Hitachi 2SK/2SJ 300 Watt Class A/B Amp Completed - diyAudio
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Old 6th April 2005, 05:34 AM   #1
Coulomb is offline Coulomb  England
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Default Hitachi 2SK/2SJ 300 Watt Class A/B Amp Completed

Well here is another project I finally finished, I am on a roll 4 Projects completed over the last 4 weeks! Not completed in 4 weeks, more like 16 months.

This latest project is built on a pair of Kits out of Taiwan that actually sound pretty good, all things considered. The kits were $150 CAD each for PCB and all parts to mount to it. I replaced some parts with some slight upgrades, but al in all they were built as supplied. I built up the power supply with 4 x 69,000 uF caps a Fast Bridge from BigParsnip and a 1KVA 2x40VAC Plitron Toroid I had kicking around.

The chassis is made from rescued Car Amp Heatr sinks and some aluminum from my favourite jobber, Metal Supermarket. I have yet to put it through it's paces as a stereo configuration, but I did have one channel already running a Centre Channel in my Home Theatre. It has some real Bass Slam and Midrange Detail, great for Dialogue. It is a little harsh in the upper registers, I will probably use it as a Sub Amp for my DPL12's

Here is a link to some Photo's, feedback is always welcom as well as questions.

http://www.briangt.com/gallery/view_album.php?page=1
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Old 6th April 2005, 07:51 AM   #2
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4 weeks !!! Are you trying to get me depressed ?

Mmm, which Hitachi 2SJ/2SK , Monsieur Energique ?

I just paid 4.5 CAD per pound for a 60 pound 10 mm aluminium plate for my Extended Leach amplifiers.
Me thinks i need to hit the car amplifier sinks too.
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Old 6th April 2005, 10:27 AM   #3
Coulomb is offline Coulomb  England
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Quote:
Originally posted by jacco vermeulen
4 weeks !!! Are you trying to get me depressed ?

Mmm, which Hitachi 2SJ/2SK , Monsieur Energique ?

I just paid 4.5 CAD per pound for a 60 pound 10 mm aluminium plate for my Extended Leach amplifiers.
Me thinks i need to hit the car amplifier sinks too.

Hey Jacco, that would be the 2SJ162 & 2SK1058.

Here is the link again, the one I posted in the initial message just does not seem to work all the time.

http://www.briangt.com/gallery/album01

Regards

Anthony
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Old 6th April 2005, 11:11 AM   #4
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Antonio,

had the link worked, i could have spotted the mosfet types myself.
That is an un-usual way of mounting power devices, never seen it done like that.
It must be nice hodging next to the Dubilier depot ?
A very original and economical way of building an Aleph variety.
Care to convey how to get the corners on the aluminium bottom plate so smooth ?

Did you swap to GB flag, i thought you carried the Maple leaf ?
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Old 6th April 2005, 01:30 PM   #5
Coulomb is offline Coulomb  England
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Quote:
Originally posted by jacco vermeulen
Antonio,

had the link worked, i could have spotted the mosfet types myself.
That is an un-usual way of mounting power devices, never seen it done like that.
It must be nice hodging next to the Dubilier depot ?
A very original and economical way of building an Aleph variety.
Care to convey how to get the corners on the aluminium bottom plate so smooth ?

Did you swap to GB flag, i thought you carried the Maple leaf ?

Well I hate to gloat, but I got about 20 or so of those caps plus some 100 VDC versions for a pair of Anthony Holtons AV800's.

As far as the circuit goes, it is very similar to an Aelph but biased into A/B operation. I can increase the Bias to about 2 amps, normally set at 100 Milliamps, which would definately push it into Class A I suppose. I posted the scematic some time back for discussion but never got any feedback on the circuit. I should post it again here.

Round Corners, well you need a CNC milll or a coordinated XY drive on a standard mill or an Index table. If you look at the front Heatsink you can see where I was practising with an index table. In the old days a metal saw and file would have to suffice. Yes I admit having a Machine shop and being a trained machinist could have some bearing on the quality of my metalwork.

BTW Jacco I also graduated College as an Electronics Technician, went back for Digital Design, and again for Military Production training.

Regards

Anthony

PS. We never leave school, life is about learning, adapting and evolving, everything else inconsequential.
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Old 6th April 2005, 01:51 PM   #6
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Quote:
Originally posted by Coulomb
Yes I admit having a Machine shop and being a trained machinist could have some bearing on the quality of my metalwork
I figured as much from the 2 stray center points on top of the square bar.
My dad had a thing with center points, i grew up in a machine shop, got my machinist training from the Dutch navy.

PS : Personally, i am training as a Leech currently.
My tutor, Mr Marshall, doesnt see much progress, but i am sucking diy-audio dry.

Nice work, Anthony.
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Old 6th April 2005, 02:27 PM   #7
AR2 is offline AR2  United States
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Hello Columb,
Have you completed Holton's AV800 amp, anad how does it sound comparing to this new amp?
Would you care to post the link where did you get the PCB and parts from Taiwan?
Thanks
AR2
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Old 6th April 2005, 02:47 PM   #8
Coulomb is offline Coulomb  England
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Thanks Jacco,

BTW the GB Flag represents my Nationality, I am not yet a Canadian Citizen, even after 30 years here.

AR2 I will try to track down the supplier for you. In answer to your question I have not yet completed the Holton Amps.

I said earlier the Bias Current was adjustable, I meant the idle current is adjustable and the DC offset which is at 3mV on the right channel and 0.01 mV on the left channel. The acceptable limit according to the broken English instructions is 500mV, I guess it is within tolerance.

Regards

Anthony
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Old 6th April 2005, 04:29 PM   #9
Coulomb is offline Coulomb  England
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Hello Jacko, now I see what you were referring to when you mentioned off centre holes. The hole centre's were determined by the top cover irrespective of where they would end up on the posts. I guess you can not see that the holes for the top cover are symmetrical.

Regards

Anthony
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Old 6th April 2005, 04:44 PM   #10
AR2 is offline AR2  United States
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Thank you Colomb for the quick reply.
Out of all searching on the web you captured two best sources for the higher powered Class A/AB amp. There are many designs for Class A up to 100 - 150 W or for amps that are 60W. It seems like choices are ether now-days digital amps or bridged configuration to reach 400 - 800 W. When we speak about this power many people react with "Do you really need that amount of power?" but if you have low sensitivity low impedance speakers that amount of power get used easily. I do not know what is yours intended use for these amps, but I am assuming for bass drivers in active config. in the decent room size. I have a same need for amp with decent current capability for sealed bass driver.
Great work on your amps, they really do look awesome.
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