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General Category => DIY => Topic started by: Stefan I on September 11, 2009, 08:49:58 PM



Title: Another CII modification..
Post by: Stefan I on September 11, 2009, 08:49:58 PM
Well, i have now listened enough to my CII,s to get an idea of what to do in first place, the worst is harsh sounding tweeters and some lack of definition in higher frequencys, the dip in the upper midrange is also noticed but it isn't the biggest problem.
My plan is to remove all innercables like i did in the C/V,s to put in Silspeak 440, they are quiet more opensounding than the original monster cable wich i experience suffer from some kind of nasality, in the same time i will change all bipolar capacitors to polypropylen except those on the bassdriver where it will be new bipolars, i also found new tweeters wich have almost exactly the same sensitivity as the original and the frequencycurve looks very good, hopefully i not need to adjust the level with some external resistors in the signalpath, i was so satisfied with the Seas tweeters i put in the C/V:s so i will go for Seas again, but this time i will try an aluminium dome, partly based om my listening experience where i want to add some more definition in the upper frequency and to compensate a little bit for the Silspeak 440 wich is also on the dark side with much body compared to the Monster, we'll see if it turns out the way i want.
A funny thing i recognised is that i haven't some tweeter adjustments on my CII:s like Vesa II has, furthermore i don't have bipolars at all for my tweeters wich is also different from Vesas.

Link to tweeters:

 http://www.seas.no/index.php?option=com_content&task=view&id=90&Itemid=114


 


Title: Re: Another CII modification..
Post by: vesaII on September 12, 2009, 08:20:42 PM
Hello Stefan

Have you checked impedance of your Seas? If it is same as original around 3000-3500Hz then your swap work ok electrically.

Funny how different your CO is.

This sure is one nice tweeter which measures and also looks like original Vifa d26tg-06 http://scan-speak.dk/datasheet/pdf/d2606-920000.pdf

/Vesa


Title: Re: Another CII modification..
Post by: Stefan I on September 14, 2009, 09:43:47 PM
One speaker is finished and listened to, i have made mono comparisons to the original one and that is not funny..
The modified behaves much more neutral and transparent and also separates instrument and actors in a much better way, the new Seas tweeter is also a lot different, it's now very easy to follow frequencyvariations in the top, the old Vifa was like mixing all frequencys in one, and sound very monotonous. Despite the new tweeter is good i will yet compare it to a Seas textildome wich i found had aproximately the same spec as the metal one, then i decide, but the Vifa it will never be again..

Crossover picture, Monster is only left for the rear tweeter, everything else is changed, even between the filtercomponents, to me those Monstercables sounds very coloured, VesaII i highly recommend you try some other stuff here.

Your Scanspeak is also very interesting!


Title: Re: Another CII modification..
Post by: Stefan I on September 15, 2009, 11:18:12 PM
Tweeter is now decided, my thoughts were right and the metaldome was the best here, the textildome was too soft on this speaker and together with my other modifications, i am satisfied and it's time to go further. Midrange is (like also Vesa said) a problem, it lacks resolution and some 3D soundstage is not to think about with this Vifa. This problem i think will be the most delicate and also the most difficult, finding a unit with good integration against both tweeter and bass, this can take some time.. :-\


Title: Re: Another CII modification..
Post by: vesaII on September 16, 2009, 06:04:09 PM
Looks good, but it might take same time to burn in.

And yes mid is most difficult. You can change tweeter and have immediate improvement. But whe you put in new mid or woofer, then you need to alter CO and that is not easy one. Expecially with Snell: it really have strange values on parts...

My problem now with mid is too low efficiency and i also like to have more definition. This migh be next try: http://www.audax-speaker.de/index.php?module=shop_articles&index%5Bshop_articles%5D%5Baction%5D=details&index%5Bshop_articles%5D%5Bcategory%5D=4&index%5Bshop_articles%5D%5Bdata%5D%5Bshop_articles_id%5D=19&lang=en

Now link works. Sorry..

It has very similar frequency response as original Vifa, a bit less peaky only.

/V


Title: Re: Another CII modification..
Post by: Stefan I on September 23, 2009, 06:41:17 PM
Unfortunately your link doesn't work! :-[  Those days i have put in some new midrange units, Seas again.                      

http://www.seas.no/index.php?option=com_content&task=view&id=102&Itemid=124

The sound reminding a bit of Vifa but without that dip around 1 Khz, it is quite more open up there..
After further listening  i am not 100% sure that the tweeters are the right ones, i will also try those Scanspeak wich seems to be an improved version of the original.  New Bassdrivers next, but i will play them like this for a while first.  I am also a bit curious of trying an active crossover, we'll see..



Title: Re: Another CII modification..
Post by: vesaII on September 24, 2009, 04:53:45 PM
What is your problem with tweeter? Tweeter too loud? First aid could be L-pad. 3-5db

No Audax link works.

/V


Title: Re: Another CII modification..
Post by: Stefan I on September 24, 2009, 06:19:12 PM
Since last i have tried with the frontgrills on, and then it was better, i was just thinking the same as you, to adjust level instead.


Title: Re: Another CII modification..
Post by: Stefan I on April 07, 2010, 10:23:45 PM
This is how it looks like today, i have put the crossover outside the box and the bandpass is changed with new crossover points wich have resulted in a more natural upper bass and some more energy in the upper midrange, but this is just the first step, further modifications is now very easy to do, and i am afraid it will be some more before i am fully satisfied, and it will not be laying on an old carton in the end.. ::)



Title: Re: Another CII modification..
Post by: Stefan I on April 17, 2010, 05:00:46 PM
12/18 12/18 with midrange working at 200-3000Hz sounded Ok at the beginning, but after a few listeninghours i experienced some shortcomings against original crossover, it appeared to be some distorsion around upper crossoverpoint wich caused unfocused soundstage, acoustic or electrical problem i don't know, i reconstructed the bandpass to a narrow band type and changed the order to 12/18 18/18 and 200-2700Hz, together with level adjustments on midrange and tweeter this looks like a better idea, i have not yet found some areas where i not prefer the new one, accept in the bottom end (wich is still left untouched and the same), so this is good enough so far. Now it's about to make one more with identical values as the other.. :P





Title: Re: Another CII modification..
Post by: Pure_Brew on May 01, 2010, 06:38:46 AM
How do you know you are getting those slopes?


Title: Re: Another CII modification..
Post by: Stefan I on May 01, 2010, 04:50:30 PM
How do you know you are getting those slopes?

Yes, it is the electrical slopes, i haven't the equipment to measure the acoustic ones yet.


Title: Re: Another CII modification..
Post by: Pure_Brew on May 01, 2010, 06:02:25 PM
ok gotya. It's hard to even produce a solid electrical plan since the resistance dramatically changes with resistance.

I found that with change-and-listen experimentation, I get better results purposely gapping the crosspoint. Obviously this could/would create a bit of a drop-out at those frequencies, but it's much more pleasing to listen to on axis to me then having having big bumps there. Laying things back in the 2-3k region make the sound stage also sound like things are really coming from behind the speakers. Abonormal peaks in the 2-3k region make me feel like I'm being stabbed in the ears.


Title: Re: Another CII modification..
Post by: Stefan I on May 01, 2010, 06:47:52 PM
ok gotya. It's hard to even produce a solid electrical plan since the resistance dramatically changes with resistance.

I found that with change-and-listen experimentation, I get better results purposely gapping the crosspoint. Obviously this could/would create a bit of a drop-out at those frequencies, but it's much more pleasing to listen to on axis to me then having having big bumps there. Laying things back in the 2-3k region make the sound stage also sound like things are really coming from behind the speakers. Abonormal peaks in the 2-3k region make me feel like I'm being stabbed in the ears.

Yes, many speakers have that dip around 2-3khz, and i have read something about that it is there for bringing some kind of stereo compensation for the human ear and how it works with frequencys and sound coming from different directions, a linear frequency is not always that wich sound most natural.
And yes, the electrical slopes is calculated with a fixed impedance, i was just going to add that in my last reply but you were faster.. ;)


Title: Re: Another CII modification..
Post by: Stefan I on June 18, 2010, 12:57:22 PM
This project shows how important it is to listen during some period before drawing definite conclusions, lack of dynamics and onfocused soundstage was evident after a period of listening, it become boring to listen to music. To compare in mono in an initial stage under construction work wasn't so reliable after all, it told little on how the speakers behaved when played together, so back to electrical 12/18 on bandpass and further adjustments on co-points wich seemed to solve those problems (could be the phase), the Crossover construction is now actually much like the original but with different Crossoverpoints and component values to match the spec of the new speaker units. I also found the same Bassdrivers as in Vesas project at a good price, and need to rebuild the lowpass and maybe some work with the acoustics (cabinet) to make them produce a more linear fidelity.

Remember everything is made by ear so far...


Title: Re: Another CII modification..
Post by: vesaII on October 15, 2010, 07:34:04 PM
Hello Stefan

Did some experiment with my little spekers with Peerless mids. Friend of mine calculated a zobel (one cap and resistor) for it to make impedance same all the way to 3000hz and new highpass according to lower impedance. Much better!

Your Seas also has much higher impedance at 3000. Zobel might help.

CII also have some peak around 40hz. At least if you put it in small room as i do. Issue i like to solve...

/V


Title: Re: Another CII modification..
Post by: Stefan I on November 01, 2010, 08:49:33 PM
Hello Stefan

Did some experiment with my little spekers with Peerless mids. Friend of mine calculated a zobel (one cap and resistor) for it to make impedance same all the way to 3000hz and new highpass according to lower impedance. Much better!

Your Seas also has much higher impedance at 3000. Zobel might help.

CII also have some peak around 40hz. At least if you put it in small room as i do. Issue i like to solve...

/V
Hi Vesa, in fact i use a Zobel Circuit to my midrange, and bandpass values is calculated based on that.
New smaller midrange enclosures is under construction, hope to be able to play them soon. The project has been passive during the summer..


Title: Re: Another CII modification..
Post by: vesaII on November 06, 2010, 03:00:49 PM
Hi

If you do it my way, you really need to double check things. And do not make parts too tight or you have problem with glueing.

Hope we see some pictures soon :)

/VK


Title: Re: Another CII modification..
Post by: Stefan I on April 07, 2011, 11:57:55 AM
Time to put in some new information about this project :).

I will start with some pictures to show how the work has proceeded.



Title: Re: Another CII modification..
Post by: Stefan I on April 07, 2011, 12:36:08 PM
The crossover is also different since last, an Amplitud Parallel notch circuit is mounted on midrange to decrease energy in a decided area, in this case mostly between 600-1000Hz.
A Zobel circuit is seen under the speakerterminals.
Under construction everything looks very messy, it has to bee that way to make it easier for fast adjustments.





Title: Re: Another CII modification..
Post by: Stefan I on April 07, 2011, 01:06:40 PM
Something fun is that despite very little is left from the original design, the sound is still a lot Snell i think, that indicates that my philosophy in reproduction is not very far from The designers, but with the new drivers the overall resolution is much better than original CII.
Especially the Scanspeak woofers is on a totally different level compared to original Peerless, i will describe it as they have a very good timing and is quiet when the signal say so, instead of a monotonous background rumble wich was significant with peerless.
I also have some thoughts about testing Ring Radiators from Scanspeak in the future to see if i can make it even better and more homogenus in the upper range.


Title: Re: Another CII modification..
Post by: vesaII on May 28, 2011, 07:21:17 PM
Hello Stefan!

Looks great and a bit different construction as mine. Diagonal is good idea, which i missed ;(
But in other hand your back wall have no support from mid-box as i have. Does it vibrate much if you try with hand?
Maybe it have no big influence, but i like to build cross support in every place it is possible. I even have five veneer things on lower end of cabinet end cross support bars between them all. Overkill just feels good ;)

As i understand you did not change anything else but only built a box for midrange?

Do you think it made a big improvement?

/V


Title: Re: Another CII modification..
Post by: Stefan I on May 31, 2011, 11:47:12 AM
Hi Vesa, yes i didn't fastened the midrange enclosure to the backpanel of the cabinet, it would be interesting to see how the cabinet behave with an accelerator, to see where the resonancefrequency is, and take decision from there.
Anyway it's a relative easy job to do if necesary, with rectangular clumps with tight passform glued outside each corner between the surfaces.

The result however is better i think, amplitude feels more linear in both bass and midrange and i have also taken away that original yellow fiber and tried some other stuff with a smaller dampfactor.

It feels like it's going to be real good when the Crossover is working properly, it still has some shortcomings, mostly in the crossing between midrange and tweeter, the most painful area for the ears if something is wrong.. :(





Title: Re: Another CII modification..
Post by: vesaII on July 02, 2011, 09:50:52 AM
Hi Stefan

I try to collect power to do some necessary improvements to this uneven pair...
Have even plan to make it to two way + back tweeter ;)

And one thing is to get bass somewhat muted. Originally CII is 12/16 & 12/16.

What if i changed it to 16/12 & 12/16. At least it would make midrange a bit louder and midrange crossover more simple. In other hand it will make it more costly, but luckily we do not need to ask P. Snell's opinion of this ;)

You have not explained your crossover yet...? At least i am curious to know what you have found on path.

Best,
/V





Title: Re: Another CII modification..
Post by: Stefan I on July 02, 2011, 01:14:11 PM
I see your point in 18/12 & 12/18, a disadvantage though would be bigger coilvalues on Lowpass compared to 12db, but it is definitely worth a test.
Regarding the crossover i have mostly worked with adjusting crossover points and ouput levels, ones i tried 18/18 on midrange but went back to 18/12 because of an experience of some lack of dynamics.
Later on i was adding that amplitude circuit to get rid of what i thought was a peak in the upper midrange, and moved it a bit up and down to find the right frequency for it.
Next up will be to lower one crossoverpoint in midrange, to increase balance between lower midrange and upper bass.

Whats your plan for a two way system? Can you explain the design?

It is always difficult to explain with words whats happening when you don't have the possibility to measure things after adjustments, anything comes out to experiences only.  /Stefan


Title: Re: Another CII modification..
Post by: vesaII on July 03, 2011, 08:41:34 AM
Two way idea is to replace tweeter and current midrange with small Scanspeak 10F8424G00 fullranges i have http://www.snell.no/forum/index.php/topic,1292.0.html And drive them with 18/12 & <300Hz + back tweeter.

First i will get two cardboard box or big baffles of feneer just to hear if scanspeak really is better than these very nice Audax carbon fibres have now.

Maybe we also should learn to use at least microphone to find peaks...

/V


Title: Re: Another CII modification..
Post by: Stefan I on July 03, 2011, 11:07:47 PM
I understand, the crossover will be much more simple that way and thats good, the backside is that you get bad off-axis performance when using the midrange in fullrange. But if you tolerate a smaller sweetspot it's not a big problem, but for me i want the dispersion to be as smooth as possible.

By the way, after years with discussions i still don't know your position? Mine is in Sweden. :)

Quote
Maybe we also should learn to use at least microphone to find peaks...

Absolutely!!



Title: Re: Another CII modification..
Post by: vesaII on July 04, 2011, 05:57:51 PM
Yes, bad part is bad off-axis and one nice thing with Snell's is just good off-axis.

But it i like to try and see how bad this issue will be. Scan-speak 10F/8424G00 have so light cone, even less than the praised mid in AIIIi, i cannot resist. Can also happend that i get those original AIIIi midranges and put them in CII, if Scan-speak sound is no good  ;);) http://www.seas.no/images/stories/vintage/pdfdataheet/h143.pdf

Quite likely i will go back to 3-way, only with higher x-over frequency or 3000 to get best off-axis.

Actually CII:s are bought from HifiKlubben Sthlm when i lived there at -80's av min kompis Jakob :)


/Vesa
Helsinki


Title: Re: Another CII modification..
Post by: javilha on November 06, 2011, 12:50:25 PM
Why did you just sell the C2 if they don't sound good in your ears?? It's a very sad thing to see how you are spoiling them totally. Or from the bottom, built a complete pair of speakers you own, instead of doing this.


Title: Re: Another CII modification..
Post by: vesaII on November 06, 2011, 09:05:38 PM
We do not have market here for 20year old speakers with name Snell.

And they had become quite outdated.

And cause i cannot keep my fingers out of these things.

And cause of building a decent cabinet is too big effort.

And cause of i am a heretic and prefer good sound over history.

Sorry


Title: Re: Another CII modification..
Post by: Stefan I on November 06, 2011, 11:01:33 PM
Well javilha, i don't exactly see the problem?

Snell CII is worth little or nothing on the market here, i thought i had a good opportunity to build something better of it and save both time and work avoid building new cabinets from scratch.

It's always people out there that thinks some old stuff deserves to be left untouched, it's alright with me.
I don't have that feeling with CII, thats even not a speaker from Peter Snell.

I doubt i had done the same with original type C,s.

Otherwise Vesa tells it..


Title: Re: Another CII modification..
Post by: vesaII on November 07, 2011, 07:48:57 AM
One thing we all have common. That is 'Snell Sound' which is musicality of special kind.

This is very importan for us here or at least for Stefan and i.

Sound is the only thing that matters.

/V


Title: Re: Another CII modification..
Post by: javilha on November 07, 2011, 05:25:16 PM
Hi Stefan1 :)
Ok, I see your point. C/2 is a different speaker than the original C's with the raked baffle. I just wondered why you were totally rebuilding them. I can understand, that you have a lot more respect for the older  Peter Snell designs. And I'm glad to read that. Best regards. Allan  :)


Title: Re: Another CII modification..
Post by: jonynitro38 on January 20, 2012, 08:40:44 PM
The only exclusion are the recessed 1" invisible appears at the very base of the structures- they have a few dents and dings and represents that are only noticeable if you get on the earth and raise up the audio system.


Title: Re: Another CII modification..
Post by: Stefan I on October 14, 2017, 09:40:57 PM
Hello, after having my CII,s stored for about 5 years i was recently rebuild them a bit, a new two-way x-over is replacing my old for midrange and tweeter.
The new crossover is originally made for another speaker but the construction allows to use it with pretty good results also with other drivers.
Driver-impedance is not as critical here, most x-over problems usually occurs in x-over points, with phaseproblems and peaks or dips in the frequency curve as a result, with this unit the transition is smooth, i have done adjustments in level with an L-pad because midrange was to loud.


Title: Re: Another CII modification..
Post by: vesaII on October 16, 2017, 09:19:56 PM
Strange. All pictures have gone broken. At least for me...


Title: Re: Another CII modification..
Post by: Stefan I on October 17, 2017, 04:45:03 PM
Hello Vesa, yes, it seems it's no longer possible to show pictures here, but i think i have your mail, i can show you some pics there?
If you can't show pics this diy-forum isn't much to use anymore. :-\.