VTF3 MKII Flutter

[bacobits]

I have a VTF3 MKII and on Phono only at times on high volume the sub goes nuts pumping until I turn the Sub volume down or raise the crossover. Now, I know about in the old days having a subsonic filter but I have none now, or ever had this problem before on any other Phono Pre. I just changed the Phono Pre to a Eastern Electric Mini Max Tube. Herbie's HalO's on all tubes actually on the whole system. What is going on and how do I stop it? Sub is hooked in at the high level inputs.

Den

[Lwang]

How does raising the crossover of the subwoofer eliminate the fluttering?

Otherwise, maybe you have to place your phonograph on a a highly isolated platform base. Some of the companies that makes active isolation base for electron microscopes are now making them for audio, where they allow absolutely zero vibration through.

[wuchi]

Too much subsonic information.

[bacobits]

Exactly, too much subsonic info. Raising the crossover will remove some of it.
Correct? The Phono Pre is setting on 4 Carbon/ Graphite cones. I also had it on Sorbothane pucks and did the same thing. So, I don't think it is an isolation problem. It has never happened on CD/ SACD.

Den

[Lwang]

What I don't get is how does raising the crossover remove some of the subsonic info. It usually will just let the sub produce more of the bass freq range.

CD/SACD uses light shining into pits to decode the sound information and is not dependent on the vibration of a little needle in order to produce the sound. If you put the phonograph in the next room, does it minimize the rumble?

[bacobits]

Impossible to put the Phono Pre in the next room to even try it.
TT is on a 50 lb slab of granite. This all has to be a mechanical problem right now. I'm thinking simialar to the "Grado" dance". I'll check the tracking force again.
Maybe I'll change the cartidge.
Thank You for the help.

Den

[Lwang]

Maybe time to get some Standon DJ cartridge with tracking force of 10g. And some of those massive tonearm that has so much inertia that nothing will force it to move.

[bacobits]

Maybe time to get some Standon DJ cartridge with tracking force of 10g. And some of those massive tonearm that has so much inertia that nothing will force it to move.

I picked up a Subsonic filter from KAB. I'll try this KAB RF-1 http://www.kabusa.com/index_pr.htm.

Den

[bacobits]

Sorry I have to bring this back. It's driving me nuts.

I posed this question on AA but got no answer.

I'm using the 8 Ohm taps on the MM amp. Main speakers are 8 Ohms no crossovers, HSU Sub is 4 Ohms. Using the KAB RF1 Sub sonic filter. It maybe working but not alleviating the proble. The main speakers go down to 40 hz and I'm crossing over around 45 hz on the Sub Amp. I am using the high level speaker connections from amp to Sub to keep as much signal from the main speakers. This is the correct way, I understand.

On Vinyl playback I can hardly turn up the Sub before I'm getting the sub going wild. It sounds and feels like it's hardly on. But the system sounds fine. This never happened till I changed to the MM Amp.

Tonight,I changed to the 4 ohm taps on the Amp and things are better. I have to really turn up the volume on the Sub to get it to act up.

Is there an incompatibility here between the 8 ohm Mains, 8 Ohm taps and the 4 ohm sub? Is there a problem with the BASH Amp in the Sub?

I also tightened all the Subs bolts which were not really lose. 1/4 turn if that.

I have never read about any problems like this.

Just with the above description I don't believe the Sub is exciting the room
to the point to cause this. It's seems to be some electrical interactions?

Anyone have any ideas? HELP!

Thanks

D

TT is on 50 lbs granite, and "Herbie's" on everything. This happens on Vinyl only. Yes, I know it's mechanical. I do not have much room for variable placement of the Sub.

[Lwang]

That shouldn't be an issue, since the sub amp is just tapping off the voltage signal and not draining any current like the main speakers. But you should have both the sub amp ad speaker hooked up the the same output tap so that they are both getting the true signal from the amp. This plus having the sub amp tap off an output that is properly loaded (If you the Hsu amp off the 4 ohm load and there is no 4 ohm speaker attached to it, it is not properly loaded).

[bacobits]

That shouldn't be an issue, since the sub amp is just tapping off the voltage signal and not draining any current like the main speakers. But you should have both the sub amp ad speaker hooked up the the same output tap so that they are both getting the true signal from the amp. This plus having the sub amp tap off an output that is properly loaded (If you the Hsu amp off the 4 ohm load and there is no 4 ohm speaker attached to it, it is not properly loaded).

Thanks Lwang for the answer, I'm not sure I understand all of your reply. So, It's Ok, and not an issue If the Mains are 8 ohms and the HSU sub is 4 ohms. I figured because nothing is ever mentioned as a caution in any instructions etc.

"(If you the Hsu amp off the 4 ohm load and there is no 4 ohm speaker attached to it, it is not properly loaded)."

Not sure I understand that one. It is always either connected with the 4 or 8 Ohm taps with the mains (stacked Bananas). I do think the 8 Ohm taps sound better.

I just re-read the reply. Always using only one set of taps on the Main amp never seperate. I have to move the Sub around and I didn't really want to do that.

Any possibility of something wrong with the Sub Amp?

TIA

Den

[bacobits]

It is FIXED!

This is what I did. I moved the sub to the left side of the room. Then I inverted the speaker cables from amp to sub same as my main speakers. My Pre inverts. I placed the sub on a 30 lb 3" thick solid oak board I had finished fo the TT. The TT is on 50 Lbs of granite.
I think maybe the the sub was creating a negative pressure in the room in relation to the main speakers and causing feedback. Along with the sub no longer loading the floor it is now being directed to the board not the floor directly.

Problem solved.

Den