Phono/Line & Feedback/Damping issues on turntables - advice

[Minos Kritikos]

Torque on the super OEMs is higher than on the original Techics, so that should not be an issue.

I want to pitch in on the line/phone bit here. Not wanting to fan the flame on the "is it relevant" discussion (our audience really won't notice the extra capacitor load :-) introduced into the signal path), I do feel that it's somewhat of a mute point, since many mixers and most controller will do the exact same thing with your phone signal that is done if the preamp is in your TT.

There is NO way to get sound straight from needle to your channel fader, period. You need the RIAA correction and you need preamping. Always.

The only point would be that if you use a TT with a preamp built in in phono setting, the sound goes through the pcb/preamp (assuming you are right here, you seem to have done your home work, and it's logical as there is usually one set of output connectors) and this adds some things to the signal path it shouldn't.

My argument on the flipside to that is to use the built-in preamp and have a high signal level going into your mixer/controller and bypassing it's preamp. I have had more problems in the past with the low phono signal picking up annoying noises (and don't even think about using phono outputs without hooking up the ground cable LOL) than with anything else.

So, while a true -nothing in between- phone signal might not be contaminated leaving the TT, the moment it does leave, it's like a giant antenna carrying a very low level signal to your mixer.

At the end of the day, TTs are just not the best way to get a sound signal from a carrier to a mixer/controller. Whatever way you hook it up. IMHO of course!

From a purely technical point of view, vinyl (not DVS, the actual music) is not the best medium for sound anyway. So starting with a sub-par carrier and then worrying about what happens to a less than optimal signal in the rest of the sound path seems a bit odd. If sound quality is the only true measure here, then you'd have to switch to the purest digital sound path you can find, starting with a high level lossless digital source, all sound processing in the digital realm at the same bit rate and only at the very end of the signal path ONE high end DA conversion taking place.

It is truly good to know that if I ever want to start lugging ungainly, heavy, sensitive gear around again (i.e. TTs), I can just go out and buy the cheapest stuff out there!

With musical and respectful greetinx,
Chuck

Awesome post man and your logic about the phono/line debate is good, so much so, I get the doh homer simpson feeling. Still feel happy that I got the most affordable super oem version though.

So I've had these for a year now and I am super happy with them (still prefer my tech mk5 though). However, the real concern for me now is feedback/resonance/damping issues. I took these omitronics out to the club a while ago for a strictly vinyl gig and the monitors above were causing a lot of bassy feedback. This went away when I turned down the monitor volume but this problem was a first for me as years of spinning technics in louder clubs and monitors closer to the tables than these were, never gave me feedback issues. Now these omnitronics don't have an ABS plastic base but rather a rubber one, like the technics. After reading all kinds of forum comments that people are having problems with feedback on the new Pioneer tables

https://www.youtube.com/watch?v=mNzMcH2ZbtU

http://forums.pioneerdj.com/hc/communit ... BACK-FAIL-

I wonder how common this is with other super oem tables. Are they all more prone to feedback when subject to higher SPL in clubs in comparison to technics? Would love to be able to take a table to a club and not worry about feedback but from the list of super oem HANPIN DJ5500 rebrands:

Voxoa T80
Synq x-trm1
Reloop rp 6000, 7000, 8000
Omnitronic DD 5250, 5220L
Stanton ST150
Akiyama Acura
Audio-technical AT-LP1420,
Pioneer PLX 1000

I ask because after one year of using the omnitronics, in comparison to Technics, I realise now that the slightly lower wow and flutter is imperceptible, phono/line switch is also not an issue, pitch holds fine in my hands (though technics "feels" a bit better, can't explain it) so the real PRACTICAL issue as far as I see, is feedback/resonance/dampening issues. Obviously this issue is more orientated to club environments rather than home use.

Any thoughts or experiences with any of the above models in high SPL situations would shed some light on this issue?

LukeAnnet said something about noise issues on the Stantons but I'm unsure if he is referring to high SPL situations

[DJ Vintage]

I know the Technics were built specifically to reduce/eliminate feedback through the casing, the platter and into the needle.

It was one of the main selling points.

At my first residency the DJ booth floor was actually the top of two side-by-side 18" subwoofers! Never had a problem with my mk2s.

The drive-in-show I worked with had a really clever system with rubber bands, a metal subframe and some heavy weights that totally eliminated any acoustic feedback (and even allowed us to play on a driving truck without skipping needles!).

I have two setw of those inflatable X-feet laying around that I'll throw under the TTs when I feel there is to much feedback.

Decoupling is really the only thing that will help if your TTs are susceptible to the feedback. Bass-heavy dance music played through ever more powerful subwoofers WILL make the surfaces it touches resonate in the same frequency plus a few harmonics. Those frequencies unfortunately are also the place where needles are the most sensitive due to their mechanical nature.

What I don't know is if the feedback on the OEMs is being picked up directly by the arm/shell/stylus or through the platter. Worth finding out, although the inflatables (I hate those btw) will solve the problem in either case.

[Minos Kritikos]

I know the Technics were built specifically to reduce/eliminate feedback through the casing, the platter and into the needle.

It was one of the main selling points.

At my first residency the DJ booth floor was actually the top of two side-by-side 18" subwoofers! Never had a problem with my mk2s.

The drive-in-show I worked with had a really clever system with rubber bands, a metal subframe and some heavy weights that totally eliminated any acoustic feedback (and even allowed us to play on a driving truck without skipping needles!).

I have two setw of those inflatable X-feet laying around that I'll throw under the TTs when I feel there is to much feedback.

Decoupling is really the only thing that will help if your TTs are susceptible to the feedback. Bass-heavy dance music played through ever more powerful subwoofers WILL make the surfaces it touches resonate in the same frequency plus a few harmonics. Those frequencies unfortunately are also the place where needles are the most sensitive due to their mechanical nature.

What I don't know is if the feedback on the OEMs is being picked up directly by the arm/shell/stylus or through the platter. Worth finding out, although the inflatables (I hate those btw) will solve the problem in either case.

thank you for your reply

haha your first residency sounds like it had a fun DJ box!!

Same here though, technics never presented me with real feedback problems in many clubs with high SPLs.

although this guy here has gone to great lengths to prevent feedback. https://www.youtube.com/watch?v=za4WOFv5E7A

i looked up the stuff you said and found this link:

http://www.audioheritage.org/vbulletin/ ... c350ba78e2

i imagine this is something similar to the metal frame and rubber bands you spoke of?

However, i'm quite unsure as to what you meant exactly when you said "inflatable X-feet" --> did you mean something like the Isonoe Audio Isolation feet? tried googling your phrase but was unable to nail it down. could you please point me in the right direction with a link maybe? cause its sounds like it might be the solution to feedback as you said.

Thanks again DJ Vintage

[Minos Kritikos]

Ahhh, think i've found the inflatable feet you mentioned!! Doh!

http://images.junostatic.com/full/IS139 ... 01-BIG.jpg

EDIT.. What is it about them that you hate? Too wobbly for mixing?

[DJ Vintage]

Yeah ... this is a more modern and definitely more compact version of what we had. Ours occupied the better part of a 4 feet high flightcase/discobar element and needed a couple of street bricks for counter balance. I can imagine this works well though. Nice, thanks for pointing this out.

As for the Freefloats, yes, those are it.

Yeah wobbly and frankly looking like you are made for taking a bath with in lieu of rubber duckies. Maybe if they had been black ... LOL

More practically, if you do some serious platter manipulation you do get some lateral movement (front/back, side to side) but that might just be me and my big hands :-)

[Minos Kritikos]

Yeah ... this is a more modern and definitely more compact version of what we had. Ours occupied the better part of a 4 feet high flightcase/discobar element and needed a couple of street bricks for counter balance. I can imagine this works well though. Nice, thanks for pointing this out.

As for the Freefloats, yes, those are it.

Yeah wobbly and frankly looking like you are made for taking a bath with in lieu of rubber duckies. Maybe if they had been black ... LOL

More practically, if you do some serious platter manipulation you do get some lateral movement (front/back, side to side) but that might just be me and my big hands :-)

Awesome! thanks again