The Dansette

Senator

CAUTION: If you're a traditionalist and like keeping your kit original (nothing wrong with that) - LOOK AWAY NOW.

So: Why would anyone buy an old Dansette?

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Pros:

  • Pure nostalgia

  • Cool looks

  • The great smell when they warm up

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Cons:

  • They will eat your record collection **

  • NOS replacements for the obsolete cartridges (which cost about half the price of the whole player) are all dying of old age

Dansette Senator

** Only joking. Dansettes have been a great favorite with record buyers since the fifties and, properly set up and looked after, they'll outperform most of the new imports on the market. Nothing lasts for ever though, and high output crystal cartridges are no exception. This is the inside of an Acos cartridge from the 1960s.

ACOS GP71

If you feel like bringing your player a bit more up to date, a ceramic cartridge might be the way to go. That's going to need some mods to the player to compensate for the lower output, but there are plenty of used and NOS ceramics available. As a cheap starter for experiments, you could try one of the Chinese mass produced cartridges available for a couple of pounds.

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EBay has a particular range that look identical apart from the different quality stylus assemblies. Sometimes known as "red and blacks", they're similar to (or probably the same as) the ones used on cheap and nasty USB decks. Although most (probably all) of them will be copies, sellers will mention CZ800 (Chuo-Denshi) and P-188D (Pfanstiehl) just to confuse buyers. Watch out for stylus damage and try them out on something you don't value too much. At any rate they'll do as something to get going with.

Being ceramic instead of crystal, output levels are down by about two thirds, so they need a pre-amp. The good news is that they're designed to play stereo records and they track at a (slightly) lower weight than the originals. They don't sound too bad (feel free to argue) but I wouldn't suggest using one long term, given the questionable stylus quality.

The original TC8H cartridge was tracking (with the factory setting on the adjuster spring) at 9gms. Just replacing it with a new red and black (plus adapter) brought that down to 8.6gms. The new cartridge, tracking at 5gms, was having problems following old, worn out microgroove LPs, probably not helped by the ancient deck. 6gms seemed to keep everything happy and that's about what you'd expect from a USB deck with this cartridge.

The stereo option obviously won’t work on a mono Dansette, but it’s the mechanical design that’s important and you can just parallel the outputs without a noticeable effect on the sound. Before anybody has a go about load impedance, we're talking Dansette not B&O. Plenty of opportunity to experiment though.

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Try to get a cartridge with a mounting clip. They're available separately now and again but are quite expensive.

If you don't want to just glue it in, the clip needs an adapter to convert it from half inch centres to a single 6BA screw. This one is 2mm aluminium drilled and tapped 6BA in three places. The clip needs to be drilled out (a rat tail file would be safer) and relieved slightly to clear the heads of the screws coming upwards.

Measure the old cartridge to get the new mounting hole in the same place relative to the stylus tip.

Thinking about it, it would have been a lot less bother to just buy a decent cartridge with a single fixing hole. Keeps you occupied though. Just as a side note; if you go for a Sonotone 9TA, make sure it's got the connector plug with it.

Schematic and Wiring (as found)

Dansette Senator Schematic.jpg
Dansette Senator Wiring Connections.jpg

Things To Think About

This isn't a "How To" article, just some some ideas that actually work with a bit of effort and, ideally, some mechanical and electrical experience.

CAUTION: DANSETTE RECORD PLAYERS USE VERY HIGH DC VOLTAGES AND HAVE EXPOSED 240VOLT MAINS CONNECTIONS EVERYWHERE. BE CAREFUL.

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We know!

Get on with it!

The Senator uses a single EL84 so it needs a lot of drive from the cartridge. Some other Dansette models use two valve stages and they could have easier options.

If you just want to get the player working with a modern cartridge, it's probably not worth trying to design a preamp (unless you really want to). You can buy a perfectly good, ready made one (or a kit, anyway) for less than a tenner. Getting power to it needs some thought though. It's possible to use the dc supply on the valve and drop the voltage across a resistor. Rectifying the heater supply might work too, but the valve needs getting on five or six volts peak to peak to get it somewhere near clipping (I did measure it but I can't remember exactly) and that's going to be marginal with a 6.3 volt ac supply by the time it's regulated. It's not really neccessary to drive the valve flat out but it's nice to have the headroom. The setup below uses a separate low voltage transformer.

Had a quick look around the internet and came across (and stole) the idea of a Velleman mono preamp kit plus some ideas for mods to match the cartridge and cut down the gain.

Power requirements are 10 to 30v dc at 10mA and aiming at 18 to 20v would be easy and give a useful output voltage swing.

The power supply in the picture in the next section was made from the parts bin, but it would be a lot quicker to buy everything from someone like Rapid.

These parts would work (a 2x12v transformer would work just as well).

  • Mains Transformer: 2x9v @ 6VA. Vigortronix VTX-126-006-609 (Rapid order code 88-3711). £7.50

  • Voltage Regulator: 130312 PCB Voltage Regulator Kit for LM317-T 1.2-32VDC (Rapid order code 50-0487) £7.08
    (this actually turned up fully built by Conrad, complete with comprehensive German instructions).

  • Preamp: Velleman K1803 Universal Mono Pre-Amplifier Kit (Rapid order code 70-4084). £6.85

  • Three 1M and one 22K 1/4w resistors for board mods

Vigortronix Transformer.jpg
LM317 Kit.jpg
Velleman Preamp copy.jpg

Worth noting that any hum and noise pickup that was originally present on the cartridge wiring is going to be amplified as well, so, with a lower cartridge output, the signal to noise is going to get worse. That didn't seem to be a problem in practice though.

The Cheap Way To Do It

This is how the first attempt ended up after some experiments. It works, so it's staying as it is. (edit: No it isn't - see below). The transformer is from an old wall charger. It didn't have any mounting lugs, so it's held down with Velux rooflight flashing (always handy). Grounding the transformer metalwork helps a lot with hum reduction.

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The cabinet is quite thin, so the mods are mounted onto 5mm ply glued to the bottom.

Dansette mounted the valve assembly onto wood strips for the same reason, but there isn't a lot of headroom over to the left.

One problem with the pcb kits is the size of the mounting holes. They're designed for small bolts (can't remember which size) not wood screws, so it might be worth mounting them on ally or paxoline and then screwing that down.

The Senator already has four wires going along the arm to the cartridge. This one didn't have terminals on the two spares though, and they were cut short. A couple of spare terminals, a few inches of thin wire and some some small heatshrink or rubber sleeves will probably be needed.

The Expensive (and easier) Way To Do It

Dansette Senator Preamp Suggestion.jpg

The LM317-T board is working at a fraction of it's capacity and needs about a four volt drop across the device to regulate properly, (preferably, five volts to be rock solid). Things may look alright on a voltmeter with less drop, but a scope will show a lot of ripple. With 18volts ac input, the peak voltage at the input would be about 25.5v and a reliable maximum output would be 20v dc. 18v dc would be fine. All the measurements were done with an output current of 10mA. Power dissipation in the LM317-T with this setup is under 100mW so it's quite happy with no heatsink.

The maximum recommended input from the transformer is 25v ac (about the same as a 12v + 12v Tx with low load current).

LM317T Board Schematic.jpg

Mods To The Velleman Preamp

Values pinched from Herald1360 on vintage-radio.net

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More Messing About

Dansette Senator With Preamp.jpg

OK. So it's a wet Tuesday afternoon in February and the wife wants me out of the way.

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That's not true!

The old bugger just likes sheds

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Took out the DIY regulator and fitted the LM317. It works very well.

Is It Worth Doing?

Definitely. It's a lot of work, but that's what sheds are for and it's lovely to listen to music instead of worrying about the player. There are a good selection of replacement ceramic cartridges available if you want to invest the money, and matching them to the amp is just the turn of a trim-pot. The cheap ones will be fine for experimenting with and it's not the end of the world if they get damaged messing with the deck. Best of luck with whatever you decide to do.