Kenwood Basic M2 amp

Love-Vinyl

It's about the Music
I've got a Basic M2 amp driving a pair of vintage Infinity RS3b's in full sigma mode. Any one else using one of these or something similar to drive their Infinities? I was using a Hafler DH500 and loved the way they played but while going through my closet I found the Basic and I knew I had tried them on the Infinities before but without the full sigma drive working. I just got it so cheap at the time, I think about 140 plus shipping in the original box -since gone - and the user manual.

The biggest thing I notice is I had to cut back on the tone adjustments on the speakers because I had to tweak them a smidge with the Hafler but the Kenwood just "breathes" crispness. It also has a super tight grip on the woofers I wasn't expecting. I'm still sort of letting them get to know each other at this time so I haven't really pushed anything hard as yet. Currently I'm listening to a BB. King and Stevie Ray Vaughan SACD and it is just that bit of sparkle I hadn't noticed that I'm enjoying right now. I've some specially made SACD's I will be using to listen a little deeper in the next day or two. I'm used to vinyl mostly but on this system I don't have a turntable as yet but I am liking what I'm hearing! :music:

I was just wondering if anyone else here has had a similar experience?
 
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Similar experience here with the same amp and my Infinity 6 Kappa speakers. I can't imagine ever separating the two.
 
Right now I have a M2 with the sigma drive hooked up to some Polk RTi-A7s and it sounds great. I briefly had a pair of M2s bi-wired running these speakers with the sigma enabled....rocked real hard and sounded great. Then one of them developed an issue with the speaker selector. There is a metal strap that goes from the switch on the front to the switch on the output board. This broke and caused the switch on the output board to cross over contacts, that is it was stuck between selections, and it fried itself. So sad, it looks great too. Guess I'll have to send it in for some repair and upgrades. This place looks like my best bet. But I'll have to find one for parts as the switch is unobtainum.
http://www.drmaudioht.com/proddetail.asp?prod=8001041
 
Oh yea, Kenwood Basic M2A power amplifier!

I have a Kenwood Basic M2A power amplifier that drives 4 Bose 901 Series V speakers and it makes them sing! :music:
I've had it brand new, from the box, since the mid 80's and it still kicks ass!
 
My Basic M2 is driving 4 ohm Norman Laboratories Model Tens. I took it down for a few months to enjoy a Kenwood KR-7400, but the M2 is back in service as of a few days ago. Sourced from a C1 preamp, there's really a magnificent amount of detail top to bottom with this combo. The EQ on the C1 is kind of in-yo-face (maybe it needs a recap), so I'm tempering it a little with an outboard Pioneer EQ. I wish I could use the sweet-sounding KR-7400 as a preamp, but it doesn't have pre outs.

I've tried the Basic M2 with and without the sigma drive and haven't really noticed any noteworthy enhancement, but maybe I'm not hooking it up right.

I've seen the Basic series amps go very inexpensively a few times on CL since I got mine. They seem to be about the best bargains out there.
 
The manual explains how to do it but I didn't see one in the database so I scanned mine and sent the files to the database. They have it up now and they did a great job of it. It's in pdf format so you can download it very easily.

Basically you take 4 speaker cables of the same size of which I use 14ga cable, nothing fancy.

lay 2 of them out and on one end twist the positive sides together and do the same on the negative side. These ends go into the speakers. Now the other ends go into the connections on the amp. It doesn't matter of course which one you pick for the main clip or the sigma side as long as you match positive to positive and negative to negative. This allows the amp to apply minor correction to what it senses to be distortion in the drivers. I find it mainly comes through best at higher volumes on what might typically appear to be congested passages such as large orchestral works where you might be straining the speakers. If you have a good set of speakers already you may notice little differences at all. At least that's what I find from my experience. I do find that the amp seems to work just that little faster and is more dynamic with it working than if it isn't.

From what I understand this is not a strictly class a/b amp but uses some alternatives to give it it's dynamic boost. However it only works at it's best if you "complete the circuit" if you will by hooking up the sigma drive. I do also find soldering the ends going in to the speaker helps as they suggest in the manual.

And yes there are some very good bargains out there for these amps because I think they are flying under the radar as how they operate still isn't well understood and Kenwood wasn't exactly forthcoming with information. What I understand I've picked up from hints, suggestions and a few educated guesses from folks who know a lot more about it than I do!

I've seen others on here and elsewhere who have listened to both the C2 and the C1 and say that if properly restored the C1 is the better sounding amp. Can't speak to that myself but it does sound as if it could use some TLC.
 
I would love to have a M2A, bought a M1D back in the 80's which I still use today. See them come up and sell out fast. Had a C1 T1 M1D with a Fisher Studio Standard 5 CD changer, Kenwood dual auto reverse cassette player and BSR 15" 5ways Ah the 80s.....rock on.
 
Thanks for that clarification moejr. I had to go look it up and read up on it. Interesting design challenge and then to throw in the servo feedback correction though the Sigma portion. Yikes! What a nightmare.

undergroundr: As I understand it you need everything matched to form a more perfect loop. I had some old Monster XP speaker cable not in use so I wrangled mine together with that. I also have some Kimber 8 speaker cable but it's just too big to fit in the slots. I could have used some banana plugs and custom fit something but I mainly wanted to test it out so I used the XP instead. Remember this was from a time when lamp cord was typically your speaker cable and before all the cable hoopla started. I doubt it was engineered to require anything more than that. I do remember it being mentioned soldering those 2 ends together that go to the speaker because it does make the signal strength that much stronger back to the amp.

If I remember correctly this was all to do something similar to what a servo controlled sub does but for any speaker you choose. Kind of like bringing that servo static array concept and applying it to any brand you want. I do know Kenwood still uses this in amps specialized for car audio in a much smaller and more refined package. As cheap as these units go for on the used market I'm surprised more people haven't used or at least tried them out. I have used them in bi-amping for the bass module and a smaller Mosfet amp for mids and highs and thought I was in heaven. However the speakers died of old age and the Mosfet amp, I can't remember the name even, died with parts no longer made or available. All long gone to the trash now but now I wish I would have saved them and used them for practice if nothing else. Ah well...
 
[I am a new subscriber, and this is my very first post so bare with me, please.]
I know this thread is old, yet i have gotten so much great information from this forum, i wanted to add to the value of this thread if i can by adding more information.
I just brought home an M2 last night and am excited to give it a try! But i need to know if i can adapt the Sigma drive to my set up or do i have to settle on one pair of speakers and run new wires the full length.
What i have is a Yaoin 2100 driving 4 speakers per side in a parallel/series configuration so it is still an 8 ohm load. [We can talk speakers later, as it is, i have a pile of middle of the roaders…so i dance with the one that brung me :))>]
Now the question: Can i run the Sigma leads to the connection i have made just before the amp - where the 2 wires from the speakers connect to 1 wire that i attach to the post on the amp [hope that makes sense! I could draw a diagram if it would help]??? [Again, i had a spool of 10 gage, so i used it to wire up my speakers.]
As a side note, if i had to pick one pair, it would probably be the Altec Model Five's. They are good, yet to me, lack low end definition/clarity so i have paired them with a pair of Technics SB-2665's. They seem to handle lows better yet are a little "boxy" [they could probably use some bracing and fill to be better, eh?] The other speakers are there to keep the load at 8 ohms - a pair of Bose 501 Series II's [no mid's] and a pair of mid-'90's Optimus 745's [maybe good speakers but the boxes are crap!].
I am so looking forward to everyone's input.
 
To get a better understanding, as you suggested, why not post a diagram on what exactly your description of the connections, layout, etc. on all audio components involved? :scratch2:
 
First time uploading so I hope it comes through:
 

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I gave up the "wall of sound" idea...

I had been experimenting with a wall of sound, which is why I had my above question. I have since set up a single pair of speakers trying to use the rule of thirds the best I can with just my Altec Model Five's (because I think they are the best speakers I have running). It does seem that the sound is coming from behind/around the speakers. I didn't believe I would get such nice, 3-dimensional sound that way. Only sorry I had to embarrass myself in public to be reminded that science and math work every time!

That is a big part of why i became a subscriber: to listen, learn, and then pass it on!

I may cancel my cable and just spin records & play tapes when I am home :))>
 
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