, mid and treble knobs.

For comparison:

Ampeg Ultra Lo is +2dB @ 40Hz, -10dB @ 500Hz No treble boost!
GK Contour is +2db @ 50Hz, -10db @ 500Hz, +3db @ 7kHz, +9db @ 10kHz
Trace Eliott Series 6 boost at 50Hz and the high end between 2kHz to 5kHz, cut at 400Hz (dB levels not specified)

I’d try it myself on my BH-260 but I’m too lazy, I just press the button when I want the scoop My own favorite setting is actually leaving all EQ at 12:00 and using the tone balance to bring up the bass while bringing down the treble. I only touch the mids when playing my DB which needs a cut around 800Hz.

Bam! You lead me down the right path! After looking at the Ampeg and GK eq values, I tried cutting at 500hz and that was it! I wasn’t going high enough with the mid cut in my earlier attempts, I was always cutting in the 300-400hz range and thinking the fatness was in where the low boost was….dead wrong. After a couple hours of tweaking, I ended up with a slight boost around 50-60hz, significant cut at 500hz and a very slight boost at 1100hz and that’s it, sounds amazing!
Moral of the story, always trust your ears and ignore what your preconceived notions tell you to do.

 

[GruvMeister]

Long time user of BH-420, have had and sold several. I always come back to it because I can never find something else that sounds and feels as good. That being said, I became curious about the enhance button. I almost always have the enhance function engaged, only disengage when using certain cabs (typically 1x15s). A few months ago I got curious about the “baked in” tone that button provides and decided to try to mimic that sound with the EQ section only, leaving the enhance disengaged. I can’t replicate it using only EQ. I have more hours than I want to admit sunk into trying to replicate that sound. I have a copy of the schematic of this amp, is there a way to figure out what actual EQ curve is from the schematic? Ultimately it doesn’t matter, but the rabbit hole of curiosity is eating my brain…

I used a BH420 from 87-92ish. Great amp as i remember until i cooked it. Used many different amps since.
I stumbled on a BH420 for sale on Reverb. I had to! Cant wait to plug into this thing.

 

[GruvMeister]

Long time user of BH-420, have had and sold several. I always come back to it because I can never find something else that sounds and feels as good. That being said, I became curious about the enhance button. I almost always have the enhance function engaged, only disengage when using certain cabs (typically 1x15s). A few months ago I got curious about the “baked in” tone that button provides and decided to try to mimic that sound with the EQ section only, leaving the enhance disengaged. I can’t replicate it using only EQ. I have more hours than I want to admit sunk into trying to replicate that sound. I have a copy of the schematic of this amp, is there a way to figure out what actual EQ curve is from the schematic? Ultimately it doesn’t matter, but the rabbit hole of curiosity is eating my brain…

wondering if possible to find rack ears for one of these?

 

[Wasnex]

I’m curious about specific frequencies mostly so that when I’m playing a gig with provided backline, I can get that tone.

Sounds like the curve is complex. You need the right frequency centers, the right bandwidth, and the right amount of cut and boost. The only way to duplicate the required curve would be to use enough channels of fully parametric EQ to dial it in.

If you could get a trace of the required EQ curve, you could probably get pretty close to duplicating the curve with a Source Audio EQ2. However, you also have to consider the baked in voicing of whatever amp and cab your are using. Additionally, what you like about the BH420 may involve more than just a simple EQ curve. Consider things like how the BH420 compresses, transient response, how well it damps speaker motion, and the characteristic of any distortion it generates.

 

[gtirard]

Sounds like the curve is complex. You need the right frequency centers, the right bandwidth, and the right amount of cut and boost. The only way to duplicate the required curve would be to use enough channels of fully parametric EQ to dial it in.

If you could get a trace of the required EQ curve, you could probably get pretty close to duplicating the curve with a Source Audio EQ2. However, you also have to consider the baked in voicing of whatever amp and cab your are using. Additionally, what you like about the BH420 may involve more than just a simple EQ curve. Consider things like how the BH420 compresses, transient response, how well it damps speaker motion, and the characteristic of any distortion it generates.

Without knowing the EQ parameters, you could alternatively download the NAM model from Tone3000, and load it on a NAM Player pedal (AMP BH-260 being a less powerful version of the BH-420, I suppose the preamp sections are identical, therefore the NAM capture of the BH-260 with enhance switch on is identical to that of the BH-420).