Designing a new Class D Amp - What features would YOU want?

[tomographs]

Hey

I'd like to design a new Class-D Amplifier. The idea behind it is that although there are a few similar products on the market, many have gimmicky extras that most people would not use (who needs an Aux In on a Bass Amp?!) and some leave out features that I see as important (Tuner Outs, Clip Lights etc).

Also none of them, apart from perhaps Aguilar's Tone Hammer 500, have good industrial design; that is, how the product looks, from shape, to graphics, or ergonomics; control layout and usability.

What features are important to YOU as a bass player?

Some food for thought, but please share anything you feel strongly about:

- EQ Style (3-band, Active/passive, parametric (with a Q control?), graphic)

- FX Loops (They don't seem too important myself, but would NOT including one make you less inclined to purchase?)

- Built in compressor? Or would you just prefer to choose your own? Many built in compressors have just one knob, is that really enough?

- Aesthetic. Do you lean towards a vintage vibe (Aguilar, orange, fender) or a sci-fi powerhouse (trace elliot) or something else? what is it about how an amp LOOKS that makes you attracted to it?

- Control Layout - All in a line? Stacked? Should DI outs be on the front (like the Aguilar Tone Hammer), or the back?


Really looking forward to your responses guys, thank you in advance.

Tom

[Electricblue]

My idea amp would have these:

Graphic EQ of at least 7 bands. Possibly two EQs, switchable.
Single FX loop, if any. I never use mine, but I'm guessing most people do.
Maybe a simple one-knob compressor.
Aesthetics similar to the Fender Rumble 150 and 350 heads.

Control layout from left to right:

Active/passive inputs in a vertical arrangement.
Input gain.
Graphic EQ.
Compressor.
FX loop wet/dry blend.
Master volume.
FX loop in a vertical arrangement.
Buttons for EQ, Compressor, Mute and Low-cut.

Power switch on the back, along with DI, line out and speakon outputs.

Compatibility with 2 ohms would be very nice.



There's a 16-year old's opinion ^

I wish you luck

[rad bassman]

Interesting idea, often thought about what features i would like, heres an out line of what i would like in a head

front panel
input jack
gain knob with padding switch for active basses
3 stage clip lights, i.e, signal, good signal, clip
1 knob compressor for simplicity

4 band EQ with 2 parametric mid bands, maybe other voicing options too

FX loop blend
master volume control with 3 or 4 lights (or more) to indicate how hard the power amp is working
DI out level control

rear panel
speakon out (or 2)
balanced DI out with ground lift and pre/post eq option
line out , for use with a more powerful PA amp if needed
FX loop
tuner out


you say your aiming for a 500 watt head here, but could it be possible to have more power options, more and more bassists look for headroom these days, in many cases 1k+, and with some of the cabs available these days that sort of power is needed

[sad_katz]

EQ controls:
5-band semi-parametric mids (low, lo-mid, mid, hi-mid, highs)

FX Loop:
don't need them so far. Don't mind them hanging around tho.

Compressor:
Optional. Two knobs (strength and threshold) is ideal but may be complicated to design in a small lightweight box.

Aesthetics: Personally I would like the amp to match the cab, vintage or otherwise. As an amp only, I like a minimalist metal/rugged rubber box. The kind that looks like it can survive shot by a tank.

Front Layout:
Gain, Tube Gain (if any), Mute switch, Clipping, High/Low-Z switch, 5-band para EQ (stacked para), Tone Shaping switches (lo boost, mid scoop, bright, etc), FX blend, Master Volume, Standby/Ready lights

Rear Layout:
Voltage switch, DI out (line/mic, gnd lift, post/pre), 2 speakon outs, FX in/out, tuner out, footswitch in, line-in, headphone/line out. Maybe add pre-amp in and power amp out if possible.

Would like to know where this project is going

[keko]

- only one input 1/4" jack with "automatic" detection of active/passive bass connection (like shown on TC RH series)

- mute switch (with LED indication)

- gain control knob with 5 LEDs peak meter, 3 greens, 4th orange, 5th red (clip/peak/overload indication) for precise gain control

- one knob compressor with LED indication of use, up to 3:1 ratio with threshold, gate and limiter (all in the one knob control)

- EQ standard: bass, parametric low mid, parametric high mid, high

- DI out with control knob and pre/post switch (post position must including compressor too) must not affect to master volume!

- master volume knob (independent of DI out)

- speakon and 1/4" speaker output connectors (double set, to avoid cab to cab connection)

- fx loop for those who may use it (I don't)

- headphones and tuner out as You wish, someone may need it (I don't)

- rear mounted fuse socket (so user can replace it without opening an amp)

P.S. ...can You design whole digital preamp with back-lighted LCD display like car audio systems have, ...so we can make a few gain/EQ/comp presets?

Cheers, Keko!
Just curious!

[EscapeNote]

Hey Tom - well, since you asked and since it's late and I'm not sleepy yet, I'll throw down a few thoughts! At one time or another I have owned pretty much everything out there - Aguilar, Mesa, Ampeg, Genz, GK, SWR, Eden, on and on....

My favorite integrated amp, tonewise: the Aguilar DB750. But too damn heavy and limited EQ. Sold it. No regrets.

I am welcoming the "Micro" trend. Curious to see what develops...

My preferences for live bass sound have been greatly influenced by my experiences in the studio. The best, most consistently inspiring bass signal path for me is my current recording chain: Sadowsky 24/5 > Pedalboard (FEA Dual Band Comp always on) > Empirical Labs Lil FrEQ > Pendulum OCL-2 compressor.

What is most significant about this signal chain to me:

1 - the fidelity of the Lil FrEQ (specifically the transformer output, said transformer being very similar to the old Neve 1073's).

2 - the power of having 4 bands of fully parametric EQ, plus shelving low and high and a hi pass filter.

3 - Having tubes at the final stage, in the optical compressor, so as to add a bit of sheen and presence in a subtle (IMHO musical) way, as opposed to the over-done, hyped up sound of most tube-preamp designs.

I'm gravitating toward using the Lil FrEQ in my live rig, through a power amp into a pair of Bergantino 112 cabs. Have been checking out the Barefaced cabs... but so far the Bergs are giving me the closest thing to what I hear in studio while at the same time working great with a band in live performances. The missing link for me is the power amp; recently sent back a Crown XLS 1500 because it sounded crappy (harsh top end, "gakky", sterile - uninspiring). Currently hunting for the right power amp for this combination.

I've also been using the TC RH 450 and 750 amps. I love the sound of the power amp sections in these amps. But, as with most other bass amps, EQ is limited to Semi parametric at best.

If someone made an integrated amp with fully parametric EQ (4 bands) and combined that with either a "solid state with attitude" aesthetic or incorporated tube coloration in a less strident, more versatile way, then I'd be all over it.

I'm one of those who likes to have all the extras - DI, tuner out, etc - in the back.

That's my 2 cents...

Hey, good luck with your new amp designing/building/selling venture!

[tomographs]

Your replies are very much appreciated! Thanks guys.

Keep them coming. Everybody's thoughts are of equal importance to me, from bedroom hobbyists to seasoned pros.

Tom

[rtslinger]

I would like to see a A/B foot pedal switch to switch from one bass to another so everything could already be plugged in. I have one bass strung with round wounds and one with flat would be nice to switch between them without having to unplug during the show. And maybe an on board tuner and a built in wireless system.

[tom-g]

Originally Posted by EscapeNote

The missing link for me is the power amp; recently sent back a Crown XLS 1500 because it sounded crappy (harsh top end, "gakky", sterile - uninspiring). Currently hunting for the right power amp for this combination.

A pro power amp only amplifies what is put in. It doesn't and shouldn't color the sound in any way. With heads that is different but again the voicing is usually the preamp - especially where many companies are using the same power amp modules.

[Edward G.]

Headphone loop

CD/iPod input

[riotorgun]

an overdrive function/channel not many bass amps have these not ones i can afford anyways...

[DWBass]

I'd like to see an affordable 'basic' amp. Volume, Bass, Mid, Treble, Mute switch, On/Off. On the rear....DI w/pre_post, Ground lift, 2 speakon speaker outs, Leave off the parametric and graphic eq's! No extended mid controls. 500w@4ohms.

[IngerAlb]

- power on button on front (I hate when it's on the back...difficult to power when racked)
- active/passive input
- simple EQ section, yet not limitative: gain + bass + low mid + hig mid + treble + master would do; all in 1 line (the amps that have all the knobs on multiple levels look very confusing to me)
- mute switch
- tuner out (on the back - it helps when the amp is in rack)
- 2 speakon/1/4 connectors
- DI pre/post (I hate the pre only ones) - on front
- world ready power supply
- all the controls must be clearly visible even in dim light (I hate Ashdowns on a dark stage, you can't see how the knobs are set)

I prefer a modern look over vintage (what's the point of making a D class amp that looks like it was designed half a century ago anyway).

I couldn't care less for FX loop - but a lot of folks do, thus I'd say it's something the amp should have.

I don't like the built in compressors - most are just rubbish.

Last, but least: it has to be rackable So rack ears, please

[Avezzano]

1) S-M-A-L-L!!!

something like 200 x 250 x 50 mm!!!

2) with the defeatable fan for very low watts home practice use

[Eminor3rd]

Every amp should have a mute switch!

[Windreaper]

O well, I'll bite too.

Don't really care for comp/limiter on heads. Also, definitely fixed EQ, instant gratification. I would rather have an adjustable HPF (sweepable or 2/3 way toggle) to conserve power and protect more exotic cabs (high tuning, horns etc).

As far as aesthetics go, I think Rane equipment (white/dark grey on black) looks great . Bright colors seem a bit gimmicky and toyish to me.

Layoutwise large knobs in a line with decent spacing works for me. Only really need instrument input on the front panel, the rest are better off on the rear panel imo. Might as well include aux in/out (doubles as tuner/line and headphone output and people like to connect their i-pods etc).

Also, I would immediately buy a modern bass amp with an integrated electronic crossover. However, building one would not be commercially viable, I think. O well, one can always dream.

[hover]

Originally Posted by DWBass

I'd like to see an affordable 'basic' amp. Volume, Bass, Mid, Treble, Mute switch, On/Off. On the rear....DI w/pre_post, Ground lift, 2 speakon speaker outs, Leave off the parametric and graphic eq's! No extended mid controls. 500w@4ohms.

Ampeg PF350 / PF500

[Hactar]

Here's some features I would love to have in an amp:

-Rackmount

-Three-band full parametric+hi/lo shelving

-FX Loop

-Power switch and Mute switch on front

-Variable speed cooling

-DI pre/post

-Rear tuner out/DI out/line out

-Speakon/6.5mm Neutrik combo output

Aesthetics: Clean, modern look (metal), should be rock solid, no plastic. Needs to be usable on a dark stage, maybe backlit controls?
I can't wait to see the product

EDIT: just thought of something else. For those who use a racked wireless, a rear input is very helpful.
A front input is better for straight to head input. So why not have front and rear inputs, and when both are plugged in, the front takes precedence.
Then you could have a racked wireless, and if you needed to bypass, you could plug straight into the front.

[Matthijs]

Two inputs or an extra aux in. I use those for doubling or mixing a clean and a effected signal.

A high ohm input (10meg?), fit for piezo's

Never used the effectsloop

Would like the Eden semi parametric tonestack

input level/clipping light

DI and inputs on front

Looks don't matter, but I like the 'weaponsgrade look'.

It doesn't need to be a modern amp/old school tone combination. Something nice and clear like those older hartkes would be interesting.

[father of fires]

OP,

What have you figured out already?

Whose amp module are you using?

Which amps do you think will be competitors?

What preamp topology do you most favor?

Do you have any favorite amps that inspired your design?

Also, are you designing it yourself? What's your background if you don't mind me asking?