The Mini-A

[Zen Mod]

Originally posted by jleaman



Why would you spend and build a Mini A for a headphone amp, that does not make sense to me.

because


of this

[d to the g]

Originally posted by GRollins
When only the very best will do...

Grey

the 6moons article was pretty telling.

[winslow]

I want to build one of those one day.

That and a Pumpkin in one kit. Nice integrated kit right there.

Originally posted by Zen Mod



because


of this

[Zen Mod]

Originally posted by winslow
I want to build one of those one day.

That and a Pumpkin in one kit. Nice integrated kit right there.

that will need lots of case .........

[ssmith]

Hi again,

re my previous question re coupling, managed to figure it out.

However wondering if anyone would mind taking the time to look at my layout.
Everything has been wired up since and is working fine -- although there are just a couple of things that are bugging me right now -- a high frequency buzz only detectable when volume is at max, and a very very slight hum -- again only audible when the ear next to speaker.

I suspect I may have run into an issue mentioned in the aleph-X wiki, that Magnetic fields from inductors may also be a concern, especially for air-core inductors, so give due consideration to mounting and shielding.

My diy'ed inductors (0.9mh, DCR 0.2 ohm) are enclosed next to the caps. But the tubing and cap enclosing them is aluminium. I presume that this provides inadequate or no shielding? When powered on, there is also some vibration from them, so I think I will have to damp them too (what is recommended, filling the enclosure with sand, varnish?).
Finally, the steel mounting bolt goes through the centre of the inductor. Could this cause a problem? -- I could alway change it to a plastic mounting bolt.

My rails are at about 21.7v and after an hour or so the heatsinks are 'crikey hot' (5 seconds hands on), so I may add a resistor to make the PSU a CLRC, just to drop the rails a bit more. PSU is running two channels, each biased at 2A.

thanks in advance.

[Zen Mod]

Originally posted by ssmith
Hi again,

...........

temporary replace chokes with resistors - if buzz is gone - there is culprit ;

same for steel bolts ; sometimes they are bad , sometimes not ; try without them and you'll know

[ssmith]

Zen Mod,
Thank you.

[posxia]

my dear DIY brothers, I found some old IRF120 in the electric market, It can work well in MINI-A £¿their packing are TO-3.
hahaha ,I like TO-3 packing ,especially in class A amp.

[posxia]

some datasheet about IRF120.PLS give me some advice.thanks!

[GRollins]

The voltage is fine, but the current looks to be a little scant, particularly if you have a lower impedance load. It might be a good idea to parallel two sets of outputs, or perhaps even three.

Grey