[Jolly Bodger]

As you will probably realise as you read this post, I know nothing of electronics. However I thought I might tackle this as a first project.

I want to build an impedance adjuster/attenuator to reduce the hiss in my Sansa Fuse/Custom 2 combo. I have found a few circuit diagrams but they all refer to attenuators for microphones so I need help.

Firstly is an 'impedance adjuster' the same as an 'attenuator' if not then whats the difference?

It would help if it also improved the bass and reduced the slight sibilance as well.

I'm thinking either:
1. a couple of resistors in series (one on each chanel) soldered direct into a 3.5 jack.
2. one resister in series another in parallel to ground (on each chanel) ('L' circuit)

I have no idea on values of resistors needed The Custom 2s are 16 ohm with 112 dB sensitivity.

I would be grateful for any help and advice.

Brian

 

[S J]

I would use option (1) that you listed above... 1 resistor in each channel. Resistor values between 50 and 200 ohms are typically used for things like this; it depends on how much the hissing bothers you (higher resistance = lower hiss). I don't find the Fuze to be a particularly hissy player, so you'd probably be looking at more like 50-100 ohm resistors. There's a good video guide and a bit more info on making one here

 

[qusp]

definitely option 1, 2 is just adding unnecessary elements and you dont have room or TBH the experience to be doing that in a mini plug. its kinda redundant if you just use the right value in the one. since you arent using an amp; I wouldnt make it too high. I would keep it around 60-80 ohms with the maximum being 100 ohms. p[lus I would recommend you make a short cable rather than doing what you suggest. putting them in a plug is a recipe for killing your headphone jack with the added stress IMO. so make a short cable with a female mini at one end some wire in the middle and a male mini at the other.

 

[Punnisher]

I would do option 1 as well.

Are those single driver? I ask because adding a resistor before a crossover network on a multi-driver iem will change the frequency response.

 

[S J]

Quote:

Originally Posted by qusp /img/forum/go_quote.gif putting them in a plug is a recipe for killing your headphone jack with the added stress IMO

x2. That happened to me... urgh.

 

[Jolly Bodger]

Quote:

Originally Posted by Punnisher /img/forum/go_quote.gif I would do option 1 as well. Are those single driver? I ask because adding a resistor before a crossover network on a multi-driver iem will change the frequency response.

They are "Dual Balanced Armatures"

I'll have a go at the 1st option and see what happens.

Thanks for the help.

Brian

 

[qusp]

Quote:

Originally Posted by Punnisher /img/forum/go_quote.gif I would do option 1 as well. Are those single driver? I ask because adding a resistor before a crossover network on a multi-driver iem will change the frequency response.

i've heard that too, but in reality I havent heard any changes to either SE530 or W3 when using mine with lisa 3 as opposed to just using a simple 1/4" to mini adapter.

 

[Punnisher]

I tried various values with my westone UM2 and the more resistance I added, the worse it got. I tried values from 10 ohms to 90 ohms. It chopped off the high end and the low end leaving a muddy midrange. It was highly noticeable, not not subtle at all.

Ymmv, though. Not all crossovers are built the same.

 

[qusp]

also not all resistors are the same; I agree with you when using half assed resistors; surely all a volume pot is is a series of resistors; I dont find my volume pot to cause this problem you speak of. I use vishay S102 (nude) which come in at about $12USD each, so not cheap, but I find them to be superb and like I said, I dont feel i'm getting a bad result.

 

[Iniamyen]

Quote:

Originally Posted by qusp /img/forum/go_quote.gif also not all resistors are the same; I agree with you when using half assed resistors; surely all a volume pot is is a series of resistors; I dont find my volume pot to cause this problem you speak of. I use vishay S102 (nude) which come in at about $12USD each, so not cheap, but I find them to be superb and like I said, I dont feel i'm getting a bad result.

Isn't this different than adding impedance to the load? A volume pot attenuates the input, not the output. So you aren't changing the load "seen" by the output devices with a volume pot.

 

[Jolly Bodger]

Tried option 1 using 68 ohm resistors - SQ not good chopped top and bottom too much. Guess I'll just have to wait till my new amp comes and see what effect that has.

Brian

 

[qusp]

ahh you are correct with that,

all I can say is I have none of these such problems, did some A/B ing last night just to double check. no problems with the output of my lisa III feeding SE530

 

[Punnisher]

I forgot to mention: I wasn't using an external amplifier when I got my results. I wanted to eliminate hiss from my mp3 players. I don't need to do this with my tomahawk since there is no hiss when using that.