Canuck Audio Mart Hifi and Audio ForumCanuck Audio Mart Hifi and Audio Forum
It is currently Tue Nov 21, 2017 12:10 am

All times are UTC - 8 hours




Post new topic Reply to topic  [ 9 posts ] 
Author Message
PostPosted: Wed Nov 08, 2017 9:55 pm 
Offline

Joined: Sun Jan 25, 2015 11:44 pm
Posts: 379
Location: Calgary, AB, CA
Curious how many watts I’m pushing with a pair of Nikko Alpha 220 bridged through a Nikko BTL-I.
The 220’s are rated at 120 watts into 8 ohms. Can anyone help me with the math?


Attachments:
469F1438-18CA-44A9-9F2A-F68605CAE516.jpeg
469F1438-18CA-44A9-9F2A-F68605CAE516.jpeg [ 374.42 KiB | Viewed 285 times ]
Top
 Profile  
Reply with quote  
PostPosted: Thu Nov 09, 2017 4:51 am 
Offline
User avatar

Joined: Sun Mar 31, 2013 6:10 pm
Posts: 3025
Location: Toronto, ON, CA
From what I've read online its somewhere between 300-500 watts.

_________________
"You don't know what you've got 'til its gone
..........JONI MITCHELL.


Top
 Profile  
Reply with quote  
PostPosted: Thu Nov 09, 2017 4:54 am 
Offline

Joined: Thu Aug 03, 2006 4:43 pm
Posts: 558
Location: Ottawa, ON, CA
Bridging an amplifier effectively doubles the output voltage, which in term means four times the power under ideal circumstances.
So in theory, your amps would deliver four times 120 watts, or 480 watts in bridged.

However, rarely will an amp have sufficient power supply or a strong enough output stage to actually achieve this x4 power level. I don't know enough about your Nikko's build to say with any certainty, but you're probably in the 300-350 range...


Top
 Profile  
Reply with quote  
PostPosted: Thu Nov 09, 2017 6:07 am 
Offline
Premium User

Joined: Thu Dec 22, 2011 7:16 pm
Posts: 28
Location: Yellowknife, NT, CA
According to the service manual, the Nikko Alpha 220 is rated at 130 wpc into 4 ohms @ .02% THD, so that would give you 260 watts into 8 ohms bridged, per amp. Probably a little more at clipping.

Nice looking rack set-up 8)


Top
 Profile  
Reply with quote  
PostPosted: Thu Nov 09, 2017 6:29 am 
Offline

Joined: Wed Oct 10, 2012 10:07 am
Posts: 117
Location: Repentigny, QC, CA
3x the 8 Ohm rating would be considered good - as other posts indicate, there are p s limits - when the amp is bridged.
Likely less than 360 watts p/c, imho.


Top
 Profile  
Reply with quote  
PostPosted: Thu Nov 09, 2017 6:32 am 
Offline

Joined: Tue Jul 04, 2006 5:15 pm
Posts: 235
Location: Cambridge, ON, CA
Its going back awhile :? but with the proprietary adaptor and you have it............ I believe it doubles the power
There was a Nikko 450 amp in that era that did 220 watts a side and with adaptor and 2 450's connected you did over 400 watts a side


Top
 Profile  
Reply with quote  
PostPosted: Thu Nov 09, 2017 7:03 am 
Offline
Dealer/Sponsor

Joined: Tue Jun 14, 2016 8:33 am
Posts: 1124
Location: Kingston, ON, CA
Alpha 220's and 230's have fairly fine wiring on their mains transformers. One of them, the 220 or the 230, can't remember which..has 22g wiring on it's output, the other has 20g. These are barely sufficient to work, at all. 20g is the more acceptable, obviously. The 22g wiring is, to me, unacceptable. This is a recommended line level gauge of wiring, not mains transformer output wiring.

It is a fairly robust design, but almost purposely kneecapped by 'current control' via small gauge mains transformer wiring. the thinner wiring tends to blunt transients under loading. so the amp might sound a bit light, uneven and slight bumpy/uneven/blurry in it's bass delivery. Now think of what people say when they use these amps. Their listening impressions have a source point.

When you go to the high voltage balanced configuration, you'll be trying to get twice the current from each channel. This is not possible with this amp. but with lets say a belles 450, not as much of a problem, with it's 1500va rated transformer, and approx 50A 'potential' in current swing per channel (8x 7A Hitachi mosfets per channel, 4 per rail). bigger capacitors and it might be possible with the belles 450. It has the grunt to back things up.

The alpha 230-220 series should not be bridged. Not going to work very well, unless one has 10-12 ohm speakers, minimum. The 230-220 series does not have the current swing to back things up.

To do this best, or ..functionally, ie less chance of amplifier failure, one generally needs an amplifier that can do maybe a 3-2.5 ohm load, per channel, all day long, at high power.

Eg the belles 450, when I tested one, did about 525 watts continuous, clean undistorted sine wave, at 2.7 ohms. (per channel) This is with a 1500va transformer, that has dual output windings, and is connected in parallel, to cut transformer output impedance in half. (a pair of big gauge wired 750va rated windings, run in parallel)

It's coming back to me..the 220 transformer has the 20g wiring. The 230 is thoroughly kneecapped with the 22g wiring on the output of the mains transformer.

Considering the build of these amplifiers, bridging them is likely stressing them to the max. Also, nikko's primary design or common design among most of the amps in this series, is prone to failure at turn on when aged. replace all the small capacitors on the main amplifier board, if it has not been done. Otherwise nikkos will do what nikkos do, and go 'poof!' one day, when you turn it on. Almost every single alpha 220 and 230 that has died, has died this way. 450-440's all go the same way.

There will be zero hints that something may be wrong or is nearing. It will just..one day.. go bang -at turn on. Untouched older nikko amps are a hard core Russian roulette game, when you hit the power switch. Original output transistors and the small fet pack are pretty well extinct and tend to have to be pulled from other dead nikkos or amps from the same time period that were using them. So save some coin, big time,and re-cap all nikko amp main boards, if one owns a nikko amp. Always. yesterday.

That's more information than people wanted, but I'm chock full of a pot of coffee right now.. so..

_________________
(Ken Hotte, of) Teo Audio


Top
 Profile  
Reply with quote  
PostPosted: Thu Nov 09, 2017 12:01 pm 
Offline

Joined: Sun Jan 25, 2015 11:44 pm
Posts: 379
Location: Calgary, AB, CA
Attachment:
38E2BCD0-37FE-4F4D-8FBE-5AF39BD4C015.jpeg
38E2BCD0-37FE-4F4D-8FBE-5AF39BD4C015.jpeg [ 289.13 KiB | Viewed 159 times ]
Thanks for all the great information guys! Both of these amps have been re-capped and wiring has been upgraded.
It’s curious that the Nikko Bridging Network owners manual shows the 220 in the connection diagram.


Last edited by Scoup on Thu Nov 09, 2017 5:11 pm, edited 1 time in total.

Top
 Profile  
Reply with quote  
PostPosted: Thu Nov 09, 2017 1:15 pm 
Offline
User avatar

Joined: Sun Mar 31, 2013 6:10 pm
Posts: 3025
Location: Toronto, ON, CA
Scoup wrote:
Attachment:
38E2BCD0-37FE-4F4D-8FBE-5AF39BD4C015.jpeg
Thanks for all the great information guy! Both of these amps have been re-capped and wiring has been upgraded.
It’s curious that the Nikko Bridging Network owners manual shows the 220 in the connection diagram.

They may use 220 in Japan.

_________________
"You don't know what you've got 'til its gone
..........JONI MITCHELL.


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 9 posts ] 

All times are UTC - 8 hours


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
cron
Powered by phpBB® Forum Software © phpBB Group