I picked up a used PA7 locally last week, and... 
I knew it would be better than the two power amps I had, but it has exceeded my expectations. I was temporarily using a Rotel RB-1070 for the past several months, and the PA7 (to borrow an overused phrase) kills the Rotel. I knew I didn't care for the Rotel, as it sucked the life out of the music--I found it to be sterile, even bland. Now that I've jumped up the ladder, I can hear how poor the Rotel really sounded to me.
The person I bought this PA7 from is a big-time audiophile, and while he has moved along to higher end equipment (his system was stunning to hear!), he still had a lot of praise for the PA7 (he sold one a few months earlier--he used to bi-amp the speakers with a pair of these), and also said that he really felt the CA7 was an even better preamp, praising its phono section especially.
I am leaning towards a tubed preamp as my goal, but the CA7 has me thinking of trying one if I find a deal.
I realize the CA7 was also a Nelson Pass design, but is this like the amplifiers, where the original version is the best of the bunch? I think I've seen a CA7A, and a CA7A-II, but not sure if I've seen a CA7.
Any input here from the experts (or reasonable facsimiles thereof) would be greatly appreciated. 🙂
I knew it would be better than the two power amps I had, but it has exceeded my expectations. I was temporarily using a Rotel RB-1070 for the past several months, and the PA7 (to borrow an overused phrase) kills the Rotel. I knew I didn't care for the Rotel, as it sucked the life out of the music--I found it to be sterile, even bland. Now that I've jumped up the ladder, I can hear how poor the Rotel really sounded to me.The person I bought this PA7 from is a big-time audiophile, and while he has moved along to higher end equipment (his system was stunning to hear!), he still had a lot of praise for the PA7 (he sold one a few months earlier--he used to bi-amp the speakers with a pair of these), and also said that he really felt the CA7 was an even better preamp, praising its phono section especially.
I am leaning towards a tubed preamp as my goal, but the CA7 has me thinking of trying one if I find a deal.
I realize the CA7 was also a Nelson Pass design, but is this like the amplifiers, where the original version is the best of the bunch? I think I've seen a CA7A, and a CA7A-II, but not sure if I've seen a CA7.
Any input here from the experts (or reasonable facsimiles thereof) would be greatly appreciated. 🙂
I have no idea if the CA7 is a NP design, but it sounds exceptional (former Nak dealer).
I especially like the low-midrange tone control (cardboard-box frequency).
I especially like the low-midrange tone control (cardboard-box frequency).
That does sound like a nice tone control option--there are a handful of recordings I own that sound so much better if a decibel or two of "muck" is removed. (I haven't had an equalizer in my main system for over 20 years now.)
I was hoping The Man™ might recall if he designed this preamp. Or not. 🙂
I have heard from a couple of varied sources how nice this preamp sounds. (Which leads me to believe it is a Pass design.) I just wonder how the capacitors might be getting along in the preamp, as well as my PA-7. I have no problem with redoing the caps if needed--I just recapped one of my Hafler preamps (DH-101) and it is noticeably cleaner sounding. The PA-7, though, continues to amaze me...I can't get over how free-flowing and natural the sound is now.
I was hoping The Man™ might recall if he designed this preamp. Or not. 🙂
I have heard from a couple of varied sources how nice this preamp sounds. (Which leads me to believe it is a Pass design.) I just wonder how the capacitors might be getting along in the preamp, as well as my PA-7. I have no problem with redoing the caps if needed--I just recapped one of my Hafler preamps (DH-101) and it is noticeably cleaner sounding. The PA-7, though, continues to amaze me...I can't get over how free-flowing and natural the sound is now.
I don't think the Nakamichi preamps were designed by Mr. Pass, but it would nice if someone confirm this with certainty. From what I've read Nakamichi just licensed the Stasis amplifier designs from Mr. Pass & Threshold.
I currently own a ST-7 / CA-7 / PA-7II, and have had the CA-5 and PA-5 in the past.
I don't think there was a mark II version of CA-7, at least I've never seen any photos online, nor is it in any of the brochures I have from the era. I also have owners and service manuals for all of the other Nak products of the era, but nothing for a CA-7II. There was a mark II version of the CA-5, which added tone controls.
The letter designations after the model number indicate which market the product was made for; A is for America, O is for Asia (Orient), and E is Europe. I have a PA-7IIA brochure where Nakamichi explains that the "A" designation means that the amp meets local voltage and safety regulatory approvals for the USA and Canada. The letter designations were not on my CA-5 / PA-5, so I think that naming convention may have started during production.
I agree the CA-7 is an excellent preamp, especially when you consider the phono stage and full remote control it offers. As far as I can tell the only electrolytic caps in the CA-7 are for the power supply, I'm not sure replacing them would improve the sound or not.
I currently own a ST-7 / CA-7 / PA-7II, and have had the CA-5 and PA-5 in the past.
I don't think there was a mark II version of CA-7, at least I've never seen any photos online, nor is it in any of the brochures I have from the era. I also have owners and service manuals for all of the other Nak products of the era, but nothing for a CA-7II. There was a mark II version of the CA-5, which added tone controls.
The letter designations after the model number indicate which market the product was made for; A is for America, O is for Asia (Orient), and E is Europe. I have a PA-7IIA brochure where Nakamichi explains that the "A" designation means that the amp meets local voltage and safety regulatory approvals for the USA and Canada. The letter designations were not on my CA-5 / PA-5, so I think that naming convention may have started during production.
I agree the CA-7 is an excellent preamp, especially when you consider the phono stage and full remote control it offers. As far as I can tell the only electrolytic caps in the CA-7 are for the power supply, I'm not sure replacing them would improve the sound or not.
I agree--I wish we could get confirmation if this were Mr. Pass's design. That is why I posted it here. Since Threshold had preamps, it is no stretch to think Nak may have wanted to keep the sound in the NP family.
I think I had seen a CA-7AII listed somewhere (maybe FleaBay) but don't quote me on it.
For the power supply caps, refreshing them might lower the noise floor slightly if the caps are prone to leakage. I just recapped my Hafler DH-101, and while I'd done PC4 first (the signal board), I did the power supply a week later, upsizing the primary caps from 1000uF to 3300uF (and also bumped to 50 volts to prevent them from failing again), and the caps following the 7818/7918 regulators from 100uF to 330uF. The difference is subtle, but the already strong bass I experienced with upgrading to the PA-7 was even more enhanced by this little power supply upgrade.
I think I had seen a CA-7AII listed somewhere (maybe FleaBay) but don't quote me on it.
For the power supply caps, refreshing them might lower the noise floor slightly if the caps are prone to leakage. I just recapped my Hafler DH-101, and while I'd done PC4 first (the signal board), I did the power supply a week later, upsizing the primary caps from 1000uF to 3300uF (and also bumped to 50 volts to prevent them from failing again), and the caps following the 7818/7918 regulators from 100uF to 330uF. The difference is subtle, but the already strong bass I experienced with upgrading to the PA-7 was even more enhanced by this little power supply upgrade.
I remember my CA-7 fondly. Sadly, it did not come with a remote control. It was very good. I don't believe something has to have been built by NP to be good. A lot of equipment from the Far East were excellent performers in their own right.
We were told the CA5II had the same circuitry as the CA7, it certainly sounded better than the original CA5.
"Sadly, it did not come with a remote control" I think you may have meant " it did not come with the remote control."
http://d2heru13qkbk4q.cloudfront.net/media/1001126/scaled/Nakamichi_CA_7A_front.JPG
"Sadly, it did not come with a remote control" I think you may have meant " it did not come with the remote control."
http://d2heru13qkbk4q.cloudfront.net/media/1001126/scaled/Nakamichi_CA_7A_front.JPG
Yes, that is right. I had rescued it from someone who thought that it was an integrated amp. He had attempted a "repair" because he thought that it "lacked power", and said that the local repair shop could not fix it. I never found a remote, and its IR codes did not (does not) exist in the Logitech universal remote database.
This is true! But, I was trying to confirm (for my own sake) that this was, or wasn't, a Nelson Pass design.
It just occurs to me to check the rear panel. My PA-7 clearly says the designs were used under license from Threshold. There are no such markings on the rear of the few CA-7A preamps I've seen photos of on eBay a few moments ago.
The seller of this amp was raving at how good the CA-7A was, especially the phono stage. I am actually more interested in tube preamps at the moment, but I'm certainly not counting out the CA-7A either (or even an actual Threshold preamp).
You nailed it right there Wildcat...no Threshold licensing on the back pretty much confirms that the CA-7 is a Nakamichi exclusive design. There's no mention of Threshold on the CA-5 that I can see either.
This thread re-kindled my love for the old Nak stuff that I had sitting on the shelf. I'm now well into a complete recap / refurbishment of my PA-7II (thank's in no small part to other contributors on this site and their many useful threads). I also took my CA-7 apart and cleaned and lubed all the pots (aside from the Noble volume pot that seems to be sealed). Lastly I changed the notorious "supercap" in my ST-7 to restore it's ability to save radio stations.
I may recap my PA-7 in a year or two--the caps are getting near the end of their lifecycle, and I do hear a very faint buzzing when I'm only a foot or two away from a speaker (which is there whether or not the preamp is attached or not). These threads will come in handy.
I recapped my Hafler DH-101 a month ago and had no issues at all. The PC-4 board only took me a evening to do (slowly, with family interruptions 😀 ), and I ordered caps for the power supply and did that separately, only taking a half hour or so.
Those who have done the recap speak highly of the sonic benefits.
If you read up on the PA-7 threads there's more reason than just old caps to reburb them, sounds like Nak screwed up and put the wrong cap value in the feedback circuit on the original PA-7 amp. Changing that one cap can apparently make a large difference on it's own.
It's been interesting discovering the various enhancements Nak made for the MKII version I wasn't previously aware of, including using the correct feedback cap value.
Once I'm done mine I'll post some photos and a parts list.
If you read up on the PA-7 threads there's more reason than just old caps to reburb them, sounds like Nak screwed up and put the wrong cap value in the feedback circuit on the original PA-7 amp. Changing that one cap can apparently make a large difference on it's own.
It's been interesting discovering the various enhancements Nak made for the MKII version I wasn't previously aware of, including using the correct feedback cap value.
Once I'm done mine I'll post some photos and a parts list.
A parts list is always a big help to someone like me--I don't have as much free time as I'd like, and having it wrapped up in one place saves me a lot of grief. 😉
nakamichi CA7-A
Will Mr. Pass and/or Mr. Curl finally put to rest whether or not they were involved with the design or circuit topology of either the CA-5 and/or the CA-7 Nakamichi preamps Please. The circuits look like something You guys would design?
Will Mr. Pass and/or Mr. Curl finally put to rest whether or not they were involved with the design or circuit topology of either the CA-5 and/or the CA-7 Nakamichi preamps Please. The circuits look like something You guys would design?
Another happy CA-7A owner here.
Recapped mine a few years ago: just replaced power supply filtering caps with the new ones, bumping up values by ~20%. For my ears, it increased quality of sound in the line stage.
Also changed the trimpots to sealed Bournes ones. Helped with idling current adjustments. Changed a Zener in the remote control circuit so now the volume control rotated to a lesser degree if pressing button on remote. Changed also power cord to some $60 Pangea and bass became better.
The phono stage schematics, five or six FETs after one another, looks like threshold preamp phono stages (IIRC).
Someone here mentioned that CA-7A's optocouplers might be changed to better ones; however, no details were provided.
Overall, wonderful preamp.
Recapped mine a few years ago: just replaced power supply filtering caps with the new ones, bumping up values by ~20%. For my ears, it increased quality of sound in the line stage.
Also changed the trimpots to sealed Bournes ones. Helped with idling current adjustments. Changed a Zener in the remote control circuit so now the volume control rotated to a lesser degree if pressing button on remote. Changed also power cord to some $60 Pangea and bass became better.
The phono stage schematics, five or six FETs after one another, looks like threshold preamp phono stages (IIRC).
Someone here mentioned that CA-7A's optocouplers might be changed to better ones; however, no details were provided.
Overall, wonderful preamp.
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