Naive headphone amp question

[Candy]

My apologies for reposting a picture (except the CD5i is now swapped with a Meridian G08). I’ve got some naïve questions, which it helps with.

The Can Opener is a device, from late 1980s, which takes a signal from the 42-5/90 and sends it to a headphone input (had the signal not gone to the Can Opener it would have gone to loudspeakers). You’ll see from the photo that there are also a pair of Stax Lambdas in this system. The 42-5/90 feeds into an early Stax SRD 6/XB, which has an Earphones (Stax) or Loudspeaker (Can Opener) switch.

First question. What is the Can Opener doing that allows me to listen to a Naim output on headphones? I imagine it must be degrading the signal in some way, but I’m ignorant

Second question. Where could a Naim headphone amp (desk top?) sit in that little system? Would it be taking a signal direct from the CD player, so that the 42-5/90 was redundant?

Third question, which follows on. Am I right that it would be impossible to incorporate the Stax headphones into that little system if the Can Opener were replaced with a Naim headphone amp?

Thank you for taking the trouble to read this far, love, Stevie xx

[robert_h]

As I understand it, the can opener is a passive device that takes speaker output from an amp and (through resistors) makes it suitable to drive headphones.

[Candy]

Yes, you’re right, it’s passive. Now I starting to get a bit clearer on my questions. Thank you xx

[Geofiz]

I am assuming that the CD is connected to the Tuner input or have you replaced the phono boards on the 42.5 with CD straight connect boards? I assume you want to replace the “The Can Opener” with a Naim Headline?

If that is the case, to use the Headline you will have to connect the captive interconnect to the Tape or Tuner DIN socket on the 42.5. The STAX SRD 6/XB will remain connected to the NAP90 as you have it now. You can leave “The Can Opener” attached to the SRD 6/XB as currently configured if so inclined or remove it entirely (Stax switch would be set Headphones only in this case).

You need the 42.5 in the system to control volume levels.

Apparently you can control the volume on the CD output from the Meridian G08. To connect to a Headline directly to the CD player you would have to use the analogue RCA outputs and have a conversion cable made to go from RCA male to 5 pin 180 deg DIN (female) to connect the signal from the CD to the captive Headline input interconnect but check the manual of the G08 to verify that the volume control does control the output from the analogue out RCAs. This would unnecessarily complicate the wiring of your system and require you to physically change the connection of the CD to the 42.5.

The Headline also requires a separate power source as you are using the NAP90 to power the 42.5. You would need one of the following (from the Headline manual):

• i-Supply via captive lead and adaptor.
• NAPSC via captive lead.
• Flatcap via SLIC lead to Power Out Socket B.
• Hi-Cap via SLIC lead to Socket 4.
• Supercap via SLIC lead to Socket 2.

I assume you are looking at a Headline as “The Can Opener” is no longer functioning?

Good luck!

[Candy]

Thank you. That is wonderfully helpful. Yes, you’re quite right, the CD player is connected to the tuner input of the 42-5, which is the master volume as things stand. In fact the Can Opener still works fine. My concern was that it must be degrading the signal. But given that it works it’s perhaps best for me to leave it as it is. It’s not a main system, and it is nice to be able to compare the electrostatic Lambdas with dynamic Sennheiser HD 800s at the twist of a button. I’m a lot clearer on what would be required now, for which I’m grateful. love Stevie xx

[Adam.Meredith]

At the risk of repeating points already made -

The Can Opener was the work of Neil Ramsden to ran the The Den (record shop at the time) in Keighley.

I was a little involved with the development - such as it was. It’s essentially a couple of, carefully chosen, resistors to allow speaker level signals to be used for dynamic headphones.

At the time it was offered with NACA 4 and Linn internal cable options. Input 4mm sockets, output standard headphone jack. Between these, within the box, your cable of choice, a chunk of metal plate to help it stay in place and a couple of big resistors.

I used it then with some lovely Beyers and the results were spectacular although ‘switching’ from speakers was a faff.

A late observation arises from a review I did of several Stax headphones.
Each energiser was plugged directly into the speaker output sockets of my NAP 110 power amplifier. I didn’t much like any of the models - which I had compared with my resident Can Opener/Beyer combination. In line with convenience, the Can Opener was attached at the end of 3.5m of Naim speaker cable - convenient and providing the necessary loading for the Naim amplifier. The Stax models, omitting the beneficial and necessary effects of the speaker cable, were probably disadvantaged in a way I missed at the time.

The ideal in your case would be to introduce a minimum of 3.5m of Naim speaker cable for both the Can Opener and Stax. The use of the switch in the Stax Energiser isn’t optimal but, with the higher signals involved, may only degrade things a little.

If this is a dedicated 2nd system for headphone listening I wouldn’t bother to buy a Naim Headline. When I was at Naim I got around to building one for myself and paired it with the NAPSC power supply and a replacement (less delightful) pair of Beyers. I was underwhelmed - preferring the Can Opener.

As for the Headline - I found it improved considerably with a PowerLine into the NAPSC and, I suspect, could have been improved with the use of a HiCap. I’m reluctant to recommend such upgrades as it’s expensive with a NAPSC and verging on silly with the better ancillaries.

[Candy]

I’ve only just seen your post, so apologies for the slow acknowledgement. And thank you for your insights into the Can Opener which were fascinating, along with your helpful Naim info, love Stevie xx