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need help with DUAL 1214
need help with DUAL 1214
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Old 10th July 2004, 02:28 AM   #1
needtubes is offline needtubes  United States
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Question need help with DUAL 1214

Hi all-

I recently inquired about building a phono preamp for the turntable I had purchased off of eBay. Well, it came in today, and I hooked it up... but only one channel worked. Now, I don't know a thing about turntables, but I was able to troubleshoot this. There was a lead on the cartridge that was not contacting the wire going to the outputs... so I bent that back into shape and both channels are up and running.

However, I have a small amount of hum and a scartchy, fuzzy sound coming from the TT when it is not in use. Could anyone possibly help me find this and get rid of it?

My turntable didn't come with an enclosure... and I am guessing that most DUAL's didn't. So, the bottom is open and it is more or less sitting on the motor/transformer. I guess this is normal... Could this possibly be causing my problem?

The buzzing sound could be my cable... but I am not sure about that. If building an enclosure would help me out, does anyone have any recommendations on what I should build?

I have searched the internet for DUAL 1214... and have found next to nothing. I searched the forums and only found two topics, one of which was mine... and the other kind of helped give me an idea... but didn't give any specific info. If someone could help me find some useful information, here, I'd really appreciate it... I really just want to get this thing set up and running flawlessly so I can enjoy the music. Thanks all!!
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Old 10th July 2004, 08:06 AM   #2
analog_sa is offline analog_sa  Europe
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need help with DUAL 1214
Not knowing how the chassis is grouned i would suggest you run a separate wire between the chassis, motor and preamp ground.
The absence of a plinth has no relevance to your hum problem but i wonder if this is a good solution. Most Duals and very possibly yours, use a spring suspension to decouple the chasis from the plinth. Letting it rest upon the motor won't do much good to the sound.
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Old 10th July 2004, 02:53 PM   #3
needtubes is offline needtubes  United States
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Ya... I didn't figure letting it sit on the motor was good... but I don't have a chassis now... so that is kind of my only option. I'll try grounding it to the preamp. Thanks
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Old 13th July 2004, 11:45 AM   #4
sprucemoose is offline sprucemoose  United States
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if the spring location is like mine, a 1245, just throw together a base made from 1x4 boards ( i actually used MDF pieces left over from my double advent cabinets) with triangular gussets in the corners for the springs to rest on. i put blocks in the corners before i made the gussets to figure out the correct height to get the plinth about 1/4" above the edge of the new base. then i painted it with grey granite paint. looks kinda cool. pics if you like.

sm.
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Old 13th July 2004, 12:24 PM   #5
sprucemoose is offline sprucemoose  United States
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heres a quick shot of the TT and base. sorry its a bit fuzzy.

sm.

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Old 13th July 2004, 06:10 PM   #6
needtubes is offline needtubes  United States
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That looks really nice.

That is pretty much what I was thining about doing... get some 1x4's and build a base.

Just another quick question... when I place the stylus on a record, I get a crackle, which I am sure is normal... and sometimes I get a somewhat low hum, which is probably also normal... but throughout the entire playing of a record, my speaker cones jump the whole time... like they are playing some sort of bass signal, but you can't hear anything from them. Sometimes they jump REALLY far, and I am getting a little scared. Is this normal, or is there something wrong? Thanks
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Old 13th July 2004, 09:17 PM   #7
analog_sa is offline analog_sa  Europe
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need help with DUAL 1214
Quote:
my speaker cones jump the whole time
He,he. A vinyl virgin

You should do some searches on compliance and effective mass. The vinyl asylum may be a good place to educate yourself.
It all boils down to the resonant frequency of the arm/cart combo being too low. A stiffer cart will likely cure it.
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Old 14th July 2004, 06:48 AM   #8
Elso Kwak is offline Elso Kwak  Philippines
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Lightbulb need help with DUAL 1214

Hi, Very often the Duals have the ground of one of the channels connected to the arm in the shell, well actually it is just behind the shell. This creates a ground loop when you connect the chassis to the groundpin of the amplifier.
Check with an Ohm/multimeter!
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Old 14th July 2004, 07:37 AM   #9
phase_accurate is offline phase_accurate
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Apart from all other sources: Resting the chassis on the motor doesn't help either with subsonic rumble !

Regards

Charles
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Old 15th July 2004, 08:52 PM   #10
PsykoK is offline PsykoK  France
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Default DUAL 1214

Hi,
I have some DUAL TT : 1214,1216 and a 606.
I build a preamp for the 1214 some times ago. The preamp is based on a plan from the Grado PH1.
The PH1 is working very well but with the 1214 I have some hum. These hums are in most case product by the motor because the 1214 have a bipolar motor. To avoid this kind of motor hum, you have 2 solutions:
- changing the bipolar motor for a quadripolar one
- making insulation for the motor

In my case I do nothing, because I take 2 other Dual TT.
The 1216 in an evolution from the 1214 and it have a quadripolar motor and a grounded chassis, the result is 0 hum.

All these information about the motor are provided in the user guide from the 1214. I have the original one, I you want a copy of it send me a mail!
I have the plan of the original enclosure too.

An other important think, is the length oh the cable in the RIAA preamp and the ground plan. I had several problems with all this thinks when I build my PH1. The input cable of the preamp must be shorter as possible and the ground plan must be absolutely built in star.

Good lu

Regards,


Alex
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