(Diy) Amp needed for Infinity Renaissance 90

[AllenB]

finding out the impedance curve

 

[ClaudeG]

Yep, thanks, I have this aswell since relased but the scale is quite odd. Depending on how you read the graph min seems to be anywhere between 2.4 and 3 Ohm

Anyway, more interested in the driver's modelisation (complex impedance of each driver) to see how I could improve the Xover components, especialy eletrolytics as these will age. In particular, changing electrolytic caps for polypropylene caps may require (or not depending where) an additional resistor to compensate for the ESR variation... this is where I need to understand how the Xover works, Xsim might be the solution... when I find some time.

Cost is a secondary consideration, aswell as space as it could still fit in most cases...

Thanks again

Claude

 

[AllenB]

the scale

 

[ClaudeG]

Thanks Allen!

Your reading confirms then my best case reading... I was afraid to be too optimistic with that odd scale starting at 2R.

So the Ren 90 would be quite friendly speakers, with 3R worst case... and quite little module variation across the range. That's also my interpretation, although it seems too nice to be true, but well 🙂

On the other side, the phase variations look also quite OK for such drivers and filters, with no horror story such as low Rtogether with lot of phase shift...

Thanks for your help and analysis effort Allen, reconforting indeed !

Claude

 

[TubySS]

Yep, they simply sound fabulous, still today... they would probably cost a fortune nowadays to manufacture with these drivers...

I shall be delighted to read your measurements, whenever you have the time to carry them out.

Regarding the required power... What I did to evaluate my real needs was the following, might help you.

I played the loudest track I new the loudest way, picked up rather compressed music with lot of (really) deep bass. Not sure it is that relevant, but bass is where you need the most power and where your hearing is not the most sensitive. I kept note of the volume position and assumed that would be the loudest party I would ever want on my seat, not very audiophile listening and maybe just one track at that level or a few minutes.

Then I played a track with a sinus tone that is recorded at 0dB (but could have been another value then scaling numbers), assuming that my recorded music couldn't be recorded louder per definition. I measured the AC voltage at my LS with a small scope still with that max volume setting, that is quite a torture but well, don't do it too long. If you don't have a scope, use a then sinus tone at 60Hz and a multimeter that can measure AC voltage, they can do 60Hz but are often crap at higher frequencies.

You can then calculate the power needed given you know roughly your LS impedance at that frequency (or estimate it). To avoid the bass impedance variations, I used a scope and a 1kHz tone, quite close 3-4R impedance... and realy very loud then.

Based on that, and giving a 3 to 6dB extra factor for power (another extra margin on top of the recording), I found out that I usualy needed in average around 1W per speaker and under 40W on forte in the bass... of course a bit extra margin can never hurt.

This is due to me being not too far away from the speakers (3m) and somewhere the losses are in real life way lower than in an open field due to reflections so at the end power needs tend to decrease quite lineary in a room with listening distance (in close field & small rooms).

Somewhere, I am with my needs exactly between USSA and FSSA, and they have different DF and properties, hence my hesitation 🙂

Enjoy music very much

Claude

Probably wouldn't be cheap yeah.

Great, hope that I'll carry the measurements out sooner than later.

I'm not too far off, since I'm somewhere in the 45W region, give or take a little.

Let me know, which amp you have chosen in the end and of course why.

 

[TubySS]

Yep, thanks, I have this aswell since relased but the scale is quite odd. Depending on how you read the graph min seems to be anywhere between 2.4 and 3 Ohm

Anyway, more interested in the driver's modelisation (complex impedance of each driver) to see how I could improve the Xover components, especialy eletrolytics as these will age. In particular, changing electrolytic caps for polypropylene caps may require (or not depending where) an additional resistor to compensate for the ESR variation... this is where I need to understand how the Xover works, Xsim might be the solution... when I find some time.

Cost is a secondary consideration, aswell as space as it could still fit in most cases...

Thanks again

Claude

I have the same problem as you and I'm not satisfied with their measurements either, plus theirs give only a very rough idea of what mine will look like, since their x-over is not the standard one, that's described in the technical sheet /the one in my Ren90's, so I'll have to measure my own speakers.

 

[TubySS]

Thanks Allen!

Your reading confirms then my best case reading... I was afraid to be too optimistic with that odd scale starting at 2R.

So the Ren 90 would be quite friendly speakers, with 3R worst case... and quite little module variation across the range. That's also my interpretation, although it seems too nice to be true, but well 🙂

On the other side, the phase variations look also quite OK for such drivers and filters, with no horror story such as low Rtogether with lot of phase shift...

Thanks for your help and analysis effort Allen, reconforting indeed !

Claude

Yeah, thanks Allen!

The Ren90's look way to friendly in those measurements...but I guess they really must be.
I'll know for sure when I have the results from my own measurements, but I guess theirs can't be too far from the truth.