Do I have an impedance mismatch?

[juniper]

So I was noticing that the sound of my system wasn't as loud as I like sometimes. I am biamping using a dx 38 and even with the volume on my cd player/preamp at 9 I am only registering 0.3 watts.... My bass amp is 1.62 volts at 60k ohms, my amp for the highs is 22k ohms and my cd players line level output impedance is 10ohms. The dx 38 manual says its output impedance is <100ohms, min. load impedance is 600ohms .Also my bass amps gains are pinned but the controls aren't working, but the amp for the highs volume control works.... I have no clue if these numbers are ok? Thanks any info would be great!!!!!

[Coytee]

Are  you going directly from your CD player into your DX?  I don't understand most of those numbers but I believe the Dx, being a commercial type unit, "expects" a higher voltage than normal residential components might put out. 

 

I have two preamps I have used and one of them can be 100% maxed and still not drive the DX properly.

 

Look at your input lights (on the left)  You want them maxed but, not into the red.  Are they hitting near the top of their range?

[xxJPMxx]

. My bass amp is 1.62 volts at 60k ohms

 

Please be more specific. Are you saying the input impedance of your bass amp is 60k and that you measure 1.62V across the input coming from the DX?

 

 

 

my amp for the highs is 22k ohms

 

Again the input impedance of the highs amplifiers is 22k? What are you measuring across it's input from the DX?

 

 

 

and my cd players line level output impedance is 10ohms.

 

That is common, and can easily drive the DX's 20k input impedance.

 

 

I am assuming your CD player is putting out 1.6V and so the DX is putting out 1.6V to each amp.

 

 

 

I am biamping using a dx 38 and even with the volume on my cd player/preamp at 9 I am only registering 0.3 watts

 

Where and how are you measuring this? Which amp? What are each amplifiers input sensitivity, if they are greater than 1.6V then you arent driving them hard enough,   you can feed the DX with up to 24V input, the max output will be 8.7V.

Edited November 30, 2015 by xxJPMxx

[babadono]

Yes you have an impedance mismatch, this is normal for line level audio signals. Sounds like you are mixing balanced and unbalanced equipment. How is it wired? There are some on this forum that have had no problem mixing the two, others are not so fortunate.

[juniper]

Are  you going directly from your CD player into your DX?  I don't understand most of those numbers but I believe the Dx, being a commercial type unit, "expects" a higher voltage than normal residential components might put out. 

 

I have two preamps I have used and one of them can be 100% maxed and still not drive the DX properly.

 

Look at your input lights (on the left)  You want them maxed but, not into the red.  Are they hitting near the top of their range?

I am going directly from the cd to the dx... as far as the lights, they are barely hitting the second set of lights at -24.....  No where near the top of the range, I might need a preamp..... ugh.... I have tried about 10 of them......Thanks Coytee!!! 

[juniper]

 

. My bass amp is 1.62 volts at 60k ohms

 

Please be more specific. Are you saying the input impedance of your bass amp is 60k and that you measure 1.62V across the input coming from the DX?

 

 

 

my amp for the highs is 22k ohms

 

Again the input impedance of the highs amplifiers is 22k? What are you measuring across it's input from the DX?

 

 

 

and my cd players line level output impedance is 10ohms.

 

That is common, and can easily drive the DX's 20k input impedance.

 

 

I am assuming your CD player is putting out 1.6V and so the DX is putting out 1.6V to each amp.

 

 

 

I am biamping using a dx 38 and even with the volume on my cd player/preamp at 9 I am only registering 0.3 watts

 

Where and how are you measuring this? Which amp? What are each amplifiers input sensitivity, if they are greater than 1.6V then you arent driving them hard enough,   you can feed the DX with up to 24V input, the max output will be 8.7V.

 

I  didn't measure, I just pulled the "specs" from the manuals I have. I can try to find the other info, and post it, and maybe it will help, getting closer to an answer... The amps I am using are a Yamaha MX1000u which is 260watts per channel for the low input, and a Panasonic saxr 55 for for the high input which is around 100watts per channel....

[xxJPMxx]

Have you found that the Panasonic amp is much louder for the highs than the Yamaha? The input sensitivity for the Panasonic amp for CD, Tape, TV, DVD, Recorder, VCR1, and VCR2 are all 27mV for IHF '78 models and 200mV for IHF '66 models. The Yamaha on the other hand has an input sensitivity of 1.6V, big difference. Even though there is a more than double wattage difference, that will not make much of a difference in db, just higher headroom. You will basically have to turn the Yamaha's volume control up a lot more than the Panasonic's.

[juniper]

Yes you have an impedance mismatch, this is normal for line level audio signals. Sounds like you are mixing balanced and unbalanced equipment. How is it wired? There are some on this forum that have had no problem mixing the two, others are not so fortunate

Thanks, for the info!!!! Still scratching my head..... The way it is set up, XLR/RCA, cd player to the dx 38's L mono, and R. Panasonic saxr cd input to dx 38's Hi output 2&4, Bass amp to 1&3 output.

Edited November 30, 2015 by juniper

[juniper]

Have you found that the Panasonic amp is much louder for the highs than the Yamaha? The input sensitivity for the Panasonic amp for CD, Tape, TV, DVD, Recorder, VCR1, and VCR2 are all 27mV for IHF '78 models and 200mV for IHF '66 models. The Yamaha on the other hand has an input sensitivity of 1.6V, big difference. Even though there is a more than double wattage difference, that will not make much of a difference in db, just higher headroom. You will basically have to turn the Yamaha's volume control up a lot more than the Panasonic's.

More great info.... yes it is louder and I had to turn the volume all the way up on the Yamaha.... odd thing is at one point the Yamaha's dual gain controls worked, now its just a constant feed that I have no control over but still registering only 0.3 watts, whereas the pany unit's volume control still functions... very odd.. thanks again to you and all!!!!!!

[Coytee]

I'm not technical enough to know what the impedance of "A" verses "B" does for you.

 

I have however, found out the hard way that you need sufficient voltage to drive the Dx and it sounds like you're not getting enough irrespective of what the impedance conversation might mean.

 

Welcome to the world (madness) of mixing residential and commercial components!!

 

I had a real mish-mash of an issue in my beginning.  I had one power amp (dbx BX-1) that had a 1V input sensitivity, my HF amp, McIntosh MC-2102 had as I recall, a 2 1/2V input sensitivity.

 

They both  had a fixed gain so by the time I was getting a single light on my DX to illuminate, the sound was thunderous.

 

I ended up selling both amps and today, use a Crown K2 that has some gain control on the amps.  Now I can dial the gain structure together much better than before.

 

No idea what to say about the CD player.  I do wonder though, how do you control the volume unless the CD player has a variable output? 

[Coytee]

Have you adjusted for the gain difference (of your amps) inside  your DX?

 

20*Log(V1-V2) if I recall correctly where V1 and V2 are the respective input sensativities of your amps.  That will tell you by how much you want to attenuate the more sensitive amp.  Once done, they will be in unison to each other.

 

Thing to remember about the formula above, if  you SWAP the numbers V1 and V2, you will get the same number but, a different sign in front.  one method gives for example, a positive 3.4 and swapping the numbers would then give a negative 3.4 (or whatever the value may be)

 

Don't pay attention to the positive or negative, just know that it's the number you want and reduce the more sensitive amp by that many db's inside your Dx.

[juniper]

I'm not technical enough to know what the impedance of "A" verses "B" does for you.

 

I have however, found out the hard way that you need sufficient voltage to drive the Dx and it sounds like you're not getting enough irrespective of what the impedance conversation might mean.

 

Welcome to the world (madness) of mixing residential and commercial components!!

 

I had a real mish-mash of an issue in my beginning.  I had one power amp (dbx BX-1) that had a 1V input sensitivity, my HF amp, McIntosh MC-2102 had as I recall, a 2 1/2V input sensitivity.

 

They both  had a fixed gain so by the time I was getting a single light on my DX to illuminate, the sound was thunderous.

 

I ended up selling both amps and today, use a Crown K2 that has some gain control on the amps.  Now I can dial the gain structure together much better than before.

 

No idea what to say about the CD player.  I do wonder though, how do you control the volume unless the CD player has a variable output? 

Thanks Coytee!!! I think I am feeling your ex pains........ The cd player does have a variable output.  I thought that if it worked in my last system, which were based around  M19's, with fairly expensive passives x-overs, it would work easily with the active dx-38..... I think I was wrong...  it still  sounds very sweet though, just want a little more gain....

[juniper]

Have you adjusted for the gain difference (of your amps) inside  your DX?

 

20*Log(V1-V2) if I recall correctly where V1 and V2 are the respective input sensativities of your amps.  That will tell you by how much you want to attenuate the more sensitive amp.  Once done, they will be in unison to each other.

 

Thing to remember about the formula above, if  you SWAP the numbers V1 and V2, you will get the same number but, a different sign in front.  one method gives for example, a positive 3.4 and swapping the numbers would then give a negative 3.4 (or whatever the value may be)

 

Don't pay attention to the positive or negative, just know that it's the number you want and reduce the more sensitive amp by that many db's inside your Dx.

Thanks Coytee!!! I hope this is the answer!!! I haven't adjusted for the amps, is this a race software input or can it be done from the front panel? If anyone has more info, please lead on!!!

Edited November 30, 2015 by juniper

[CECAA850]

You need a Cleanbox.

[Coytee]

is this a race software input or can it be done from the front panel?

 

 

"yes"

 

 

Meaning, you can do it from either location.  Go into Edit mode and as I recall from rusty memory, go to gain or something.  Just remember to reduce your MORE sensative amp....and that is the one with the LOWER input number.

 

Carl is right in that a Cleanbox would help.  I might have one that I used to use.  I wanted to get away from it but it clearly helped step it up a bit.

 

I've read some negatives about them.  One in particular if I recall, was that it truncates the LF a bit and the way around that is to swap out a cap on the inside.

 

I know I have one.  I just don't know if I can find it.  If I can, you are welcome to try it out.

[CECAA850]

it truncates the LF a bit

 

I think below 20Hz on the original.  Maybe they addressed it on the II?  I'd have to look it up.

[xxJPMxx]

20*Log(V1-V2) if I recall correctly where V1 and V2 are the respective input sensativities of your amps. That will tell you by how much you want to attenuate the more sensitive amp. Once done, they will be in unison to each other.

 

Wouldn't it be 20*Log(V1/V2) ?

 

V1=1.6V for the Yamaha and V2=.2V for the Panasonic   1.6/.2=8       The Panasonic is 8 times more sensitive vs. the Yamaha.

 

(Log8)20 = 18db   

 

You will want to attenuate the Panasonic 18db through the DX. Also what speakers do you have hooked up to the Yamaha? You will want to set the correct load for them.

[Coytee]

Yep, it is divided.  My bad.  (I was at work)

 

Thanks for the correction.

[Coytee]

Been a long time since I've messed around inside the RACE program but it looks like you would click on the far right items (Out 1, Out 2....)

 

Keep in mind which amp is plugged into which output channel and you can attenuate the Panasonic there.

 

This mixing/matching was one reason I went with the same amp.  I wanted to simplify things.  The Crown's have detents on their gain knobs so to keep them in the ballpark with each other, I go to the "5th" click if I want every day listening or the "20'th" click if I want to annoy the neighbors.

 

Keeping them toned down a bit allows me to use more of the output from my preamp.

 

By the way, none of this is original thinking on my part.  It was offered to me through various people here on the forum.  I, being dumb as a rock, didn't know diddly squat about this stuff but paid attention.

[juniper]

You need a Cleanbox.

 

You need a Cleanbox.

Thanks CECAA, did some reading about the cleanbox, great advice!!!! never heard of one...... in your experience does it introduce noise, or distortion?