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Old 4th December 2012, 08:09 PM   #11
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Default Nakamichi amp and pre

I have a Nakamichi PA5 amp and a Naki C5 pre amp both in great condition how much are they worth?
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Old 9th December 2012, 01:55 AM   #12
synth is offline synth  New Zealand
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Default PA5-mkII

Hi Kotofei,

First up thanks for the great thread combining these mods into one location.

Just one question, how many of these apply for the MK2 model that Naka released?

thanks,
Synth
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Old 6th January 2013, 10:59 PM   #13
kotofei is offline kotofei  United States
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Guys,

Sorry for delayed replies: that was kind of crazy Christmas season.

Pat C: The CA-5 preamp in a great condition should worth not less than $300; the PA-5 in the same condition might go for $550-$600. The sale price AFAIK varies between different Websites: on Audiogon it will be lower than at the ebay.

Synth: I have no idea since I didn't see Nak PA-5 MKII schematics. In any case, you can replace electrolytes, potentiometers and diode bridge rectifier.

All: many of you probably interested how the PA-5 sounds after I modded it. The short answer is: MUCH BETTER!

Specifically, the"mugginess" at the bottom end is gone, the bass became much more tight and natural. Is this actually bass or a lower midrange I don't know. The soundstage is better now, instrument positions are better defined than they use to be. Not sure re. 3-D depth of the soundstage. The way how instruments sound (tonality?) is now more natural for guitar, jazz bass and, naturally, drums.

So overall I like the amp better than before and mods were definitively worth it. BTW, the output power is 150 WPC at the bench before clipping vs. IMHO 100 WPC before. However, to get the best sound I need to warm the PA-5A up for at least 1 hour; if I listen to the music just after powering up it sounds good but thin.

Again, thanks to all who was involved in helping me with this project. In the future I plan to change the input/output jacks to Cardas ones and increase the bias to perhaps 80 mV to get the amp working temperature in the 50 degrees range as Mr. Pass suggested.

Happy New Year to all!

Andrei
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Old 20th May 2013, 09:56 PM   #14
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@kotofei

Hi kotofei, is it possible to do the same upgrades from the PA5 to the PA5 MK II? And can you say me whats the effect of the upgrade?


Chris
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Old 21st May 2013, 12:27 AM   #15
kotofei is offline kotofei  United States
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Chris,

I don't know what are differences between Nak PA-5 and PA-5 MKII; however, both have electrolytic capacitors, a diode bridge and potentiometers. I think that replacing of those parts in PA-5A MKII will have the same positive effect as in MK I.

Regarding the effect of upgrade pls see my posting of January 6th. I have nothing to add to it.
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Old 15th November 2013, 07:48 PM   #16
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Smile PA-7 LIST OF UPGRADES

HELLO A LOT OF DISCUSSION ON THE NAKAMICHI PA-7 UPGRADES

DOES SOMEONE HAVE A LIST OF THE ITEMS THAT HAVE BEEN USED WITH SUCESS

TYPE AND BRAND CAPS I AM TAKING MY AMP TO BE SERVICED AND NEED A LIST OF THE PROPER COMPONENTS THAT I WILL NEED TO REPLACE AND UPGRADE. AND LET HIM KNOW OF THE THING THAT GENRALLY FAIL

THANKS PAUL
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Old 22nd August 2014, 08:18 PM   #17
dbear44 is offline dbear44  United States
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Quote:
Originally Posted by cegtv View Post
HELLO A LOT OF DISCUSSION ON THE NAKAMICHI PA-7 UPGRADES

DOES SOMEONE HAVE A LIST OF THE ITEMS THAT HAVE BEEN USED WITH SUCESS

TYPE AND BRAND CAPS I AM TAKING MY AMP TO BE SERVICED AND NEED A LIST OF THE PROPER COMPONENTS THAT I WILL NEED TO REPLACE AND UPGRADE. AND LET HIM KNOW OF THE THING THAT GENRALLY FAIL

THANKS PAUL
I posted this on the solid state PA 5 forum:

Greetings!

I have been rebuilding a PA 7. It has been rewarding but frustrating since the info is scattered about. I am considering starting a PA 7 update page so that we can bring our collective knowledge together. I totally missed this PA 5 page and for a long time didn't have some key information.

Regarding the main cans, I was not completly satisfied with the sound even after recaping the boards with wima, muse, and cerifine caps. The amp still sounded rather closed in with soft bass and poor high end extension.

I have recaped many vintage recievers and have heard many of them sound really sub-par with the old cans. It is amazing what a difference they can make! Sometimes the old ones will reform and sound really good. I am using a HK 930 that sounds great with the origional cans! Often though, they will sound awful at first listen, really dynamicly constipated. Try turning up the volume and it's like running into a wall. Then after a few days the sound really loosens up. It seemed the same thing was going on with the NAK.

Replacement cap options are rather limited. Specs are: 33kuf @ 100v, 2.5in (64mm) dia, 6"h If you look at what's available, the Nicicons and most others are 3" dia. They will NOT fit in the PA 7! That leaves Rubicon Digikey: Not stocked minimum order of 10. $59.71 each. If someone can find them stocked Please let me know!

I ended up going with the TCI caps from an ebay seller. Very little info on them. They are US made and appear to be very rugged. TCI makes industrial power products and these are apearantly surplus. 2pcs TCI 100V 33000uF Computer Grade 105C Bus Capacitors New | eBay Less than $150 for 4. I took the plunge (out of options at this point) and have been very satisfied. You have to drill out the holes on the buss plate and use larger crimped rings since the screws are HUGE. The improvement in sound is really substantial. Much more linear. Tighter bass, better dynamics, much better on the highs.

Hope this helps.

Also, I just added Clairty caps 4.7uf @ 250v for bypass. I still need to change the bias pots and the 200v fb caps. But right now I am totally thrilled with the sound on my Newform RS 645's.
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Old 23rd August 2014, 03:54 AM   #18
dbear44 is offline dbear44  United States
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Here are a couple of pictures.
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File Type: jpg 20140820_205612.jpg (665.2 KB, 129 views)
File Type: jpg 20140821_151107.jpg (740.1 KB, 122 views)
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Old 23rd August 2014, 04:48 AM   #19
ci11 is offline ci11  United States
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Quote:
Originally Posted by dbear44 View Post
Here are a couple of pictures.
Thanks, dbear44!

I am in the process of a complete upgrade but have been a little hesitant as mine is completely original and have never been touched.

So far, I have waded into bypassing the PSU with 3.3F of CDE 941 and 10nF of polystyrenes but next on the list would be the probably tired bridge rectifiers and wires. I see you have changed yours to what appears to be IXYS HexFred's. Am I right? What are they rated at and how would you rate their contribution to the improvement in sound?

Once the bridges are done, next on the list would be to bump C102/C202 to 470F as in the Threshold 400A. These caps are noted as non-polar on the schematic so I still have to decide whether it's Mundorf ECap Raw or Muse ES. Unfortunately, I have yet to find any film cap that would fit in that space - the Mundorf at 25x38 barely

I would very much welcome comments and input. Attached is the picture of what my PA-7 looks like now.
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File Type: jpg Bypass caps.jpg (371.6 KB, 127 views)
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Old 23rd August 2014, 12:20 PM   #20
dbear44 is offline dbear44  United States
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The IXYS bridges I got from PCX. I used VBE 26-12 NO7 which is rated at 32A and 1200V. This is probably way overkill since with the soft start circuit they are never stressed, but the price is not much different from the smaller ones so why not.
I can't say that it made much difference with the old cans. I think it is more like icing on the cake. If the cake is old and stale the best icing in the world isn't going to help much!

Which brings us back to those big cans. What condition they are in depends on a lot of factors. Was the amp used regularly or in storage for years? Was it kept in some hot attic or damp basement or unheated garage? My amp had not been used in years so maybe that is why I needed to change them. YMMV.

I do know that I tried bypassing them with .47uf Wima's (the only thing that I had 4 that matched) and was not happy with the results. The sound became bright and edgy on top while still being soft and congested in the rest of the range. I ended up taking them out. What was happening was when you put a very small value low ESR cap in paralell with an extremely large high ESR cap you are making a filter. The bypass only helps on the high frequencies leaving lower ones still straining to get current.

So what I am saying is if your cans are in OK shape you may be able to get away with bypasses if they are large enough to affect most of the frequency range. If the amp still sounds overly soft and sluggish with the bypasses then you should replace the cans.
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