Need help with Output Impedance match. Learn the lesson from me!!!

[SE_ClassA]

I had an old NAD CD player. Few months back one of my friends wanted to upgrade his CD player and offered me his Audio Aero 24 / 192 Prima at a great price. It was a relatively new CD player at about 5 times the price of my old NAD CDP.

It had it all. Upsampling, Tube output, 24bit DAC 192 kHz ….and the sound of this player in my friend’s house was JUST AMAZING!

To me it was just an irresistible offer. So, a week later my wallet becomes the “Biggest Looser” and my old NAD was officially retired. The improvement was obvious. The mid became more refined and the high was very sweet (thanks to the upsampling). I was supposed to listen to it happily ever after…

However, the story taken a twist when I pluged my old NAD CDP back one day. I just wanted to assure my self that I have made a great decision…

Then it striked me. Something was wrong! The NAD didn’t sound bad at all. The first thing I notice was the better bass control and mid texture. Yes, Audio Aero was good but the bass and the top end was not as natural and full body as I would like. Compares to my old NAD it sounded very “refined” with a touch of gloss. It was like my music has been sugar costed and all edges has been round off… Is it good? I guess it depends on your personal taste.

The point is my old NAD provides faster bass impact and a fuller mid…! But when I bought the Audio Aero back to my friend’s place the bass control and the mid improve considerably.

So. The Audio Aero could not perform to its true potential in my system!!!!

My friend suggested this could be an Impedance mismatching issue. I looked up a few posts and there was not clear defined rule that I can follow. It seemed that the relative high output impedance of my Audio Aero (1kohm) was not a good match for my tube amp which has a relatively low input Impedance.

The question is: what can I do to lower the output Impedance of my CD player? Please bear in mind that I am not very good at building thing up from the starched.

[janneman]

Originally posted by SE_ClassA
I had an old NAD CD player. Few months back one of my friends wanted to upgrade his CD player and offered me his Audio Aero 24 / 192 Prima at a great price. It was a relatively new CD player at about 5 times the price of my old NAD CDP.

It had it all. Upsampling, Tube output, 24bit DAC 192 kHz ….and the sound of this player in my friend’s house was JUST AMAZING!

To me it was just an irresistible offer. So, a week later my wallet becomes the “Biggest Looser” and my old NAD was officially retired. The improvement was obvious. The mid became more refined and the high was very sweet (thanks to the upsampling). I was supposed to listen to it happily ever after…

However, the story taken a twist when I pluged my old NAD CDP back one day. I just wanted to assure my self that I have made a great decision…

Then it striked me. Something was wrong! The NAD didn’t sound bad at all. The first thing I notice was the better bass control and mid texture. Yes, Audio Aero was good but the bass and the top end was not as natural and full body as I would like. Compares to my old NAD it sounded very “refined” with a touch of gloss. It was like my music has been sugar costed and all edges has been round off…L Is it good? I guess it depends on your personal taste.

The point is my old NAD provides faster bass impact and a fuller mid…! But when I bought the Audio Aero back to my friend’s place the bass control and the mid improve considerably.

So. The Audio Aero could not perform to its true potential in my system!!!!

My friend suggested this could be an Impedance mismatching issue. I looked up a few posts and there was not clear defined rule that I can follow. It seemed that the relative high output impedance of my Audio Aero (1kohm) was not a good match for my tube amp which has a relatively low input Impedance.

The question is: what can I do to lower the output Impedance of my CD player? Please bear in mind that I am not very good at building thing up from the starched.

Tube amps generally have a high input impedance. How much is it? The test is to use another amp to see if that's it.

There is also the issue of different room acoustics and different speaker systems. And the additional shining highs of the Aero would lead to thinking that the bass/midrange is less strong and well controlled. These are many interrelated issues and follow a well-known pattern. Before you start fiddling with the CD player I would first do a few more tests. It is VERY uncommon that 1k Zout of the CD player gives these result.

Anyway, putting a resistor of 1k to ground from the CD output makes the Zout 500 ohms. It also lowers the volume so you need to crank that up but if you carefully match levels it can be a quick test to see if that is the problem. And ask a few friends to come around, it is EXTREMELY difficult to judge these things with some objectivity if you are heavily involved yourself. For instance, your conclusion that the Aero cannot perform to its true potential in your system is an example of expectations not supported by factual data. Maybe it already IS performing to its potential.

Jan Didden

[kt88music]

As far as I can see you only have two options.

1. You can look around for a good buffer project and build one up your self. There are a few good designs around. You can chose from a simple opamp base design to more a more complicated fully discrete component design¡K ƒº have fun.

2. If you are not very good with your soldering then you can buy a fully assembled buffer designed for CD players.

Musical fidelity tube buffer: http://www.musicalfidelity.com/products/smlx/x10v3.html

Burson HDAM Buffer: http://www.bursonaudio.com/Burson%20HDAM%20Buffer.htm

These products will help you lower the output Impedance of your CD player but which one is better I have no idea

[SE_ClassA]

Thanks for the tips guys. I will investigate into your various suggestions.

Thanks.

[SE_ClassA]

Hi Guys,

Over the weekend, my friend bought over his solid state amplifier to try on my system. Audio Aero definiately perform better when team up to his amplifier! His amplifier is cheaper than my single ended tube amp! So looks like impedance is the issue.

KT88, Those Bursonaudio Buffer and Musical Fedility Buffer seems like good options.

But these Buffer idea is new to me. I will look into them further.

Thanks very much guys,

[SE_ClassA]

KT88,


I was looking into those Bursonaudio upgrade kits. I wrote to them and they said that their Burson Buffer will definitely resolve the mismatching of impedance between my player and tube amp.


On their website, I downloaded a step by step instruction on how to modify a Marantz CD52. I was surprised to people still spend money on this old 40euro machine because I had one under my bed for years collecting dust. So I downloaded their instruction and bought a pair of their Burson dual HDAM to see if their products are as good as they claimed to be.


After I installed their dual HDAM onto my CD52 the improvement was amazing! the sound became very natural, very relax and the stage widen up considerably. It actually sounded better than my NAD which is 10 years more advance than CD52!


I will try to install the HDAMs into my Audio Aero next, if there is still impedance mismatch, I will try their buffer. Just like their football team, Hi end audio stuff is finally coming out of Australia. ha ha


Here is a couple of photos of my old CD52. From now on, I will use it to test DIY products.

[Rocky]

What tubes are in the input stage of your amp? Sure they can't handle a higher impedance pot? or are you using TX gain?

[SE_ClassA]

My imput tubes are 12AU7*2 and 12AX7*2, driving tubes are KT88*2 SE class A. It's a very old amp, but It sounds great.

I've found a way to post photos of my Marantz CD52 upgrade with Bursonaudio HDAMs. Please take a look.

After the upgrade, this Marantz CD52 has become one of my favour CD player. It outperforms much newer and much more expensive players.

http://i6.tinypic.com/11lj3if.jpg
http://i6.tinypic.com/11lj42h.jpg
http://i5.tinypic.com/11lj6er.jpg
http://i6.tinypic.com/11lj70x.jpg
http://i6.tinypic.com/11lj809.jpg
http://i6.tinypic.com/11lj876.jpg
http://i5.tinypic.com/11lk3mw.jpg

[SE_ClassA]

[Ruach]

http://www.diyaudio.com/forums/showt...ghlight=burson

Interestingly, a lot of Burson lovers seem to register themselves on May 2006 and share the same IP at 202.7.176.xxx. This includes kt88music too.

SE_ClassA appears to be from Sydney as indicated by his IP: 220.253.22.xxx