OA-14: what should it sound like?

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Infinitely Baffled
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OA-14: what should it sound like?

Post by Infinitely Baffled » Fri 22 Mar 2019, 15:41

Hello, Carlson Planet users. This is the first post from a new joiner.
First of all, I apologise for not being able to post in Swedish - I hope you will bear with me.
Secondly, I apologise for my country and its behaviour in this shocking Brexit business. I disown my government!
Now, about loudspeakers ...
I have recently bought a pair of OA-14 loudspeakers. I very much like them: their looks, their quality and I love the whole concept. In terms of sound there is a lot to admire, but I often feel that the speakers are quite fierce in the high-frequency region. Their sound can be quite harsh. They seem to have very good capabilities in the bass and midrange and something I especially enjoy is the very articulate and distinct way they separate-out different instruments, voices and lines of music. I enjoy them very much, but I would love to know if the harsh treble is normal for these speakers or is there a problem with mine?
Best regards
I.B.

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STDI!
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Re: OA-14: what should it sound like?

Post by STDI! » Fri 22 Mar 2019, 22:23

The tweeters are old and might have had a hard life. They sometimes sound harsh. Either you find better specimen of the original tweeters. Or you upgrade to Obi T22oa. https://www.hifikit.se/t22-oa.html. Then you also have to upgrade the filter or buy new ones (https://www.hifikit.se/od-11-oa-14-delningsfilter.html).
Search for "t22" on this forum and you will find lots to read.
OD-11(T22+B65OAII), 3xOA12(T22+B65OAII), 5xOA14, OA14 (T22+Satori), 2xOA50, OA52.N, 2xL8, SC6, SC6.2

Infinitely Baffled
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Re: OA-14: what should it sound like?

Post by Infinitely Baffled » Fri 22 Mar 2019, 22:40

That's very helpful. Thanks, STDI.
I.B.

therob
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Re: OA-14: what should it sound like?

Post by therob » Mon 25 Mar 2019, 15:58

Hi!

The first thing you should do is try and adjust the jumper that resides between the tweeters. That adjusts the treble (I think ~2khz and above) +/- 1db or so, w/ the middle position being some sort of 'neutral' position or so.

The 'harsh' sound you're experiencing is most probably distortion, and there's really nothing you can do about that, except buy new drivers / filters, which will cost you.

Note however, if you do switch out the drivers, you'll need new filters as well just like the previous poster said.

Infinitely Baffled
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Re: OA-14: what should it sound like?

Post by Infinitely Baffled » Wed 03 Apr 2019, 01:30

Many thanks, Therob. I have read about the distortion associated with the original tweeters. I was not sure, though, whether that was what I was hearing in the overly-bright treble. I take it that the Obi tweeters are a distinct improvement? Do they still fit under the mesh cage?
IB

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Re: OA-14: what should it sound like?

Post by STDI! » Wed 03 Apr 2019, 09:28

Infinitely Baffled wrote:
Wed 03 Apr 2019, 01:30
...Do they still fit under the mesh cage?
IB
Yes they do. At least if you place the magnet in "the hole" where the old magnets where.
OD-11(T22+B65OAII), 3xOA12(T22+B65OAII), 5xOA14, OA14 (T22+Satori), 2xOA50, OA52.N, 2xL8, SC6, SC6.2

therob
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Re: OA-14: what should it sound like?

Post by therob » Tue 09 Apr 2019, 14:16

Infinitely Baffled wrote:
Wed 03 Apr 2019, 01:30
I take it that the Obi tweeters are a distinct improvement?
Yes, they are, the distortion, or most importantly the 3rd harmonic is well below audibility (0.1%) most of the range, closer to 2khz (from above) it starts to get a bit out of hand, but, if should you choose to go over-budget, then the satori woofers that grafpro at carlssonkult suggest are split at 2.7khz, and that makes for that nasty third harmonic to be way below audibility for the whole frequency range of the speaker.

I should also say, that I'm using oa12 speakers w/ exactly this combo (satori - t22 - grafpro-filters) and I'm not able to hear any distortion there.

Now, the second harmonic distortion is a bit higher then the third (it almost always is), but, that's exactly one octave above the first harmonic (the actual tone that's supposed to be playing) so it shouldn't hurt your ears.

The frequency response will also be even better w/ these drivers and if you have the money to do it, you will have great speakers for life.

Sorry if it feels like I'm lobbying for these products, I guess I'm a bit biased since I use them and they still impress me daily.

//Rob

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Re: OA-14: what should it sound like?

Post by Infinitely Baffled » Wed 10 Apr 2019, 11:00

Many thanks for this info, Rob. I am in two minds about whether to buy the new Obi T22 tweeters. The problem is that I bought the speakers a year ago and I have already replaced the midrange/woofer units since those in the speakers were non-standard items. I replaced them with standard Carlsson drivers, so I would not really want to throw those out and buy the Satori units now. So that leaves me with the question: would I still see an improvement if I replaced the 8 tweeters with Obi T22 units, but retained the Carlsson mid/low drivers?
I guess I would still need to get new crossover filters even if using the T22s with Carlsson mid/base drivers?
By the way - silly question maybe - what does the "distortion" sound like? Is it the rather bright harshness I have noticed?
Thanks for your help with this.
Regards

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Re: OA-14: what should it sound like?

Post by momus » Wed 10 Apr 2019, 12:01

It will be quite expensive to buy 4 Obi T 22 tweeters. And you must buy new filters, otherwise the sound will be very harsh in the upper region. I myself compared OD 11:s with and without the new tweeters (with B 65 OA) and I couldn't hear much difference. Maybe the old Peerless tweeter was somewhat "softer". I also found that the distorsion was much less with Satori (compared with the B 65 OA). I now have Satoris in my OA12 and in my OA 50.

therob
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Re: OA-14: what should it sound like?

Post by therob » Wed 10 Apr 2019, 12:40

Infinitely Baffled wrote:
Wed 10 Apr 2019, 11:00
...what does the "distortion" sound like?
How distortion works is there are manymany harmonics in what the speaker plays that is not in the signal it gets. Mostly the only ones audible in normal conditions are the first (not distortion, actual tone), the second, and the third (this one we don't like).
These are called the first harmonic (this is not actually distortion, but the actual tone that's playing), the second harmonic, that's the first harmonic frequency * 2 (example will follow), and the third, thats the first harmonic (actual tone) * 3.

So, lets consider an example, lets take 440hz that's 'A', that would place the second harmonic on 440hz*2=880hz which is the same tone, one octave higher (so not really bothersome), the third harmonic however, would be 440hz*3=1320hz, which is not a musical frequency.

There are 4th, 5th, 6th etc harmonics as well, but they diminish in db the higher up you go and are not audible so its basically the third harmonic that makes the 'harsh' sound.

Now, imagine what the distortion frequencies of a 2khz tone will be where the distortion is highest in oa14.

Try and play a pure sine-tone at 2khz and if you can hear many tones at once then that's the problem you are experiencing.

The best way (I can think) of explaining how distortion sounds is to use a guitar amp and crank up the distortion.
Infinitely Baffled wrote:
Wed 10 Apr 2019, 11:00
I guess I would still need to get new crossover filters even if using the T22s with Carlsson mid/base drivers?
Yes, because of many things, like the the sensitivity of the t22 compared to the mt20(the original tweeter), and the frequency response.
Infinitely Baffled wrote:
Wed 10 Apr 2019, 11:00
...I replaced them with standard Carlsson drivers...
Regards
What is a standard carlsson driver? The SC165? (if so, you're in luck, grafpro has ready filters for that)! The B65OA-IV? If so, I'd mail grafpro asking him what he thinks (he's the man when it comes to this!).

However, you should know that the B65OA-IV is really poor choice of woofer to use in oa14 (a 35L cabinet tuned to 30hz) when that woofer really works best in a *really* small cabinet, ~5L tuned to ~60hz (at least according to the T/S parameters).

I'm sry I cant just tell you "press that button and everything will sound perfect!".

//Rob

P.S. If you tried adjusting the jumper and you still get *really* bad sounding treble, then I'd check the tweeters one - by - one to see if one of them makes really ugly sounds (probably broken) and then try and first see if I could get my hands on used mt20 tweeters somewhere.

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