Nagaoka MP-500

[Arkless Electronics]

Aha the service manual schematic didn't really make it clear that the op amp part is on the main board and only the input transistors are on the plug in cards... if the tants don't show dead short they're probably OK. You can test the resistors on the resistance scale of multimeter but some may be loaded down by other components so may need to lift one end.. The lighter bodied ones on far left and right nearest input sockets are actually capacitors. 220pF ceramic. Transistors most likely culprit and easiest just to change the lot as they will be pennies each and only four so quicker to change them than test them.

 

[Tony L]

Transistors most likely culprit and easiest just to change the lot as they will be pennies each and only four so quicker to change them than test them.

I’ll try that if I can find the right ones, there seem to be two types: MB413C B40ZF and BC214C MB40 assuming my eyes are working right.

PS I can’t get a continuity beep across any of the tants if that is what you were suggesting. I tried reading the capacitance too, but can’t get anything consistent there (my meter, a Fluke 17B, isn’t that great with small capacitance values, plus I don’t really know what I’m doing!)

 

[Tony L]

Are these the things: BC413C? I can’t find any exact match to the numbers actually printed on the things.

 

[Arkless Electronics]

Are these the things: BC413C? I can’t find any exact match to the numbers actually printed on the things.

Yes. The service manual says bc413 with no c but I'd get C if I were you. It says c for the bc213 (bc213C) and it is a gain banding, C being highest gain. No letter after the number means unselected for gain generally.

 

[Tony L]

Yes. The service manual says bc413 with no c but I'd get C if I were you. It says c for the bc213 (bc213C) and it is a gain banding, C being highest gain. No letter after the number means unselected for gain generally.

Thanks Jez, so I can ignore the other letters written on them, e.g. the one labelled a MB413C B40ZF is actually a BC413C and the other stuff is just a batch code or whatever? I’ve no experience in reading these things as they aren’t old valves!

 

[Tony L]

...Talking about old valves I’ve just chucked the Verdier Control B tube preamp in for a quick run. I like this preamp, though it really hated my 2M Black and didn’t think much of the 540/II either. It just pushed the hi-hats and surface noise out which makes me suspect it has a lot of onboard capacitance. This being why its sat doing nothing for a while. Anyway it seems to work rather well with the Nagaoka, here’s another quick and dirty plot:

Much to my surprise it looks all but identical to the other one! It sounds different though (as these things do despite what measurement junkies claim!); smoother up-top, more upper mid presence (sax, snare etc) which was sounding a little sucked-out before, and that lovely slightly stereotypically tubes ‘n’ vinyl midband. It sounds bloody good, which is good to know as its annoyed me just sitting there. I now have a valid choice to make between preamps (the Quad is better than anyone expects or gives it credit for, so its not as easier choice as some might think!).

PS One thing that needs to be pointed out is that as a 54 year old ex-rock muso I don’t have all the hearing acuity I’d like. I looked after my ears far better than most of my friends and used plugs etc, but I’m still only good to about 10-12kHz as far as I can measure, so the very right of the plot is none of my business! Its actually one of the reasons I’m doing these basic measurements, i.e. just making sure there are no huge spikes or dips way up top I can’t hear.

 

[delange]

... Certainly a great tracker, very quiet and no sign of end of side issues. It is noticeably lower output than either the 540/II or 2M Black, so needs another click or two on the 34’s volume knob. No hum from the TD-124’s hefty motor either.

Hi Tony,

I take it from the above post that you also own the 2M Black?
What do think of that cart and how does it sound?

 

[Alex S]

How worrying would spikes you can’t hear be?

 

[Tony L]

I take it from the above post that you also own the 2M Black?
What do think of that cart and how does it sound?

I had one for a while but moved it on. It is a very good cart, but a bit too brightly lit (even when correctly loaded) and analytical for my taste. I prefer the preceding 540/II which is a little warmer and friendlier if not quite as dynamic, and keeping two very similar carts made no sense. I also found the 2M Black dug out a bit more surface noise than I like. It is very good though. You need to load it right though, too much capacitance and it can strip paint! I liked it best with as little capacitance as I could get, which was about 120pf total including the arm lead.

How worrying would spikes you can’t hear be?

I figured it may well impact stuff lower down, plus other folk have been known to listen to my system!

 

[Arkless Electronics]

Thanks Jez, so I can ignore the other letters written on them, e.g. the one labelled a MB413C B40ZF is actually a BC413C and the other stuff is just a batch code or whatever? I’ve no experience in reading these things as they aren’t old valves!

Yes indeedy

 

[Seanm]

Just stuck the spare 47k/220pf board into the Quad 34 and annoyingly its broken, it makes a loud white-noise hiss out of the right channel, so assessing capacitance just got a whole lot trickier. IIRC I’ve never even used this board and just bought it off eBay as a ‘stock’ spare as I’d modified the one I use. I’ll keep an eye out for another as it will no doubt be cheaper to replace than to get this one fixed.

Tony I’d be very interested to hear what the Nagaoka sounds like with the standard Quad 34 loading, so you’d be welcome to borrow my board: it’s doing nothing at the moment as I need to send the whole unit in for repair. Once you get a sense of what capacitance suits there’s a guy on eBay - also a PFM member I believe - who’ll upgrade the card and match it to your chosen cart for £50, dare say that would include repair if it’s straightforward.

 

[Tony L]

Tony I’d be very interested to hear what the Nagaoka sounds like with the standard Quad 34 loading, so you’d be welcome to borrow my board: it’s doing nothing at the moment as I need to send the whole unit in for repair. Once you get a sense of what capacitance suits there’s a guy on eBay - also a PFM member I believe - who’ll upgrade the card and match it to your chosen cart for £50, dare say that would include repair if it’s straightforward.

Thanks Sean, but no need, I’ll just have a go at fixing mine. For the cost of four transistors and maybe four caps it is well worth a go.

There is absolutely no need to pay someone £50 to set up these boards, it is simple assuming you can solder/desolder, and its a really nice quality glass-fibre board so can take a good few goes without tracks lifting or anything. If anyone wants to have a go looking at my picture upthread the row of four comonents directly beneath/behind the RCA sockets are the ones you should focus on. The outside pair (left and right) are the loading capacitors despite looking like resistors, and by default they are 220pf. Most cartridges will like a lot less, my board is set to 39pf. The inner pair of components are the loading resistors and by default they are 47k. This value will be right for the majority of carts, but its nice to know where they are. That’s it, that is all you need to know!

I really liked what the Nagaoka was doing with my JC Verdier Control B last night so I’m going to leave that in the system for a while as the cart beds in. By the fact it worked I am all but certain that the Nagaoka likes quite a lot of capacitance.

The Verdier has no ‘spec’ as such, and whilst it comes with a full circuit diagram I don’t have the electronics skill to read it, but my guess from having owned it for a good few years and having tried a fair few carts is it is setup for classic Shures etc. It sounds great with my old 70s M95ED, and that likes around 400pf total. The Verdier sounds terrible with the Ortofon 2M Black, just unusably bad, and that likes to see around 150pf IME (spec is 150-300pf, but it prefers the lower end), it is a little better with the 540/II, but I’d still not want to listen to it and the Quad set to 39pf just kills it with the 540/II. With the Nagaoka the Verdier sounds a good bit better than the 39pf loaded Quad. As such I’m confident that the Nagaoka will actually sound very good with the stock Quad 220pf board. It will certainly not sound bad even if there is a little further tweaking possible. FWIW I think the Verdier is about 220 to 300pf.

One other thing is that the Quad 34 has an aggressive/bloody horrible ‘rumble’ filter. I got Rob to dramatically reduce its impact when he fully recapped my 34. I think it is just a matter of altering a couple of capacitor values, but it transforms the phono stage of this preamp from ‘meh’ to something that is actually seriously good. By default it just sounds gutless and sat-on, ditch the rumble filter and it has some proper heft and kick to it.

 

[Seanm]

Thanks Sean, but no need, I’ll just have a go at fixing mine. For the cost of four transistors and maybe four caps it is well worth a go.

There is absolutely no need to pay someone £50 to set up these boards, it is simple assuming you can solder/desolder, and its a really nice quality glass-fibre board so can take a good few goes without tracks lifting or anything. If anyone wants to have a go looking at my picture upthread the row of four comonents directly beneath/behind the RCA sockets are the ones you should focus on. The outside pair (left and right) are the loading capacitors despite looking like resistors, and by default they are 220pf. Most cartridges will like a lot less, my board is set to 39pf. The inner pair of components are the loading resistors and by default they are 47k. This value will be right for the majority of carts, but its nice to know where they are. That’s it, that is all you need to know!

I really liked what the Nagaoka was doing with my JC Verdier Control B last night so I’m going to leave that in the system for a while as the cart beds in. By the fact it worked I am all but certain that the Nagaoka likes quite a lot of capacitance.

The Verdier has no ‘spec’ as such, and whilst it comes with a full circuit diagram I don’t have the electronics skill to read it, but my guess from having owned it for a good few years and having tried a fair few carts is it is setup for classic Shures etc. It sounds great with my old 70s M95ED, and that likes around 400pf total. The Verdier sounds terrible with the Ortofon 2M Black, just unusably bad, and that likes to see around 150pf IME (spec is 150-300pf, but it prefers the lower end), it is a little better with the 540/II, but I’d still not want to listen to it and the Quad set to 39pf just kills it with the 540/II. With the Nagaoka the Verdier sounds a good bit better than the 39pf loaded Quad. As such I’m confident that the Nagaoka will actually sound very good with the stock Quad 220pf board. It will certainly not sound bad even if there is a little further tweaking possible. FWIW I think the Verdier is about 220 to 300pf.

One other thing is that the Quad 34 has an aggressive/bloody horrible ‘rumble’ filter. I got Rob to dramatically reduce its impact when he fully recapped my 34. I think it is just a matter of altering a couple of capacitor values, but it transforms the phono stage of this preamp from ‘meh’ to something that is actually seriously good. By default it just sounds gutless and sat-on, ditch the rumble filter and it has some proper heft and kick to it.

Cheers Tony, I'll investigate this rumble filter business.

 

[Tony L]

The new transistors for the Quad board turned up, so I soldered them in... and the hiss/white noise problem on the right channel was just the same. Arrgh. After pulling the lid off I’ve managed to track the issue down; when the Quad was recapped the electrolytic caps used (Panasonic IIRC) were physically larger and for some reason this board sat on the top of one cap and I assume grounded or shorted a component in the phono board, whereas the other (identical bar two components) one was fine. A little sticky address label stuck on top of the offending cap has fixed it. I’m a bit annoyed at replacing the transistors, but I assume they are all but identical to the original Quad ones, and I’m neat so no one would know I’d been in there!

Anyway, first impressions (just one track to test it works) suggests 220pf is superb with the Nagaoka. It sounded big and weighty with no sign of MM glare/tizz and with a very nice natural and open top-end. I’ll report back this evening once I've played a few more tracks, but this is very promising indeed.

PS Again the humble 34 surprises me, it gives nothing up to the £2k Verdier!

 

[Tony L]

...on further listening and going back the other way the Verdier is comfortably ahead, it just sounds more solid, together and effortless, so that can stay in the system. I’d really like to hunt down the fancy PSU for it one of these days, mine only has the little plastic thingy.

Anyway, the loading at 220pf on the Quad sounds fine to me, so I guess it is perfectly ok seeing about 300-320 total. I suspect the Verdier is higher again and that really does sound good.

 

[Ganders]

Hi Tony,

This is a little off topic really but I've got a MP-500 in it's box sat in a drawer, bought it a couple of years ago as a back up to my Cadenza blackout was a bargain so couldn't resist,but haven't needed it yet.It's only had 20hrs use in total from its original owner, and not used since,so will it still be fine sat there until I might need it?Can a cartridge deteriorate whilst not being used,I'm thinking possible suspension problems,or am I just being daft and there's no problem keeping it sat around?

Incidentally,I reckon my Cadenza's done probably close to 2000hrs by now and still sound great to me.How long are these things meant to last anyway?

 

[Tony L]

No credible answer I’m afraid as it depends on the specific materials used, but I’d suspect something as recent as a MP-500 should be absolutely fine. There are many who argue old cartridges decay, usually dealers trying to get a sale, and some do e.g. you’ll be lucky to find a working vintage Ortofon MM like a VMS20E as their suspensions tend to collapse. By saying that I’ve got an old Shure M95ED that has to be from the ‘70s and that is fine with no sign of droop or poor tracking. I bet it will be fine.

 

[monstrous lie]

On this capacitance issue, I think I might have got myself in a tangle: I thought that cables with a high measured capacitance acted as a low-pass filter - ie. they rolled off the high frequencies, resulting in a loss of sparkle in the sound. (It was specifically to avoid high frequency roll-off that I bought Rothwell Audio's low capacitance "River" interconnect when I had to increase the distance from passive pre-amp to power amplifier to about 4 metres.)

I'm now getting the feeling that everybody else is going in the opposite direction! Any views?
ML

 

[Tony L]

It all depends on the inductance of the cartridge and is a complex thing. some cartridges, e.g. modern Ortofons, Audio Technicas, just hate high capacitance values as they grow a huge resonance peak at about 8kHz that makes everything about the hi-hats and surface noise. A 2M Black is pure hell over about 200pf total (arm and phono stage) IMO. Conversely an old Shure V15 is dull as ditchwater with that loading and needs to see about 500pf total. Great explanation/calculator here. My guess is the Nagaoka sits somewhere between the Ortofons, ATs and the vintage Shures and likes to see something like 350-400 total. I know it works very well with the Verdier pre, but I don’t know what that value is (the Ortofons sound awful into this preamp, searingly bright). The experiment with the 220pf Quad board earlier gave very acceptable results, it sounded very good, but it may well be improved again with more capacitance, I don’t know.

 

[monstrous lie]

It all depends on the inductance of the cartridge and is a complex thing. some cartridges, e.g. modern Ortofons, Audio Technicas, just hate high capacitance values as they grow a huge resonance peak at about 8kHz that makes everything about the hi-hats and surface noise. A 2M Black is pure hell over about 200pf total (arm and phono stage) IMO. Conversely an old Shure V15 is dull as ditchwater with that loading and needs to see about 500pf total. Great explanation/calculator here. My guess is the Nagaoka sits somewhere between the Ortofons, ATs and the vintage Shures and likes to see something like 350-400 total. I know it works very well with the Verdier pre, but I don’t know what that value is (the Ortofons sound awful into this preamp, searingly bright). The experiment with the 220pf Quad board earlier gave very acceptable results, it sounded very good, but it may well be improved again with more capacitance, I don’t know.

OK, That's interesting.
There are clearly a number of variables - as you say - but if I have understood the linked article correctly, for a cartridge of a given inductance value and against a given resistance load, increasing the capacitance in the arm and interconnect cable has the effect of shifting the resonant peak lower in the frequency range. Perhaps this is the source of the "capacitance as a low-pass filter" idea that I have picked-up somewhere.
ML