Demeter 1200 watt Bass Amplifier /Need Bass community input on design

#42
Love my VTBP M 800D.
(No more rack gear for me ever again).
800w is great at 4ohms, pretty good at 8ohms. 1200w is good. Love the Jensen.

I have a Mesa 800+ for a backup amp but prefer my Dem.

I never use the loop. I like the box format but would consider a cage style if I was going to do a backup amp replacement.
 
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#44
JKdemeter said:
What frequency range would you like? 12 or 24 dB per octave?
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Here are the specs on the f deck that I have found to be very effective, hope this helps....... The "12+12" filter curve is two filters in one. The first filter has a fixed corner frequency of 35 Hz, and 12 dB/octave slope. The second filter is adjustable from 35 to 140 Hz, and also has a 12 dB/oct slope. Thus it always has 24 dB/oct slope below 35 Hz. I designed the Series 1 and 2 filter (same circuit in both) for double bass amplification, to tame the infrasonic "thump" produced by the acoustic instrument, which interacts poorly with the low frequency excursion behavior of ported speakers. Interest in a 24 dB/oct filter came from electric bassists who are experimenting with the latest high-performance speakers, to avoid driving the system at frequencies below the port tuning frequency. I designed the "12+12" filter with the same input conditions and "front panel" as Series 2, so that either could be used for double bass.
 
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#45
@JKdemeter ......
James, thank you for inviting the Talkbass community into this conversation.
I played the 1200 watt Demeter prototype at Winter NAMM, it's extremely flexible yet simple and easy to adjust on the fly. A wonderful sounding bass amp. My Santa wish list......

"Lunch box" format (black tolex covered plywood box with top handle), 800D features with 1200 watt power section, added Jensen transformer, no compressor or additional eq.
 
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#46
briandavismurph said:
Here are the specs on the f deck that I have found to be very effective, hope this helps....... The "12+12" filter curve is two filters in one. The first filter has a fixed corner frequency of 35 Hz, and 12 dB/octave slope. The second filter is adjustable from 35 to 140 Hz, and also has a 12 dB/oct slope. Thus it always has 24 dB/oct slope below 35 Hz. I designed the Series 1 and 2 filter (same circuit in both) for double bass amplification, to tame the infrasonic "thump" produced by the acoustic instrument, which interacts poorly with the low frequency excursion behavior of ported speakers. Interest in a 24 dB/oct filter came from electric bassists who are experimenting with the latest high-performance speakers, to avoid driving the system at frequencies below the port tuning frequency. I designed the "12+12" filter with the same input conditions and "front panel" as Series 2, so that either could be used for double bass.
Click to expand...
Yes, I discovered what happens below port tuning. Running a 5 string on a cabinet tuned to 40HZ was a very ugly sound. I changed the cabinet tuning to 32Hz and fixed it. I can see why that could be a useful feature. I will experiment this idea. It would have merit out in the real world. Thanks for your input
 
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#47
JKdemeter said:
Yes, I discovered what happens below port tuning. Running a 5 string on a cabinet tuned to 40HZ was a very ugly sound. I changed the cabinet tuning to 32Hz and fixed it. I can see why that could be a useful feature. I will experiment this idea. It would have merit out in the real world. Thanks for your input
Click to expand...
Last night I played a 4 string [Flats] P bass through a GK MB500 and an Epifani 2-12 cabinet. The low E was overwhelming in presence without any filtering. The F Deck tamed the "boom" at around 140HZ give or take. At 35 to 100 cut not much difference, at 140 or so all the difference in the world. Basically just balanced the strings [tamed the E String], the other 3 were fine "as is". Just my observation.
 
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#50
Considering that I have yet to run out of headroom with my VTBP-M-800D (or even get close), the thought of "merely" a more powerful version of that particular head is not as attractive to me, personally, as seeing something more like a new "ground-up" design from you based around this module. Or if you'd rather build off of prior designs, maybe base this one off of the HBP-1 or 201s. Yes, you have both of those available in a rack format, but as many have mentioned, the rack format is not as popular now as it once was.
 
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#51
IMO: at a given perceived volume level, the 1200 sounds rounder, fuller, richer and smoother than the 250 based module amps. I dont have a lot of volume needs beyond what the 250 can provide, but I have desires for more smoothness, effortless delivery and robust headroom. I mean hell, I run the 1200 into a 1x12 cab at restaurant gigs and IMO am absolutely getting a benefit over the other class D modules in terms of tone and "feel".

Not to be contrary, just to expand on the value of this component beyond a strictly loudness/volume perspective.
 
#52
J.Wolf said:
IMO: at a given perceived volume level, the 1200 sounds rounder, fuller, richer and smoother than the 250 based module amps. I dont have a lot of volume needs beyond what the 250 can provide, but I have desires for more smoothness, effortless delivery and robust headroom. I mean hell, I run the 1200 into a 1x12 cab at restaurant gigs and IMO am absolutely getting a benefit over the other class D modules in terms of tone and "feel".

Not to be contrary, just to expand on the value of this component beyond a strictly loudness/volume perspective.
Click to expand...

Duly noted, and I do have several amps with that 1,200w module, so I am familiar with it (and like it!). The various heads with the 250 module do tend to vary a bit in terms of both real-world and on the bench performance, but for my personal needs, the VTBP-M-800D has always been plenty round, plenty full, plenty rich and plenty smooth, in addition to being plenty loud. YMMV, of course.
 
#53
Just out of curiosity, which amps do you have with the 1200 W ice module?

I agree, some of the 250 based heads aren’t lacking by any reasonable standard. Jim’s definitely come to mind
 
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#55
tombowlus said:
Or if you'd rather build off of prior designs, maybe base this one off of the HBP-1 or 201s. Yes, you have both of those available in a rack format, but as many have mentioned, the rack format is not as popular now as it once was.
Click to expand...

I’ve got an HPB racked with a Crown XTI, so the rack format would be perfect for me, and more compact than what I’m using now. I use the Crown’s DSP for a HPF, it would be great if you incorporated something like the FDeck into the HPB front end and kept the rack format.
 
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#56
JKdemeter said:
At NAMM 2018 we showed a pro to type of a 1200 watt Bass amplifier. It was based on our Bass 800 pre-amp board and the new ICE 1200 watt power Amplifier module. It sounded wonderful, but before we start production I thought we should get input from the Bass community as to how we should package it and what features are wanted. The prototype was build in an amp head style similar the the VTBP-M-800D and the Bass 800D only a bit bigger. That head box does add about $100 to the retail cost, would a simple metal box with a handle be better? The proto-type also had our stock Bass 800 Tube passive front end, treble, middle, Bass/ with EQ switch, and presence as well as a Bass boost and bright, Dark, and normal mode switch also active/ Passive inputs, Loop and studio out on the back, would adding parametric EQ and or Optical compression be a good idea or should we keep it simple? Is 1200 watts too much? What other features would be wanted. Please let me know, Thanks to all. Attached is a preliminary Data sheet and Photo of the Prototype.
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Parametric would be cool. Compression I don't like to be part of the amp. I think being stable down to 2 ohms would be nice. Aux I. And headphone would be great too. Kinda like d800 plus from mesa.
 
#59
A 1200W amp will sell. Please accept these comments related to the design based on my personal preferences.

  • I don't like the knobs. All black would look classier.
  • You use black screws to mount the screen and corners, why chrome for the badge mounting screws. The handle is fine with the hardware used.
  • The badge is huge. It looks like it is blocking airflow. A better solution is needed, like that used on some of your other products.
  • Then there's another large logo on the chassis, make this one smaller. It looks busy
  • The model name, Bass 1200D is good.
  • The line "Tube pre-amp/1200 watt Amp" is not necessary. Perhaps locate it on the back panel. The capitalization is inconsistent, why only "Tube" and "Amp". Watt should always be capatilized. If you want to highlight a preliminary amplifier, be consistent and use the term 1200W power amplifier. It looks more like it was there for the NAMM show.
  • The power lamp would be better if it were located below or just to the right of the toggle switch. It looks isolated where it is.
  • Is bass freq a high pass filter? If yes don't label it bass boost, call it HPF. Bass players know what that means.
  • "Deep boost" can be simply "deep".
  • Is the active input a special circuit or simply a pad. If it's a pad, label it as -15dB or whatever it is, but don't call it active.

I appreciate that this is a prototype and packaging is full of tradeoffs but attention to detail is important at all stages of the design. :)

Bass 1200D.jpg
 
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