Hi,
I've bought a jlh 1969 kit from e bay
2pcs JLH 1969 A CLASS A amplifier kit sc | eBay
I've built a few class d amps from 41Hz Audio - Main page which are quite nice, but can become a little tiring to listen too after a while. I hope that a super simple class a will take some of the edge off.
If I may, I'd like to ask a few questions?
1. would I be better off changing any of the kit component before I start? ie caps, resistors etc. (i dont want to change the output transistors, not yet anyway)
2. I need to set Iq, which I can do with an ammeter in series with the + rail input yes? A value of about 1a seems common.
3. I have a 2x18v 300va torroid, will this be enough to power both amps? I am thinking it will be close but should be ok.
4. I am confused as to what needs to be grounded to the case? Do I ground - signal input, - power out, are the transistors needing to be grounded?
Thanks in advance for any help given on the subject 🙂
matt
5.
I've bought a jlh 1969 kit from e bay
2pcs JLH 1969 A CLASS A amplifier kit sc | eBay
I've built a few class d amps from 41Hz Audio - Main page which are quite nice, but can become a little tiring to listen too after a while. I hope that a super simple class a will take some of the edge off.
If I may, I'd like to ask a few questions?
1. would I be better off changing any of the kit component before I start? ie caps, resistors etc. (i dont want to change the output transistors, not yet anyway)
2. I need to set Iq, which I can do with an ammeter in series with the + rail input yes? A value of about 1a seems common.
3. I have a 2x18v 300va torroid, will this be enough to power both amps? I am thinking it will be close but should be ok.
4. I am confused as to what needs to be grounded to the case? Do I ground - signal input, - power out, are the transistors needing to be grounded?
Thanks in advance for any help given on the subject 🙂
matt
5.
Hi, The Class-A Amplifier Site , rgds, sreten.
A 300VA transformer is plenty more
than you need for two 10W amplifiers.
Also see : http://sound.westhost.com/project15.htm
And read up on class A heatsinking ......
A 300VA transformer is plenty more
than you need for two 10W amplifiers.
Also see : http://sound.westhost.com/project15.htm
And read up on class A heatsinking ......
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Thanks for the reply! I have seen and read through that site having found it via google, but much of it is beyond me I'm afraid so I thought I'd ask here 🙂
added...
Thanks for adding the extra information, I will also look into heatsinks.
added...
Thanks for adding the extra information, I will also look into heatsinks.
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18-0-18 is fine for the JLH.
It can take 20-0-20VAC which would give you the +/-27VDC.
Reducing the voltage by a couple of volts will just mean that the maximum output power is slightly reduced.
It can take 20-0-20VAC which would give you the +/-27VDC.
Reducing the voltage by a couple of volts will just mean that the maximum output power is slightly reduced.
Hello, I plan on buying an unregulated board with big smoothing caps rather than make my own. They seem quite cheap.
Thanks for the help!
The transformer is AC18V. Only need a group.
Through the rectifier filtering into DC24V-0.
The transistor need to unscrew connected in PCB above. Because of the transistor iron shell is the collector.
Through to unscrew conduction.
But pay attention to the transistor's shell. Can't the heat conduction. This must be a test of security.
Through the rectifier filtering into DC24V-0.
The transistor need to unscrew connected in PCB above. Because of the transistor iron shell is the collector.
Through to unscrew conduction.
But pay attention to the transistor's shell. Can't the heat conduction. This must be a test of security.
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