Weekly Headphones.com Contest!
Now with harder questions!

It's time again to offer up Brian's very generous offer of a $50 gift certificate at Headphones.com to some lucky winner.

Only this time I'm hoping it's less luck, and more brain cells.

Here We Go!
Last time it took all of 47 minutes for j.SoundLabs to come up with the correct answers, and 63 minutes for inarc to point out that a quick trip to Google and all question were answered. This time I'm gonna try to make it a bit harder. Here we go!

What's wrong with this amplifier?

From what headphones do these common Grado replacement pads come?

This is the begining of what melancholy Jazz Standard? Who wrote it?

Good Luck!

30 Ruta Ct.
south Hackensack, New Jersey 07606

Tyll Hertsens's picture
Geez, I guess I made them too hard. :(
sunmermaster's picture

I just have problem with the jazz part, arghhh XD

Tyll Hertsens's picture

... I figured people who could solve the schematic would likely not get the Jazz, and vice versa.

Here's a hint: sooo, do do do do, re re re re, mi mi mi miiiiii ... mi re re mi mi mi miii ... etc.

Brentagon's picture

The pads are for the Sennheiser HD414. That's the easy one.

The jazz standard is Billy Strayhorn's "Lush Life".

I'm not so sure about the circuit. Is it broken, or just less than optimal? I'm going to go with broken and say that it is missing the -V rail. That's my official answer. My unofficial answer was going to be that it would sound better without the feedback loop on P2.

Tyll Hertsens's picture
I probably shouldn't say right or wrong on the first two, but I will say that your guess about the circuit is wrong. It's a single rail amp, that's why is has to have the coupling capacitors on the in and out --- Cin and Clsp (loudspeaker, I guess).
Brentagon's picture

Then it's beyond what I learned in half a semester of EE, 20 years ago. I'm lucky I remember that much. Oh well, maybe next week.

thegr8brian's picture

The collector of T2 should be connected to the base of T3. T2's emitter should be at T4's base. So you can flip T2.

Sennheiser HD414 pads.

Billy Strayhorn - Lush Life

Tyll Hertsens's picture

We have a winner!

Transistor T2 is flipped upside down. The easy way to identify that as the problem is that all the arrows on the transistor emmitters should be pointing towards ground ... T2's is pointing up.

The pads are indeed from the venerable HD 414, claimed to be the first supr-aural headphone ever according to Sennheiser.

And the tune is Billy Strayhorns gorgious "Lush Life" --- my favorite Jazz tune. He wrote for Duke Ellington and it's fair to say he was half of Duke's brain when writing music. Probably my favorite Jazz composer. Quite unique in his style.

I'll forward your email to Brian at Headphones.com, and he'll let you know how to redeam your $50 gift cert.


Oh, would you have gotten "Lush Life" had it not been mentioned? Just curious.

thegr8brian's picture

Thanks Tyll!

I probably would not have gotten Lush Life, but with the notion in my mind and a listen online it sounded right to me. So I must give some credit to Brentagon.

The $50 should help soften the blow of a potential SE535 purchase.

Tyll Hertsens's picture
I love those things!