OK all, so I just spoke to another tech. She says that the ND "does not have an output impedance because it is not an amplifier. It is just a digital amplifier". Huh? I asked: "Do you mean that the variable out is in fact a line level attenuator". She answers "correct". WTH. This still does not explain the 4.5V RMS they claim in the specs. Got to love these large manufacturers. They can't even explain what their own stuff does or how it works.
I am going to do a simple test: plug the Marantz into the peachtree through the fixed outputs and set a volume. Then switch to the variables and see what volume I am getting. I suspect 100% volume through the variables is the same as line level was.
If that is the case, think I might try the ACP+... does that make sense? Sorry to clutter the thread with this.
I am going to do a simple test: plug the Marantz into the peachtree through the fixed outputs and set a volume. Then switch to the variables and see what volume I am getting. I suspect 100% volume through the variables is the same as line level was.
If that is the case, think I might try the ACP+... does that make sense? Sorry to clutter the thread with this.
I do not have wanted SPL Zen. I'm not far off but I do need more if I want to avoid swithcing to my other amp for rock & roll etc. The Wall at 81db max is not going to cut it!
Thanks for explanation of goals and gear.
Not sure what the peachtree unit is that you mentioned above.
Yes, if the volume is the same from the fixed outputs and the variable at max, then that points to one part of the issue.
Someone much more versed in D/A products like this may say that I'm the dodo, but....
A proposed question for a Marantz tech might be:
If this unit is fed a digital signal with the equivalent of a 0dBFS 1kHz sine wave, what will my rms output voltage be using the analog variable outputs with the volume set to 100? What will the output be on the fixed output when the unit is fed the same digital signal?
I don't have enough expertise to sort though what the real issue may be, but I agree something is "off". I'd start with the output of the Marantz.
If your catalog of music is recorded well below 0dBFS (I don't know what levels are targeted by recording studios) - that may explain some of it. I dunno.... I might be tilting at windmills.
Not sure what the peachtree unit is that you mentioned above.
Yes, if the volume is the same from the fixed outputs and the variable at max, then that points to one part of the issue.
Someone much more versed in D/A products like this may say that I'm the dodo, but....
A proposed question for a Marantz tech might be:
If this unit is fed a digital signal with the equivalent of a 0dBFS 1kHz sine wave, what will my rms output voltage be using the analog variable outputs with the volume set to 100? What will the output be on the fixed output when the unit is fed the same digital signal?
I don't have enough expertise to sort though what the real issue may be, but I agree something is "off". I'd start with the output of the Marantz.
If your catalog of music is recorded well below 0dBFS (I don't know what levels are targeted by recording studios) - that may explain some of it. I dunno.... I might be tilting at windmills.
well, then just make that test with 1KHz sine, both outputs, to confirm functionality of Marantz
ACP will bring you 6db (2V/V) and even more - easily settable if you need few db on top of that
of course, one always need to differentiate - is there lack of (max. amp's) power for my speaks in my room, or there is lack of input signal in my amp
one of the ways is to do what I explained - to be sure in value of source signal
ACP will bring you 6db (2V/V) and even more - easily settable if you need few db on top of that
of course, one always need to differentiate - is there lack of (max. amp's) power for my speaks in my room, or there is lack of input signal in my amp
one of the ways is to do what I explained - to be sure in value of source signal
I must not be too dodo.
That's what I'd do, but I wasn't ready to recommend it to autodidact... I don't know enough about that product to say that if one were to accidentally short the outputs while taking that measurement if the product would release any magic smoke, go kaploooooooow, go into protection, or just shrug it off. I'd do it myself, but I don't know if they want to do that.
@Autodidactosaurus - if you're feeling froggy, and you know you can do it successfully, give it a try. DMM set to ACV. Measure the output with a test signal input. I'd use a cut RCA cable or similar and ensure that you don't short the outputs vs. going all sticky pokey with pointy probes, but I'm a big ol' fraidy cat. Others may say that my concerns are completely unfounded.
no danger of unintentional short on RCA
damn buggers didn't even declared Rout for RCA outputs, you can bet that there is at least 330R series resistor, so it can do squat current even in dead short
same as Papa did with original iteration of B1 - had 1K series resistor - to ensure it stays alive while regular Greedy Boy is plowing fields with it
damn buggers didn't even declared Rout for RCA outputs, you can bet that there is at least 330R series resistor, so it can do squat current even in dead short
same as Papa did with original iteration of B1 - had 1K series resistor - to ensure it stays alive while regular Greedy Boy is plowing fields with it
OK, I did some "testing". First, I connected the fixed outs to the Peachtree. At roughly 12 O'clock, the volume at the speaker was 82-92db on program music, so not even 1 watt (meter closer than 1M). I chose a Van Halen 5150 track because as you all know this has a lot of continuous noise as opposed to the huge dynamic swings of an orchestra. I guess what I am saying is that Van Halen is a good surrogate for white noise ;-) in the absence of testing equipment... Next I swapped to the variable outs. I did not expect to see any difference but in fact, at "100%" output, with the same volume position on the Ptree, I was up about 6db over fixed, 88-98. So there does appear to be gain in the variable (4x?), which means the second tech was wrong.
I did try to test the fixed outputs off the Marantz with a multi-meter but was not able to get any meaningful readings. I didplug it into the wall and saw 120.5 so I know it is working and in the AC range. Readings at the RCA were anywhere between nothing and 3.3V but appeared to have no relation to the music program (I even got 2.9V when the CD was not playing), so that's garbage. At least there was no magic smoke...
Next I tried boosting the volume on the Ptree. With fixed outputs, I think I began to hear distortion about 4PM on the knob, but frankly it was also playing very loud so I did not stay there for long. Plus, Van Halen is distorted by definition. Repeating with the variable set to 100%, I heard distortion around 3PM. In any case, the peachtree definitely drives the F7 much harder than the Marantz. I'm going to guess about 6db at least but my ears are not that well trained.
So I am not sure where this leaves us, without knowing what the Marantz is actually putting out voltage-wise. I read somewhere yesterday that your typical consumer source (CD/DVD) puts out -10dbV by industry convention, which is about 0.32V. If my math is right, this would be enough to drive the F7 to about 0.3W, which would be consistent with my db SPL observations when driving my F7 at 100% output with just the Marantz with classical redbox program. I'm not sure what relation any of this has to Marantz's stated specs of 4.5V but it's clear by now to me that it does not put out anywhere near this number in actuality.
Yesterday, I did not know anything about Ohm's Law. So there's progress....
And thanks Zen for directing me to that article on system gain and attenuation. I understand much better now how this all works.
I'm thinking there is no harm in building an ACP+, right?
I did try to test the fixed outputs off the Marantz with a multi-meter but was not able to get any meaningful readings. I didplug it into the wall and saw 120.5 so I know it is working and in the AC range. Readings at the RCA were anywhere between nothing and 3.3V but appeared to have no relation to the music program (I even got 2.9V when the CD was not playing), so that's garbage. At least there was no magic smoke...
Next I tried boosting the volume on the Ptree. With fixed outputs, I think I began to hear distortion about 4PM on the knob, but frankly it was also playing very loud so I did not stay there for long. Plus, Van Halen is distorted by definition. Repeating with the variable set to 100%, I heard distortion around 3PM. In any case, the peachtree definitely drives the F7 much harder than the Marantz. I'm going to guess about 6db at least but my ears are not that well trained.
So I am not sure where this leaves us, without knowing what the Marantz is actually putting out voltage-wise. I read somewhere yesterday that your typical consumer source (CD/DVD) puts out -10dbV by industry convention, which is about 0.32V. If my math is right, this would be enough to drive the F7 to about 0.3W, which would be consistent with my db SPL observations when driving my F7 at 100% output with just the Marantz with classical redbox program. I'm not sure what relation any of this has to Marantz's stated specs of 4.5V but it's clear by now to me that it does not put out anywhere near this number in actuality.
Yesterday, I did not know anything about Ohm's Law. So there's progress....
And thanks Zen for directing me to that article on system gain and attenuation. I understand much better now how this all works.
I'm thinking there is no harm in building an ACP+, right?
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Using music, which constantly varies in voltage, does not give meaningful results when trying to assess gain.
There are audio test signals that can be downloaded from the internet. Some examples:
https://www.mediacollege.com/audio/tone/download/
https://www.churchsoundcheck.com/audio-test-signals.html
There are audio test signals that can be downloaded from the internet. Some examples:
https://www.mediacollege.com/audio/tone/download/
https://www.churchsoundcheck.com/audio-test-signals.html
^ +1 
Edited to add - I think you may be conflating all the admittedly potentially confusing dB values whether they related to a digital signal at Full Scale (dBFS), a relative voltage to a known scale (dBV), or a sound pressure level (dB-SPL). An increase of 1dBFS =/= an increase of 1dBV at your outputs =/= an increase of 1dB-SPL at your ears (or measurement device).
What you're trying to determine is what a Full Scale digital signal (0dBFS) results in at the output of your Marantz unit. It should be ~4V5 for variable with the volume knob at 100%. It should be ~2V2 for the fixed output.
You could be getting lower voltages at the output simply because the music is variable both in frequency and amplitude, and an RMS DMM is not going to pick up on that very well (Ben's point), and it's likely recorded even with peaks well below 0dBFS (ZMs and my points from a post up and earlier).
Use a test signal for your input, and see how it turns out.
You may know that, but just in case.
Edited to add - I think you may be conflating all the admittedly potentially confusing dB values whether they related to a digital signal at Full Scale (dBFS), a relative voltage to a known scale (dBV), or a sound pressure level (dB-SPL). An increase of 1dBFS =/= an increase of 1dBV at your outputs =/= an increase of 1dB-SPL at your ears (or measurement device).
What you're trying to determine is what a Full Scale digital signal (0dBFS) results in at the output of your Marantz unit. It should be ~4V5 for variable with the volume knob at 100%. It should be ~2V2 for the fixed output.
You could be getting lower voltages at the output simply because the music is variable both in frequency and amplitude, and an RMS DMM is not going to pick up on that very well (Ben's point), and it's likely recorded even with peaks well below 0dBFS (ZMs and my points from a post up and earlier).
Use a test signal for your input, and see how it turns out.
You may know that, but just in case.
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Thanks for all the help guys. I will try the test tones later tonight after decorations (Honey-do). Please understand that there is nothing that does not need to be explained to me at this stage... imagine yourself explaining to a 3 year old why a car needs wheels to move.
Also, please let me know if this is gumming up the DIY ACP+ thread... I certainly did not intend to get you guys embroiled in my system complications.
Also, please let me know if this is gumming up the DIY ACP+ thread... I certainly did not intend to get you guys embroiled in my system complications.
would-it be possible to design an amplifier mid way between the J2 and ACP+ to drive high sensitivity speakers (96dB like mine)?
same power as ACA mini: 5-10W
use N Jfet at input 2SK209 (last toshiba available) and mid power P mosfet at output (for example FQP8P10 or FQP7P06) same way as UDNESS
symmetric -+15V or single 24-30V PSU
what do you think about it Papa?
same power as ACA mini: 5-10W
use N Jfet at input 2SK209 (last toshiba available) and mid power P mosfet at output (for example FQP8P10 or FQP7P06) same way as UDNESS
symmetric -+15V or single 24-30V PSU
what do you think about it Papa?
Hope everyone had a decent X-Mas. My neighbor put me in touch with a sound engineer and he agreed to come over and run some tests on my equipment. He sets up pro gear for bands locally and nationally and has been Jimmy Buffet and Huey Lewis's sound guy at one point. Interesting guy.
The long story short is that the Marantz is in fact capable of driving the F7 to full power under certain conditions. More specifically, it put out a 2.2V signal at "0db" sine wave, 1khz. The issue here is that, as there are no analog inputs to the unit, there is no way to determine whether 0db is actually that at the output. He says it is definitely not....read on. As he explains it, a hi-fi consumer device like this is designed to play a ton of digital sources, which may be recorded within a huge range of levels. Being a high end piece designed, engineered and built in Japan with "reference" aspirations, the engineers are focused on a circuit which under no circumstances introduces meaningful distortion into the signal chain. He said the refence level stuff from japan is typically engineered to stay at or below .003 or .005 THD, regardless of what is thrown at it. It is likely that the DACS have circuitry that is designed to attenuate what he referred to as overly processed signal. So while the Marantz may have a 4.5V max output spec, it will probably never reach that output under normal operation.
He brought with him test media, including CDs designed to deliver maximum dynamic range of the format and similar digital sources (USB and computer). The Marantz put out similar voltage with the various inputs, suggesting there is some sort of internal attentuation occurring. He also brought a couple of demonstration consumer CDs which were showcases of the CD format's dynamic range back in the early days of CD. He says these demonstrate the outside limit of what a source component will output under realistic playback conditions. The results are that the Marantz typically puts out somewhere in the range of 0.52-.80V of normal program playback at 100% volume (zero attenuation) which is what he calls the "RMS floor", with typical peaks to 1.6-2.2V on transients, and is capable of peaks exceeding 3.2V. This occurred on more than one of the demo CD's a Telarc digital recording of Tchaikovsky's 1812 overture with digital HDR recordings of live cannon fire and bells as part of the presentation. He measured a momentary 16V at the F7 amplifier taps in that case.
So while the Marantz will likely never reach 4.5V, it has more than enough to drive the F7 to the spec output and adding a pre-amp as a linestage gain would just push the F7 into distortion on anything having more than 3-6 db of dynamic range, which is pretty much 100% of what I listen do (I don't do MP3). I think that is what some of you were trying to tell me. Thanks for all the help.
The long story short is that the Marantz is in fact capable of driving the F7 to full power under certain conditions. More specifically, it put out a 2.2V signal at "0db" sine wave, 1khz. The issue here is that, as there are no analog inputs to the unit, there is no way to determine whether 0db is actually that at the output. He says it is definitely not....read on. As he explains it, a hi-fi consumer device like this is designed to play a ton of digital sources, which may be recorded within a huge range of levels. Being a high end piece designed, engineered and built in Japan with "reference" aspirations, the engineers are focused on a circuit which under no circumstances introduces meaningful distortion into the signal chain. He said the refence level stuff from japan is typically engineered to stay at or below .003 or .005 THD, regardless of what is thrown at it. It is likely that the DACS have circuitry that is designed to attenuate what he referred to as overly processed signal. So while the Marantz may have a 4.5V max output spec, it will probably never reach that output under normal operation.
He brought with him test media, including CDs designed to deliver maximum dynamic range of the format and similar digital sources (USB and computer). The Marantz put out similar voltage with the various inputs, suggesting there is some sort of internal attentuation occurring. He also brought a couple of demonstration consumer CDs which were showcases of the CD format's dynamic range back in the early days of CD. He says these demonstrate the outside limit of what a source component will output under realistic playback conditions. The results are that the Marantz typically puts out somewhere in the range of 0.52-.80V of normal program playback at 100% volume (zero attenuation) which is what he calls the "RMS floor", with typical peaks to 1.6-2.2V on transients, and is capable of peaks exceeding 3.2V. This occurred on more than one of the demo CD's a Telarc digital recording of Tchaikovsky's 1812 overture with digital HDR recordings of live cannon fire and bells as part of the presentation. He measured a momentary 16V at the F7 amplifier taps in that case.
So while the Marantz will likely never reach 4.5V, it has more than enough to drive the F7 to the spec output and adding a pre-amp as a linestage gain would just push the F7 into distortion on anything having more than 3-6 db of dynamic range, which is pretty much 100% of what I listen do (I don't do MP3). I think that is what some of you were trying to tell me. Thanks for all the help.