John Curl's Blowtorch preamplifier part II

[Esperado]

I just got an idea - I have this vibration sensor I used for speaker enclosures, maybe I should try it out on my record player!

Jan

You have yet a nice detector in your record player: Its head.
Just store the diamond on a stationary disk, and play your generator in your speakers.And you will measure what matters, IE, including the head+arm resonances.

 

[snup]

Yes. Lower a cartridge on your plinth.
You get a vibration signal to look at.

 

[billshurv]

Question for the turntable crowd. How come the townsend style fluid damper has not been adopted further. Either Max is a bit 'out there' or people don't think its actually an issue. Or just too messy.

 

[snup]

Too messy. Moerch tonearms goes to show.

 

[billshurv]

how does the Moerch show that? seems thin wibbly arm that would be helped by damping at the cartridge. otherwise the tail is still wagging the dog?

 

[snup]

At the same time, the dog is wagging it's tail.
At first glance its hard to see how the damping works.
Different silicones (viscosity) makes all the difference.
The arms are quite clever, but messy.

 

[billshurv]

if the source of vibration is the cartridge why damp at the bearings? makes no sense as you cannot make the arm tube infinitely stiff. The Townsend method makes sense as you damp at the headshell.

 

[snup]

Have a quick peek @Reference components-tonearms.
Damping and elimination of resonances is a pita.

 

[snup]

On top you have the unpredictable feedback from the music you listen to.

 

[Hiten]

Thanks guys for the suggestions and pointers. My initial interest is to see how much (or not) the TT vibrates from the sound in the room.
I'l report back here.

Jan

I have not measured but have experimented with a basic idea. On my Philips belt drive turntable, I placed stylus on a wooden peg which rested on the plinth. I kept the turntable on thick folds of cloth so as vibrations from floor doesn't creep in the turntable. With platter running (to generate noise) I increased the volume of my amplifier. The sound waves from speaker did produce vibration in the cartridge only to be amplified again. Kind of feedback of microphone. Here is the video. I tried to cutoff vibrations in the air with dust cover. This is just unrefined experiment as I have no knowledge of measurements etc.
Regards

 

[snup]

As with all hifi, measurements are not needed, to show something is wrong.

 

[billshurv]

Sorry Snup, you are making no sense. Please add links or explain.

www.townshendaudio.com Rock 7 - www.townshendaudio.com | Vibration Isolation shows some (hopefully measured) results from front end damping.

 

[snup]

billshurv
I was talking general terms.
I have no experience with Townshend and I dont want any.

 

[snup]

Resonances at the headshell will move along the arm. No matter how dampened.
Elimination is not possible.

 

[billshurv]

your point being? So you would rather have undampened flapping to deal with rather than dampened? Note that the Rock with the DP-8 was reviewed in TAS 209. Perhaps someone with a copy can see if the front trough was used.

Damping an oscillation at source makes a lot of sense. Yet few do it. Odd.

 

[billshurv]

As with all hifi, measurements are not needed, to show something is wrong.

Ah, forgive me. I thought you were here for a serious discussion. Clearly you are not.

 

[snup]

few do it, because its messy.
I dampen everything as well I can.
But that affects dynamics and no compromize will do.

 

[snup]

I left TT's a while ago.
They just dont cut it for me.
Too messy.

 

[snup]

As for serious discussions, I am not qualified. sorry

 

[Max Headroom]

Agree - a well set up sub does wonders for the sound stage

Hello Andrew.
What is actually meant by 'the sound stage' ?.
And how is serious bottom end a benefit to 'the sound stage' ?.

With my active 8" 2 ways I have pin sharp centre (perfectly narrow and stable), infinite depth (mic distances perfectly revealed ), precise positioning from out past each speaker and sounds from behind.
IOW clarity and positioning to die for.
The downside is subtle lack of bottom end....or is that lack of subtle bottom end ?.
I have tried a touch of graphic eq and that helps.

I recently grabbed a pair of 15's in 137L cabinets.
What's your mileage on suitable rollout frequency, slope and filter type.
And active or passive for that matter ?.

Dan.