Nakamichi CA-7A Preamp

@uncleang yeah I never said that, but do test other units he did design.  My local tech did work at Threshold, lives down the road, and cautioned about the boards in those older units, so I don't run an of that in my primary system for that reason.

For my secondary system I do have some upgraded Pass/Forte' gear, and it's fairly simple inside, and no need to keep a bunch of spare boards and bits around. My main system is all tube, point to point wiring, so thankfully I don't have to worry about aging, brittle or warped boards, or anything like that. 

@decooney :

The NAK - CA series preamps were not designed by NP, but as I stated earlier the circuitry in these pres are very NP like in form and function.

The PA & CA Naks were built when Nakamichi was at its zenith, so much so that they didn't mind paying to use some one else's stasis technology as opposed to the 'not invented here' approach of many corporations. 

My tech tells me that the parts and assembly were superior to just about anything else on the market at the time regardless of cost. 

BTW: he works on Thresholds also, and he states that they're no match quality wise to the NAKs.

As a Nakamichi fan - when I was specifically looking for the right CA-5 preamp instead for other reasons, simplicity, sonically - I had scoured CA-7s out there and spoke with many owner-sellers who enjoyed them a lot.

For a secondary SS system, I ended up going a different direction searching for some of Nelson’s other brand/lines and designs for preamps. Its fun to compare under the hood of these units to see how they were designed and built back then.

@invaderzim : It would be a real shame for you to get rid of your NAKs.

Your PA-7 which is now almost 40 years old is pretty much bullet proof.

The main things that wear on it are the bias trim pots, some smaller caps and a few transistors mostly related to the negative feedback circuit. Yes, it has NFB but very little. The main caps are of very high quality and if the bias has been kept around the factory recommended 40 mA they should last pretty much forever.

All of the above have been serviced in my MKII version, cost was around $750 to get it all done.  Given that an equivalent new amp of this quality cost  $5K plus, I saw it as a worthwhile investment.

I too noticed that if one pushes the 'balance' knob in and out on the CA-7A it may restore contact on both channels.  Ironically, mine has been working great for almost a year in the center position.

From a brochure on the CA-7A....

"Discrete Balance Control uses 20 precision metal-film resistors and a 21 position switch to ensure precise repeatable settings.  The switch introduces less noise than a conventional control and, in the normal position, all resistors are out of the circuit".

Hence 'straight wire with gain' at the 12 o'clock position.

Great thread! I have a Nakamichi CA-7A that I bought at Paris Audio in Torrance, CA in 1985/1986, along with the matching PA-7 amplifier and ST-7 tuner. Not the PA-7A -- this was earlier. Still have the sales receipts -- paid $1935 for the CA-7A. I just dug these out of my closet and they're playing right now behind me in my office. I don't see a way to upload a photo, so here's a link to a photo at my email provider.

In the early 1990s, I moved to Texas, got a much larger house and built out my dream system with a pair of Apogee Duetta Signatures (full range ribbons) that I first heard at Paris Audio and could now afford. Sigh. They produced the best sound I've heard before and since. The PA-7 did a nice job of driving those until we decided all the AV stuff should be in the family room where surround sound would eventually go (also, my wife wanted her living room to actually be a living room after 7 years). No room for the Duettas which have to be at least four feet from the walls, so I regretfully sold them, and I got a pair of more wife-compatible B&W 801s. The PA-7 drove those speakers for years as well, first with the CA-7A and later, by various surround sound receivers, but just 2-channel sound because I never quite got around to choosing and installing surrounds. I retired earlier this year and finally have some time -- finally have a true surround system with a Denon 8100HA and use a Parasound A21+ to drive the 801s. Yep, I'm old now and my hearing isn't what it used to be, but that combination sounds absolutely terrific even in 2-channel mode and surround music can be stunning. So the PA-7 joined the CA-7A and ST-7 in the closet.

With more available time, I recently reconnected the CA-7A (not used for probably 15 years) and the PA-7 (not used since 2022) in my office, hooked them to a pair of B&W bookshelf speakers and they sound... well, stunning after I let them warm up for a few hours (that made a big difference). In keeping with the 80s theme, right now "The Pretender" by Jackson Browne is playing and... goosebumps.  Literally.  One thing I remember that's still true is that these components take time to warm up, and the sound improves over a period of time. I used to just leave them on all the time for this reason. They run pretty warm (almost hot) to the touch, so not a good long-term thing to have in my home office in the summer. 

Part of me finds it hard to believe that these 37-year old components still work. Out of curiosity, I took the top off the CA-7A and it's incredibly clean inside (Nakamichi CA-7A guts). Except for the dubbing and volume, the bypassable equalizer and balance knobs go into boxes. I mention this because I noticed exactly the same thing described @uncleang described with the balance knob: in the center position, the audio is shifted to one side but rotating it shifts the balance as expected. I found that gently pulling/pushing on the knob a little bit fixes that, but it sounds like it's an endemic problem. The three equalizer knobs may have the same issue, but when enabled with the front panel switch, the effect is subtle anyway.

The way the volume is handled is cool: the remote (which I was happy to see I had taken the batteries out of, so no leakage) mechanically rotates the volume knob with a motor. That still works perfectly, as does switching the inputs. I also have the separate Nakamichi power strip that the CA-7A can control (it connects with a DIN-like cable and turns on the PA-7 and other components when the CA-7A is turned on with the remote), but I dimly recall that there was a problem with that strip, like a relay got stuck. 

Because I'm too lazy to move my BluRay player (only CD player left in the house), I hooked my old iPad up to it and have been enjoying lossless Apple Music with the iPad doing the D2A conversion. Probably not ideal, but as I said, it sounds fantastic. I still need to connect my turntable to it and see if the phono stage still works, though. That'll be even better!

After I finish playing with these components and I finish determining the condition, I'll probably finally part with it and put the whole kit-and-kaboodle on EBay. Still need to take the top off the PA-7 and make sure none of the caps are leaking, but it certainly sounds great right now. And the ST-7 AM/FM tuner display is a little borked -- some segments in the display are brighter than others (although the tuner sitll works), so that'll probably be a free bonus.

Anyway, thanks for the memories. I don't think they make 'em like this anymore.

@uncleang  nice!!!!

 I shut off the use of my Western Electric 300 B tubes on my SET amp, for ballgames. ( trying to save tube life… I wish I knew at my age of 70, how many years of life they had, using them 4-6 hours at night only… any idea?)

yeah the making of the NAK is amazing  I got interested when I saw the Sky Hi Fi video on YouTube  

Those tubes might outlive us... I'm 74.

@uncleang 

im impressed! You know your stuff! 
 

if I hadn’t given (4) banana boxes of vinyl to the thrift store, I’d buy a turntable just to hear that phono transformer. 
 

for right now, I rarely listen outside of streaming and Bluetooth through a Node v3… including TV. I shut off the use of my Western Electric 300 B tubes on my SET amp, for ballgames. ( trying to save tube life… I wish I knew at my age of 70, how many years of life they had, using them 4-6 hours at night only… any idea?)

yeah the making of the NAK is amazing  I got interested when I saw the Sky Hi Fi video on YouTube  

@moose89 

The CA-7A has two torrodial transformers, so one would think that they're for left and right channels respectively.  They're not. One transformer is for line inputs and the other for phono; each transformer has separate windings for left/right channel.

There's trim pots to adjust MM, MC and line inputs which should be done periodically or after shipping.

Yes, the buttons are very fragile (use remote whenever possible); I've broken two but glued them back on so they're all there.

This pre will easily reveal the weakest links in your system, but when you've addressed them all the rewards are sublime.

@uncleang 

yesssss! I was happy to get the CA-7A pre. I bought it off of a fellow in Texas who knew his stuff and back-and-forth messaging on eBay. I knew it was the real deal because he knew all about the inner portion of this amplifier. I also got a remote control that works even though I only have one CD button on the front it doesn’t matter. And I don’t even have a turntable yet, but I am thrilled to use it with my Dennis Had Inspire western electric 300B into my Klipsch Cornwall IV’s. Game over. Bluesound Node 3, SVS MICRO 3000 SUB. I think my disease has come to an end lol.

I have a NAK PA-7A MKII amp and a CA-7A pre. They are a phenomenal combo. The phono section in the pre is in a league of it’s own. I use an AT33PTG/II cart and it’s hard to describe how utterly clean the sound is.

The one weakness the pre has is the balance control may lose contact with the left or right channel when set in the mid position. Even after proper cleaning it only lasts about 6-9 months before the problem reappears.

Both units were manufactured in 1990; I purchased them used in 1998 for $2500.

BTW: The CA-7A is not a Nelson Pass design (the amp is) but it is based on Pass technology.  From the sales brochure for the CA-7A .... We developed a direct coupled output stage using a complimentary-symmetry emitter follower with a current bootstrap.  Same principles as in Stasis amplification.

Best money I ever spent.

I bought off EBay. Great Seller. Knowledgeable and a tech 

The Nelson Pass designed series for Nakamichi has always been very popular and very well thought of...and yes, if you bought from SkiFi ...

😊 I agree. Attenuation for this Pre is fabulous… so much more in recordings now to discern… feels like I was born yesterday and I’ll be 70 in the Fall. I am hearing a lots more detail with my Cornwall iv heritage series and this Pre. The amp doesn’t mean anything with the NAK CA-7A having last dibs to the sound. 

I still have my Nakamichi TA-3 from the late 80’s on a second system. Still sounds great. Originally it was driving some Heresy’s, I think the Naks play well with Klipsch.