Question about Monitor Amp use on McIntosh C-40 and headphones

MavG1955

New Member
Hello All,

I am, new to this website/forum and I hope I can get some help with my question. I am preparing to purchase a McIntosh C-40 and I am wondering if it is possible to use headphones with the built in monitor amp and when used that way will it disconnect the output to the external connected power amplifiers so I am only hearing sound through the headphones, or will I have to physically shut down the power amplifiers anytime I just wish to listen to music through the headphones? Any help would be appreciated. Thank you, in advance.

Greg
 
The headphone output jack is powered by the C40's internal monitor amplifier. There's no other option.

Insertion of the headphone pin has no effect on the preamplifier outputs which will remain "hot". However, amplifier connections can be made at the numbered jacks, ie #1 and #2. The output to these numbered jacks can be shut off/on by way of the front panel buttons 1 & 2 therefore it would not be necessary to manually shut off amplifier(s) to stop the speakers from playing.

The MAIN preamplifier outputs, however, are always hot and there is no way to shut them off. An amplifier will therefore need to be switched off when connected to those jacks for those speakers.
 
The headphone output jack is powered by the C40's internal monitor amplifier. There's no other option.

Insertion of the headphone pin has no effect on the preamplifier outputs which will remain "hot". However, amplifier connections can be made at the numbered jacks, ie #1 and #2. The output to these numbered jacks can be shut off/on by way of the front panel buttons 1 & 2 therefore it would not be necessary to manually shut off amplifier(s) to stop the speakers from playing.

The MAIN preamplifier outputs, however, are always hot and there is no way to shut them off. An amplifier will therefore need to be switched off when connected to those jacks for those speakers.

So, what you are telling me is if I hook my monoblock amplifiers up to the C-40 using the "Switched Listen Output" connections on the back, I can simply switch the amplifiers off via the front panel 1 or 2 selector buttons (depending on which one the amps are hooked up to) and then I can listen to headphones without having to physically shut off each power amp at their power switch? Then, simply remove the headphones and push the appropriate switch on the C-40 to activate the amps and speakers, again? I assume the amps will always remain "on", just disconnected from being able to play at the same time the headphones are in use?
 
So, what you are telling me is if I hook my monoblock amplifiers up to the C-40 using the "Switched Listen Output" connections on the back, I can simply switch the amplifiers off via the front panel 1 or 2 selector buttons (depending on which one the amps are hooked up to) and then I can listen to headphones without having to physically shut off each power amp at their power switch? Then, simply remove the headphones and push the appropriate switch on the C-40 to activate the amps and speakers, again? I assume the amps will always remain "on", just disconnected from being able to play at the same time the headphones are in use?

Summed it up perfectly.

As you say, the amplfiers will remain powered up but there will be no sound because the input is disconnected.
 
Works that way for a C32, 33, and 34, too. Hold on too that 40 it the last of the full functioning Mac pre-amps. Yes you will need a MP100 if you want to do MC cartridges. I really enjoy the MP100 with my C-34. A C-40 won't fit in my cabinet. so I stick with the 34. I wish you many hours of good listening with the C-40. My Sennheisers sound great with my C-34.
 
Great headphone outputs on these earlier preamps. I much preferred the headphone output on the C34V compared to later preamps such as the C2300. Of course, if your significant other goes to bed much earlier than you (like mine does) and you do a lot of headphone listening, it's worth investing in a separate headphone amp.
 
I ran across this thread while researching a C34V. It brings me to this question. Can I use my C20 preamp (rebuilt by Terry DeWitt by the way) to power headphones and disconnect my MC40 mono-blocks as described here?

Coincidentally, I was reading about the C34V preamp today and saw that it has a 20 watt monitor amp. Wasn't sure what it was used for. I know someone with a C34V for sale and I was learning what I could about it.
 
I ran across this thread while researching a C34V. It brings me to this question. Can I use my C20 preamp (rebuilt by Terry DeWitt by the way) to power headphones and disconnect my MC40 mono-blocks as described here?

Coincidentally, I was reading about the C34V preamp today and saw that it has a 20 watt monitor amp. Wasn't sure what it was used for. I know someone with a C34V for sale and I was learning what I could about it.

I don't believe the C20 has connections for headphones. The front panel jacks appear to be convenience points for making quick connections for temporary connection of external tape machines for recording/playback. The signal would not be usable to drive headphones.

In your system, headphones would need to be driven by the amplifiers via a step down transformer.

The internal monitor amplifier of the C32, C33, C34 and C40 is used to power headphones in these models as well as for powering an additional pair of speakers in a remote location or for a pair of rear satellite speakers used with a delay device for surround sound in the main system.
 
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62caddy,
Since this last exchange I bought a McIntosh C34V preamp and have been reading the Operators Manual. Thanks to your message above, I was at least a little familiar with monitor amps.

I was after a MC 2500 amp, but hesitated and lost it to someone else. I don't need 500 wpc, but it was so clean and sold for only $3100. I won't make that mistake again.

I bought the guys preamp and his MCD 7000 CD player with the remote controls, and now I am looking for a good clean amp. I like what I read about the 2255. So I am watching for one of those.

I intended to flip the C34V and the MCD 7000, but now that I have them at home and am learning to use them, I may keep them and sell something else.

I will attach some photos.

Thanks again for educating me on the monitor amps.

Couldbfishin

IMG_3620.JPG IMG_3626.JPG IMG_3627.JPG IMG_3631.JPG
 
62caddy,
Since this last exchange I bought a McIntosh C34V preamp and have been reading the Operators Manual. Thanks to your message above, I was at least a little familiar with monitor amps.

I was after a MC 2500 amp, but hesitated and lost it to someone else. I don't need 500 wpc, but it was so clean and sold for only $3100. I won't make that mistake again.

I bought the guys preamp and his MCD 7000 CD player with the remote controls, and now I am looking for a good clean amp. I like what I read about the 2255. So I am watching for one of those.

I intended to flip the C34V and the MCD 7000, but now that I have them at home and am learning to use them, I may keep them and sell something else.

I will attach some photos.

Thanks again for educating me on the monitor amps.

Couldbfishin

View attachment 1541807 View attachment 1541808 View attachment 1541809 View attachment 1541810


Do yourself a favor and keep the C34.

You should also take advantage of the remote volume function of the CR7. Run an IC from the TAPE 1 (REC) output of the C34 to the PREAMP input of the CR7. Run another IC from the CR7 (outputs) to the TAPE 1 INPUT jacks of the C34.

To use the CR7 remote volume, set the CR7 to "PREAMP"; and set the LISTEN selector of the C34 to TAPE 1 and from now on the RECORD control is used to select the desired source. You can also connect the CD player directly to the CR7 which will enable you to toggle between the CD player and source selected at the C34 RECORD selector by remote control.

When using the CR7 to control volume, set the volume control of the C34 at roughly the 12:00 position where it can be left permanently, more or less.

You should also make A/C connections for the C34 (and power amplifier) at one of the switched outlets of the CR7, leaving the C34's power switch permanently ON, thus enabling the entire system to be switched on/off via remote control and sparing wear and tear of the power switch.

A/C power to the CD player can be provided by one of the C34's convenience outlets.
 
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I am going to print this thread because I am learning a lot from it.

62caddy, thanks for the tips on using the C34V and the CR7 remote box and the H7 handheld remote. There are so many features to this preamp, it will take me some time to understand them all.

I have another question, and maybe I should ask in a separate thread. But there may be others who will benefit from it. Otherwise, please let me know and I will resend as another thread.

I bought from the same seller as the C34V preamp and the MCD 7000 CD player, a couple of Bower and Wilkens Nautilus 805 speakers, a center B&W speaker, and a powered B&W subwoofer, or super woofer. I got with the deal a Teac AV receiver. I hooked up the speakers to the Teac receiver last night and listened to the them. Phenominal channel separation and good sound, but I am betting with a better quality preamp and amp the speakers would sound much better. I don't have a better AV receiver. So I was wondering how I could use the video features of the C34V. It was late so I didn't refer to the manual, but I once again looked at the connections on the back of the C34V.

For anyone who has used the video side of the C34V, is it set up for a front/center and a powered sub woofer? In other words is it 2 channel only, even though it was designed to work with a TV and video system? How would I wire the speakers using a separate amp?

Is the C34V capable of handling a speaker system like this? Or would I have to stick with a AV receiver?

As you can tell I am not experienced with surround sound systems or home theater systems. I primarily want to listen to LPs, CDs and RTR tape using the C34V, separate amp, and this B&W speaker system if possible. If I cannot do it with a two channel stereo system, then I probably won't invest in a better AV receiver. I would use the pair of front speakers, the C34V and an amp to listen to stereo music, and the Teac AV reciever with the front, center and super woofer speakers for TV and movies.

Thanks
 
The only thing that's "video" about the C34 is the fact that a pair of stereo inputs (and REC/LISTEN) selectors have been labeled "VIDEO", such as would be used for connecting the stereo outputs of a TV, VCR or DVD machine.

The unit is otherwise strictly two channel and does not have facilities for providing multichannel signal processing. Will need something different for HT applications.
 
McIntosh did make a external hardwired switch box to switch composite video via the listen control on the C34, 31,and 35. Might have worked with the MAC4300 receiver.
This was back when Larry Fish promised that Mac's video switcher would always be external to the audio casework.......of coarse that did not last, hence all the obsolete video units.

This was back in the day when a HIfi VCR was just shy of 1k and RCA and Pioneer were having a format war for videodisc acceptance.
 
McIntosh did make a external hardwired switch box to switch composite video via the listen control on the C34, 31,and 35. Might have worked with the MAC4300 receiver.
This was back when Larry Fish promised that Mac's video switcher would always be external to the audio casework.......of coarse that did not last, hence all the obsolete video units.

This was back in the day when a HIfi VCR was just shy of 1k and RCA and Pioneer were having a format war for videodisc acceptance.

Well they kind of did keep them seperate. While McIntosh did release a number of AVP/AVRs they never stopped making dedicated 2 channel preamps.
 
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