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Nikko Beta 30 Preamp - simple upgrades yield major improvements!

w1jim

w1jim

I can fix it but good...
Subscriber
I recently picked up a Nikko stack from a local AKer and performed some upgrades that yielded some major improvements.

I posted a separate thread detailing my upgrades to the Alpha 230 power amp.
http://www.audiokarma.org/forums/showthread.php?t=570935&highlight=nikko+alpha

I also upgraded the Beta 30 preamp - which resulted in a startling improvement, which brought it from the realm of nice to superb (IMHO).

The main improvement was from replacing the 2 opamps with modern audio grade parts.

I pulled the old opamps, installed sockets and then used dual Burr-Brown OPA-627's (which are single channel units) mounted on a small PCB to yield a dual channel device.
I got these from an eBay seller. A good off the shelf alternative to these would be the OPA2134 - though I prefer the sound of the OPA627's.

I also upgraded 2 PS caps and 10 caps in the signal path.

I think this would a great project for any opamp based preamp.

Replacements:

C803-804 - was 470uf/25V - replaced with 3300uf/50V - this was what I had on hand - a 1000uf would probably been plenty adequate.
C603-604 220uf/16V

The following are all BiPolar caps - I replaced them with Nichicon Muse caps:

C501-502 - 1uf BP / 50V
C711-712 - 2.2uf BP / 50V
C715-716 - 1uf BP / 50V
C413-414 - 2.2uf BP / 50V



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Heard this setup at the New England AK meet and it was very impressive indeed. I was definitely not expecting to hear such considerable differences in the sound of each of the three OpAmps that were tested. Great demonstration, Jim, and thanks for the education!
 
I know that this thread is pretty old, but it contains some excellent information. I just picked up a Nikko stack (Alpha 230, Beta 30 and Gamma 30) and I'm looking to perform these upgrades. I have never done this before, but I'm good with a soldering iron and used to assemble Hafler kits back in the day so I should be able to handle this. My only question is regarding the OP AMP swap. You used 2 single channel units to replace a stereo OP AMP. Do you have a picture of this? Is there a dual channel unit that you recommend to keep the swap out easier? Thank you in advance for any advice.
 
It's a little confusing - I used a part that had two single channel opamps mounted on a very small PCB that plugged into the socket I installed. The part replicates a dual channel opamp - it has one on each side of the PCB. If you look closely at the picture you can see them - one is partially hidden under the ribbon cable in the first picture.
If you're coming to the FrankenFest in Clinton at the end of the month I could bring the preamp for you to examine.
I suspect that this would be an easy project for you to do - just use a rather small soldering iron and take your time.
 
I see it now. The small board with the two single channel chips on it. Where did you find the small board? I might just use the OPA2134 for ease of installation, but I will install a socket just in case! It looks like the stock is a JRC (Japan Radio Company?). I picked this equipment up on a Craigslist find and just set them up to a pair of Martin Logan 35XT speakers in my office. Without any mods this stack sounds much better than I expected. I'm trying to figure out what I want to use in my main system that has a Denon DP-62L front end and Martin Logan Theos speakers. Currently I have this Nikko stack, a Soundscraftsmen MA5002 & PE2217R stack, and a Nakamichi PA5II and CA5II stack. I like them all, but for different reasons. I will do the mods on the Nikko before making any decisions and then probably sell one of the setups. Are you familiar with the Nakamichi and Soundcraftsmen gear? I used to work at Tweeter, etc. and sold the Nak gear in the late 80's. I don't recall any of the amps or preamps ever requiring service...the cassette decks were another story (clutch issues). I don't think that I could make it to Clinton but I would love to!

I really appreciate your help and quick response. BTW, I have the factory service manual and owners for the Alpha 230 if you need it. They came with the stack, originals, not reprints!
 
I'm not particularly well versed in the Nak or Soundcraftsmen gear though I've owned each over the years. I do currently have a DP-62L (amongst others) in my "fleet" and it's an excellent TT.
I purchased the PCB with the opamp on it from an eBay vendor and it is very well regarded but that series isn't available in a DIP footprint.
I'd say put in a socket and go with the OPA2134 and I'm sure you'll love it. If at a later date you want to experiment you can try another opamp.
In general any audio grade opamp is going to be a noticeable improvement over the JRC.
IN FACT, while many of us obsess over upgrading the capacitors I've found improved opamps make a huge improvement in a variety of situations.
 
I just upgraded in a similar way by dropping a new opamp into my Technics SU-V6 - provided you get the specs right -an incredibly simple, cheap & worthwhile upgrade.
 
@slimecity-I have heard good things about the V6, how do you like it?

@ w1jim-Once I get the preamp completed I will live with each setup for a while and go back to my favorite. At the end of the day, it's all about the sound, and experimenting is (at least) half of the fun. I ordered the caps and OPA2134s through Mouser and will have them soon. I couldn't find the sockets but I really didn't know what to search for and there are so many parts available. I agree with the cap replacement; the caps don't show any sign of leaking or expanding but it's so cheap to replace them it just makes sense. I really love the DP-62L, I fell in love with the look and functionality of multiple tonearms but never expected it to perform like it does. I had a Marantz TT-15S1 and sold it since I thought the 62 outperformed it. Did you replace the caps in the 62L for safety reasons due to age?
 
I really do recommend installing sockets - you can pick them up cheap on eBay - just search for "8 pin dip sockets".
No - I never did recap the Denon TT.
Here a picture of it and its sibling.

IMG_3092.JPG
 
Very nice! My 62 came complete with the box, both arm tubes and weights. It also came with an Adcom Crosscoil on it. I was very happy with that find, it was from the original owner. BTW, in general, which deoxit do you recommend? There are so many choices that it's confusing. I just want to clean out the pots on devices. I also want to clean the slide contacts on a few EQ's that I have. Right now there is no noise, dropout or problems. Thanks for any advice and sharing the picture.
 
I picked up a mint Nikko Beta 20, Alpha 220 and Gamma 20 set up from the original owner. The build quality is great but I find the preamp lacking. I wish I had the ability to upgrade these units.

Nikko set up.jpg
 
funny, hadn't seen this before. Just ordered the caps for my beta II and the insides of the two preamps are completely different. Mine was made in 79, and not an opamp in sight. Seems they dropped all the fets in favor of opamps in 80 along with the roman numerals...
 
I just started working on the upgrade. I swapped out the opamps and I just started the caps. I competed two sets (started with the largest and worked my way down) and I realized that I did not buy bi-polar caps where you noted. Is it an issue using polarized caps instead? The caps are inexpensive, it's the shipping that'll get you!
 
jdrcapecod said:
I just started working on the upgrade. I swapped out the opamps and I just started the caps. I competed two sets (started with the largest and worked my way down) and I realized that I did not buy bi-polar caps where you noted. Is it an issue using polarized caps instead? The caps are inexpensive, it's the shipping that'll get you!
Click to expand...

Without knowing the Beta 30, If it says bipolar caps, you should use them. To the best of my knowledge they're not interchangeable that way. you can replace a polar with a bipolar, but not the other way around.
 
Correct - you must use bi-polar caps where specified.
I recommend the Nichicon Muse series for the best results.
 
Thank you both for the information. It already sounds a LOT better with the new opamps installed. I'll order the Muse caps for this. It's been a fun project.
 
Hi. I have a Beta 30 that I'd like to try this swap out of "Oamps". Never did anything like this before. I've Recapped some Marantz receivers so I can do some soldering. Would you have any more detailed Picts to show exactly how this is achieved? Thanks.

GT.
 
There are a few outstanding opamps now a days. Out of all those, I like OPA2604 Dual opamp. OPA2134 is close. Then you have the ultra low THD LMH4562. For single, I use OPA604 which is the single version of the OPA2604. If your preamp are opamp based, remove and put a socket on the pcb. Then you open yourself up to a whole world of new opamps to try.

I did detail comparison of a lot of the latest opamps, they do make a difference in the sound, I am surprised how much they sounded different between each other.

Other than the phono stage ( which I don't know and don't care to know), all the CD, AUX type input are only going through a buffer opamp, very simple circuit, it's all depends on the opamp.
 
Just finished modding my Nikko Beta 30 with the OPA2604 in sockets and all caps recommended... Wow, the before and after is amazing. This preamp was crap before, but now it is pretty damn good.

I just finished upgrading my Hafler DH-110 (search "Upgrading a Hafler DH110" in this forum). The Hafler sounds great. But comparing it to the Nikko, I think the Nikko now may sound better.

Thanks for everyone who has contributed to this thread. These types of threads help sort out vintage equipment.
 
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