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Minidsp 2x4HD and Marantz PM8005

The input/output you should use are these.
Pre out to miniDSP input.
miniDSP output to Power amp direct in.
Then you can keep the amplifier with your devices hooked up the way it is.
View attachment 419578
Here is a block diagram of how the subwoofer would be integrated.

1737138192818.png


Also see
 
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Hi, thanks for your efforts. Curious in how you have done the cropping.
I do notice the lows are now not included. I already read that the lows take up most taps, so that is probable why... (correct?).
Will give it a listen though.
If you mean that the line doesn't extend all the way to 2Hz, you're looking at the wrong line

The extra-squiggly line that stops short of 10 is your file, the smoothed line that goes down to 2 is mine. How far down to the sub Hz it reads is just an artifact of REW, that I compensate for in the case of the 1024 tap filter by adding zeros after the end (and I overcompensated)

A short impulse won't crop out your lows, it will just not be able to control their response in any resolution. e.g. that's why the graph is smoothed out.

I did the cropping in Audacity, used the dB view of the vertical axis to see the low level content of the impulse more clearly (after setting it to go down to -145dB).

Added lead in and lead out via "Fade in" and "Fade out" commands.
 
If you mean that the line doesn't extend all the way to 2Hz, you're looking at the wrong line

The extra-squiggly line that stops short of 10 is your file, the smoothed line that goes down to 2 is mine. How far down to the sub Hz it reads is just an artifact of REW, that I compensate for in the case of the 1024 tap filter by adding zeros after the end (and I overcompensated)

A short impulse won't crop out your lows, it will just not be able to control their response in any resolution. e.g. that's why the graph is smoothed out.

I did the cropping in Audacity, used the dB view of the vertical axis to see the low level content of the impulse more clearly (after setting it to go down to -145dB).

Added lead in and lead out via "Fade in" and "Fade out" commands.
Ok, great! I guess I will load them up in Roon dsp first, so I can a/b them…
 
The input/output you should use are these.
Pre out to miniDSP input.
miniDSP output to Power amp direct in.
Then you can keep the amplifier with your devices hooked up the way it is.
View attachment 419578
Ok, I followed the advice and went for a Minidsp. Spend more money on it and went straight for the Flex (I read 2x4HD gives pops when shutting it down and on while amplifier powered, but dissapointingly the Flex does that also...).

I must be stupid though: I can not figure out how it works...
Pre-amp to the analogue in, analogue out 1 and 2 to the Power-amp of the pm8005. Analogue 3 to the subwoofer.
With the flex on, the sub get signal. With the flex off not. As I would expect.

BUT: nothing happens when I dial the gain settings on the input or outputs of the flex... Or set filters whatsoever..: when muting I can see that the flex stops processing it, but sound signals still pass through??
 
Ok, I followed the advice and went for a Minidsp. Spend more money on it and went straight for the Flex (I read 2x4HD gives pops when shutting it down and on while amplifier powered, but dissapointingly the Flex does that also...).

I must be stupid though: I can not figure out how it works...
Pre-amp to the analogue in, analogue out 1 and 2 to the Power-amp of the pm8005. Analogue 3 to the subwoofer.
With the flex on, the sub get signal. With the flex off not. As I would expect.

BUT: nothing happens when I dial the gain settings on the input or outputs of the flex... Or set filters whatsoever..: when muting I can see that the flex stops processing it, but sound signals still pass through??
You say that when changing the gain in the Flex, it doesn't change the volume?
How does your matrix settings look like in your Flex settings?
And you have connected it like so:
1738345015985.png
 
But how does the routing look like in you Flex settings?
Input 1 to output 1, no attenuation (or with: makes no difference), input 2 to output 2, and both input 1 and 2 to output 3 (the sub).
Can I ask: do you also have a PM8005? I mean: can it be that the Marantz amps do not allow for a pre-processor in the chain?
 
Input 1 to output 1, no attenuation (or with: makes no difference), input 2 to output 2, and both input 1 and 2 to output 3 (the sub).
Can I ask: do you also have a PM8005? I mean: can it be that the Marantz amps do not allow for a pre-processor in the chain?
Hi

No, I don’t. But the pre-out and power amp-in configuration is not unusual at all -it needs to be a loop to function properly. Other brands offer this feature as well. The PM8005 connects its preamp to its power amp using the bars between the two sets of RCA jacks, so there shouldn’t be any need for an "allowance."

Does the Marantz have a Pure Direct button, setting, or something similar?

You still have all your devices connected to the inputs of the PM8005, right?
 
Hi

No, I don’t. But the pre-out and power amp-in configuration is not unusual at all -it needs to be a loop to function properly. Other brands offer this feature as well. The PM8005 connects its preamp to its power amp using the bars between the two sets of RCA jacks, so there shouldn’t be any need for an "allowance."

Does the Marantz have a Pure Direct button, setting, or something similar?

You still have all your devices connected to the inputs of the PM8005, right?
The Marantz has a "direct source" button as well. But makes no difference. Thee are also no bars between the two sets of rca jacks, so I gues it works differently...
When using it only as power amp the settings on the minidsp work... (in power amp mode no sound and when not muted gain settings work, in other mode sound... and gain makes no difference).
minidsp Screenshot 2025-02-02 183822.png

I guess I can only use the Flex as a pre-amp, so will then need a phono amp between turntable... Not too happy with this scenario...
 
Alright. Disconnect the RCAs from the Marantz Power Amp Direct In.

Play a tone or some audio, and monitor Input 1 and Input 2 on the Flex. Does the signal level change when you adjust the volume on the Marantz?

Next, observe Output 1 and Output 2 on the Flex while adjusting the volume on the Marantz. Does that level change as well?
 
Ok: the Marantz needs either an external pre-amp or power amp, it is not a loop.

Now I wonder: should I use the minidsp as pre-amp and Marantz as poweramp (and use an extra phono amp for turntable), ór introduce my old, still lying around waiting to be sold, PM7004 as pre-amp/poweramp so the minidsp can be used as processor in between?
That would be the most convenient usage wise, but maybe not best option soundwise?
 
To be sure: output 1 and 2 have no connection (as not connected to power amp of Marantz)?

Inputs follow volume. Outputs seem to get nothing.
Exactly.

Alright. So you have now confirmed that the Marantz pre-amplifier signal get's into the Flex proper.
1738643556274.png
But the output signal bars don't react to volume change from the Marantz?
1738643629023.png

You are certain that you haven't muted the two output channels, right? (They are muted on the picture).
 
Exactly.

Alright. So you have now confirmed that the Marantz pre-amplifier signal get's into the Flex proper.
But the output signal bars don't react to volume change from the Marantz?

You are certain that you haven't muted the two output channels, right? (They are muted on the picture).
Sorry I was wrong: with the Flex inputs from pre-amp and no poweramp connection, the minidsp follows the volume of the Marantz on both inputs and outputs.
 
Alright.


We now understand that:
  • The Marantz preamp transmits a signal.
  • The Flex receives this signal.
  • The Flex then routes the signal to the Flex RCA outputs.
Next, we need to eyeball the output signal level from the Flex RCA outputs.
Play something again and observe both the Flex input and output levels in the software. They should display similar levels on both the input and output meters if the gain is set to 0 dB and no EQ adjustments are applied.
 
Alright.


We now understand that:
  • The Marantz preamp transmits a signal.
  • The Flex receives this signal.
  • The Flex then routes the signal to the Flex RCA outputs.
Next, we need to eyeball the output signal level from the Flex RCA outputs.
Play something again and observe both the Flex input and output levels in the software. They should display similar levels on both the input and output meters if the gain is set to 0 dB and no EQ adjustments are applied.
They do. The only issue is that the Marantz only allows input to the poweramp when the switch is pressed. In that case all pre-amp is shut off. So no loop possibility...
 
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