DIY Audio Projects Forumhttp://diyaudioprojects.com/Forum/ Question of the amplifier circuit Jean Hiraga's Class-Ahttp://diyaudioprojects.com/Forum/viewtopic.php?f=10&t=1044 Page 9 of 14

 Author: mwhouston [ 14 Oct 2015, 16:59 ] Post subject: Re: Question of the amplifier circuit Jean Hiraga's Class-A Can't help, never built one.

 Author: daan [ 15 Oct 2015, 02:04 ] Post subject: Re: Question of the amplifier circuit Jean Hiraga's Class-A Hello all you friends out thereSorry for abruptly posting a question without introducing myself. My name is Daan and I am from South Africa. I am a retired person and electronics is my hobby. I am still feeling my way around the Forum system and hopefully do not make too many mistakes in the process as I am not a computor boffin.

 Author: daan [ 15 Oct 2015, 02:32 ] Post subject: Re: Question of the amplifier circuit Jean Hiraga's Class-A HiWhat is the function of the Pi filter in the power supply. I can see that it can be used for trimming the final output voltage of the power supply by altering the resistor values. My transformer is rated at 30 - 0 - 30v on the AC side @ 300va resulting in 42 v DC. From the power supply I run a split system incorpurating 2 Capasitor Multipliers each feeding a power amp. With this system I am a but low on the voltage to the amps, 32v instead of 35v. Can I lower the value of in the Pi filter resistors to increase the power supply output or remove them all together.

 Author: suztek [ 15 Oct 2015, 04:54 ] Post subject: Re: Question of the amplifier circuit Jean Hiraga's Class-A 60 watt version at what +/- voltage? Altering the 47 k resistor is the correct way to adjust for the bias current, leave the 1k8 resistors as specified.

 Author: daan [ 16 Oct 2015, 06:10 ] Post subject: Re: Question of the amplifier circuit Jean Hiraga's Class-A Hi SuztekThe amp that I refer to is the Jean Hiraga running off + and - 35v. The power supply consist of 300va transformer with 30-0-30v sec. and 3 x 22000µF X 63V Caps. I used 2 x 50A bridge rectifiers. Following the power supply I used 2 x Capasitance Multipliers, each supplying one amplifier. Because of the Cap. Multipliers the voltage to the amplifiers is a bit on the low side i.e. ±32v.

 Author: daan [ 17 Oct 2015, 09:15 ] Post subject: Re: Question of the amplifier circuit Jean Hiraga's Class-A Hi SuztekSorry man, my mistake. 3 x 22000µF in my previous post should read 6 x 22000µF Caps.

 Author: saraswat [ 19 Nov 2015, 21:47 ] Post subject: Re: Question of the amplifier circuit Jean Hiraga's Class-A Hi Daan, Was working on the Jean Hiraga project, required your valuable inputs for final calibration.setting the bias and DC offset. have already procured componenets as per the circuit posted in the build page. The links posted here in the forum are not working. Please help on the links. thanks in advance.

 Author: SonusBonum [ 12 Dec 2015, 13:33 ] Post subject: Re: Question of the amplifier circuit Jean Hiraga's Class-A Hi y'all... I started working on this amplifier a few months ago. I don't know anything about it, so I had to put my trust in Dan and the rest of you guys. I think I am getting pretty close to the test drive. Can't wait to hear it. I build it to be fully balanced as the rest of my gear is that too. On top of that I do bi amping so we're looking at a total of 8 amps in two boxes. For those interested here are some pictures. Anyway, it's really nice to meet you.Attachment:12308566_458332437703200_2123645780280590660_n.jpgAttachment:12311314_458553747681069_3366465810252931953_n.jpgAttachment:12308323_458788977657546_8029506127508842490_n.jpgAttachment:12310702_458974810972296_3242224327667637873_n.jpgAttachment:12366273_461779277358516_5613724741749534843_n.jpgAttachment:12342562_461779290691848_3185350536463529864_n.jpg

 Author: giann1234 [ 11 Apr 2016, 17:17 ] Post subject: Re: Question of the amplifier circuit Jean Hiraga's Class-A Hello,can i use ic 7317p for speaker protection with hiraga's amp?

 Author: JamesSQ [ 16 May 2016, 01:00 ] Post subject: Re: Question of the amplifier circuit Jean Hiraga's Class-A Hello all, I would really like to have a go at making this amplifier, for a car audio project (I am planning on using Horn Loaded Compression Driver setup) and a Class-A amp would be absolutely perfect. I compete in sound quality competitions. There are pretty much no pure class A Car amplifiers available to buy (There are some, but they are thousands of dollars!) Obviously the power supply is something I will have to tackle separately.What I am hoping is someone would be kind enough to make me some printed circuit boards, as I have no access to the correct equipment to do it! There seems to be a few of you (SonusBonum, Grega) that have produced high quality PCBs. I would be of course willing to pay a few \$\$ for anyone willing to help me out! The rest of the componentry and soldering I can take care of.Kind regardsJames

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