How important is impedance matching?

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zhopudey
Stammgast

#1 erstellt: 06. Okt 2007, 13:49

Hi, I'm back again with my neverending problems

I'd gone to surrealistix's place today. Had taken my sound card along. He has a really nice setup:

PC(Creative X-fi spdif)-> Odeon Lite Dac -> Odyssey Candela Tube Preamp -> Odyssey Stratos Poweramp -> Monitor Audio RS 6 speakers.

We plugged in my sound card, and tried 4 diff configs:

1) PC > Analog > Pre > Power

This sounded quite nice. There seemed to be some overall noise. Highs were not completely clear, and bass was not as tight as it could have been. But overall, it was quite enjoyable.

2) PC > spdif (standard rca cable. Not special digital one) > DAC > Amp.

The dac has a buffered output with a volume control. The sound suddenly opened up

Everything was better, but it was a bit brighter than before. Some mp3s sounded a bit harsh at the top end. The tube pre must rolling of the highs, hence we heard a difference here.

3) PC > spdif > DAC > Preamp > Power Amp.

Waah! Now everthing was perfect in the world.

Dido was velvety. Prodigy was barbaric. Dire Straits came with a heavy machine gun.Massive Attack was like depth charges dropping all around...And he played some jazz numbers which had sounds just floating in the air like butterflies. Well you get the general idea, I'm not any good at this

4) Finally we tried to reproduce my situation.
PC > Analog > Amp.

Volume was controlled through my soundcard. Anndddd...it was still pretty good! It was somewhat worse than "1" above, but still very listenable.

So what is wrong in my setup?

Why doesn't my amp like my soundcard?

(which brings me to the title for this thread :P)

Surrealistix is lending me his DAC next week. I'm hoping it'll solve my problem, else I fear something must be seriously wrong.

Will keep you guys posted.

Voodoo_CHild
Stammgast

#2 erstellt: 06. Okt 2007, 17:24

zhopudey schrieb:

Hi, I'm back again with my neverending problems :D

hey zhopudey...this time someone else's sailing on the same boat as yours...with a different problem

keep them coming!

PS - Most of the problems can be solved

bombaywalla
Stammgast

#3 erstellt: 06. Okt 2007, 19:31

zhopudey schrieb:

Hi, I'm back again with my neverending problems

So what is wrong in my setup?

Why doesn't my amp like my soundcard?

(which brings me to the title for this thread :P)

Surrealistix is lending me his DAC next week. I'm hoping it'll solve my problem, else I fear something must be seriously wrong.

Will keep you guys posted.

i think that your sound-card DAC does not
(1) have a large enough output to drive the power amp directly. look @ your power amp specs & find out what its input voltage signal sensitivity is. Does it match up w/ what the soundcard DAC can provide?
if you are operating at the max volume of the soundcard DAC to obtain reasonable listening volumes then any reduction in soundcard volume will only make the fidelity worse.
(2) the soundcard was designed to be used more for a digital output rather than an analog output i.e. the DAC quality is not good. you might need to spend more money to get a better quality DAC.

zhopudey
Stammgast

#4 erstellt: 07. Okt 2007, 05:05

bombaywalla schrieb:

For some mysterious reason, I can't find output specs for my sound card.

if you are operating at the max volume of the soundcard DAC to obtain reasonable listening volumes then any reduction in soundcard volume will only make the fidelity worse.

Ahh, but I use my passive volume control at home. Sound card volume is always full. And if I connect the card directly, then I have to reduce volume, or I'll probably end up blowing my speakers.

(2) the soundcard was designed to be used more for a digital output rather than an analog output i.e. the DAC quality is not good. you might need to spend more money to get a better quality DAC.

Well, we tested that as well, and my card held its own just fine. The dac was better, but then it costs 10 times more than my card.

Arj
Inventar

#5 erstellt: 07. Okt 2007, 05:25

Zhopudey, i believe what bombaywalla wants to say is that the symptoms may be the samke but your problem is not the same as your friends.

your problem seems to be due to your Source-Amp-speaker combinations which is unique to that setup. the pre is not buffering the amp load and shielding the sourcew from it hence your problem.

if you are not looking at an active pre then changing your amp into an int am (even if it means downgrading) might give you better results.

B'Walla/Amp nut a slightly techie Quest for you. the following is the impedance curve of the audience 40..should not be very different for Zhops speakers as well

the lowest impd seems to be at around 50-70hz and then around 200-300. both of which areas do contribute to the "fullness " of sound. do you feel the speakers load is being passed on to the source indirectly vi the amp (due to lack of enough input juice) and hence a lack of body ? room acoustics may oly add to it as these two freq are affected by suckouts as well as humps !

zhopudey
Stammgast

#6 erstellt: 07. Okt 2007, 05:41

Arj schrieb:

Ohh, can this happen?

Now I can't wait to try out with the surrealistix's dac. Keeping all my fingers and toes crossed

zhopudey
Stammgast

#7 erstellt: 16. Okt 2007, 15:34

Wheeee

Ok, so I'll spare everyone and not start a new thread

So I was sitting at home, wondering what voodoo magic to invoke to make my system sound better. There were so many variables to take care of, I didn't know where to start. So I decided to tackle the biggest variable 1st - the room

So I huffed and I puffed, and somehow managed to drag my stands out to the living room. Its 'L' shaped, and I placed the speakers length wise in the center, firing down one arm of the 'L'. Speakers were about 2 feet from the rear, and about 6 feet apart. One speaker was around 4 feet from the side wall, while the other had the other arm of the 'L' beyond it. And I was sitting some 8 feet away.

The living room has the same flooring, which bhagwan69 had pointed out is a big no-no

But there are plenty more sofa/chairs with nice thick upholstery, and thicker curtains on the windows behind me.

So I fired up my PC, prayed to the audio gods, and started the music.

And there was bass! Without any boom! And the mids and highs suddenly seemed better

Of course, the bass was not as good as I'd heard at surrealistix's place (Monitor Audio RS6), but I would be stupid to expect that from bookshelves

I kept playing track after track, and tried a number of movies as well. Everything was so much better

The sound seemed to somewhat justify me almost going bankrupt buying these

(Well not completely, but somewhat :P)

Now what do I do with my room??

Arj
Inventar

#8 erstellt: 16. Okt 2007, 16:55

zhopudey schrieb:

Now what do I do with my room??

er.. sell it ??

congrats on solving the mystery of the missing (hidden) bass.
the problem may actually be your placement rather than the room so perhaps a different placement might work ..

zhopudey
Stammgast

#9 erstellt: 16. Okt 2007, 18:53

Today, I placed them lenghtwise in my room. About 18" behind them, and 2-3' on the sides. 5' apart, and I sit around 7' away. Quite an improvement over the earlier placement

Though not as good as in the living room.

The negative point being, the speakers are blocking the wardrobe, so I can't access my fresh clothes.

Arj
Inventar

#10 erstellt: 17. Okt 2007, 05:32

zhopudey schrieb:

The negative point being, the speakers are blocking the wardrobe, so I can't access my fresh clothes. :(

Cmmon you are a budding audiophile..music is more important than clothes!