Help updating and setting up my mix’n’match hifi

Help updating and setting up my mix’n’match hifi

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Discussion

Jorrocks

Original Poster:

132 posts

158 months

Thursday 13th April 2023
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I have an old hifi setup that I’ve just started using again after a break of a few years, and as I am very far from being an audio buff, I’d appreciate some advice as I may already have started acquiring kit that I either don’t need, or that duplicates kit I already have.

The existing old set up comprises:

Rotel RC980BX pre-amp
2 x Rotel RB970BX power amps (bi-amped)
A pair of Castle Acoustics Howard S1 floorstanders

To which I have added:

Cambridge Audio CXC CD transport
Audiolab MDAC+

I’m not really sure how to set the Audiolab up with the Rotel pre-amp, I’m constantly fiddling about with two volume controls now! I wanted to add a streamer too, and was set on the Cambridge CXN V2, but am I better off looking at something without a DAC onboard as I already have the MDAC?

Any advice on setup and product options much appreciated!

WolvesWill

151 posts

156 months

Thursday 13th April 2023
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Have a look at the manual for the Audiolab M-DAC+, see if you can set it to a fixed output mode, that way you will only need to use the remote for your Rotel pre-amp to control the volume (rather than having two volume controls fighting against each other).

If you want to add streaming to your setup, and are happy with the sound of your existing DAC, then I'd add something like the WiiM Mini or WiiM Pro to your setup, these are affordable streaming devices that offer a digital (coaxial or optical) output that you can plug straight into your existing DAC for bitperfect sound. These WiiM devices are compatible with all of the most common streaming services so gives you a chance to try them out and decide which you like best.

TonyRPH

13,144 posts

175 months

Thursday 13th April 2023
quotequote all
You have a couple of options:

Disable the volume control in the MDAC and set it to fixed level output, and use the volume control on the Rotel preamp.

Doing this will of course lose the remote volume control option, as the Rotel doesn't have remote control.

If you have other analogue sources such as a turntable, tuner or tape deck, then the above is the best option.

If you only use the MDAC - then you can actually plug it directly into one of the power amps (you'll need a splitter to use both power amps) and then do away with the Rotel preamp. This will of course retain remote control of the volume (obviously you won't want to set it to fixed output mode!) but will limit your usage of analogue sources (if any).

The rest of your system is good even by today's standards, and if you're happy with the sound it produces, there's no reason to change anything else.





Jorrocks

Original Poster:

132 posts

158 months

Thursday 13th April 2023
quotequote all
Thank you guys,

I’m happy to pass on the remote control facility! I have found the menu to fix the output level on the MDAC+, there is the option of either 0dBr (2.2Vrms) or +3dBr (31.1 Vrms). Which should I choose?

Edited by Jorrocks on Thursday 13th April 16:51

TonyRPH

13,144 posts

175 months

Thursday 13th April 2023
quotequote all
Choose "0dBr (2.2Vrms)" which suits the input levels of the Rotel preamp.


Jorrocks

Original Poster:

132 posts

158 months

Wednesday 19th April 2023
quotequote all
Thanks, Tony.

On the subject of splitters, are they likely to affect sound quality? If not, then I probably ought to do away with the Rotel pre-amp and have the convenience of a remote. The only sources I’ll be using are the Cambridge CD transport and eventually a streamer of some description.

TonyRPH

13,144 posts

175 months

Wednesday 19th April 2023
quotequote all
The output of the Rotel preamp is just two sockets in parallel, which is all a splitter is.

Additionally, the MDAC has quite good drive capabilities (meaning it won't have a problem driving to power amps via a splitter).

So the answer to your question is no, it won't affect sound quality.

From memory, some Rotel power amps had a loop through option (an additional pair of sockets on the power amp to loop through to a second amp).

You can use two of these splitters (put them on the power amp side, not the DAC side).

If the amps are side by side, you'll obviously need something a little longer.



Dragster

45 posts

21 months

Friday 21st April 2023
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TonyRPH said:
Choose "0dBr (2.2Vrms)" which suits the input levels of the Rotel preamp.
If Jorrocks decides to remove the Rotel preamp and feed the 980 Power Amp directly from the MDAC+ the they will have to take a little care with how far the volume control is turned...........the RB-980 might not be too happy if fed with the full 2.2V that the M-DAC+ is capable of delivering.

Rotel power amps of that generation had an input sensitivity of 1.0V for full scale output. ( I use several a combination of six RB-971s and RB-981s in an active system ). https://www.hifiengine.com/manual_library/rotel/rb... 2.2Vrms is the setting



TonyRPH

13,144 posts

175 months

Friday 21st April 2023
quotequote all
Dragster said:
If Jorrocks decides to remove the Rotel preamp and feed the 980 Power Amp directly from the MDAC+ the they will have to take a little care with how far the volume control is turned...........the RB-980 might not be too happy if fed with the full 2.2V that the M-DAC+ is capable of delivering.

Rotel power amps of that generation had an input sensitivity of 1.0V for full scale output. ( I use several a combination of six RB-971s and RB-981s in an active system ). https://www.hifiengine.com/manual_library/rotel/rb... 2.2Vrms is the setting
It'll be fine, so long as the volume is kept in check. The MDAC will only yield 2.2v at maximum output (the option I recommended), and distortion from the power amps being driven to maximum output would have set in long before then.

My (home built) preamps can output 5 - 8vRMS at maximum volume, and I drive various power amps with them, without issue.

I even have one power amp with an unusually high input sensitivity (500mV) and even that doesn't get overloaded at normal listening levels, it just makes the volume control on the preamp quite sensitive to small movements (unlikely to be an issue with the digital volume control in the MDAC).


Dragster

45 posts

21 months

Friday 21st April 2023
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TonyRPH said:
Dragster said:
If Jorrocks decides to remove the Rotel preamp and feed the 980 Power Amp directly from the MDAC+ the they will have to take a little care with how far the volume control is turned ...........the RB-980 might not be too happy if fed with the full 2.2V that the M-DAC+ is capable of delivering.

Rotel power amps of that generation had an input sensitivity of 1.0V for full scale output. ( I use several a combination of six RB-971s and RB-981s in an active system ). https://www.hifiengine.com/manual_library/rotel/rb... 2.2Vrms is the setting
It'll be fine, so long as the volume is kept in check. The MDAC will only yield 2.2v at maximum output (the option I recommended), and distortion from the power amps being driven to maximum output would have set in long before then.

I even have one power amp with an unusually high input sensitivity (500mV) and even that doesn't get overloaded at normal listening levels, it just makes the volume control on the preamp quite sensitive to small movements (unlikely to be an issue with the digital volume control in the MDAC).
Agreed...........it will be fine if care is taken. The post was to bring the potential issue to the OP's attention.

I set the gain structure of my active crossover to make sure that its max level output equates to 0.9v being fed to the Rotel power amps.............this limits the need for any digital attenuation / volume control in the system. Digital attenuation often has a negative impact on sound quality.


Edited by Dragster on Friday 21st April 13:49

TonyRPH

13,144 posts

175 months

Friday 21st April 2023
quotequote all
Dragster said:
Agreed...........it will be fine if care is taken. The post was to bring the potential issue to the OP's attention.
Fair enough, although unless the OP has really bad cloth ears or has lots of wild parties the risk is minimal.

Dragster said:
I can the gain structure of my active crossover to make sure that max output equates to 0.9v being fed to the Rotel power amps.............this limits the need for digital attenuation / volume control in the system. Digital attenuation often has a negative impact on sound quality.
The digital attenuators in modern DACs have no impact on sound quality. This has been measured and proven by Amir at Audio Science Review.