SpeakerTalk

willem-57 · Posted: Thu Jul 23, 2015 8:28 am Post subject: Vifa Vivace 87

While i was searching the net i came across a set of Vifa vivace 87 self build speakers. They where so cheap that i thought, why not buy and refurbish them because these kind of speakers i can easily sell again. They are from a more simple design as the RR 105.4 that i have refurbished. You can compare them with the Kef CS7 from the same time area. In a german test in the stereoplay magazine 1988 they got about the same verdict. I have already did the job and they are now playing at my house. Indeed it are very nice speakers with a deep bassnote. But the imaging is less as the rr 105.4. Probably i will sell them in the future. The speaker units used are all from Vifa, the 25WP250 bass, DM760 dome midrange, HT275 tweeter. The DM760 is a very well designed and fresh sounding dome midrange speaker, the HT275 tweeter can be significant improved by using a ScanSpeak D2905/9300 or 9500, witch can be implanted without altering the crossover. The crossover is a hardwired type.

As i bought them:

Being overhault:

The hardwired crossover with the old green oxidated wires that i have replaced:

The components on the table:

Yust sprayed:

Almost ready with the new design:

Playing in my house:

Together with the RR 105.4:

willem-57 · Posted: Mon Jul 27, 2015 8:36 am Post subject:

It's really a very nice speaker indeed. So i decided to refurbish the 20+ years old crossover. Because it's hardwired i can easily improve it to a really audiofile standard on a modest budget. The capacitators will almost all be replaced except 1 on the tweeter. On a Dutch forum i had help from someone who has more knowledge of this than i have. Because the tweeter is a bit edgie, or sharp, he recommended the Mundorf EVO oil capacitators that are more airy. The very good midrange speaker gets the Clarity PX witch will be mutch better as with the current one. And the woofer site will be replaced with the simple but good Jantzen 100 volt, it's now a 40 volt old one that is not so good. I,ve ordered the capacitators already.

Here site about all kinds of capacitators: http://www.humblehomemadehifi.com/Cap.html

The order:

proffski · Posted: Wed Jul 29, 2015 11:35 am Post subject:

A great project finished perfectly.
Thank you for sharing, I found it most interesting!
_________________
I contend that for a nation to try to tax itself into prosperity is like a
man standing in a bucket and trying to lift himself up by the handle.
-Winston Churchill

willem-57 · Posted: Thu Jul 30, 2015 7:02 am Post subject:

Thx Proffski,
As they be finished i will post the listening results. Can take some time, the suplier is on a holiday.

speakerguru · Posted: Thu Jul 30, 2015 9:21 am Post subject:

Always nice to see the progress of a project with lots of photos. The link leads to another link to an interesting article about capacitor microphony.

proffski · Posted: Fri Jul 31, 2015 8:16 am Post subject:

Gosh, I’ve known about the phenomenon in ceramic capacitors (1st hand) and how it now increasingly manifests in surface mount components but are you indicating problems with NP electrolytics as well?
_________________
I contend that for a nation to try to tax itself into prosperity is like a
man standing in a bucket and trying to lift himself up by the handle.
-Winston Churchill

audiolabtower · VIP Contributor 500+ Joined: 06 Jan 2009 Posts: 686

I was interested in the level of signals used to get the measurements, but not much detail was given. As one who has external crossovers I thought it was worthwhile just from the multi-amping point of view, and have read opinions that the pressures inside cabs can cause microphony, but little in the way of scientific proof, as with so many "hi-fi" tweaks.

willem-57 · Posted: Sat Aug 01, 2015 7:00 am Post subject:

Maybe you read this: http://www.troelsgravesen.dk/coils.htm

By the way, it's an enourmous site with lot's of information: http://www.troelsgravesen.dk/Diy_Loudspeaker_Projects.htm

audiolabtower · VIP Contributor 500+ Joined: 06 Jan 2009 Posts: 686

Interesting links, thank you. I hope Kef measured the crossovers with the final layouts so any inductor coupling was compensated in the values chosen, the reference coils having been wound to suit the cap values, although my 105 layouts are very correct for minimum interaction Smile

Mr Gravesen did a very good page on one of my favourite speakers the Spendor BC1 trying to understand why the midrange was so spectacular (although there is a small error in the crossover circuit where the HF1300 phase should be reversed).

willem-57 · Posted: Sat Aug 01, 2015 1:57 pm Post subject:

The way the Kef rr105.4 crossover is designed is the right way, the coils are standing correct for a low induction as possible.
The self made vifa crossover they used a bigger surface to achieve the same purpose. Only the small coil L1 is to close to the bigger L4, so maybe upright the L1 like on the Kef crossover for the best result.

audiolabtower · VIP Contributor 500+ Joined: 06 Jan 2009 Posts: 686

Yes, L1 should certainly have been hot glued as per Fig5 in your first link Smile

willem-57 · Posted: Sat Aug 08, 2015 10:02 am Post subject:

I,m starting to rebuild the crossovers. Tuesday i will have the new components en will finish them.

willem-57 · Posted: Sat Aug 15, 2015 9:46 am Post subject:

The crossovers are finished and the result is indeed a more open tweeter and also the midrange is more clear. Only the lower octave is too mutch and i have too finetune this by changing the length of the reflex pipe.
I will let you know the result.

New crossover, as you can see i made a central - pool and also added tie ribs for the + wires. So nothing is hanging on the solder points as before. The new wires for the mid and treble are van den Hul cables.

willem-57 · Posted: Sun Aug 30, 2015 1:09 pm Post subject:

The Vivace's are ready, took me a while to get the sound in balance because the tweeter was too loud in the original design. First i made a L-pad minus 2,5 db and still i was not 100% satisfied with the result. Happenly i found a vivace crossover update on a dutch speaker site. Here there is a 2.2 ohm resistor placed before the high section of the crossover. This way there is no phaseshift and the signal is already weakened before it goes through the capacitators etc. Result is now very good, mutch better balanced.

The L-pad i first made, but later removed:

Ioannis · Introductory Contributor Joined: 03 Oct 2021 Posts: 7

I know this is old enough thread, but the Vivace is too good to leave alone!

I have the same box and would like to finish building them.

Questions:
1. Doesn't need the mid to be somehow insulated from the rest of the box? I found that the woofer is affecting very much the response in the mid band.

2. the tube of the bass reflex, how long should it be? Could not find any info on that.

My mid and tweeter drivers are a bit different (but optically the same): DM75 for the mid and D26TG-35 for the tweeter. Tweeter is too loud in relation to the rest of the drivers. It the 2.2 resistor enough to balance it ?

Thanks
Ioannis