Amps for Passive Monitors ideas?

[iomegaman]

So since I got educated on Yamaha NS10's I decided to re-visit my monitors...my main system used powered monitors but I do have some passive Tannoys and did pick up a set of NS10's...
I'm thinking of running the Yamahas off of an older Nikko Alpha-1 thats been n my closet for a long time, I do have a passive speaker volume controller (TECHNOLINK TK-727/rated for only 60 watts RMS which would be my "fail safe" to keep the NS10's from getting futzed since they come in at 24-50 RMS)...

The Nikko stuff is pretty highly regarded by some audiophiles, but I'm not that good and just looking for something to drive these without going out and spending another $700 on an amp...I'm pretty sure I can go through this unit and getting up to snuff.


The Nikko Alpha 1 is rated at around 220 Watts @ 8 Ohms (NS10's probably fitted with inline fast fuses on both tweeter and bass, but I never listen to stuff loud anymore, if I can't hear it at normal volumes I don't want to hear it).
I need to set up some sort of soft-start "pop" preventer because the Nikko does not have a power switch, and since I am going to go through it and replace caps (all but the huge 33,000uf/100volt cans at the power supply) I'm looking for ideas on how to install something like that inside the box.

Any ideas? Thoughts? Criticisms?

I'm all ears...which is why my soldering looks like crap.

Here's the Manual on the Nikko:

 

[k brown]

You could use the NS-20s as stands for the Tannoys . . .

 

[iomegaman]

You could use the NS-20s as stands for the Tannoys . . .

I used to think that way but this article reset my thinking on them...the NS10's have a unique characteristic that makes them "not terrible" in certain frequencies..

https://www.soundonsound.com/reviews/yamaha-ns10-story

 

[capacitor]

I'm considering Purifi for my passives:

https://purifi-audio.com/eigentakt/eval1/

 

[iomegaman]

By the way on page 11 of the manual it says the big can capacitors are 33,000F...surely thats a typo? Or did they use a different system in Japan in the 70's?

A 33,000 Farad capacitor would be the size of 55 gallon drum if I'm not mistaken...?

 

[DarwinYang]

It sounds like you have a good plan in place to power your Yamaha NS10's with the Nikko Alpha 1. The Nikko Alpha 1 has a high power rating at 220 Watts @ 8 Ohms, which should provide enough power to drive the speakers.

As for the soft-start "pop" preventer, there are a few options you can consider. One common method is to use a thermistor in series with the power supply to gradually ramp up the voltage and reduce the initial current surge that causes the popping sound. Another option is to use a relay to disconnect the speakers from the amplifier until the amplifier has stabilized. You could also consider using a dedicated pop-preventer circuit, which can be found online or in some audio equipment stores.

 

[iomegaman]

Thanks!

I think I tracked down the issue with the Nikko (it was drawing HUGE current and popping fuses, I stopped plugging it in and started using a current light and variac to gradually get it up enough to test circuit points)...

It runs 2 dedicated power amp boards for the right and left sides...after much sleuthing I discovered the left side had some toasty looking spots and decided to disassemble the power transistor heat sink assembly which is very involved...

One of the NEC 2SB600 transistors was showing a continuity connection to base from the emitter...which also explained why I got huge power draws when I engaged the negative side of the capacitor fuses...I think it was feeding direct power back into the rectifier board...

I still haven't figured out what the "protector board" protects unless its the speakers...
(Protector board is the dotted line in the top right corner board, it pulls AC from tranx and and half of the bridged power...when I disconnected the left power amp board and slowly ramped up variac I could finally hear the relay kick in once my voltage crossed around 76v DC)

 

[iomegaman]

I finally got this Nikko Alpha-1 running...had to replace a few transistors and oddly enough the factory wiring did not follow the schematic or the legend/boards...not sure that it made much difference because it was with the 2SD555 PNP's and the base of all of the 6 of them were in series with each other...(on each side, this is essentially a dual mono block amp)...

I hated cutting the little hand tied plastic wire wraps...(this was before the days of zip ties and everything was apparently handmade)...but sorta had to to trace out connections.


There was some cool history about Nikko on Audio Karma:

"Although I can't speak for the complete line of Nikko, I can say that during my tenure there, we have made some awesome products. The quality of the front panel metal extrusions and the metal enclosures were much beefier than the standard receivers of that era. The Alpha III MOSFET DC amp was only 80wpc but if you had efficient speakers, it was the cleanest amp you have ever heard. If you wanted more power, we had the Alpha VI, which was rated at 300wpc (for a measly $1400.!) that was great for driving speakers like the AR LST or the Bose 901's. Both amps had high slew rate and excellent square wave response while maintaining extremely low THD and TIM distortion. The Beta III had a direct coupled phono preamp coupled with its high speed circuitry. The Gamma V FM tuner had selectable IF bandwidth with amazing tuning accuracy. We also created the ATD1, which was Nikko's version of the Audio Pulse's and Advent's time delay processor. I also presented a white paper at the AES convention titled "Application of gyrators in graphic equalizers" for the development of the inductorless graphic equalizer called the EQ1. A little history behind the company:

Nikko started off as a circuit breaker manufacturer and their main customer was JNR (Japan National Railroad). The company chairman's daughter married a true audiophile and the chairman started the audio division to fulfill his son-in-law's interest. The son-in-law cared very little about marketability of the product and basically, it was his pet project to crank out audiophile type products. I certainly am not knocking the son-in-law because he truly had golden ears and he designed products like the Alpha V, which was a true class A 100 wpc power amp that sounded awesome but it was not marketable due to the insane price tag of the product. Because the revenue from the audio division was so small compared to the circuit breaker division, we were eventually phased out to consolidate Nikko's efforts in their main business. By the time we developed the 19 series (NR-1019, NR-1219, etc.), we could not compete against the giants like Marantz, Sony, and Pioneer who had an immense price/unit advantage over us. The strange thing about Japanese manufacturers in that era was that they were stolidly against outsourcing the manufacturing outside Japan. Perhaps, if we subcontracted the production to Taiwan like NAD did, we would have had a fighting chance for survival.

With warmest regards,

Tom Ishimoto
Northridge Electronics"

 

[boji]

https://all-audio.pro/en/c159/discussions/upc1237-speaker-protection-schematic.php

 

[iomegaman]

https://all-audio.pro/en/c159/discussions/upc1237-speaker-protection-schematic.php

Yea after spending a few weeks toying around with this amp I'm pretty sure it has speaker protection built into it...mainly because the primary capacitors are so big and have drain resistors on them...there is a relay board that sends everything to ground until everybody is happy...it leaves speakers out of circuit until te inrush is done...it's kinda how I trouble-shot the unit...I used a variac and waited until I heard the "click" to test the power amp boards voltage...

I might still throw a cheap inline protection circuit for the NS10's since they are no longer cheap...your link got me searching and there's a ton of them out there, hell Walmart sells circuit boards now!

 

[iomegaman]

This is the first time I've really paid much attention to how much a power amp affects the sound of NS10's but I gotta say it's night and day from how I had it set up...
Was using a Peavey PMA 200 and I just hooked them up to this Nikko in my work room so I could test it out and holy muffle batman it was like a wet sheet was removed from these speakers...really punchy and clear I can see why these speakers find use now...

 

[JohnRoberts]

The PMA 200 is not much of an amp... something like 100W... a nikko with 220W could easily sound better...

JR

 

[iomegaman]

The PMA 200 is not much of an amp... something like 100W... a nikko with 220W could easily sound better...

JR

Yea but I took a bunch of my rack gear to California and shoved it in storage...the PMA also has some sort of "compression" that you should bypass...I've searched high and low for a manual but to no avail...(you pull the level switches OUT to bypass it otherwise its always engaged for why?)

NS10's are rated for like 50 watts...so I thought a 100 watt amp would kind of clear that hurdle (got it off CL for $80) but apparently the sweet spot is a few watts beyond Peaveys range...I have no idea what this amp was originally for...maybe church sound or powering a store sound system to play Bruce Hornsby "Just the way it is" for Home Depot...

 

[boji]

Timely post- decided last week to also get a 'real' amp for mine.
Way back when I used em' all I had was a Hafler TA1100. Couldn't understand how folks found N10's useful...
Of course, internets says can't go wrong with a 4b, but apparently the PC2002M was designed to pair to yammy speakers?

gotta say it's night and day from how I had it set up

Scooped a PC2002 for a fair price. Once it arrives I'll be sure to dust off the Hafler and do an A/B.

 

[JohnRoberts]

Yea but I took a bunch of my rack gear to California and shoved it in storage...the PMA also has some sort of "compression" that you should bypass...I've searched high and low for a manual but to no avail...(you pull the level switches OUT to bypass it otherwise its always engaged for why?)

The compression you heard is the DDT clip limiter, so maybe don't drive it past clipping? It's only 100W amp.

NS10's are rated for like 50 watts...so I thought a 100 watt amp would kind of clear that hurdle (got it off CL for $80) but apparently the sweet spot is a few watts beyond Peaveys range...I have no idea what this amp was originally for...maybe church sound or powering a store sound system to play Bruce Hornsby "Just the way it is" for Home Depot...

But they sounded better to you when you drove them with 220W?

Mating amps to speakers is not that linear or simple

Powerhandling - 120 watts (maximum); 60 watts (program) Frequency Range - 60 Hz to 20 kHz

I am not a fan of NS-10s, or PMA200.... sorry.

JR

 

[iomegaman]

The compression you heard is the DDT clip limiter, so maybe don't drive it past clipping? It's only 100W amp.

But they sounded better to you when you drove them with 220W?

Mating amps to speakers is not that linear or simple


I am not a fan of NS-10s, or PMA200.... sorry.

JR

I'm not really a huge fan of them either, but I've been steering the shop towards allow other mix engineers in and decided to revive the NS10's...sort of outsourcing my gear in place.

Really I'm not that good at this stuff and my goto speaker is these trusty Mackie HR824's...I have a set of vintage JBL's with 12" woofers some Tannoy passives as well and a set of ADAM A5X's to go along with stuff...basically if you want to go back in time this is the place to do it...but there's enough newer stuff to get by with...I am not a fan of spending 10's of thousands of dollars on speakers that I personally will not be able to hear that much of a difference on.

I gave my KRK's to my grandson...they were to "meh" and he uses them with the Kurzweil keyboard I gave him.

The place I DO feel the NS10's poke through a bit is in transient response in the mid frequencies...but thats just me...again I'm not real listening expert.

I do keep the input level turned down on the NS10's...as is my practice on all the passives here...

The PMA will go back on CL, it is not gonna get any use here, I didn't engage the compression "feature" on the PMA...it just sounded smeared to me thats all.

 

[JohnRoberts]

This feels a little like ancient history. The NS10s popularity happened because they were associated with successful recordings. IIRC they were also notorious for blowing tweeters.

One theory for that success is that they have a hyped upper midrange that highlights harshness while tracking instruments and vocals. So pretty much if you EQ the content to sound good, on NS10s, the final result will sound great on regular speakers. Studios would often have multiple different monitor speakers and use them all, at different stages of the mix process.

Caveat: I am just repeating popular wisdom about the NS10s. They were involved in many popular recordings, and widely used.

Again, DDT (clip limiting) is a speaker protection feature, not a dynamic effect (compression). DDT is a very fast attack, fast release limiter designed to be transparent or relatively neutral sounding while protecting speakers. Of course it becomes more audible the harder you clip the amplifier output.

In listening tests I have seen customers prefer the sound of amplifiers allowed to clip, rather than safely limited by DDT. When an amplifier is driven past clipping, the output power and perceived loudness will increase dramatically. 3dB more output level past clipping will put out 2x the output power. In uncontrolled A/B listening comparisons, louder often sounds better. Clipping is routinely tolerated if the LF envelope content is not getting severely distorted.

Good luck...

JR

 

[iomegaman]

This feels a little like ancient history. The NS10s popularity happened because they were associated with successful recordings. IIRC they were also notorious for blowing tweeters.

One theory for that success is that they have a hyped upper midrange that highlights harshness while tracking instruments and vocals. So pretty much if you EQ the content to sound good, on NS10s, the final result will sound great on regular speakers. Studios would often have multiple different monitor speakers and use them all, at different stages of the mix process.

Caveat: I am just repeating popular wisdom about the NS10s. They were involved in many popular recordings, and widely used.

Again, DDT (clip limiting) is a speaker protection feature, not a dynamic effect (compression). DDT is a very fast attack, fast release limiter designed to be transparent or relatively neutral sounding while protecting speakers. Of course it becomes more audible the harder you clip the amplifier output.

In listening tests I have seen customers prefer the sound of amplifiers allowed to clip, rather than safely limited by DDT. When an amplifier is driven past clipping, the output power and perceived loudness will increase dramatically. 3dB more output level past clipping will put out 2x the output power. In uncontrolled A/B listening comparisons, louder often sounds better. Clipping is routinely tolerated if the LF envelope content is not getting severely distorted.

Good luck...

JR

Yes this is kind of where I plan on using them, they are definitely NOT for final mix listening...more of a focused tool to get to a fast mix then turn them off/down...

I detest clipping of any kind...(except in a decent guitar tube amp of course)...I have never been a fan of "loud" and generally avoid plugins that cannot gain match out of the box...

For me personally driving things too hot clutters the sound stage with broken glass and shards of bass...

My favorite headphones are still the vintage Grado RS-1's open backs...I think letting things clip leads to ear fatigue way too soon.
All these new plugins with clipping can sit in a drop down menu waiting for someone else to use them, I do try to be careful with the illusion of "louder = better"...one of the things I regularly do to listen for compression is turn the mix waaaay down until it smears into that "next room" sound...

For me personally quiet tells me much more than loud.

All I really want for these NS10's is for them to be as clean and clear as possible...maybe more watts can do that or maybe a better newer designed amp might be the trick...

The modern take on them is to use a powerful vintage amp of some sort, but I'm not paying for a Bryston...it's not THAT important to me.

As usual I'm trying to get to the high table by taking the low road.

 

[thomasdf]

Another user and lover of the NS10s here. I’m following

 

[JohnRoberts]

Yes this is kind of where I plan on using them, they are definitely NOT for final mix listening...more of a focused tool to get to a fast mix then turn them off/down...

for today's TMI Peavey anecdote: back last century Peavey took a run at the studio monitor business with some AMR models. To deal with the paradox that the loudspeakers that were good for tracking, were not optimal for final mix down, we designed studio monitors with two position switches, selecting between two alternate voicings. One for tracking, and the other for mix down. Of course AMR/Peavey was generally held in low regard by the recording community in the bay area.

A small recording magazine invited a bunch of studio types to a blind listening test/shoot-out between popular studio monitors. Since the AMR monitors had the two position voicing switches they were tested twice as if they were two different speakers. The 2-way 8" AMR PRM-208 fared well against the NS-10 that it was voiced similar to in one switch position. The Best of the entire group was the AMR PRM-308 (an 8" three way). The 308 did so well in the blind listening test that it came in 1st and 3rd place overall. Now for the real humorous punchline. A couple participants withdrew and refused to allow their names to be used in the shoot out article, after they were informed that they had chosen the AMR (Peavey) speakers as best. Overcoming the anti-Peavey bias was a constant head wind I dealt with while working at Peavey.

All I really want for these NS10's is for them to be as clean and clear as possible...maybe more watts can do that or maybe a better newer designed amp might be the trick...

The modern take on them is to use a powerful vintage amp of some sort, but I'm not paying for a Bryston...it's not THAT important to me.

I'm not sure it has to be vintage, but my recollection is they were happy with more than 100W, but fragile. The Bryston amps have good name recognition so might help the crowd who don't actually listen with their ears.

As usual I'm trying to get to the high table by taking the low road.

I am not sure that amps when operated in their linear region have significant characteristic sounds to speak of... of course clipping etc can make audible differences. Speakers OTOH do indeed have characteristic sounds...

JR

PS: FWIW I still have a pair of 308 in my home theater surround system (used for rear channels). I had to replace the woofer surround a couple years ago but otherwise they are OK.