EQ preferences

[fretless]

Ok, so here's what I have in mind: Stompbox preamp/line driver/DI: 40+dB of gain Capable of 6VRMS (+18dB) on the line output (enough to drive any power amp) Switchable HPF: Out; 30Hz; 50Hz 3 band EQ. Low and high shelving, baxandall-type (will interact with each other a bit). Low shelf at about 60Hz, high shelf at about 7k. Basically everything below the low shelf point and above the high shelf point will be equally boosted or attenuated. Semi-parametric mid, sweepable from 200Hz to about 4kHz. All +/-15dB. Defeatable with a switch. Any more EQ than this in a stompbox-type affair isn't really feasible, PCB real estate and power consumption-wise Transformer balanced DI (Lundahl transformer) pre or post EQ. Will require a pair of 9 Volts or an 18V adapter. I have this breadboarded on my bench right now and it's sounding good. The EQ is quite responsive and musical. Next step is a perfboard prototype. Next would be a full-on rackmount preamp. I was thinking of doing a 2-band passive tone stack (defeatable) with a 4 band active EQ. I was thinking of using fixed Low and high bands and 2 sweepable mids with switchable bandwidth controls (wide and tight), but perhaps I'd add a frequency sweep on the active low and high. It also occurred to me that offering a couple of different EQ formats could be feasible. Say, an optional 4 band fixed frequency EQ as well as what I just described. Since I've been laid off, I've been putting in a lot of hours at these projects. I'm seriously considering taking these projects to the commercialization level.

is the db variable on the HPF ?
Is the Lundahl your prefered tranny , just wondering , I have a ADK AP-1 on the way and that is one that is included along with 4 or 5 others .

[L. Ron Hoover]

is the db variable on the HPF ? Is the Lundahl your prefered tranny , just wondering , I have a ADK AP-1 on the way and that is one that is included along with 4 or 5 others .

 

The HPF is a critically damped second-order filter so it's a 24dB/Octave rolloff below the corner frequency. Variable rolloff is doable but is a bit hardware intensive for a stompbox-sized preamp.

 

Ooh cool! You'll have a lot of fun with the AP-1. Did you get all the different opamps too?

 

I'm designing around the Lundahls because I have a relationship with them from my previous job and they are very nice transformers to boot. Every bit as good as Jensen or Sowter. I really like the Jensen ones too, but a lot of manufacturers use them, so part of my motivation is to offer something a bit different.

 

I'm designing around audio grade opamps (like the OP275, AD8599 and LM4562). The stompbox preamp will probably use the 275s because they draw 1/3 the current of any of the others.

 

I also have some discrete circuits in the works.

[fretless]

The HPF is a critically damped second-order filter so it's a 24dB/Octave rolloff below the corner frequency. Variable rolloff is doable but is a bit hardware intensive for a stompbox-sized preamp. Ooh cool! You'll have a lot of fun with the AP-1. Did you get all the different opamps too? I'm designing around the Lundahls because I have a relationship with them from my previous job and they are very nice transformers to boot. Every bit as good as Jensen or Sowter. I really like the Jensen ones too, but a lot of manufacturers use them, so part of my motivation is to offer something a bit different. I'm designing around audio grade opamps (like the OP275, AD8599 and LM4562). The stompbox preamp will probably use the 275s because they draw 1/3 the current of any of the others. I also have some discrete circuits in the works.

Thanks ! Yes got 5 or 6 opamps too , all the folks I've talked to said the Lundahl was the one for Bass DI so I'm going to start there but pics on the way of my new AP-1 , Good Luck with your DI it sounds like something I want ! Thanks again

[LanEvo]

 

3 band EQ. Low and high shelving, baxandall-type (will interact with each other a bit). Low shelf at about 60Hz, high shelf at about 7k. Basically everything below the low shelf point and above the high shelf point will be equally boosted or attenuated. Semi-parametric mid, sweepable from 200Hz to about 4kHz. All +/-15dB. Defeatable with a switch. Any more EQ than this in a stompbox-type affair isn't really feasible, PCB real estate and power consumption-wise Transformer balanced DI (Lundahl transformer) pre or post EQ. Will require a pair of 9 Volts or an 18V adapter.

Not trying to be a jerk here, but what will this do that an Aguilar Tone Hammer, EBS MicroBass II, Radial Bassbone, MXR M-80, SansAmp BDDI, or John East STMP-01 won't do? I ask because I think it might be pretty challenging to market a product like this if you can buy something similar from Aguilar for $190.

 

Now, if I had two bands of semi-parametric mids, then that would be a big selling point for me. That's certainly something no one else offers. One reason I paid $600 for what's basically a bedroom practice amp (PJB Briefcase) is because I loved how much control the preamp offered. When you're trying to dial in the perfect amount of mid-range growl and mwah on a passive fretless bass, you really appreciate the tone-shaping abilities of PJB's preamp section.

 

Personally, I would be VERY interested in the preamp/DI you're working on. I'm looking for something like this to complete my pedalboard and I would ALWAYS buy something designed and built by someone like yourself rather than by a major corporation. (Maybe that's why I love my Decware SET mono-blocks so much. Who knows?) But it would be a tough sell if it ends up being massively more expensive than comparable products and/or doesn't really offer anything different.

[georgestrings]

I find that I can get the best sound out of an amp with a fully parametric EQ. That said, it's a pain in the ass to use live. If I've got an amp on stage that I may need to adjust during a performance, I prefer a graphic EQ because it's easier to grab the slider that I want on the fly.

 

 

 

Exactly how I see it - it's like you read my mind...

 

 

 

- georgestrings

[brake]

Para but graphic EQ can work almost as well if you have ears. As for bands, as many bands as you can fit in there..but I'm not exactly a good one to ask.

[82Daion]

In a pre, a full 4-band with bandwidth adjustments would be my favored choice, but that's only because I've put in some studio time and prefer the flexibility it offers. It's overkill for most.

 

Realistically, an Eden-type or SM-900-type setup would do me just fine.

[FuzzyJackrabbit]

I am also someone who prefers keeping it simple.

[L. Ron Hoover]

Not trying to be a jerk here, but what will this do that an Aguilar Tone Hammer, EBS MicroBass II, Radial Bassbone, MXR M-80, SansAmp BDDI, or John East STMP-01 won't do? I ask because I think it might be pretty challenging to market a product like this if you can buy something similar from Aguilar for $190.

{censored} you, jerk! Kidding. Seriously, thanks for your input. I don't think you're being a jerk at all.

Well, let's take the MXR and Sansamp out of the equation because this would be going for a different vibe completely. Clean, clean, clean is what I'm aiming at. I spent the last 4 years as an engineer with a high end home audio manufacturer so that's kinda rubbed off on me.

In a lot of ways it's similar to the the Tone Hammer, the East and the Bassbone. As it stands, it's the only one that would have a high pass filter. That's a feature that folks have mentioned as being useful on a number of occasions. It's also the only one that uses a split power supply, which requires some extra power supply components but allows simpler operation of the active devices and actually improves the noise behaviour of the opamps. I'm also biasing the op-amps output stages into class A, which makes a subtle but noticeable improvement and had the unexpected effect of really improving the clipping behaviour. I'm planning to have a balanced line level output as well.

Now, if I had two bands of semi-parametric mids, then that would be a big selling point for me. That's certainly something no one else offers. One reason I paid $600 for what's basically a bedroom practice amp (PJB Briefcase) is because I loved how much control the preamp offered. When you're trying to dial in the perfect amount of mid-range growl and mwah on a passive fretless bass, you really appreciate the tone-shaping abilities of PJB's preamp section. Personally, I would be VERY interested in the preamp/DI you're working on. I'm looking for something like this to complete my pedalboard and I would ALWAYS buy something designed and built by someone like yourself rather than by a major corporation. (Maybe that's why I love my Decware SET mono-blocks so much. Who knows?) But it would be a tough sell if it ends up being massively more expensive than comparable products and/or doesn't really offer anything different.

2 bands of semi-parametric mids is doable but does require more board real estate and more components. I'm going to look into it, though. It would significantly add to the cost because the frequency sweep pots need to be dual ganged, reverse log taper types, which have to be custom ordered and are expensive.

Would you rather the second semi-parametric mid to the HPF?

I haven't really done much research into marketing and costs as this is just a project at this point, but it would have to be competitive with the higher end offerings (Aguilar, EBS, East) to make it feasible.

I've done costing estimates on the active DI I designed and it would be comparable in price to the Radial and Countryman active DIs, based on me selling directly. I'd need to do large quantities to keep the costs in line if I used distributors and dealers, which I'd imagine is true for Radial and Countryman as well.

[countrybass]

The less knobs for me the better. I had an Ampeg 6 pro with a parametric eq and I didnt like it at all. Also had a 4 pro with the graphic. I dug that better. What I really liked was my SVT-VR, and now the LM II that I'm using. I kinda dig my tone flat with a slight bass boost, and contrary to what alot of bro's do, i crank all my eq settings on my active bass wide open with a tad more neck PU than bridge.

[ThudMaker]

Ok, so here's what I have in mind: ................................................. I'm seriously considering taking these projects to the commercialization level.

Keep us posted on this project. I'd be interested at taking a closer look.

[bnyswonger]

I'm with Chris on the variable bandwidths - that really lets you do something.

No problem with fixed low and high shelves, but if you can really tweak those mids, you've got something special IMO.

[ThudMaker]

 

Would you rather the second semi-parametric mid to the HPF?

Yes. Then I would add this-a mute button and a tuner out jack. Actually I only need 1 semi parametric mid, but if you're going with 2.

 

Good luck with getting your projects off the ground and commercially viable, L. Ron.

[Kindness]

Would you rather the second semi-parametric mid to the HPF?

 

 

I'd rather a HPF + two sweepable mids and give up the bass or treble controls. That would be the most functional for me. However, I can't imagine you'd sell many of those units because people "need" their bass and treble controls.

[bassplayer7770]

In a pre, a full 4-band with bandwidth adjustments would be my favored choice, but that's only because I've put in some studio time and prefer the flexibility it offers. It's overkill for most. Realistically, an Eden-type or SM-900-type setup would do me just fine.

My Peavey Pro Bass 500 provides bandwidth adjustments for Low Mids, Mids, and High Mids. It also has separate Pre Gain and Post Gain controls. The Pre Gain controls how much you overdrive the preamp tube, and the Post Gain is adjusted so you're not clipping. I haven't tinkered with it much yet, but I'm really liking that amp so far.

[ThudMaker]

Another idea . . . .why not have an FX loop for insertion of a fully parametric eq, that is also a little box you sell in addition to the basic design? That way it's modular.

[L. Ron Hoover]

Yes. Then I would add this-a mute button and a tuner out jack. Actually I only need 1 semi parametric mid, but if you're going with 2. Good luck with getting your projects off the ground and commercially viable, L. Ron.

I didn't mention it but I intend to have a tuner out with footswitchable mute and an FX loop on it. Those are routine engineering things, pretty easily and cheaply done. EQ on the other hand, is a tough nut to crack.

I'll keep you guys in the loop, don't worry.

[fretless]

I got my AP-1 today and tested it all day , I settled on the Lundahl with a Melcor opamp , for now anyway I think you should do a "purist" version too , no eq offered , or needed The Lundahl is magic !





I borrowed these pics but thats it