[micah356]

I just got my grandfather's old turntable - a Rotel RP-6400. I'm guessing from what he told me, and the style of the fake wood-grain material, that it is probably a product of the late 70s. I sent an email to Rotel asking about it, but the tech support guy said their records don't go back more than 25 years. Anyone know anything about it? It definitely seems pretty decent, especially through HD600 headphones.

Here's a craigslist link (not mine) with some pictures:
ROTEL RP 6400 turntable

 

[NightOwl]

I don't know that model, but you're pretty close. It probably dates from the very early 80's since that's when Rotel (along with all the other Japanese manufacturers) started using low mass straight arms instead of s-shaped medium mass on most of their tables. I know that Rotel had a belt-drive RP-4400 model no later than 1982.
Around the same time they started making a name for themselves with a budget line of amplifiers. Giant killers comparable to Nad, but cheaper. This is where most of their effort went and turntables were an afterthought. With one exception based on a Rega (very good), Rotel's tables were always decent models, comparable to similar models from Pioneer and Technics. They did hang on a little longer than most of the others using wood-grain vinyl though

.

Nice score and welcome to vinyl.

 

[micah356]

It is direct drive if that tells you anything. Also I have the owner's manual, if I can find any clues in there. It doesn't contain any year or dates or anything though.

 

[NightOwl]

The fact that it's direct-drive won't really help you. Direct-drives had already been around for years by the time your table was made. All the Japanese manufacturers made both belt-drive and direct-drive models. The RP-4400 would have been part of the same series as your RP-6400 and manufactured about the same time.
At least you have the owner's manual. Unfortunately owner's manuals hardly ever show manufacturing dates. The only real clue is the tonearm which is a fairly standard Japanese-manufactured low-mass straight arm. It's very similar to the tonearm on a lot of other Japanese made tables like Harman-Kardon, Luxman, Hitachi, Pioneer, etc. This arm first started showing up in 1980. If your table was manufactured after 1984, then Rotel would have a record of it.
There are no tweaks specifically for that model turntable. It sounds like it's in pretty good shape. It's direct-drive so you don't have to worry about a replacement belt, and the tonearm is fairly standard so finding a cartridge to fit is easy. I wouldn't worry too much about the exact year it was made.

 

[micah356]

Ok, well here's another question for you, if you can help. I've got it hooked up to a Harman Kardon 930 receiver. Any good? I just googled it, seems it was made in the early 1970s. I also have a Marantz 2230, that I'm guessing is around the same age. It seems to work properly, but needs to have the speaker connections repaired. Know anything about these two? As for speakers, the two big ones connected right now don't seem to have any labelling on them, but I would guess they are at least as old. In storage along with the Marantz I have two old KEF speakers, which I'm guessing might be better than these unmarked ones. And I'm on the verge of buying headphones, looking for something like a HD600 or K701.

 

[NightOwl]

Both receivers are very good vintage receivers. The Marantz is the better known of the two. It's worth getting repaired, because even if you don't like it you could sell it for a good buck. I prefer the Marantz. The phono stage is definitely better than the HK and even the headphone output is said to be pretty good (didn't listen to headphones much when I had my Marantz). The Marantz is definitely on the warm side and a little "soft" but great for long listening sessions. The HK is more neutral and a little crisper. Power output is about the same on both.

As far as speakers go, I'm partial to vintage British speakers (I own a couple of pairs myself) and Kef always made pretty good speakers. Obviously I can't help you on the other speakers, but if you want to pull off the grills and post a picture, you might get lucky.

As far as headphones go, I'm partial to AKG's as you can see in my profile. You'd be better off searching in the headphone forum for that answer though.

Boy you came up with a nice haul of vintage stuff. I wouldn't be embarassed to own any of it.

 

[micah356]

Yeah, pretty lucky. Apart from the turntable, the rest of this stuff has been my parents' since it was new. Unfortunately they sold all their vinyl long ago! The speaker grilles don't seem removable, but the rear panel is. I'll grab a screwdriver once Lost is over.

 

[memepool]

Quote:

Originally Posted by micah356 /img/forum/go_quote.gif Anyone know anything about it? It definitely seems pretty decent, especially through HD600 headphones.

This actually dates from 1980 but I didn't include it in my best-budget-vinyl-sources thread because Hi Fi Choice preferred the cheaper RP-300 belt drive at that time. Given it was 2/3rds of the price that isn't too surprising and I shouldn't worry too much.

This RP-6400 was actually more expensive than a Rega P(lannar)2 then and also faced stiff competition in affordale direct drives from the bigger Japanese combines.

It was therefore a bit of an oddball concoction which Rotel presumably tried in order to stand out. It actually came with an Audio Technica moving coil the AT-30E, which as one would expect wasn't a brilliant success on the then fashionable very low mass tonearm ( 7gms !), even though they did make higher compliance MCs for this purpose back then.

HFC said it was a noisy combination despite the fact the motorboard on it's own was 71dB Din weighted, which is very respectable. It didn't have much isolation from feedback either so you should keep it well away from the amp and especially the speakers and put it on as high a mass surface as possible.

They weren't too impressed with the speed stability either but again this is within the context of test firgures for direct drives at the time and they said it would be subjectively unnoticeable.

They also criticised the lightweight platter as prone to ringing, as with most cheaper direct drives, so a better mat would be a good
investment. KABUSA sell the original heavy Technics rubber mat or on the cheap just cut one out of a thin cork tile with a Stanley knife.

Rotel were lauded at this point for their cheaper belt drives and obviously failed to make a move upmarket with this model. Their reputation improved later on when the bigger Japanese players left the field, and they faired far better taking on the British at their own game with well engineered belt drives like the RP-830 / RP-850 which I'd actually still take over a Rega P3, even today.

Don't be put off by any of this though as it's still a very respectable deck and you'd need to pay 500USD today to better it. The best thing to do would be to get a more appropriate cart which works properly with a very low mass arm. Ortofon OM series are the obvious contender, Shure M97 and also Grado would work. KABUSA also favour high compliance Stanton carts for the Technics and carry a good range of pretty rare ones.

My personal favourite would be a Nagaoka MP11 if you can find one, and this also would balance the slightly lush phonostages on your vintage recievers as well for a more modern sound

Well done on the Kef 'speakers as well . Do you know which model?

 

[micah356]

Wow, you obviously know your stuff!

Anyways it does currently have an Audio Technica cartridge, but I'm not sure if its the original one or not. Either way though my first buy will be some better headphones, but my E2C will do until I find some on craigslist or in the for sale forum here. After that will be repairing the speaker outputs on the Marantz. I figure I can manage to do that myself, but may have to get it done at a shop.

I'm not at the same place as the Kef speakers (and the Marantz) right now though, so I don't know anything about them. I guess I can say they are the same age as the 2230 though.

 

[memepool]

Your first priority as far as the turntable goes is a new stylus as it's very risky playing records on an old one. Even if you know for sure that it hasn't been used for more than 500 hours or whatever, if it's not been played in years the rubber in the suspension usually perishes.

This is especially important in your case as I mentioned since the tonearm on that Rotel is very low mass indeed and therefore needs a well sprung cart to work properly.

If you do have the original, and I don't see any reason why this would have been upgraded, although it could possibly have been downgraded I guess

, then a new Audio-Technica AT30E stylus is expensive.

Moving coils with replaceable stylii are very very rare because of the complexity involved, so not cheap. You could probably make a tidy profit flogging it on ebay.

The one I mentioned is available for much less at LP Gear.

Review here Nagaoka MP-11 . Although he uses it on a Rega arm which is not really suited. I bought one for a friend recently to go on a similar vinyl starter system and the treble peak he mentions balances out nicely through an average '70s Reciever phonostage, and sounded lovely through my Marantz PM94.

As far as your speakers go, Kef are one of the most famous British manfacturers and their drivers are found in many important designs like the BBC LS 3/5a and pro monitor series, which date from that time and are still widely used today. Kef make speakers at all levels of the market so you could have anything from a humble Coda III right upto the Reference Series.

 

[micah356]

So I will be picking up my new (used) Sennheiser HD 580 tomorrow. Then I guess I will get a new cartridge. When I initially set this up at my friend's house through his HD 600 it was abit noisy, but it may have not been properly grounded as it was only a temporary setup. Would you say that the sound quality of the Nagaoka is at least equal to the original AT? Also, there doesn't seem to be any labelling on the cartridge (apart from the Audio-Technica logo), unless it is concealed by the mounting point.

 

[memepool]

Quote:

Originally Posted by micah356 /img/forum/go_quote.gif When I initially set this up at my friend's house through his HD 600 it was abit noisy, but it may have not been properly grounded as it was only a temporary setup. Would you say that the sound quality of the Nagaoka is at least equal to the original AT? Also, there doesn't seem to be any labelling on the cartridge (apart from the Audio-Technica logo), unless it is concealed by the mounting point.

The markings on the AT should be underneath as in the pic. I dug out an old review of it on it's own and it pretty much concurs with what they said about the Rotel, which is good news because as I supected a lot of the issues they highlighted were cart related.

It's not so much that there is anything wrong with either the tonearm or the cart but the way Rotel sold it as a package was less than ideal and one supects more to do with marketing than anything else. This is a bit of a steep learning curve for someone unfamiliar with the history of turntable design so read up on mechanical matching issues here

In a nutshell the AT30E cart you have is better than the Nagaoka MP11. Given it's still nearly double the price, just for the stylus alone though that's not surprising.

The AT is rare as I said because the stylus is removable which isn't usually the case for moving coil carts. It's technically difficult to engineer the tolerances to make this work which is why few designs like this were made and it's resulted in a noisier cart.

However there is another bigger issue which is that a Moving Coil cart puts out a much lower signal than a Moving Magnet. The AT30E is 1.03mv which is high for an MC, but given the noise issues outlined above it really means a step up transformer should be used, and AT in fact used to sell this as a package if you bought the cart separately. There is no mention of it on the Rotel review though so I doubt you have this?

If not then you really should buy a separate phonostage to get the best out of this cart, as although it would work ok through a standard MM stage like you'll find on the recievers you have, it will be a little noisy for headphone listening.

Better I think, at least to start with, to get a decent MM cart like the Nagaoka which is a better mechanical match for the Rotel arm, and a better electrical match for a standard phonostage, putting out 5mv. I'm sure you'll be very happy with the sound.

Another thing to bear in mind is that Nagaoka offer an upgrade path as stylii are interchangeable and you can upgrade an MP11 to an MP20 or MP30 Boron, just by buying a more expensive stylus, which would then be more equivalant to the AT cart. This isn't going to be cheap either but the original Nagaoka tips are still available. Musonic in England have the full range so I'm sure you'll still be able to some find some closer to home.

 

[micah356]

I just removed the cartirdge to see which one it was. Turns out it is not the AT30E, but in fact it is a Signet TK7E. From what limited info I could find online, this is a better cartridge than the AT30E, as well as being the magnet type. I guess as you were sayng it may still be good to replace it depending on how old it is. Any thoughts? I also checked the overhang, and it was off by about 3mm.

 

[memepool]

Signet was another brand name from Audio Technica around this time, aimed at a kind of premium market for high compliance models. It was about half way up the range so not quite as expensive as the AT30E but it would have been a more sensible match for your arm.

Hi-Fi Choice were impressed with the stylus (Audio Technica have a good reputation in this regard) but worried about capacitance issues. This is another can of worms I'm afraid. There is a good discussion here Cartridge loading explained

Basically with a modern phonostage like a Cambridge Audio 640P one can alter capacitance loading, but with a standard moving magnet phonostage of the kind you'll find on a vintage reciever it's usually just set at around 150pF.

The capacitance of a regular tonearm cable adds another 100pF at least, and this may or may not be too high for your Signet cart which was designed with very low loading requirements. Getting too high a value will act like turing down the treble so there is a risk it may sound dull and lifeless.

Add to this the fact that Signet carts arn't made anymore and original stylus tips don't seem to be available. Lpgear sell their own brand replacment which will work but may not be the best quality considering the price, and given the other potential issues I'd probably still say you would be better off with a new cart altogether.

 

[NightOwl]

I've had both the AT30e and the Signet TK7e and liked them both. William S. Thakker (in Germany) has a NOS replacement stylus for the Signet for $125. + free shipping. Occasionally they come up on eBay, but who knows what condition they're in.
I would probably follow memepool's suggestion and get a new cartridge. It's been a while since I've heard a Nagaoka MP11, but I remember that I liked it. LP Gear (which is also LP Tunes and Elex Atelier) has the Nagaoka for $69.99
If you wanted to spend a little more, you might also consider the Audio-Technica AT440MLa, especially if you decide you like the Marantz since they match well. LP gear has this on sale for $119.99