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Location: NW NJ | Originally posted by Mark in Boise:
Get Plugged In to what? I'm still working on why I can't see the Phantom power. Because it wears this white mask thing most of the time and is kinda hard to see when it has it on. |
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Location: NJ | ". . Kirsty was one of the finest English songwriters ever . ."
- in THESE shoes?? |
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Location: Columbus, OH | Do all OFC threads go this off topic? I feel like I'm back on the Hamer board! ;-) LOL... |
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Location: NW NJ | Topic ... what topic? |
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Location: Arizona | Originally posted by Paul Templeman:
Originally posted by Slartibartfast:
The overall flatness spec for the Op-Pro has a 3dB rolloff at 7.5kHz compared to 100kHz for the Op-30. Neither makes much sense, but at least the Op-30 is flat throughout the audible spectrum. The low EQ center frequencies for the Op-Pro high-band (as you point out) means it's tough to recover that HF rolloff with the EQ.
And 86dB SNR for the Op-Pro vs 92dB for the Op-30 is pretty glaring. As far as I can tell from the various specs on the Ovation site the Op-Pro is technically the worst pre-amp that they make, and noise in the pre-amp gets amplified throughout the subsequent stages of the system.
I don't wish to appear smartass or churlish, but I used to teach this stuff to post-grad level and I'm struggling a little with your terminology.
BTW, I'm not a n00b at this. I've an advanced degree in Electrical Engineering and over twenty years of experience, and also taught EE at the college level for a while, so we should be able to talk the same language.
I respectfully suggest that it is absolutely impossible to arrive at your conclusions purely from the specs published on the Ovation website. That's why in my original post I started with "Spec-wise...". Subjective assessments aside, Ovation does publish some relevant specs on their website. My thoughts are just that _only_ in terms of those few specs that Ovation has on their site the Op-30 looks to be a better pre-amp than the Op-Pro in at least a couple of important measurements.
Can you qualify your statements any further? Why do neither frequencies make sense? Sure. The upper 3dB rolloff point of the Op-Pro response, according to the Ovation site, is at 7.5kHz. I don't think very many people would claim that any music reproduction system is going to be very good with such a low 3dB cutoff. Of course, we don't get to see the full response curve, but even if the filter only has two poles it's going to be rolling off pretty steeply beyond that. In other words, there's either not much response above 7.5kHz (which in practice doesn't seem to be the case), or the filter is just a crappy filter, i.e., not very flat. In any case, a 3dB point at 7.5kHz for a musical system should send up yellow flags for most people. I'd have hoped for something in the high teens, e.g., ~17-19kHz.
Likewise the Op-30 spec indicates a 3dB rolloff of 100kHz! WTF? Mice don't even hear up there as far as I know. So in this case the filter is again, apparently, not very optimal but in the other direction. The downside of this is allowing noise/interference energy that isn't of interest to reduce the useful dynamic range of the amp.
What do you mean, in this context by the term "high band"? What do you mean by "recover the HF rolloff"? Please define "Flatness spec" in terms that an acoustician could relate to. In this case the point is that the Op-Pro spec on the Ovation website, whether it's accurate or not, says that it rolls off with a 3dB point at 7.5kHz. You can use their indication of the equalizer bands to define High Band, but in any case what I was referring to was that if the amp filter is really as Ovation says it is then it's attenuating anything from 7.5kHz and up by AT LEAST 3dB relative to the band peak between 10Hz and 7.5kHz. I'd think that most people would be interested in preserving the high frequencies (i.e., stuff above the 7.5kHz cutoff in this case), as it adds a LOT to the sound. I'd hope that this isn't lost on the folks around here.
What I meant by "recover the HF rolloff" is that even cranking up the HF knob on the EQ isn't, apparently, going to be very effective in recovering the high-frequency energy. Since the indicated center frequency of the HF EQ filter is only 3.6kHz (again, according to the website), it can only influence, at the most, frequencies from 0-7.2kHz, if it covers the whole range down to DC (which would make for a crappy high EQ knob), but the point is that it's not likely to be able to boost the highs lost above the 7.5kHz rolloff.
By "flatness spec" I only mean the ability of the pre-amp to pass frequencies at relatively equal energy, i.e, not filter them out. Ovation doesn't publish the full filter response, just the 3dB points, i.e., the attentuation is less than 3dB between 10Hz and 7.5kHz. Outside of those frequencies it's going to be more.
For those unfamiliar, 3dB attenuation cuts half the power from the input. 6dB reduces the power four times (it's a log scale).
Please explain the "glaring" signal to noise ratio problem with the OPpro in terms that the non-technical members of the OFC may grasp. Again, just using Ovations numbers from the website:
Op-Pro signal-to-noise ratio = 86dB
Op-30 signal-to-noise ratio = 92dB
This is essentially a measure of how much thermal noise (and or distortion, maybe Ovation should define what they mean by SNR) from the amplifier goes through with the signal from the pickup. In this case there's a difference of 6dB, so the Op-Pro, with the same level of signal, will also be passing four times as much noise power as the Op-30 according to these figures.
The problem with a pre-amp generating noise is that any subsequent amplification stages adds power to the NOISE content, i.e., amplifies the noise as much as the signal. For this reason one generally wants as quiet of a pre-amp as possible, and the Op-30 is 6dB quieter than the Op-Pro according to Ovation's numbers.
All current Ovation preamps work perfectly. Really? You must have a loose definition of "perfect", because I don't know of any electronics, anywhere, that work "perfectly".
They all sound a little different, but so do the guitars. As do the players, the sound systems they are played through and everything else in the signal path. In the grand scheme of things a few Db or couple of Khz variance between the various Op preamp models amounts to not much. The end users seem to make'em work and I don't expect the factory have had many returns because the OpPro is "technically the worst" preamp they make. Again, all I'm saying is that if you look at the number on Ovation's site, the Op-Pro looks worse than the Op-30. Look for yourself, the numbers are quite different, and they mean something. If they didn't mean anything there'd be no point in publishing them, and they are, in fact, useful specs for comparison.
I have an Elite-T with an Op-Pro, and it sounds fine to me. I haven't stuck a spectrum analyzer on it, but it sounds to me like it has highs significantly above 7.5kHz, so I'm wondering how Ovation arrived at those numbers.
And I only brought it up because there are people who can discern a couple of dB and a few kHz, but a cutoff of 7.5kHz just seems crazy to me for what is supposed to be one of their "better" amps. Why take out the highs (above 7.5kHz)? Why not preserve and reproduce the highs? There's no point in preserving high frequencies beyond the range of human hearing, though, so I don't understand why the Op-30 preserves highs up to 100kHz...??
One can adjust the EQ to change the tonal qualities of the amplification to make it warmer or brighter as one desires, but only if the pre-amp is passing the needed frequencies in the first place. If the pre-amp takes out the highs, the EQ can't restore them, and that's what I'm observing expressed in the specs on the Ovation site for the Op-Pro.
I suspect that the figures may not be accurate or they're only part of the story, but the part of the story that's told makes the Op-Pro look worse than the Op-30. |
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Location: Boise, Idaho | Obviously you didn't get scared off. I was wondering about the same thing you said in the last sentence. Ovation's website has several mistakes. |
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Location: Warren,Pa. | Keep talking gentlemen. |
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Location: Alberta, Canada | Yes, please continue! |
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Location: Hiram, Georgia | if the filtered freqencies are rolling off at steeper angles say 6 or 12dbs, wouldn't that induce phase shift, an unwanted side effect? |
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Location: Scotland | Well Slarty, that’s quite impressive, you got me. I apologise if I appeared confrontational, but in your first couple of posts in this thread you came across like any number of self-appointed web-forum experts who operate on the principle that in the land of the blind the one-eyed man is king. So on that basis I couldn’t resist a little sport and you kicked my ass. Well done.
As far as the Op-pro goes the published spec is so incomplete that it’s open to misinterpretation. It’s also quite possible that it’s just wrong, which wouldn’t surprise me. I would tend to agree with you that the Op-pro “sounds” better than it “looks” on paper, but then it’s usually more conclusive to listen with ears rather than eyes.
If you have the time, inclination and equipment it would be interesting if you could test your Op-pro and see if the actual performance is anywhere near the spec. |
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Location: Sunshine State, Australia | Aww... We woz enjoying the confrontation.
Didn't understand a bloody thing you were talkin' about, though! |
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Location: Cicero, NY | Great discussion, guys. And I'm guessing very informative to some here. As for me, you lost me at "Gigged with my new Elite T LX tonight."... but what can you expect from a guy who find shiny coins distracting... |
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Location: Arizona | Originally posted by Paul Templeman:
Well Slarty, that’s quite impressive, you got me. I apologise if I appeared confrontational, but in your first couple of posts in this thread you came across like any number of self-appointed web-forum experts who operate on the principle that in the land of the blind the one-eyed man is king. So on that basis I couldn’t resist a little sport and you kicked my ass. Well done.
It wasn't confrontational from my perspective, I'm just passing on my observations.
One thing I did notice since my last post, though, is that the power consumption listed for each pre-amp shows that the Op-Pro is in a different class from the Op-30,50.
Op-Pro Idle current: 2.10mA
Op-Pro sleep current: 34 microAmps
Op-30 Idle current: 5.1mA
Op-(40) sleep current: 40 microAmps
The more than 2x difference in the idle currents suggests a pretty significant design change from the Op-30 through 50 with an eye toward extending battery life. So perhaps the performance suffered a little bit in order to get the power consumption down, which isn't an unusual tradeoff at all. |
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Location: Alberta, Canada | Originally posted by Mitzdawg:
And I bought my Op-Pro because I thought it looked prettier.
(BSME) And we all know they sound better when they look pretty! :D |
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Location: ranson,wva | it hepls to have a good preamp even if you dont plug in..lol jason |
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Location: Budd Lake, NJ | I got scared for a moment; I thought I'd accidently been enrolled in a course that I didn't understand but would still have to take (and pass) the final. S-s-i-i-g-g-h-h of relief. ;) I am glad for those people who do understand this particular field--their knowledge and expertise develop products that greatly increase the fun levels of my playing; I'm just happy, though, that my enjoyment of my guitars doesn't depend on an academic understanding of how they work!
--Karen and the crew
1111-4 "Gertrude;" CE868LX-4 "Jewel;" CC026 "Estelle;" 1271-4 "Blanca;" 1211-4 (I think) "Nonnie;" Guild D-50 "Gilda;" American Strat "Ivory;" Steinberger Spirit 5-string bass "Sugar;" Galiano mandolin "Plink;" Vega 5-string banjo "Twang;" and fiddle of uncertain antecedents "Shriek" |
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Location: Boise, Idaho | For most of us this was like listening with dog ears: "Blah, blah, blah, blah, blah, Fido, blah, blah, blah . . ." |
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Location: NJ | Actually, if you're a "FarSide" fan, it's:
". . Blah, blah, blah, blah, blah, GINGER, blah, blah, blah . . ." |
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Location: south east Michigan | Bulletin board for two...
Cliff... I'll bring my Farside books to the next tour. |
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Location: Boise, Idaho | Yep, it was Farside. Couldn't remember the dog's name. |
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Location: North Carolina | [ The idea was to be able to use the two guitars at a gig (one being a backup) without there being a drastic volume difference between the two. [/QB]
This might have been addressed somewhere in the thread, but my solution to this problem would be the use of a small, inexpensive mixer outputting to your guitar channel, or using a separate channel for each instrument on your main board. |
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Location: Sunshine State, Australia | Here's the easy solution...
...turn the louder guitar down.
Next! |
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OP30 vs. OP Pro
