CA 640A + miniDSP Tape in question?

thunk303 · 15th November 2010, 11:51 AM

This is an odd one.

I need to run my MiniDSP (2.1) back into the TAPEIN on my Cambridge 640a but am unable to actually get any output when i hit the 'tapemon' button.

Its a bit complicated (says me

) but this is what I am trying to achieve:

CD > AMP(CDin)
AMP(PREout) > MiniDSP(in)
MiniDSP(out) > (2) AMP(TAPEin)
> (.1) SUBWOOFER amp

The idea is to use the 640a's volume control on the first pass through then have the MiniDSP(2.1) send everything below 300Hz to the sub amp and above 300 back to the 640a.

Answer, it doesn't work.

1. Does the 640a switch the PREOUT signal off or over to the RECOUT?
2. Is there another way I could be doing this all together??

I'm absolutely broke atm so more parts (preamp/amps) are not an option.

Cheers
Dean

thunk303 · 16th November 2010, 06:14 AM

Are there any other 640a owners out there who may be able to shed some light???

Dean

sharpi31 · 16th November 2010, 07:03 AM

Not familiar with the 640a amplifier, but I think you should be taking the Amp (Tape out) to Minidsp (in) and Minidsp (out) to Amp (Tape in). Then it's a simple case of selecting tape monitor when you want to hear the Minidsp in action, and selecting the right source. With tape monitor not selected on the amp, the Minidsp will be out of line and the amp will work with sources in the usual way.

Not only should this work, but by avoiding the Amp (Pre out) you should be sending a full line level signal through the Minidsp at all times, irrespective of volume setting. Assuming the Minidsp is configured accordingly, this should minimise the losses incurred by running the signal through the ADC and DAC within the Minidsp.

sharpi31 · 16th November 2010, 07:15 AM

Oops forgot that you're taking a subwoofer output from the Minidsp. The method I detailed above will still work, but you will need to adjust the subwoofer level as well as the amplifier volume (changing amplifier volume alone will not change the subwoofer volume).

Many amplifiers that have a 'Pre out' also have a 'Power amp in', but unfortunately not your 640a. If it did, you could connect the Minidsp between these inputs and outputs and then the subwoofer volume would change automatically as you adjusted the main amplifier volume.

Not an ideal pairing to be honest. I'd go with the first solution and live with the fact that I'd have to adjust both sub amd amp level every time I changed volume.

sharpi31 · 16th November 2010, 07:21 AM

Alternatively..... :-)

You could connect the Minidsp between the Amp (pre out) and the Subwoofer (in). In other words, there would be no line out from the Minidsp going back to the amplifier.

This way the amplifier volume control will change the subwoofer level too, but the signal going to the main loudspeakers will always be full range. This might be ok if you want the sub to fill in the bass that is rolled off by the main speakers, but won't allow you to shave off bass from the main loudspeakers and send it to the sub.

thunk303 · 17th November 2010, 04:33 AM

Thanks heaps sharpi.

You've hit the nail on the head , I following and experimented with the same line of reasoning too (wow that sub can go loud!!!)

It seems i am going to have to commit to more equipment to achieve universal volume over the sub-amp and the main-amp. I will have to do this eventually with my dipole rig anyway when i get another minidsp and go active three way (T/M/S)

I have been looking at the the B1 pre which seems reasonably priced atm with the american dollar.

Do you know if this is the right direction and what remote control options might available for the B1.

Cheers
Dean

15th November 2010, 11:51 AM	#1
thunk303 diyAudio Member Join Date: Mar 2005 Location: Eltham, Melbourne, Australia	CA 640A + miniDSP Tape in question? This is an odd one. I need to run my MiniDSP (2.1) back into the TAPEIN on my Cambridge 640a but am unable to actually get any output when i hit the 'tapemon' button. Its a bit complicated (says me ) but this is what I am trying to achieve: CD > AMP(CDin) AMP(PREout) > MiniDSP(in) MiniDSP(out) > (2) AMP(TAPEin) > (.1) SUBWOOFER amp The idea is to use the 640a's volume control on the first pass through then have the MiniDSP(2.1) send everything below 300Hz to the sub amp and above 300 back to the 640a. Answer, it doesn't work. 1. Does the 640a switch the PREOUT signal off or over to the RECOUT? 2. Is there another way I could be doing this all together?? I'm absolutely broke atm so more parts (preamp/amps) are not an option. Cheers Dean

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16th November 2010, 06:14 AM	#2
thunk303 diyAudio Member Join Date: Mar 2005 Location: Eltham, Melbourne, Australia	Are there any other 640a owners out there who may be able to shed some light??? Dean

16th November 2010, 07:03 AM	#3
sharpi31 diyAudio Member Join Date: Oct 2005	Not familiar with the 640a amplifier, but I think you should be taking the Amp (Tape out) to Minidsp (in) and Minidsp (out) to Amp (Tape in). Then it's a simple case of selecting tape monitor when you want to hear the Minidsp in action, and selecting the right source. With tape monitor not selected on the amp, the Minidsp will be out of line and the amp will work with sources in the usual way. Not only should this work, but by avoiding the Amp (Pre out) you should be sending a full line level signal through the Minidsp at all times, irrespective of volume setting. Assuming the Minidsp is configured accordingly, this should minimise the losses incurred by running the signal through the ADC and DAC within the Minidsp.

16th November 2010, 07:15 AM	#4
sharpi31 diyAudio Member Join Date: Oct 2005	Oops forgot that you're taking a subwoofer output from the Minidsp. The method I detailed above will still work, but you will need to adjust the subwoofer level as well as the amplifier volume (changing amplifier volume alone will not change the subwoofer volume). Many amplifiers that have a 'Pre out' also have a 'Power amp in', but unfortunately not your 640a. If it did, you could connect the Minidsp between these inputs and outputs and then the subwoofer volume would change automatically as you adjusted the main amplifier volume. Not an ideal pairing to be honest. I'd go with the first solution and live with the fact that I'd have to adjust both sub amd amp level every time I changed volume.

16th November 2010, 07:21 AM	#5
sharpi31 diyAudio Member Join Date: Oct 2005	Alternatively..... :-) You could connect the Minidsp between the Amp (pre out) and the Subwoofer (in). In other words, there would be no line out from the Minidsp going back to the amplifier. This way the amplifier volume control will change the subwoofer level too, but the signal going to the main loudspeakers will always be full range. This might be ok if you want the sub to fill in the bass that is rolled off by the main speakers, but won't allow you to shave off bass from the main loudspeakers and send it to the sub.

17th November 2010, 04:33 AM	#6
thunk303 diyAudio Member Join Date: Mar 2005 Location: Eltham, Melbourne, Australia	Thanks heaps sharpi. You've hit the nail on the head , I following and experimented with the same line of reasoning too (wow that sub can go loud!!!) It seems i am going to have to commit to more equipment to achieve universal volume over the sub-amp and the main-amp. I will have to do this eventually with my dipole rig anyway when i get another minidsp and go active three way (T/M/S) I have been looking at the the B1 pre which seems reasonably priced atm with the american dollar. Do you know if this is the right direction and what remote control options might available for the B1. Cheers Dean