[Kong132]

I recently built a Mint Amplifier for my senior project, and I noticed that it is extremely bright. I have an AD8620 in it paired with some ER4P headphones which I know is a very bright combination, but Digi-key was out of all of the other models at the time, and I was running short on time. Is it most likely that replacing this Op-amp with a more laid back type would reduce this, or is it possible that another part of the amp is causing this?

 

[dokebi]

Lower the gain and increase output resistors.

 

[tangent]

Quote:

Originally Posted by Kong132 Is it most likely that replacing this Op-amp with a more laid back type would reduce this

Yes.

 

[fewtch]

Quote:

Originally Posted by Kong132 I recently built a Mint Amplifier for my senior project, and I noticed that it is extremely bright. I have an AD8620 in it paired with some ER4P headphones which I know is a very bright combination, but Digi-key was out of all of the other models at the time, and I was running short on time. Is it most likely that replacing this Op-amp with a more laid back type would reduce this, or is it possible that another part of the amp is causing this?

What's your source (and music)?

I don't consider the AD8620 "bright" (and tests show a flat frequency graph). We may have different definitions of the word bright, though. To me, it means a boosted treble, which AD8620 does not have.

 

[Kong132]

My source is a Zen Xtra 30GB. The music is anything from metal to classic rock. It is noticeable more fatigueing to the music through the amp than without it. I believe the gain is about 3.8 or so. Mouser was out of the resistor value that I wanted in Vishay-Dale.

 

[en480c4]

The 8620 definitely strikes me as dry and detailed. I don't know if I'd say it's bright, but there's an "edge" to it.I didn't mind the 8620 with my E2c's but that edge was too much after moving to the E4's. I don't think it was necessarily grainy, but the highs definitely weren't smooth.

I ended up swapping for a 2227 and I definitely prefer it with my E4's... it may not have the detail but there's a warmth and smoothness to it that the 8620 defintely lacks. And what's more important is for long trips, the 2227 and E4 combo isn't at all fatiguing.

 

[ericj]

Quote:

Originally Posted by Kong132 Is it most likely that replacing this Op-amp with a more laid back type would reduce this, or is it possible that another part of the amp is causing this?

I will trade you, straight across, a sparkly new Burr-Brown OPA2134U for your greazy old used ad8620. I won't even make you pay shipping

Seriously though, check your resistor values? If you have a very low value in R2, maybe you're hearing an unfortunate high-pass filter configuration.

Edit: Whoops, I meant R2, not R4.

 

[sbelyo]

I used a opa2604

It has a nice laid back sound. real close to opa627 at 1/4th the price.

 

[fewtch]

Quote:

Originally Posted by en480c4 The 8620 definitely strikes me as dry and detailed. I don't know if I'd say it's bright, but there's an "edge" to it.

I like the AD8620 a lot at 9v, and notice as voltage goes up it starts acquiring that edginess (particularly with unbuffered designs where the chip itself presents the main sonic signature). At 24v, it's nearly unbearable to me.

 

[en480c4]

Quote:

Originally Posted by fewtch I like the AD8620 a lot at 9v, and notice as voltage goes up it starts acquiring that edginess (particularly with unbuffered designs where the chip itself presents the main sonic signature). At 24v, it's nearly unbearable to me.

Well that makes sense, considering my MINT's have been 18V. Thanks for the input... that helps clear things up a little.

 

[KurtW]

I had an AD8620 in my MINT and always thought it sounded too bright, and much brighter than AD8610s (the single channel version) in the PPA. I don't know why this is true, but it bothered me for some time until I finally replaced the 8620 with another op amp and the sound to my ear improved a great deal, making the MINT much more enjoyable. By the way this is with either 9v or 18 volts. Which op amp did I replace it with? Well I don't remember offhand since it was about a year ago but I think it may have been the 2227. The amp is one I use at work, so I can't take a look at it right now. If you're interested I can check it, but now I can tell you that the AD8620 is in my opinion not the best op amp for the MINT.