Eminent Technology ET-2 Tonearm Owners

One is usually coloured/informed by past experience. Coincidentally, I have a couple of FR64S's myself & you reminded me of the Hadcock GH228 that I have gathering dust.

Another recent unipivot, an Apparition 12" superseded the above. A very fine performer, to the extent that I have had little compunction to A/B with the older arms. A very top shelf pivoted tonearm in my humble experience.

Nothing is perfect in this game (audio & life in general ;)) but with my linear tracker (a Trans Fi terminator) I find the combined qualities of genuine low distortion, wide bandwidth, dynamic stability...are overall most persuasive. Are these attributes typical of linear trackers? I can't be sure at this point.

Regarding Effective Mass...with record groove modulations cut at 45deg, as we know, I think it's not entirely useful I think to dwell on Effective Mass in terms of horiz & vert properties.
Cheers.

Dover
I do wish you would stop repeating your fundamental error ad nauseum.
BT measured a rise in response of 6-12 db at the resonant frequency. Say 3 to 8 hz. I don't call these frequencies bass.
Bruce measurements show that this rise in response is reduced by 8db with the addition of an oil trough. This in test conditions which used a deliberately high Q and a low compliance cart. The amplitude of resonance decreases the further you move away from Fr. BT suggests that resonance effects frequencies up to 3xFr.
My rigs Fr is just above 5hz, almost 4 times lower than what is normally accepted to be the lower bass, 20hz.

There is no rise in bass response in my system.

This is the story of an audiophile called Dorothy and her ET2, a tonearm she has owned for many years.

For the first few years she used a light MM cartridge and used only 2 of the 4 lead weights supplied positioned in the middle of the I beam. “It looks visually balanced better this way to me”, Dorothy said. She did have a quick skim through the ET2 manual but ....oh!..... so many pages ....some really technical “guy” must have written that for sure she thought. Anyway.....how she set it up sounded good to her... so she left it this way for a few years.

Then one day she decided to buy an MC cartridge. She noticed it was quite a bit heavier. Instead of moving the existing weight further out on the ET2 I Beam (as the ET2 manual says to do) - she put on the other two weights she had stored in her drawer all this time; so they could meet up around the middle of the I-beam again. She was after all comfortable with this middle of the I Beam positioning. “It just looks visually better balanced this way” Dorothy said. It sounded good again. She was happy.

Then later on she was reading on the internet about some ET2 owners who just couldn’t stop fiddling with their ET2’s.

"Must be all guys for sure” Dorothy thought to herself.

But she was intrigued about how they were discussing the aspect of loading up the weight on the I-Beam. They were putting more thought into it; putting just enough weight on so that the weight was at the end of the Ibeam – no matter what cartridge. Some of these guys were even crazy enough to change cartridge screw sizes to accomplish this.

“Well” she thought to herself “maybe there was a screw loose somewhere else with some of them?”

But she was intrigued ....she could resist no longer. She tried it and did what was required to get the weight out at the end of that “pirate plank” even though it did just did not look right to her.

Lo and behold more music “sprang” forward ! She said to herself “all these years I was listening to my ET2 and I was loving it; But now... well I love my ET2 even more!”

She felt good about herself.
Does this story have a lesson ?

Yes, Dorothy felt good about herself, but it wasn’t because her favorite songs sounded even better to her.... which they did; no, it wasn’t the main reason. You see Dorothy always knew that she could listen to her favorite songs anywhere; even in the car and they would always put a smile on her face. It was about the music itself after all.

No, what made her feel real good – was that she had learned something and understood more about how her ET2 actually worked. That learning and knowledge is what made her really feel good. She then said to herself “maybe I should read the ET2 manual that guy called Bruce wrote? ”

Right after thinking that another thought came into her head. “If only my boyfriend was as easy to tune as this ET2”

This is how I test my vinyl setup for Structure Feedback and my ET2 (2.5) Pump for Noise and Vibrations.

I am interested to know what techniques others use. I’d like to learn different ways of doing this.

TEST FOR STRUCTURE FEEDBACK

Some people think that direct sound waves affect our cartridge. Some people put plastic shields around their turntable. If you think that direct air waves really affect your cartridge “trying yelling at your cartridge and see what happens” infamous quote from Audiogon user Halcro.

Can you hear yourself through your speakers when you do this?

Henry – if you see this I hope you don’t mind me quoting you.

My test for structure feedback is to set up the TT on mute and lower the stylus onto the lead in groove. Record not spinning. Unmute the phono and turn to a level that is considered high for your room.

Start jumping up and down right beside your TT. Pretend you are dancing with your spouse. Actually invite her/him in and jump together with no music. Just be prepared she may ask you to boogie to real music later as she gets warmed up. If your setup survives this test you should be good to go.

TESTING THE PUMP for NOISE and VIBRATIONS.

This test should actually be good for any air bearing linear tracker that uses a captured bearing like the ET2 and ET 2.5.

No jumping this time just listening.

Same as the above in regards to muting your phono with a still record and unmuting but with a BIG difference.

1st – DO NOT turn on your pump and lower your stylus onto the lead in groove. Unmute and turn the volume up. Listen to how quiet it is. When finished mute system and raise the ET2. I say raise the ET2 because I don’t know how good your pump and setup is. More on this later.

Now have a friend turn on your pump and repeat the above procedure and lower the stylus again. Is there any noise in the background now that has been transmitted down the airline into your system that was not there before?

Is it the same level of quietness, or is there now a little more background noise with the pump on. If you are using a regular aquarium type pump and no surge tank you will hear differences. For those with good pumps and a properly setup ET2, ET 2.5 there is no need to raise the stylus or unmute after listening with no pump. Have the friend turn your pump on and off while you have your ear on one of the speakers.

If you are introducing noise with your pump down the airline you are not hearing what the ET2 can do. The sound is being glazed over by air noise vibrations from the pump.

I came across this years ago – maybe 8? by accident. I had an actual small ground hum type noise and could not for the life of me figure out how to solve it. I tried for two days. I could just hear the pump at the time in the other room running faintly. It was a Medo AC110.

Finally after a couple of days of trying to fix the problem, I unplugged the pump and I tried the above test. No more noise. Damn! I substituted my backup Medo pump at the time and all was quiet again. The bad pump was still delivering PSI but had a piston problem sending noise and vibrations down. I also found back then that a long run of air tube coiled up also helps to minimize the vibrations.

I didn’t discover the above problem until I had swapped in cartridge, wires, amps, preamps, speakers first ! That set me on my pump journey the next few years and I ended up with the pump I use now.

So how do you guys test for structure feedback and airline noise/vibrations with an air bearing?

Cheers.

Further...
Mono signals of course, do result in horiz groove modulations.