A new TT from Steve Dobbins,"The Beat." ???

Kftool,
The platter of the DN-308, as is, unfortunately rings like a bell. It is the same
design as was on the DP-6000 which was replaced by the double-platter
construction of the DP-80. It is well worth treating I expect (I have not done
mine) and could be worth completely replacing IF you could replicate the
magnetic encoding on the platter which allows for the magnetic pulse speed
check. If the motor is the same AU-169 unit which goes on the DP-100 (and
I cannot be sure but I will give the Denon service guys a call today), then
there is plenty of overhead for a bigger platter though you might have to tune
torque application part of the speed control circuit to "load" it for
a different platter inertia. The DP-100 platter is 6.5kg. Assuming the motor
is the same, the motor would have a built-in suspension (the main spindle is
supported on an "oil cup" cushion above the stator). As for
vibrations, the DP-80 and DP-100 literature suggests that most of the
vibration which is defeated through the double-platter construction is borne
through the frame/spindle/bearing though the DP-80 makes some claim to
its construction lessening 'howling margin' (which is Japanese for
airborne/speaker-induced vibration) which would suggest the DP-100 does
too. In any case, the platter construction benefits of DP-80 vs DP-6000 are
apparent.

One could conceivably build that onto the DN-308 platter through a retrofit
of a spring-leaf system for the platter (If one made it too tall, one would have
to make it ultra tall and cover the spindle too with a new one). I can send
cutaway pics of the DP-80 method and the DP-100 method (which involves
oil-damping wells within the sub-platter to dampen vibrations borne to the
upper platter) if you want.

In any case, I too am curious about what Steve Dobbins has done with the
separation of motor and bearing. As long as tolerances are tight, I would see
no reason why the motor and bearing have to be physically directly-
connected other than that eventually they sit on the same platform. That said,
I don't think I am about to build one DIY...

Hi T bone,

I'll attempt to address your points one at a time.

First off, the platter does, did ring like a bell. I threw out the flimsy rubber matt and ordered a new nickel plated copper, plastic platter from TT Weights. It came with their best peripheral clamp ring and heaviest brass center weight. I ordered it when Larry had just sent a prototype to Mikey for evaluation and that new design is what I got. Right now it's sitting on the base platter on the 308.

Not only did the platter ring but the 2 inch particle board plinth transmits every finger tap. Since the 308 was meant for playback of master discs at studios it was listen to on headphones, as loudspeakers had an effect on playback of master discs; from what I understand this was, or is, standard practice in studios. The dp 100, on the other hand was designed for use at radio stations and was fitted with a large spring suspension system; supposedly the biggest difference between the 100 and 308 but I may be wrong. In any cas the plinth, as it stands now, will have to go.

I don't know if it will be necessary to replace the platter with the encoding ring as I don't see how I could do any better than just laminating another layer to the existing platter but that point is up for discussion.

I tried to reach a tech at Denon Pro and got no place as they are separate from Denon America so you may have an in that could help. Since there were less than 100 of the 308s made and not many more of the 100s I would think they use the same motor and just tweaked it electronically, as you suggested to re adjust for a different torque application.

I would appreciate it if you could send a cut away and,or, any other information on the table as I have no manual and could not get one after I bought the table.

Last night I spent a good deal of time on the phone with Steve Dobbins. He was very gracious and is a true gentleman.

I began by asking him about his new tt," The Beat." His knowledge regarding direct drive TTs was obvious as he referred to the many facets involving the design of a direct drive table. He owns around 60 direct drive tables and has done quite a study of the best and worst designs that came down the pike. It sounds like his new table will be a killer with the design innovations he's incorporated.

I finally got around to asking about his custom platters for the Garrard 301 and the few other tables he's tweaked. It was my hope that someday he may apply what he's learned about platter mods and that may lead to an upgrade for my 308. Steve said his plate was full with his present projects but said since he felt the motor on the 308 was as good as any direct drive motor ever made, he may entertain an upgrade platter for my table in the future.

I first saw the 308, I now own, advertised on Audiogon a few years ago. It was impressive looking and I thought expensive for a vintage DD table. It was up for sale for a month and I noticed it didn't sell. A year or so later I saw it up again. This time it sported a cabinet that was redone with rosewood veneer and the price was the same. Peter of PBN Audio owned it and we were friends, so I called him. He told me about the table and what he did to the aged cabinet. After seeing a few pictures of the table in general and the motor and veneering he did it was on it's way from California to Va. The table is impeccable as was the shipping crate he built for it . One could've shipped a newborn baby across the country in it without a scratch.

Dr Howard Stern, the fearless leader of the Richmond Audio Society, hosts the unofficial website of the Kenwood L-07d direct drive TT. He does upgrades for folks that ship him tables from the four corners of the world. Howard has four tables up and running in his system and it didn't take too long for me to convince myself to try a DD table. When the 308 became available again I didn't wait to think about it.

Since there is no law in Audio that limits a guy to just one table I figured it would be a Christmas present to myself for the year 2021, I've done this before!

Ken

Ken, I keep forgetting that we are near neighbors. We should get together for a dd fest one of these days. Lets make email contact. Howard serviced my L07D and it is now in use. SP10 Mk3 will soon follow.

Interesting thing about the L07D is that Kenwood planned for increasing platter mass by providing a switch on the PS that alters the servo when one is using the optional peripheral ring and center weight. In addition, there was an optional ceramic mat that added yet another 1.4 lbs. Someone else calculated that the servo and motor will take up to 21 lbs of platter mass.

Lewm,

If I'd had my wits about myself I would've called you a week or so ago. I'll be driving to ATR Services on Thursday to attend my THIRD seminar and pick up my last machine. I've attended two seminars so far and feel as though I'm the dunce in the class, which I am. Everyone else is from the studios that record the music we all listen to. The techs and studio owners leave me in the dust but I'll keep on keeping on.
Ken

Ken,
Thanks for the color. I might do the same thing on the platter for my 308. It would be great to get a better one. I would love to build a better platform as well - rather than the MDF box. As to numbers, in Japan at least, there are probably a fair bit more DN-308s than 100 because it seems like every NHK broadcast center and recording location, and a huge number of schools/universities/libraries/museums/etc were convinced to buy them (by government bureaucracy-funded NHK). I expect this was because of pressure to monetize the time spent by the engineers, and commit everyone to the NHK standard. I have heard that NHK effectively designed much of this table for Denon using their own engineers. FWIW, I have probably seen a couple dozen 308s over the years, and fewer 307s, and still fewer 306s (which I think were belt-drive). I have probably seen 20% of that number of console tables like this made by Victor and Matsushita (the original pro-use in the early 70s were Matsushita-labelled, not Technics it appears).

As to usage... it does have that funky headphone jack for headphones of a particular impedance (one can still buy them for about $350), and the mini speaker, but it is clear they were also meant to play for broadcast as well because the thing has a built-in phono stage AND preamp with 600ohm balanced output for direct-to-amp playback. When I talked to Denon today, the two people I know there separately said that Denon would refuse to service a table owned by an individual in Japan and it was explicitly up to the user to figure it out for himself. Not a terribly satisfactory response, but it is what it is. Thankfully, there are a number of people out there in the private sector who can service them.

The same people, speaking about the DP-100, said that the DP-100 was sold to a few radio stations but the vast majority were sold to consumers. Most commercial users took the DN- series because they came with a service/maintenance contract (like most companies do with copiers these days), whereas the DP-100 did not come with the same service package.

As to total numbers made, on the DN-308 (and earlier DN-307 and DN-306) they said they WOULD not answer. As to the DP-100, they said they COULD not answer because the data was lost (but noted that it was only an order-built machine, and production lasted 4 years). That is four times I have asked in the last year to four different people involved with Denon servicing and four times I have been told they have no idea. Not encouraging, but it is what it is. Based on serial numbers, I know it approaches 50.

As to the motors in the DP-100 and the DN-308. They are, I was told today by a guy who serviced the DN-308 in the past and now does old tables in the consumer section, completely different beasts. This makes some sense when I think about it because the DN-308 came out before the AU-169 cutting head motor (which is in the DP-100) which was first presented in a technology show in 1979. I think my Denon DN-308 comes from 1979 (you can check your date by looking on the bottom row of the serial number plaque on the front underneath the console portion; an "S" (or a 昭和 or a 昭) and a two-digit number; "45" is 1970 and "55" is 1980 - If you have an "H" or 平成 then a number, it will likely be a single-digit number and H1 was 1989).

Separately, you've got mail...