Boss Katana Amp - Inside View

Started by Elantric, October 28, 2016, 01:56:02 AM

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Elantric

Internal pics of Katana Head
I observe:

multiple AKM AK5720VT A/D IC's
http://www.akm.com/akm/en/product/datasheet1/?partno=AK5720VT

AKM AK5384 4 channel A/D IC
http://www.akm.com/akm/en/product/datasheet1/?partno=AK5384VF

AKM AK4482VT DAC
http://www.akm.com/akm/en/product/datasheet1/?partno=AK4482VT

DSP - Roland ESC2 (Same as GT-100, GP-10, Roland System 1m, ,etc)

http://www.vintagesynth.com/forum/viewtopic.php?f=1&t=80823&start=75


















Finnster

Thanks for posting this.  I have the 100w combo.  I am considering getting the head and putting the chassis in the combo so I would have midi in a combo format.  From the pics it looks like it would work.

vtgearhead

#2
That sounds like a rather expensive way to solve the MIDI control issue.  We have acknowledgement from at least one user that the Primova MIDX-20 (and presumably MIDX-10) can translate MIDI to USB for the Katana.

https://www.vguitarforums.com/smf/index.php?topic=19581.msg140843#msg140843

Finnster


Finnster

Price?  I have emailed them but didn't get a response.
Does anyone know of any retailers in the US?


Finnster


carlb

Wish they could have had jacks and pots with flying leads versus soldered directly to the main board.

On the plus side if things get a tad wonky over time, a bit of deoxit and connector jiggling will do wonders.

That much solid state scares me regarding ESD. But Roland/Boss stuff has been very reliable over the years, so they must know ESD protection at the chip level.
ES Les Paul, internal Roland GK
Boss SY-1000, Valeton Coral Amp pedal
Morningstar MC8 & MC6
QSC CP8 powered speaker

Elantric

#8
QuoteWish they could have had jacks and pots with flying leads versus soldered directly to the main board.

Its actually very modular, on all cables, only one side of the cable harness is soldered to a PC board, the other side of the cable harness is in a removable connector that mates with a male counterpart header.  Its easy to disassemble the whole amp under 15 minutes 

Its built identical to my Roland Cube 80's  - and Ive been gigging with Cubes for 10 years now without any problems

The Katana knobs are recessed and out of harms way - unlike a Fender red knob twin that often needs a $200 repair anytime it accidentally has a knob smacked in a doorway during transit.

hotraman

My Katana head is arriving this week.
Just in time for a Sunday rock and roll church service  ;D

grecner

Quote from: Elantric on October 28, 2016, 01:56:02 AM
Internal pics of Katana Head
I observe:

multiple AKM AK5720VT A/D IC's
http://www.akm.com/akm/en/product/datasheet1/?partno=AK5720VT

AKM AK5384 4 channel A/D IC
http://www.akm.com/akm/en/product/datasheet1/?partno=AK5384VF

AKM AK4482VT DAC
http://www.akm.com/akm/en/product/datasheet1/?partno=AK4482VT

DSP - Roland ESC2 (Same as GT-100, GP-10, Roland System 1m, ,etc)

http://www.vintagesynth.com/forum/viewtopic.php?f=1&t=80823&start=75



Very interesting, it seems that there is much more A/D converters than needed for the inputs.

I can see 2x2 channel A/D capable of line level or microphone input sensitivity (using internal 15dB preamp),
and 1x4 channel symmetrical line level A/D,
giving total of 8 analog inputs.

Katana head has 1 guitar input, one AUX input and one FX RETURN input, so what is the rest of A/D being used for ?

PRESENCE feedback ? Volume pedal ?

Also, if there really is no analog pre-apm in front of the A/D converters as the OP says, then the question is how the 1MOhm input impedance is achieved, as the A/D have input impedance of about 20 kOhms ?
I would expect at least some operational apmlifier in front of the A/D, but can not see one in the pictures...



admin

#11
its similar to the Blues Cube
https://www.vguitarforums.com/smf/index.php?topic=11865.msg148093#msg148093

There is a discrete FET preamp before the A/D conversion











admin

#12


QuoteWho makes the Roland / Boss ECS2 DSP used inside Katana?

See page 11 of the Boss SY-300 Owners manual

Since 2010 , Roland / Boss has employed  ECROS system on chip solutions from ESOL Solutions
(Roland GR-D, GR-S,GP-10, GT-100, GT-001, SY-300, System One,  Aira  Synths, etc. )

these are the chips labeled "Roland ESC2"


and have a pedigree of association with  Texas Instrument's Davinci ARM 9 (SOC) System on Chip ) processor 

http://www.ti.com/devnet/docs/catalog/companyfolder.tsp?actionPerformed=companyFolder&companyId=239



http://www.esol.com/


from r/synthesizers






Katana Class AB power Amp ic
Used in all Katana's
ST TDA7293V
http://www.st.com/en/audio-ics/tda7293.html

https://www.ebay.com/i/162779349462


Elantric

#13
More Katana Inside pics
https://www.thegearpage.net/board/index.php?posts/24954134/


This the power amp module attached to the heat sink.



this the input board. Has a standard op-amp for the input buffer. I was having issues with the jack contacts. Looks like the input jack collects dust when unused due to the vertical position.


Speaker jack board. The red and black wires attach to the internal 5 inch speaker. I dont believe the power is reduced to the internal speaker as it is connected directly to the speaker jack. The large wattage .33 ohm resistor looks to be part of a zobel network although it could use current sensing to adjust the power amp when the main speaker jack is unused.
Very well built overall and the PA board can easily be replaced if it fails.



Katana Class AB power Amp ic
Used in all Katana's

http://www.st.com/en/audio-ics/tda7293.html

https://www.ebay.com/i/162779349462

KeldAmpworks

#14
Elantric, I seem to be spending this evening bumping all your old threads. Sorry! Quick request though. If the mood takes you to take your head to bits again, could you have a quick look to see where the FX loop jack PCB connects into the main board please?

Interested in trying to find an insert point on my K50.

EDIT: Actually I'm almost certain this will turn out to be connector CN6, so don't go to any effort on my part.

admin

#15
https://www.thegearpage.net/board/index.php?posts/26103432/



And here is the Katana Artist inside view






Rogerc

Does anyone have a schematic diagram or specific info on the power supply and also how the power scaling is controlled?

KeldAmpworks

#17
The power scaling isn't power scaling in the traditional sense. It's a stepped master volume. I scoped the input connection to the power chip and the level going into the power amp changes proportionally as you change the power scaling switch.

They may do some DSP pscychoacoustic trickery too, I didn't look. I did all this at 1kHz sine - didn't look for frequency changes.

Edit: I don;t think there's anything special about the PSU. When I stripped mine it just looked like a basic linear design. See pics on my website. http://www.ampworks.co.uk/experiments/boss-katana-mod-midi-mod-rec-mod/

Quote from: Rogerc on June 01, 2018, 05:47:35 AM
Does anyone have a schematic diagram or specific info on the power supply and also how the power scaling is controlled?

Rogerc

Thanks. I'm toying with the idea of replacing the power amp board with a "stereo" LM3886 board with mixed current/voltage feedback, one channel per speaker. From your pics and the size of the transformer I'm guessing the power supply is a switching design. Wonder if it would run 2 LM3886s or I might use a separate PSU for the power amps.

admin

#19

Rogerc

#20
Thanks. I'd seen those but I don't know from the schematic how the feedback is implemented which is why I'm looking at the LM3886.

https://www.aliexpress.com/item/2015-NEW-Sep-store-ZEROZONE-LM3886-Stereo-amplifier-Kit-Pure-dynamic-feedback-circuit-L1510-9/32808769128.html

KeldAmpworks

Quote from: Rogerc on June 01, 2018, 01:33:37 PM
Thanks. I'm toying with the idea of replacing the power amp board with a "stereo" LM3886 board with mixed current/voltage feedback, one channel per speaker. From your pics and the size of the transformer I'm guessing the power supply is a switching design. Wonder if it would run 2 LM3886s or I might use a separate PSU for the power amps.

Hi Roger,

What makes you think it's a switching PSU? Certainly the K50 pics I've got on that link above show a linear - the mains goes straight into the tranny primary, the secondary goes to a BR and 35V volt caps. If it was a switcher you'd see the mains going into a BR and some 600V caps THEN into the tranny, then out to some 35V caps.

Rogerc

Just an assumption based on what a lot of modern gear uses to keep the weight down and the size of the mains transformer. I'll be taking mine apart sometime so I will have a proper look.


lionheart

Want to save yourselves a fortune if you do try speaker swapping ?
Apply a heatshrink sleeve to each of the amp's speaker cable spade connectors - I did one in red and the other in black for ease of identification.
If the heatshrink protrudes just a couple of millimetres over the ends of the terminals, there is zero chance of an accidental short if they are inadvertently left disconnected from the speaker when the amp is turned on.
I have learnt masses from other people's mistakes over the years and in doing so have saved myself a lot of money and stress.
This little trick could possibly save your amp from an early grave - it's so stupidly simple and cheap to do !