Re: AMP HEAD Build Thread
Posted: Fri Feb 24, 2012 6:31 pm
Edit: Found the info
Support forums for JLM Audio Kits and Products
https://www.jlmaudio.com/forum/
Hi Matthiasmento wrote:Hi there!
I have a question regarding the 10uF bi-polar output caps.
there's no indication how they go in on the pcb. do I fit these the same way like the 100uF ones?
thanks a lot!
matthias
The main difference is power rail voltage. OPA2604AP can run on up to +/-24v and NE5532AP can only run up to +/-18v. The OPA2604AP can put out more level on +/-24v but even the NE5532AP can drive all headphones louder than all headphones and ears can handle. Both are very clean very low THD up to there power rail clip point. Amp Head has no problem running into a dead short indefinitely even at full clipped output.digidesigh wrote:Hi Joe.
I'm very new to DIY ...have only built a few kits from Jaycar and thought this may be a good first project. So far the build thread is understandable, except the points below:
1) I can see there are different options for op amps, and even an option NOT to have one...im wondering what the differences are to the headphone amps performance with the different options.
Any single rail regulated power supply needs zeners fitted to AMP HEAD to make the +/-V. eg 48v = 2 x 24v zeners for +/-24v, 36v = 2 x 18v zeners for +/-18v. If using +/- split rail power supply NO zeners should be fitted.2) Also what are the differences between using SMPS 48v power supply, VS power + zener's as mentioned in the middle of the thread (or maybe i have misunderstood something)?
Any of our 48v SMPS can be used to run the AMP Head kits. But you only need one 48v 15w internal or 48v 25w external to run 2 to 4 AMP HEAD kits. 48v 15w internal SMPS can be turned down with a trim pot to 36v for running +/-18v.3) Which particular SMPS power supply is able to be used from the power supply section of the website, i can see 2 different types. This is the one i can use? i think???
http://www.jlmaudio.com/shop/index.php? ... oductId=80
The mute function shorts the +/- audio input together after 2 x 10k resistors together so should mute to a very very low level as long as the 0v ground for the audio input and AMP Head are connected.kante1603 wrote:Hello Joe,
I hope you´re fine.
Just a short one:On an amphead I´ve built I have a small issue.I did the "mono/mute/on"-mod by implementing a switch as described from you before.
Sadly in mute position as well as in pot position fully ccw (which is the same function,right?) it doesn´t mute completely,there´s still a very low signal audible.
Can you guide me where to look at,maybe lifting the parts prior to the pot?
Thank you in advance,
Udo.
Hi Joe,Joe Malone wrote: The mute function shorts the +/- audio input together after 2 x 10k resistors together so should mute to a very very low level as long as the 0v ground for the audio input and AMP Head are connected.
Send me a email and I will send you the AMP HEAD schematic so you can see how it works.
Sure,it´s this one:digidesigh wrote:Hey Udo,
had a look at that website you mentioned which you got your case for this headphone amp, just wondering if you know which model/part number it was? i like the look of that case
The AMP HEAD has 2 positions for zeners on the PCB makred ZD- and ZD+.digidesigh wrote:Another question for Joe, and or anyone else who's actually gone through with this project....
I'm still a bit hazy about the Zeners, where will they be fitted exactly? (i am a complete noob at all of this, so bare with me! ) The other option is, if i go down the path of using split rail power, is that ok for powering 1 pair of headphones?