[sxr71]

Go to the bottom if you don't want to read the whole thing.

I was messing around with the jumpers on my Supermini-3 today and I came to what I think is a good result. I would really appreciate it if some of you tried it out and let me know what you think and if you note any strengths and weaknesses in what you hear. I think it's gotten me wanting to listen to my whole music collection again.

As you may have read in another thread, I've become a fan of the bass boost function on this amp. The one thing I would have preferred was instead of a 7dB boost maybe a lighter 3 or 5 dB boost. I found that by removing the impedance jumper and adding an additional 75 ohms to the signal path it effects a change in the same direction of using the ER-4P -> ER-4S cable. It reduces the amount of bass while making it go a little deeper. It made the mids seem more pronounced while taking off a little off the top. It sounded really detailed with the right amount of bass.


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So could some of you try the following setup and offer me your opinions on the changes? The reason I ask is that I really like it and I'd like to hear any strengths and weaknesses you hear with this setup versus just using bass boost. The setup is as follows:

Amp: Xin Supermini-3
Headphones: Etymotic ER-4S
DC-DC boost: ON
Impedence: +75 ohms
Gain: default 5
Crossfeed: OFF

Going from left to right on the jumpers:

First Two: Down
Second Two: Up
Third Two: Down
Fourth Two (after the gap): Up

The jumper near the LED: Up

Please try it and let me know how you feel about it.

 

[gerG]

Hi sxr71.

I have tried this a couple of times. More impedance boosts relative treble, and the bass boost does the same on the other end. It is sort of loudness compensation, so not bad at very low levels. I would really like to re-contour the bass boost. I think xin can do it, but I am not going to bother him right now.

One thing I have noticed about the mini is how well it works with the ER4s. I am content with the bass even at low levels. They just work great together.

Unfortunately now I want a supermacro. Funny how that works.


gerG

 

[sxr71]

Quote:

Originally Posted by gerG Hi sxr71. I have tried this a couple of times. More impedance boosts relative treble, and the bass boost does the same on the other end. It is sort of loudness compensation, so not bad at very low levels. I would really like to re-contour the bass boost. I think xin can do it, but I am not going to bother him right now. One thing I have noticed about the mini is how well it works with the ER4s. I am content with the bass even at low levels. They just work great together. Unfortunately now I want a supermacro. Funny how that works. gerG

Actually it boosts mids from 2-6KHz and reduces treble from 7KHz-9KHz, but you're right it boosts from about 13KHz-16KHz. So I guess the extra mids I heard were real. The boost between 13-16KHz is pretty high up there and is operating in the region of overtones only so it might be adding a little "sparkle" to the sound. I predominantly heard a reduction of treble as in probably the 7-9KHz reduction as our ears are more sensitive there than in the 13-16KHz area.

Take a look at this: http://www.etymotic.com/ephp/er4-wrfy.aspx

Recontouring the bass boost sounds like a good idea but I suspect we'll have to wait for Xin to get less busy and we'll have to send our amps back to him for a while.

 

[gerG]

Hey man. Sorry to go missing. They cut off my access from work. That means no contact for most of my waking hours...during the week. But now it is officially the weekend!

I think that the differences in the treble are subtle, but there. Bear in mind that the effect due to added resistance is very nonlinear. Most changes are in the first few ohms, then it drops from there. Here is a measurement of Ety ER4s, driven with supermacro (henceforth "sm"). The trace with the boosted treble is the +75 ohm:

I don't have the ER4P anymore, but for comparison, here is the same test with the Shure E4c. Again, the trace with increased treble is the +75 ohm case:

Finally, the Ety ER4S baseline compared to +75 ohm + bass boost:

Please don't get too hung up on the high frequency details of these measurements. They are only intended for relative comparison. The other issues will be the subject of another thread.

Notice that the bass boost intrudes well into the midrange.


gerG

 

[goto2003]

Very interesting tweak. ER4B differs from ER4s primarily in 5K-8K frequency range. It seems adding 75ohm to ER4s makes ER4S more like ER4B.

 

[gerG]

Oops, forgot this one. The delta of adding 75 ohms to the ER4s:

gerG

 

[goto2003]

No kidding

ER4B has a 220nf (?) capacitor and a 75ohm resistor in the cable, and the capacitor is the only different between B and S. I am curious how do you test the f-response of the ER4S (+75ohm)?

 

[gerG]

Hi goto!

All of these data were taken with the iem driven by a Xin Supermini amp, fed pink noise from a dac. The iem was coupled to a test mic using a very simple coupling device. Not a great simulation of the ear canal, but it does provide some important boundaries. More importantly, it was the same for all tests. The data is all "wrong", but it can be compared on a relative basis. The measured difference due to the added 75 ohm is less than 1 db, and all in the treble range. I believe that the ER4B is more like 5 db (ouch).

I should clarify my reference to the changes being greatest for the first few ohms: that would be for the ER4P. The ER4S are already most of the way there, so not much more to be had with resistance alone. I used the Shures because they don't have much resistance, so they can be changed quite a lot.


gerG

 

[goto2003]

Nice test. BTW, I just got to know that Ni-MH battery is recommended for the Mini3 and Micro-3. It seems that Alkaline battery doesn' t like the DC boost at all.

http://www.fixup.net/talk/topic.asp?TOPIC_ID=1468

 

[gerG]

Whoa, good tip, thanks. As it so happens, I was using alkalines (Duracell Ultra) with the V boost on. I don't think that it will affect these results, but I will recheck tomorrow. Too tired right now.

Good night.

gerG

 

[digitalcat]

I guess I'll have to grab some Ni-mh batteries for my new amp..