CB 62/140/HiCap system - overly virile midrange/upper midrange

I just couldn’t help myself, and have scratched an itch. So I’m the proud owner of a new to me NAC62/NAP140/HiCap system. The source is exclusively Roon via a Waversa WStreamer Roon-ready streamer, and a Schiit Modi True-Multibit DAC. The loudspeakers are Audience full-range The One’s.

Well, it sounds fabulous. Much better than I expected, especially considering the very modest DAC.

I do have one issue though - the 2kHz to 4kHz region is a bit too bold for me. I tried a different DAC (iFi Zen DAC) and it made no difference.

I know it’s not the loudspeakers, as I use the Audience Ones in 2 other systems with UnitiQute 2’s, and they are very neutral.

I’ve addressed the situation with Roon DSP for now. But I just wanted to solicit input if this is typical for CB gear, or if it indicates that service is required.

The NAC62 & NAP140 were reputedly serviced by previous owner, perhaps 5 years ago. Not sure regarding the HiCap though.


Were these items serviced by the previous owner, or did the previous owner have the items serviced by an approved agent? The answer to this may be fundamental as to the reason for your issues.

An unserviced HiCap can make a system sound worse than using it without it. Perhaps try the 62/140 without the HiCap.


May be worth passing your serial numbers to Naim to see if they have a record of it being serviced.


I would look to quiz the previous owner, as to who did what, re servicing… :thinking:

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Good idea to try without Hicap.

I find there are two elements to building a vintage system. Firstly, short listing the components that I find most musically engaging. Secondly, and this is more tricky, putting them together into a system that sounds right to me - i.e. well balanced. For example, Valhalla/Ittok LP12 > CB amps > Kans/Briks usually sounds “just right” but it’s taken a while to work things out, especially the finer details.

You may have to do something similar when you mix CB amps with a modern source and speakers - i.e. try lots of combinations. One advantage of a system built solely with modern Naim electronics is that they should work well together and you only have to find the right speakers.


Thanks kindly all for all of your responses. Excellent points regarding servicing/history, system matching/configuration.

Sorry - I wasn’t clear regarding the servicing. It was 2 owners ago, and was presumably done professionally. Unfortunately, the last owner didn’t have any documentation or further details than that. Excellent suggestion to send in the serial numbers to Naim. I will do that.

That’s another great suggestion to try the system with the HiCap removed, which wouldn’t have occurred to me. Unfortunately, I get only a loud hum from the speakers and very faint music.

I assume that I had the 62 & 140 connected properly. With everything powered off, of course, I removed the SNAIC5 between HiCap socket 4 and the SNAIC5 output on the 62. So I just have the SNAIC4 between the 62’s SNAIC4 output and the 140. I double-checked, reseated the cables and tried again. But same result.

When I restore the HiCap into the system, all is well again.

By the way, upon arrival, I did an internal inspection of the 62 & HiCap just to see if anything looked amiss, like bulging capacitors or shoddy wiring. All looked tidy and professional as far as I could tell.

However, I was unable to loosen the two hex-head bolts in the center area of the 140’s sleeve. They wouldn’t budge, and I didn’t want to apply any more pressure than I did out of the fear of stripping them. Has anyone encountered this, and were you able to get them loose?

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They can be very tight (why they do them so tight I don’t know). Try tightening then to loosen them.

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Thanks Badlyread. I’ll try that.

Be very careful here - make sure you use the exact correct sized allen key (and a good quality one at that) otherwise you will end up rounding out the hex and then it’s a messy drill out job. When you do them back up again, make sure you do them up very tight as the mating between sleeve and tray is critical.


I’ve not owned a 62 but you may need a 5pin plug in order to get them working without an external PSU. It’s just a little thing that is required when using the 4pin connection directly to a 32.5 or 42.5.


Agreed, Richard. I have a 4mm hardened Craftsman allen wrench (not sure if that is sufficient quality or not). I tried again, including to attempt to break it loose in both directions. But no joy. So I have dropped the attempt, as I have a feeling that any additional force will strip them as you said.

Of course! (smacks forehead). It came with an upgrade plug, which I left in the box and forgot about.

I will try again soon.

Thanks Murmur!

I opened my CB140 the other day to check the output transistor type. It’s not been opened up for quite a few years and the two Hex bolts were extremely tight. The longest Allen key I had in my toolbox gave enough leverage to ‘free’ the bolts.


As long as the hexagon in the screw isn’t damaged and the allen key is good quality you can extent the allen key by putting a pipe on it, or give it a wack with a hammer.
(Using a poor quality allen key is not a good idea, I snapped on once, made a right mess of a knuckle). :crying_cat_face:
You could also try a drop of oil.

With regards to age of the capacitors. The large caps in the Nap and hicap will have code indicating date of manufacture.

IE. 1528 is 28th week 2015

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Thanks James & Fatcat. I don’t want to apply even more force, but perhaps I’ll try a drop of penetrating oil on each bolt, then leave it be for a few days before trying again.

That was it! Music is flowing sans HiCap. Unfortunately, the bold mids/upper-mids persist. So I’ll just stick with the Roon DSP adjustment for now.

Interesting. I know nothing about the speakers you mention but my very neutral Kans sound exceedingly good with a Nait 2 and the newer Nait5i. In the same room with a recently serviced hicap/32.5/250 CB they sound thin and reedy. It’s almost that the 250 is too much for them and is stretching them somehow. On the other hand the 250 is sweet and melodious from very low volumes up to very loud where I might have expected the sound to be a bit shouty, both with the Dalis and the A5’s. Speaker/ amp matching seems to be just as important as speaker/ room matching.

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Also bear in mind that just changing the large reservoir capacitors is not the same as a full service.


Understood, Richard.

Glad you’ve sorted that bit.

I’m not really sure what “bold mids/upper-mids” means. Do you mean it’s too prominent in the mix or is it an unpleasant sound of some kind?