I've had an SR-2A for a long time and always liked it a lot. I have a home studio with ProAc Studio 100 monitors that I've powered with a McIntosh MC2015 for a while. I decided to check out how the SR-2A sounded and it really opened up the sound for me. A lot more detail in the vocals, reverbs, and representation of space, etc. Figuring that one Nak Stasis receiver should have the same basic sound as another, I got a TA-3A on Craigslist so that I could get more power as well as power amp direct ins. It does sound more powerful, as expected, but the vocals sound quite recessed in comparison as well as some weird, very subtle distortion. The SR-2A sounds a lot more open and detailed, although less punch in the low mids.
Any ideas if this is just a function of the different models, perhaps from design differences and manufacturing techniques, or if it would be worth investigating getting the TA-3 to sound more like the SR-2A.
TIA
Edwin
Any ideas if this is just a function of the different models, perhaps from design differences and manufacturing techniques, or if it would be worth investigating getting the TA-3 to sound more like the SR-2A.
TIA
Edwin
What would be helpful? I don't have any measurements, just that when I hook up the SR-2A, it sounds as I would expect and then, same cables, same speakers, same source (Metric Halo ULN-8 as conversion), the vocals recede into the background and there is a very tiny twinge of distortion.
I am thinking it would be interesting to test the i/o with SpectraFoo, but I've never tested the output of an amplifier before, so I'd want to make sure I don't toast the input of the ULN-8. SpectraFoo has the ability to measure transfer function, so that might be helpful. I can get a load resistor, so I just need to figure out how to safely pad the signal down.
Hifiengine has the schematics you are looking for.
I took a quick look at the amplifier section of both and they are virtually identical, save for the fact the SR-2A has a +/-37VDC compared to the TA-3A's +/-53VDC rails. I was surprised to see that the TA-4A model used 2SK389 jfets as the LTP input, nice. All of the lower models used bipolars in their LTP. You might want to look at things in the signal path that can degrade over 20+ years of usage, i.e. protection relay contacts, A/B speaker switch contacts, etc. If it were mine, I'd look to install a new protection relay and figure out how to clean/deoxit the switches while I was at it. You might also want to look at other things like electrolytics to see if any are bulging or leaking.
I took a quick look at the amplifier section of both and they are virtually identical, save for the fact the SR-2A has a +/-37VDC compared to the TA-3A's +/-53VDC rails. I was surprised to see that the TA-4A model used 2SK389 jfets as the LTP input, nice. All of the lower models used bipolars in their LTP. You might want to look at things in the signal path that can degrade over 20+ years of usage, i.e. protection relay contacts, A/B speaker switch contacts, etc. If it were mine, I'd look to install a new protection relay and figure out how to clean/deoxit the switches while I was at it. You might also want to look at other things like electrolytics to see if any are bulging or leaking.
Thanks so much. I just found those schematics as well. My guess is maybe the electrolytics did degrade. Although it's weird that the older receiver wouldn't have that problem. Maybe they used better parts.
An update, if you are interested.
Well, being pressed for time and not possessed of the experience or test equipment, I dropped it off with a local tech with decades of experienced who has done great work with my Mac gear. He's going to scope it out and see how it's performing against original spec. He's quite familiar with Nak equipment, so I'm in good, if not bargain basement hands. What I'm hearing doesn't sound like dirty contacts, but it could easily be tired caps. I would think that if it were dirty contacts, or something else fixable with deoxit, it wouldn't be so focused in the midrange and it probably wouldn't be both channels. I'm really hoping that the amp isn't just operating according to spec and that it has a naturally scooped tone according to its design, but that's quite possible. In the meantime, the SR-2A is holding down the fort quite nicely.
He said that he could completely rebuild it, including a complete recap for $300. It's tempting, but I don't know if I have the cash for that at this time. Or if it would be more worth putting the money and time into something else, maybe even getting a Hypex kit. I can do simple recapping myself, having done quite a few Fender amps, etc., so I could deal with a lot of that.
I'll know later this week what the story is.
Thanks for chiming in, everyone.
Well, being pressed for time and not possessed of the experience or test equipment, I dropped it off with a local tech with decades of experienced who has done great work with my Mac gear. He's going to scope it out and see how it's performing against original spec. He's quite familiar with Nak equipment, so I'm in good, if not bargain basement hands. What I'm hearing doesn't sound like dirty contacts, but it could easily be tired caps. I would think that if it were dirty contacts, or something else fixable with deoxit, it wouldn't be so focused in the midrange and it probably wouldn't be both channels. I'm really hoping that the amp isn't just operating according to spec and that it has a naturally scooped tone according to its design, but that's quite possible. In the meantime, the SR-2A is holding down the fort quite nicely.
He said that he could completely rebuild it, including a complete recap for $300. It's tempting, but I don't know if I have the cash for that at this time. Or if it would be more worth putting the money and time into something else, maybe even getting a Hypex kit. I can do simple recapping myself, having done quite a few Fender amps, etc., so I could deal with a lot of that.
I'll know later this week what the story is.
Thanks for chiming in, everyone.
I wouldn't spend $300 on the receiver, especially when you aren't sure whether this will correct the issue. If you still do not like the sound then you'll never get your money back selling it. I would sell the TA-3A and use that money plus the $300 you would have spent recapping the receiver to buy a Nakamichi PA-5. The PA-5 is a massive step up from the SR-2A. Find a decent deal on the PA-5 and if you don't like it then you can always sell it and get your money back, or at least most of it.
Dear Zambi,
I am a shoemaker by trade. I have some technical knowledge and good ears. I too have a Nak Stassis SR3a and was amazed at the forward vocals on my DQ10s. I have read about the fact that the T series was made in China and have been known to suffer from poor wave soldering of their boards. This is a very nice amp when working properly. The MC preamp section replaced my DV6a transformer hands down!!! Good luck with your quest. I have many 200 watt amps that didn't drive the DQ's as well1
I am a shoemaker by trade. I have some technical knowledge and good ears. I too have a Nak Stassis SR3a and was amazed at the forward vocals on my DQ10s. I have read about the fact that the T series was made in China and have been known to suffer from poor wave soldering of their boards. This is a very nice amp when working properly. The MC preamp section replaced my DV6a transformer hands down!!! Good luck with your quest. I have many 200 watt amps that didn't drive the DQ's as well1
Well, I took it into a local tech who is very familiar with this design. In fact, he had a Nak receiver in his own system until recently. He confirmed what I was hearing both with his ears and test equipment. His diagnosis was many tired electrolytic caps. He said that this model did not have the quality of parts that the Japanese made ones did, so the sound was probably never as good as the Japanese ones. He said he could rebuild the whole thing, new caps everywhere (including sourcing much better caps than came in it originally) and some other upgrades for about $300. However, for my studio, I have decided to go another way: an Adcom GFA 545 (first version) that I will send to Jim Williams for all his mods. And then I will upgrade the Nak myself at my leisure as a home project. I'm listening to the GFA 545 right now and even before the upgrades, it sounds very nice, although the Nak SR-2A sounds slightly more detailed. Both are very spacious. Given that the GFA 545 was only $135 on Craig's List and that Jim's services are very reasonable, I'm feeling good about my use of funds.
Clearly, I will be back with questions about the recapping process. Thanks to all for past advice and for future help.
Clearly, I will be back with questions about the recapping process. Thanks to all for past advice and for future help.
Hi Zen Mod,
Just for general info, I picked up a Sr 3a about three months ago, and it literally blew my ears off. I have spent a lot of time (because of snow) fixing other problem in my system after I heard the amazing sound stage the Nak created in my living room. I have an old Koetsu rosewood, Dynavector DV 6a transformer. and DQ 10's. I listen to voices, jazz, and classical type of music. The MC section took the veil off of the Koetsu so much that I am not sure if it is strait, but Mitchell and Baez never sounded better. I wish you could get your hands on one of these and tell me what I am hearing. I have a Jazz at the pawn shop record set and side 4 has a drum track on it and I hear tight well balanced bass for the first time!!! This unit is supposed to be 35 to 40 watts!!!! I have had many 200 watt amps on the DQ 10's NEVER have they sounded so good. The instrument placement is also amazing with a clarity I have never heard. Thank you for all the work you do to help all of the people here!!!!
Just for general info, I picked up a Sr 3a about three months ago, and it literally blew my ears off. I have spent a lot of time (because of snow) fixing other problem in my system after I heard the amazing sound stage the Nak created in my living room. I have an old Koetsu rosewood, Dynavector DV 6a transformer. and DQ 10's. I listen to voices, jazz, and classical type of music. The MC section took the veil off of the Koetsu so much that I am not sure if it is strait, but Mitchell and Baez never sounded better. I wish you could get your hands on one of these and tell me what I am hearing. I have a Jazz at the pawn shop record set and side 4 has a drum track on it and I hear tight well balanced bass for the first time!!! This unit is supposed to be 35 to 40 watts!!!! I have had many 200 watt amps on the DQ 10's NEVER have they sounded so good. The instrument placement is also amazing with a clarity I have never heard. Thank you for all the work you do to help all of the people here!!!!
GFA 545 is a BJT amp and doesn't have even close to the same potential as the 5200, 5300, and 5400 mosfet amps that Papa designed.
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