Posts by MKB

    What about our backs, bending down to tweak a floor unit!

    Wouldn't it be cool if you could use a toaster or rack unit as a control interface for the floor unit? Through the ethernet\remote connector? That would be a seriously expensive control surface, but not if you already have one.

    Perhaps the floor unit will be meant to be part of an overall ecosystem, with interaction with a current unit in clever innovative ways.

    Oh, and I bet the floor unit is the reason that the editor has been delayed so long. The editor is required for a floor unit as nobody will want to bend down constantly to use the onboard UI. I bet they probably had the editor for the toaster\rack units completed months ago, but had to complete the floor unit integration before release.

    Helix Native sounds exactly like the hardware, and doesn't use that much CPU either.

    I have a HX Stomp and Helix Native, and IME Native sounds significantly better (smoother and warmer in the highs) than the Stomp does. This is in direct comparisons with the same presets on each, and even using different interfaces with Native (M-Audio FireWire 410, Behringer UMC22, and even the HX Stomp itself as the interface). It shouldn't be possible, but it is.

    This total lack of harshness in the highs is why I like the Kemper so much, and to hear that from Line 6 algorithms is very interesting.

    Just reminded myself of the date I asked for availability notifications from Sweetwater on availability of the F12-X200: January 13. It's now July 11. Here's what they've been saying all along: "Reserve your pre-order now, risk-free, or contact us for more information. We expect these to arrive in just a few weeks."


    MKB, Cool and Thanks. I had seen it before. Yes a simple design but effective. I too had designed circuits and their layouts for switchmode supplies, but haven't used Mentor Graphics in years. I think in their design they split the resistor values into more than one for either wattage dissipation or they may have wanted to keep the design with 1/4W resistors and maybe for using a pick and place machine? Cheers! 8)

    Very good, I've used OrCAD and Cadence since maybe 1988 or so. Perhaps they use through hole parts as the quantities they sell are better made by hand; in all the assembly houses I've visited in the last decade or so, there isn't a single pick and place for through hole parts. You can easily get 1\4W surface mount resistors all over the place.

    I have sort of more or less tried to reverse engineer what Kemper is doing from just the pictures, and no topology popped out at me from that picture. However I didn't consider the zero ohm resistors, thanks for pointing that out.

    MKB, There are Zero resistors in the Kemper DI (A single black line on the resistor). Typically used as PC board jumpers, rather than creating a double sided board. I agree, a passive DI box greatly reduces any coloring that transformers or active circuits could add.

    The Kemper DI box is a great design and well built specifically for profiling. 8)

    The Kemper DI box has 12 resistors and 2 capacitors. 9 of the resistors appear to be 1\4W metal film, and 3 are zero ohm resistors of the same size (and probably wattage). The PCB is clearly double sided construction. Here's the picture I'm referring to:…kemper-di-box/inside2.JPG

    BTW, my main job for about 20 years was PCB design, so I'm very familiar with these things.

    Thanks so much for the pics, very interesting. Will be staring at these quite a bit going forward...

    Imo, that's genius and should be elevated above mere thought-level.

    It's almost as if part of me wants to incline you to keep expressing that thought everywhere on the forums and on FB. It would be a huge leap, or possibly a feature for a future Kemper 2, but it's a simple yet genius idea that we should ensure is out there for the people that be.

    One might consider the following: you can get an accurate profile of an amp with its controls (other than gain or volume) adjusted in a particular way. We see this all the time. So you have two profiles with the knobs in different settings, and both profiles are very good. Wonder if it would be possible to do this...

    1) Program into the Kemper the number of tone knobs on the amp being profiled. Maybe create settings for Fender tweed, Fender silver face, Marshall NMV, etc. tone controls.

    2) Set the tone knobs on the amp to 0. Make a profile.

    3) Set the tone knobs on 10. Make another profile.

    4) The Kemper could perform a profile merge to make the control range of its tone knobs to cover the span difference between the first and second profile.

    This of course would require some software development, but might not require new hardware. It would give you tone control "modeling" much closer to the original amp then what is available in current profiles. There might not be a need to profile gain and volume knobs as the profiler does that now anyway. But again profiling an amp at different gain settings would be helpful to replicate say a Fender amp with the bright switch on (the bright boost reduces as the volume knob is turned up).

    I believe SD Powerstage uses Icepower, but I don't know about "plate".

    Plate simply means the power amp circuitry PCB is mounted on an aluminum plate for easier integration into a cabinet. You cut a hole in the back of the cab, screw the plate over it, and off you go. The plate has all of the controls and jacks mounted on it for access from the outside of the cab. The form factor is kind of like this:…el-class-d-amplifier.html

    I agree. Maybe the Kemper Kabinet will be available late this year. But I can't see the raw speaker available as a special order part until mid 2020 at the earliest. I am building my own cabs, so I will have a long wait.

    The thing that concerns me is the software supporting the Kemper Kone probably won't be released until the Kemper Kab is available. I'd really like to play around with that, even without a Kemper Kone driver or speaker.

    The easiest way to integrate a power amp to a cab would be an ICEPower plate amp. I'm not aware of any ICEPower plate amps at this time, but would be a bit surprised if they aren't available.

    I've had a Trio and Trio+, and noticed some interesting behavior with its frequency response. It appears that Digitech included a high end rolloff (low pass filter) with the highs set at 4.2kHz as one might expect for a guitar speaker emulation. The low pass filter seems to be on the phones and mixer out; everything sent through those outputs has the rolloff. The amp out has a flat response to 20kHz or beyond. Low end is flat down to 10Hz in all cases I measured.

    In case you connect the unit with the headphones or mixer out, and notice it sounds dull in the highs, that is the reason.

    I'm sticking to my original prediction that it's a custom version of the Celestion K12H-200TC, or maybe even the K12H-100TC.

    I'd tend to agree with you. Get rid of the divot in the response at 6.5k, and the K12H-200TC might fit the bill. It has two cones and no tweeter.

    The F12-X200 has a tweeter in it.

    That's the problem with whizzer cone speakers, it is very difficult to get any response above say 10-12kHz with a 12" cone with a whizzer, and the response gets a bit strange in the highs (weird dispersion and flatness anomalies). There are ways to improve the response with a whizzer, but it drives up the cost of the speaker and perhaps makes it a bit less road rugged.

    Thanks again for the info. I haven't yet seen a ICEpower recommended way to convert a 50ASX2 into a -BTL, but some experimenters have changed a jumper on the 50ASX2 PCB and followed the input\output connections for a 50ASX2-BTL, and it worked as a mono amp. Here's one link I found:

    Probably trying this could void the 50ASX2 warranty, but that doesn't mean it won't work. I'd try it if I had another 50ASX2.

    A very helpful accessory for a 50ASX2BTL would be a TS input PCA with a volume control, 10-20dB of gain, voltage regulators, and a balanced output. Bonus points for a matching connector and cable for the 50ASX2BTL signal\power connector P102 and P103. That would make working with the 50ASX2 much easier, as it seems to be designed for OEM integration with custom design preamps.

    Thanks for uploading the photos of the original Redsound speaker.

    That is a single-driver speaker with a whizzer cone. Definitely not in same category as the coaxial F12-X200.

    That is definitely not a Eminence 12LTA; the Redsound has a different basket, smaller whizzer, and larger magnet. Also the Fane 12250TC has a larger whizzer, different frame, and its magnet has a center port. So maybe the Redsound is an OEM?

    It's the 10K Dunlop pot out the regular Cry Bay nothing specially calibrated. But the Kemper and other units are generally pretty forgiving of the pot range so pretty much any pot within reason works without any special calibrating.

    I was scratching my head trying to figure out a 10k pot for my broken Cry Baby rebuild, but saw some info where other users just used the 100k already in the Cry Baby for an expression pedal. And many makers of products with expression pedal inputs state you can use a volume pedal as an expression pedal, those are 250k and up. So I tried the 100k pot that came with the Cry Baby, and it worked perfectly. No reason to change anything.

    That being said, a Cry Baby type shell gear drive does not rotate a pot through its entire travel. As I recall the older Boss pedals do, as do the Ernie Ball string drive types. So you might need an approved Cry Baby replacement pot to get a full travel voltage swing on a pedal.

    If you apply that logic to expression pedals no body in their right mind would buy the Mission EP1 which is literally a Cry Baby Wah with the main circuit removed for nearly double price of a Cry Baby with the circuit still in it. But people do still buy them in their droves.

    Since you're ripping the guts out of the Cry Baby anyway, just buy a broken one off ebay. I just bought one for around $20 or so, found a TRS jack, wired it to the stock 100k Dunlop pot that came with the pedal, and it works perfectly. $25 and about 10 minutes work, can't beat that.

    Be sure to look at the News page on the Kemper Amps site, some very interesting info there. From reading this and what was said at NAMM, I'm beginning to be convinced that the Kemper Kone is not a F12-X200, but a proprietary design unique to Kemper. The Kemper Celestion appears to be basically a fuller range driver that can do FRFR to a point, but the dispersion of the highs is controlled to be more like a standard guitar speaker. Maybe a variant of the F12-X200?

    The Kemper Kone can be driven by a powered Kemper, or an unpowered one with "any external solidstate power amp".

    This was very interesting: "In addition to the passive model of the Kemper Kabinet, we have plans to offer an active Kemper Kabinet as well. Further, we will offer the Kemper Kone as a replacement speaker for any regular kind of 1x12”, 2x12” or 4x12” guitar cabinet. All digitally controlled features are applicable to all kinds of cabinet configurations once the Kemper Kone is driven."