Amps with built-in / baked-in HPF

[MultiScaleMale]

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[Passinwind]

IIRC @Stumbo has already done this?

 

[MultiScaleMale]

IIRC @Stumbo has already done this?

Oh, my bad. I didn't find anything in a search. I'll look again.

 

[jnewmark]

IIRC @Stumbo has already done this?

I asked for this in the mega HPF-LPF thread. Someone replied that Stumbo did this, but I couldn't find it. If it is there somewhere, it should be at the beginning of the thread. Anyways, The Subway amps, the Genz Benz Shuttle series, and the Genzler amps have an HPF on board. Fender BXR 300, also.

 

[Passinwind]

Oh, my bad. I didn't find anything in a search. I'll look again.

I'm not sure, which is why I pinged him.

 

[Passinwind]

I asked for this in the mega HPF-LPF thread. Someone replied that Stumbo did this, but I couldn't find it. If it is there somewhere, it should be at the beginning of the thread. Anyways, The Subway amps, the Genz Benz Shuttle series, and the Genzler amps have an HPF on board.

Seems like it would a good topic for Stumbo's Wiki too.

 

[ddnidd1]

Check out the newer Mesa amps.

 

[jnewmark]

Seems like it would a good topic for Stumbo's Wiki too.

It would also be helpful if the whole " cascading " effect that Agedhorse alluded to in a previous thread, could be dummied down so the rest of us non tech guys could understand it more readily. In another thread, I said that I tried an Fdeck HPF with a Shuttle head just for grins. I could not hear much difference set at the minimum setting, but as soon as I turned the Freq knob up, the whole bottom end disappeared.

 

[Passinwind]

It would also be helpful if the whole " cascading " effect that Agedhorse alluded to in a previous thread, could be dummied down so the rest of us non tech guys could understand it more readily. In another thread, I said that I tried an Fdeck HPF with a Shuttle head just for grins. I could not hear much difference set at the minimum setting, but as soon as I turned the Freq knob up, the whole bottom end disappeared.

That's a very good question. Many if not most amps already have at least a first order HPF response going on, since just a simple coupling cap at the input leads to a 6db/octave rolloff slope. And there are often more coupling caps as you go through the internal signal chain. When I was designing the HPF for my DIY amps I spent a lot of time looking at that bigger picture, which gets pretty complicated pretty quickly, at least for this tech not engineer type. And in my case I typically have the HPFs placed after the Aux inputs, which have their own composite responses going on.

I'll sort through some of my Spice models from those projects and see I can find something that might make sense to anyone else, and that doesn't give away my humble but hard won IP. I was unsure enough about it all that I made the HPF section modular so I could try inserting it in various spots in the signal chain. Truth is, I liked how it worked in the very first iteration enough that I've never gotten around to rewiring it in the other half a dozen or so ways I could.

 

[jnewmark]

That's a very good question. Many if not most amps already have at least a first order HPF response going on, since just a simple coupling cap at the input leads to a 6db/octave rolloff slope. And there are often more coupling caps as you go through the internal signal chain. When I was designing the HPF for my DIY amps I spent a lot of time looking at that bigger picture, which gets pretty complicated pretty quickly, at least for this tech not engineer type. And in my case I typically have the HPFs placed after the Aux inputs, which have their own composite responses going on.

I'll sort through some of my Spice models from those projects and see I can find something that might make sense to anyone else, and that doesn't give away my humble but hard won IP. I was unsure enough about it all that I made the HPF section modular so I could try inserting it in various spots in the signal chain. Truth is, I liked how it worked in the very first iteration enough that I've never gotten around to rewiring it in the other half a dozen or so ways I could.

Thanks, very cool. It might be wishful thinking though. You would have to know the specs on the built in one, and also the specs on the outboard one, and then have a way to calculate how the two would effect each other's function. Might not be a problem getting the info on a say, Fdeck HPF, but good luck finding it on a Fender BXR 300 !

 

[Passinwind]

Thanks, very cool. It might be wishful thinking though. You would have to know the specs on the built in one, and also the specs on the outboard one, and then have a way to calculate how the two would effect each other's function. Might not be a problem getting the info on a say, Fdeck HPF, but good luck finding it on a Fender BXR 300 !

You already know my take: measure it yourself. I do model commercial pieces off schematics from my library occasionally, but in my case I think it would be kind of bad form to post those results on TB unless the manufacturers are down with it. And my own builds are pretty quirky, to say the least!

 

[jnewmark]

You already know my take: measure it yourself. I do model commercial pieces off schematics from my library occasionally, but in my case I think it would be kind of bad form to post those results on TB unless the manufacturers are down with it. And my own builds are pretty quirky, to say the least!

Understood.

 

[frankie5string]

There's an amp I haven't heard about in a long time. Is your BXR a combo or just the head? I remember the combo definitely had attenuation down low.
But I think it worked by keying the low frequencies to really fast compressor on the circuit. It was in the circuit even with the "Comp" switch off...

The amp could get loud, but you could never "pop" it (or get it loud via a TR-Style drum machine)

Saw a lot of those amps lose their graphic EQs in a drunken stupor on stage. It didn't take much to snap those little things right off.

Thanks, very cool. It might be wishful thinking though. You would have to know the specs on the built in one, and also the specs on the outboard one, and then have a way to calculate how the two would effect each other's function. Might not be a problem getting the info on a say, Fdeck HPF, but good luck finding it on a Fender BXR 300 !

 

[jnewmark]

There's an amp I haven't heard about in a long time. Is your BXR a combo or just the head? I remember the combo definitely had attenuation down low.
But I think it worked by keying the low frequencies to really fast compressor on the circuit. It was in the circuit even with the "Comp" switch off...

The amp could get loud, but you could never "pop" it (or get it loud via a TR-Style drum machine)

Saw a lot of those amps lose their graphic EQs in a drunken stupor on stage. It didn't take much to snap those little things right off.

TB'er Jim Chjones has or had one.

 

[JeroB666]

Bergantino Forte HP has one

 

[Al T.]

Acoustic Image Clarus SL has an adjustable HPF. It works very well.

 

[Amano]

Tech21 Powerengine. It is a 12 cabinet with a power amp with adjustable hpf.

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[Lonnybass]

Crest Proline w/ DSP has one.

 

[arbiterusa]

The GK MB series has one at 30Hz. Even the old SWR amps have them but at 15Hz, they are of dubious utility.

 

[Jamie_Funk]

Mesa Subway D800 has it preset at 30hz I believe - not adjustable like on the D800+ and WD800