Kenwood Basic M2 - Intriguing Circuitry - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 28th May 2004, 02:20 PM   #1
diyAudio Member
 
SVI2004A's Avatar
 
Join Date: Mar 2004
Location: Albany Western Australia
Send a message via MSN to SVI2004A
Question Kenwood Basic M2 - Intriguing Circuitry

I have been looking into a Kenwood Basic M2 Power Amp, initially to unravel the pinout/operation of its output devices (sanken DAT1081 DAT1521) and found the most interesting thing.... 4 devices/ch... 2 on +-45V and 2 on +-80V more interesting that is the device emitters are all paralell via the emitter resistors - has anyone seen this type of circuitry - and how does it avoid the 35v drop across the devices in high output? i guess a schematic would be useful - i can understand its operation if it were to switch supply or output between the 2 sets of devices (emulating the class H style circuit or for different impedances) nonetheless the irony of its nomeclature (BASIC M2) is not lost upon me - it appears far from basic.

suggestions? ideas? even better experience? plz enlighten

regards Baily
__________________
.:Ride the Lightning...Feel the Thunder:. - Technics Triple Thunder www.welcome.to/Technics oh yes ppl plz send me them dead (or Alive) STK or SVI ICs
  Reply With Quote
Old 28th May 2004, 02:30 PM   #2
sreten is offline sreten  United Kingdom
diyAudio Member
 
Join Date: Nov 2003
Location: Brighton UK
Sounds like a class G shunt or "commutating" output stage.

At low voltage the higher voltage devices do not conduct.

At high voltage the lower voltage devices do not conduct.

sreten.
  Reply With Quote
Old 28th May 2004, 02:39 PM   #3
diyAudio Member
 
SVI2004A's Avatar
 
Join Date: Mar 2004
Location: Albany Western Australia
Send a message via MSN to SVI2004A
Default whats the advantage?

what is there to gain from this operation over running all 4 equal devices over the 80V rail in paralell (thus only half the load is placed on each output device)
__________________
.:Ride the Lightning...Feel the Thunder:. - Technics Triple Thunder www.welcome.to/Technics oh yes ppl plz send me them dead (or Alive) STK or SVI ICs
  Reply With Quote
Old 28th May 2004, 02:45 PM   #4
sreten is offline sreten  United Kingdom
diyAudio Member
 
Join Date: Nov 2003
Location: Brighton UK
Being able to use a smaller heatsink. Sonically none at all.

sreten.
  Reply With Quote
Old 28th May 2004, 02:57 PM   #5
K-amps is offline K-amps  United States
diyAudio Member
 
K-amps's Avatar
 
Join Date: Nov 2003
Location: Indiana
Sreten has got it right.

The M2/ M2a run off dual rails. +/-56 and +/-91vdc. The smaller kenwoods run off +/-46 and +/-76vdc.

The DAT's which are basically 2 trannies in one have a common collector but separate B and E.

This not a commutation driven circuit but a pretty elaborate switching IC does the work of feeding each set of outputs. The TA2031 you see next to the heatsinks does that job.

Additionally there are big diodes on the collectors of the low rail devices that avoid leakage of higher voltage rails.

The obvious advantage is heat, these things run cool, this is a class-G design using Kenwoods DLD switching.

If you have tried to construct an amp using +/- 91 volt rails, you will know how easily you can get thermal runaway.

In my opinion, this is a very underrated design, it sounds pretty good and has killer bass. Tight and controlled not bloated and overdone. Damping of these units is in excess of 1000.

For the money, they are hard to beat.

K-
  Reply With Quote
Old 28th May 2004, 03:39 PM   #6
diyAudio Member
 
SVI2004A's Avatar
 
Join Date: Mar 2004
Location: Albany Western Australia
Send a message via MSN to SVI2004A
Thankyou very much for your input...

sounds like you're spot on... through my meter tests i established them DAT devices were common collector output devices, i was interested why the dual rails, which was explained has anyone got a schematic or info on the theory of operation of an amp this class?????

i accept the fact that this runs cooler, though i am interested in how so especially on constant high output over longer duration (as i believe that using 2 devices over 1 load makes the device run 2x as hot as running 2x device over 1 load) - moreso interested in the switching....... especially as the voltage amp ic drives all this (i gather this ic cleverly switches from LV devs to HV devs transiently based on output voltages thus switching from one set to the other over the voltage = lower heat per device per sine<360 electrical deg>)

i must say i find this circuitry highly interesting (coming from a single rail background)

Regards Baily
__________________
.:Ride the Lightning...Feel the Thunder:. - Technics Triple Thunder www.welcome.to/Technics oh yes ppl plz send me them dead (or Alive) STK or SVI ICs
  Reply With Quote
Old 28th May 2004, 03:51 PM   #7
sreten is offline sreten  United Kingdom
diyAudio Member
 
Join Date: Nov 2003
Location: Brighton UK
The "cool running" advantage depends highly on the statistics
of the input test signals, though I've don't doubt for music
replay and music signals the advantage is very real for
levels approaching the maximum output of the amplifer.

sreten.
  Reply With Quote
Old 28th May 2004, 04:17 PM   #8
K-amps is offline K-amps  United States
diyAudio Member
 
K-amps's Avatar
 
Join Date: Nov 2003
Location: Indiana
The VA amp is pretty standard. The switching IC comes AFTER the VA and driver stages. I have bypassed the TA2031 and the amp runs fine on any one set of outputs... only that it runs real hot!
  Reply With Quote
Old 28th May 2004, 05:27 PM   #9
diyAudio Member
 
SVI2004A's Avatar
 
Join Date: Mar 2004
Location: Albany Western Australia
Send a message via MSN to SVI2004A
QUOTE K-Amps The VA amp is pretty standard. The switching IC comes AFTER the VA and driver stages. I have bypassed the TA2031 and the amp runs fine on any one set of outputs... only that it runs real hot!..................................

i wonder why????????????

sounds like K-amps was right earlier
This not a commutation driven circuit but a pretty elaborate switching IC does the work of feeding each set of outputs. The TA2031 you see next to the heatsinks does that job.

- from my knowledge of output devices this amplifier workd like a four barrel carburettor - the LV rail handles the signal till the level requires the HV rail to switch in for higher signals

but if P=IxV 2 devices will run hotter than 4 though at seperate intervals (possible heat saving) as im inexperienced with such circuitry (but wish to know this fully) i have a Technics SE-A3MK2 - which i will check all collector voltages (i wonder if its dual V)

i must say i enjoy figuring this innovative drive circuit out

Regards Baily
__________________
.:Ride the Lightning...Feel the Thunder:. - Technics Triple Thunder www.welcome.to/Technics oh yes ppl plz send me them dead (or Alive) STK or SVI ICs
  Reply With Quote
Old 28th May 2004, 05:31 PM   #10
sreten is offline sreten  United Kingdom
diyAudio Member
 
Join Date: Nov 2003
Location: Brighton UK
Quote:
Originally posted by SVI2004A
QUOTE
- from my knowledge of output devices this amplifier workd like a four barrel carburettor - the LV rail handles the signal till the level requires the HV rail to switch in for higher signals
Regards Baily
No. The lower rail devices will be reverse biased - hence the diodes - and stop conducting - so your analogy is incorrect.

sreten.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Kenwood Basic M1 Amplifier Rte 66 Dave Solid State 22 27th June 2012 01:10 AM
kenwood basic m2 amp-circuits collumbo Chip Amps 7 4th January 2012 09:01 AM
Kenwood basic m2 Johnny25 Class D 0 20th January 2006 06:48 PM
Book for basic circuitry in amp building? kneadle Chip Amps 2 8th October 2004 01:26 AM


New To Site? Need Help?

All times are GMT. The time now is 08:24 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2