More....3 spring Thorens, Linn and AR stuff...

[user510]

Why don't you try "towers" (three) a la Alphason Sonata with adjustment at the top which alows for any weight of arm, as you can adjust them indiviually.

If the towers contain springs then the spring rate within each tower will determine how much load can be suspended. For that matter the Thorens, Linn and AR designs also allow for height adjustments to each spring. This allows leveling of the subchassis and is the basic element in a suspension tune up.

Albeit, spring towers that hang the suspended subchassis with extension springs rather than support from underneath with compression springs will be far less prone toward lateral motion.

-Steve

[colclarke]

Hi Steve

Still waiting for the correct size hose for the non-springs 150. Using the Linn springs for now.

Just wanted to run this one past you.

Thinking about towers or feet or whatever, I thought it may be beneficial to 'ground' the suspension elements of a 150/160. I replaced the spring bolts on the 150 with longer types about 3" and then the deck actually sits on these rather than the plinth/feet.

It's fairly stable like this and the plinth appears to be floating above the base board (1" ply). Just don't lean hard on the front left corner.

For the 160 I used some offcuts of ply to position under the spring mounts to raise it about the same amount - fiddly but doable.

Well it's different - I don't decide for sure about tweaks until I've lived with them awhile.

I've considered grinding the longer 150 bolts to points but I've got to stop listening before I can do that...........

Would be interested in your thoughts. Crazy or what?

Regards

Colin

[user510]

sounds efficient.

It would transform the outside cabinetry from a support base into dead hanging weight. The next logical step, I suppose, would be to remove non-essential pieces.

The motor plate would now hold the weight of the entire structure. Its rigidity would become important.

Just a few thoughts. Intriguing.

-Steve

[colclarke]

Hi Simcha

The concept of a predictable and maybe adjustable force counteracting the pull of the belt has potential imo. The idea of using an old belt sorta feels right too - belt against belt - similar dynamics maybe. Nice one.

As regards measuring the acoustic breakthrough - you may already know this but an old trick is to use the cartridge itself - sensitive transducer. Fit an old stylus or change headshells to an old cartridge - something you are prepared to lose if accidents happen.

There are many variations on this basic experiment but to start just lower the stylus onto an old disc with the motor off. While listening via headphones (speakers off for now) just gently tap around the support area, shelf, rack, plinth etc. Get a feel for the type of sounds produced.

Now take off the belt and repeat this experiment with the motor on - you don't tap now, just listen for motor noise getting through to the record.

With the belt still off (with idler drives remove the platter) place a matchbox on the deck to the side of the platter area so the stylus can be lowered onto it . Turn on the motor and listen to the motor noise breaking through to the deck plate.

Still using the matchbox -

Replace the belt/platter and turn on the motor - see if the noise changes - the main bearing is now in use.

Turn off the motor and do the tap routine - this is the noise getting through to the deck plate from external vibration.

I hope that all makes sense - it did when I thunk it. Apologies if it's as clear as mud. Other/better descriptions may be out there..............

These are a few ways to get a feel for how much noise gets to your deck from it's surroundings and how much noise it makes all by itself.

It helps to work slowly, and take notes.

You can get creative and record the output of the cartridge, sitting on a stationary record, while you play loud music or use power tools/hoovers close to the support structure. Just don't get the drill too close to the sensitive bits.............ouch!

All this trouble just to play records? You must be mad!

Yeah Mama, but that's where the fun is.

Regards

Colin

[Simcha]

Colin,
Thanks for the comments. the noise tracking plan is useful and a more systematic approach than I had dabbled with. I have a subsonic noise that I don't hear (duhhh..) but my CD recorder DOES, giving enough of a signal between tracks that the "auto-track-label" feature of the recording deck which depends on a few seconds of "silence" to label a track, doesn't kick in, thus requiring the manual babysit method. Now, I am not endorsing wide spread digitalization of perfectly good records, but people often GIVE me nice vinyl if I dub them. Also, I still have not got quite the playback of vinyl in the car I like yet...

The problem I initially pondered in my previous post 'though, was how to demostrate the SPECIFIC measured resonant frequency of a suspension system as we tinker with springs and mass and hoses 'n stuff.
So I was looking for a way to "excite" the base or plinth or support shelf with a specific low frequency that could be varied until the resonance became visible by the rockin' and rollin' of the platter (without record or cartidge of course!!) But of course 4 HZ is sort of just sort of BuddahBuddahBuddah so what I might need is "tapper" more thas a speaker. (Being as how 3-6 hz frequency response is hard to come by...)
Colin AKA Simcha

[colclarke]

Hello again Simcha

My mistake - as regards the cd recording, I can see how the baby sitting could get tiresome. Is electronic filtering out of the question? I know it's not very pc but may solve the problem short term while you work on a better fix.

Is the subsonic noise 'visible' on the woofers while playing lead ins - large cone excursions with no sound? First thoughts include arm/cartridge resonance or suspension jitters - sounds like Steve's hose may be worth trying.

I'd be interested to hear about your progress with this one.

Regards

Colin

[Simcha]

Colin
Good thoughts. I am looking into high pass "rumble" filtering. Can get passive filters from Harrison labs ("FMOD" )pretty cheap. A chap in Australia sell a PC board for an active filter with sharper slope which might be fun to build. It would be possible of course to only use the filters for the digital recording (since that by definition is already degrading the sound ) but it would be fun to compare any audible effects subtle or otherwise, on the "pure" vinyl signal to speakers. There is the question phase shifts and the like... Some say a rumble filter can improve the rest of the sound by taking unnecessary stress off the woofer and amp.
Or not.
Simch

[herringboy47]

I have another topic going on this for a TD150-http://www.vinylengine.com/phpBB2/viewtopic.php?t=5472 - and was wondering what size radiator hose was used as a replacement and what brand? I assume some brands are stiffer than others?