Acchuphase G-18, where in the system

[Mattia]

Hi Accuphase lovers,
I write because I have a doubt regarding the best "theoretical" placement of the G-18 EQ in my vintage Accuphase system (see signature).

I only have digital sources (the T-106 for now is not used), that is to be considered (the C-280V doesn't need to switch between sources). The switching is done by the DC-81L. The E-303x is now used as power amp (will upgrade in the future, not yet sure to wich power amp).

1) ... DC-81L --> C-280V --> G-18 --> power amp
2) ... DC-81L --> G-18 --> C-280V --> power amp
3) ... DC-81L --> C-280V --> Loop play-rec with G-18 on C-280V --> power amp (this would make sense only if I have more than one source on C-280V, for example if I use the tuner: all sources entering the C-280V will be equalised).

In summary: regarding capability to proper drive a power amp, the G-18 is equivalent to the C-280V or is better to leave the C-280V directly before power amp?


P.S. sorry for the spelling error in the thread title

[meltemi]

Originally Posted by Mattia

Hi Accuphase lovers,
I write because I have a doubt regarding the best "theoretical" placement of the G-18 EQ in my vintage Accuphase system (see signature).

I only have digital sources (the T-106 for now is not used), that is to be considered (the C-280V doesn't need to switch between sources). The switching is done by the DC-81L. The E-303x is now used as power amp (will upgrade in the future, not yet sure to wich power amp).

1) ... DC-81L --> C-280V --> G-18 --> power amp
2) ... DC-81L --> G-18 --> C-280V --> power amp
3) ... DC-81L --> C-280V --> Loop play-rec with G-18 on C-280V --> power amp (this would make sense only if I have more than one source on C-280V, for example if I use the tuner: all sources entering the C-280V will be equalised).

In summary: regarding capability to proper drive a power amp, the G-18 is equivalent to the C-280V or is better to leave the C-280V directly before power amp?


P.S. sorry for the spelling error in the thread title

I'd suggest, you check the G-18 user manual (block diagram) to find any info about how the balanced outputs realized.
If it's a mere additional phase shift stage (as in the DC-81L), I would use the recording loop.

Martin

[Mattia]

Thank you Martin!

Sadly I don't have the user manual and the product .pdf of the G-18 on Accuphase website is strangely not that deep compared to other Accuphase gear. Since the unit was launched in 1985, I think the balanced output are likely done a la DC-81L.

Btw, the product .pdf states (didn't notice before): "It is recommended to insert the G-18 between the preamplifier and the power amplifier". I don't know the technical reason for this, I thought that a preamplifier is the best option to drive a power amplifier (that is the reason for the thread).


One more question: using the G-18 after other Accuphase gear (C-280V if I follow Accuphase advise) should I set the G-18 balanced input impedance to 600 ohms or 40 Kohms?


Regarding the C-280V, I have a doubt.

Correct me if I am wrong, but one should not use the attenuation to get best results right? From what I read it is not meant to be a "permanent" setting one, but just to be used for example when one has a big pike as with record playing starting.
In my chains I generally have too much gain, and if I don't attenuate, I often am between "1" and "2" position on the volume pot. In the other system, with the C-2420, I set the gain selector to 12dB, but I think the attenuator on the C-280V doesn't work on the gain (that is 18dB) but attenuate an already "pre amplified" signal, right?

[meltemi]

Originally Posted by Mattia

One more question: using the G-18 after other Accuphase gear (C-280V if I follow Accuphase advise) should I set the G-18 balanced input impedance to 600 ohms or 40 Kohms?

40 kOhms (600 Ohms is for professional studio use).

Originally Posted by Mattia

Correct me if I am wrong, but one should not use the attenuation to get best results right? From what I read it is not meant to be a "permanent" setting one, but just to be used for example when one has a big pike as with record playing starting.
In my chains I generally have too much gain, and if I don't attenuate, I often am between "1" and "2" position on the volume pot. In the other system, with the C-2420, I set the gain selector to 12dB, but I think the attenuator on the C-280V doesn't work on the gain (that is 18dB) but attenuate an already "pre amplified" signal, right?

According to C-280V block diagram (instruction manual), Balance, Attenuator, Compensators are in front of the Volume, then followed by Subsonic Filter and after this reaching Input amp.
These are all passive elements lowering the level before the actual input amp.
I noticed some slight sonic influence, when I used the Balance. I therefore do not think that permanently using Attenuator is a good idea.
Low Volume settings on the C-280V may fall into a range where there are some channel differences.

When listening to CD, my C-3850 (gain setting +18dB) shows approx. -46.0 (depending on the music material). This represents a -28.0dB attenuation (-46.0 + 18.0 gain = -28.0 attenuation) of the input signal.
With AAVA there is virtually no sonic influence of volume setting, but some influence was reported depending on the gain settings.
With your C-2420 I would therefore recommend to set the gain to the standard +18dB and turn the volume down.

Martin

P.S. The output level of the DG-58 is higher than those of DC-37, DP-720, DC-901.