Omeg Log Pot
- Thread starter xp200061
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Is it? Omeg pots are similar to many others; the "log" taper is obtained by joining two "lin"sections. Depending on the type of ink and the way it is applied, the transition between the two sections is more or less smooth.xp200061 said:
Can you be more specific and expose your findings?
BTW, there is nothing like a true Log pot, because a true log would not start at zero-ohm. Well, in fact, no potentiometer starts at zero-ohm because of the wiper's resistance, but it's an almost uncontrollable parameter.
Can you measure it and post the results?xp200061 said:
It looks like the Omeg pot has a better approach to a log curve by using a three-segment screen. IMO the TOCOS is the wrong one, with the cross-over at more than 60% of the rotation instead of 50.xp200061 said:I measured Tocos log and Omeg log pot.
Orange is Tocos log pot. Blue is Omeg log pot.
X = angle Y = Resistance.
Now, you may prefer the Tocos for subjective reasons.
But you may know that it is often possible to modify the taper by connecting a resistor between wiper and on eof the extremities.
What is your application?
The chart is just for compare.
I use both pot on gear and I was felt strangely with omeg pot. 0 to 50% amgle does not change mostly.
and It changed sudden from about 70% angle.
Yes. I know modify the taper. But didn't work with omeg pot.
Application is normal audio gear. Forexample 1178 or 1176 input, EQP band width,,,
I use both pot on gear and I was felt strangely with omeg pot. 0 to 50% amgle does not change mostly.
and It changed sudden from about 70% angle.
Yes. I know modify the taper. But didn't work with omeg pot.
Application is normal audio gear. Forexample 1178 or 1176 input, EQP band width,,,
Yup, you can clearly see 3 slopes (ink screens) in one and only two in the other. More screen hits are extra processing step during manufacture so more expensive. The slopes do not have to be straight lines as you can vary the width of the screened pattern, but you can only vary so much with width, so use different bulk resistance inks for each hit.
I recall doing one custom gain pot at Peavey that had 4 screens (or more). IIRC something like 25K total resistance still with nice adjustability at the low resistance end.
If you sacrifice one part and take it apart you can probably see the different ink layers on the substrate.
JR
I recall doing one custom gain pot at Peavey that had 4 screens (or more). IIRC something like 25K total resistance still with nice adjustability at the low resistance end.
If you sacrifice one part and take it apart you can probably see the different ink layers on the substrate.
JR
Sorry, I misread your graphs; so the Tocos is the red one, and definitely better with 3 slopes. The Omeg is indeed weird.xp200061 said:
You may contact them; I have found them to be receptive to comments.
BTW, who are Tocos?
Tokyo Cosmos Electric coabbey road d enfer said:
JR
Thanks for the info. They are virtually unknown here. Nice range.JohnRoberts said:
ruffrecords
Well-known member
abbey road d enfer said:
Notice how the Toco is 6dB higher at the mid point compared to the Omeg. The Toco is 14dB down at the mid point and the Omeg is 20dB down. 20dB is the more common value.
Cheers
Ian
You're lucky... I used to have to deal with aggressive purchasing clerks chasing a penny cheaper part to win a cost saving. Even a penny matters when buying a million pots a year.abbey road d enfer said:
I once had a purchasing guy who was so persistent that I approved a 1,000 pcs production test for some no-name pot company. The samples were great (they always are) but the production parts were crap, and we ended up having to remove them from the circuit boards to replace with the good pots we were already using.
The factory workers were PO'd at me for even doing the test, but I invited the purchasing guy to the meeting with the factory supervisors so they could share some of that anger with him. ;D ;D
JR
Pot manufacturers should provide taper spec sheets.xp200061 said:
Volume control audio tapers are sometimes characterized by resistance at 50% rotation. 10% or -20dB at 12o'clock is pretty common, but I've seen 15% or more...
In my judgement it's more important how smooth the tapers are, but customers can have expectations for how loud things should be when the pot is turned to 12 o'clock for example.
I recall one powered mixer model upgrade I over-saw on my watch, when a channel gain/trim pot circuit was redesigned to deliver improved kill (when turned down). One pot served as both the gain control and fader for a simple powered mixer. This new improved circuit actually worked better than the previous version but an unintended side effect of the new design was that the total gain was about 2.5dB less at 12 o'clock than the old circuit..
I had to field so many complaints from customers, dealers, and even reps who should have known better who believed the new head had less power than the previous one, because when they turned them both up to 12 o'clock, the old one got louder (more gain duh). It was actually the same exact amplifier, just a different mixer front end.
Since the customer is always right (even when wrong) we ended up designing a custom pot, with the missing 2.5dB gain restored at 12 o'clock and all the field complaints about inadequate power disappeared overnight.
JR
I got many infomation about omeg pot.
The problems that I felt weren't 10A and 15A.
I think The problem is 2slopes or 3 slopes
and From Omeg E-mail.
Our Technical guy says that our log curve is nearer to 10A.
On the model PC2G16BU our log curve is smoother than on the PC2G16ECO.
I tested ECO pot. So I wish that 16bu is smooth. I will get 16BU log pot as sample
By the way, about 10A and 15A.
I think Asia log standard curve is 15A, and another is 10A.
Omeg can make 15A log, but MOQ is 500pcs. ???
The problems that I felt weren't 10A and 15A.
I think The problem is 2slopes or 3 slopes
and From Omeg E-mail.
Our Technical guy says that our log curve is nearer to 10A.
On the model PC2G16BU our log curve is smoother than on the PC2G16ECO.
I tested ECO pot. So I wish that 16bu is smooth. I will get 16BU log pot as sample
By the way, about 10A and 15A.
I think Asia log standard curve is 15A, and another is 10A.
Omeg can make 15A log, but MOQ is 500pcs. ???
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