Audax PR170M0 –100 dB or just *94 dB??

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DIY_newbie

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Joined 2004
GordonW said:
Yep, first breakup on a 6" driver is usually around 1600 Hz or so. But, from the data I've collected using this driver, the breakup is very benign... and doesn't really begin to color the sound, until well above 3KHz. In fact, even using it up to 5KHz... the dispersion is more of a sonic factor (ie beaming) than breakup... to a LARGE margin...

Regards,
Gordon.
Click to expand...

Gordon It looks like you have alot of experience with Audax PR170xxx series. Why do you recommend crossing them ~400 hz? I'm just wondering since I'm running mine with and active crossover at 250hz 48db/oct and sounds very good. I would not hesitate to recommend running the PR170m0 down to 250 as long as you're willing to cross with very high slopes...

--Chris
 
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rick57

Member
Joined 2002
Andrew

Not sure who you’re asking. I haven’t heard the Audax, but I find the Focal 7K6411 can be “in your face”. The gentler break-ups of the paper cone Audax is apparently more likable. The 100 dB paper cone PHL 3451 has severe breakups over 2100 Hz.

So while the PHL & Audax are I think intended PA duty, and the 7K6411 I am not sure, the Audax seems best for hi-fi, unless you’re a XO whiz.
 
D

DIY_newbie

Member
Joined 2004
rick57 said:
Thanks Gordon and Andrew

Chris
How mow many watts are you putting, what sort of dB do you listen at?
Click to expand...

I'm using them with Behringer A500 amplifiers but I usually keep the gains turned down pretty low so I would estimate less than 10 watts of power to the PR170. I'm almost finished building a FirstWatt F1 clone which will be used to drive the PR170s

--Chris
 
D

DIY_newbie

Member
Joined 2004
rick57 said:
Behringer to First Watt F1 clone – what a change! :whazzat:

(I’ve considered both, but for different situations) Please let us know the result

Cheers
Click to expand...

LOL,

You would be suprised how good the new A500s sound. Especially with an easy 8 ohm load like the PR170 and no passive crossovers. Before I used the A500s I had 2 Sony TA-N9000ES and I prefer the A500s.

--Chris
 
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beppe61

Member
Joined 2005
DIY_newbie said:

LOL,
You would be suprised how good the new A500s sound. Especially with an easy 8 ohm load like the PR170 and no passive crossovers.
...
--Chris
Click to expand...

Dear Sir,

please excuse my question quite off-topic.
Do you mean that the A500 is poor with demanding loads (i.e. low impedance and sensitivity) ?
I am extremely interested in this amp but on the basis of your words I am now a little worried.
With which speakers did you have problems ?

Thank you very much and kind regards,

beppe
 
D

DIY_newbie

Member
Joined 2004
beppe61 said:


Dear Sir,

please excuse my question quite off-topic.
Do you mean that the A500 is poor with demanding loads (i.e. low impedance and sensitivity) ?
I am extremely interested in this amp but on the basis of your words I am now a little worried.
With which speakers did you have problems ?

Thank you very much and kind regards,

beppe
Click to expand...

Beppe,

Please forgive me if I gave you the wrong impression. The A500 is a wonderfull amplifier, and does not have any major shortcommings that I am aware of except one... In fact i am using 3x A500s currently for my all active system. I was only bringing up the fact that when you build an all active system without a passive crossover you present a very simple load to the amplifier.

I have only used them in my own setup, and one of my friends (JMlabs Chorus ) speakers. We replaced an older solid state receiver that he was using before. It was a large and noticeable improvement. In my system I am using running two parrell 12" woofers (4 ohm nominal for the pair) without any problems. IMHO, the A500 is a great amplifier for the money, but it does have one major shortfall. It will thump your speakers every time you power it on unless you have the gains turned all the way off.. For me its not an issue since I just turn mine down everytime, but you could really do some damage to your speaker if you're not carefull..

When I purchased my A500s I also listened to samson servos and the Alesis RA series. I preferred the top end on the A500 to both amplifiers, but it was a hard decision due to the turn-on thump...

Hope this helps,

--Chris
 
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beppe61

Member
Joined 2005
DIY_newbie said:

Beppe,
Please forgive me if I gave you the wrong impression.
The A500 is a wonderfull amplifier, ...
Hope this helps,
--Chris
Click to expand...

Dear Mr. Chris,

I not only forgive you but I thank you very much indeed for your extremely kind and valuable reply.
The thump at the switch-on does not worry me.
I intend to switch it on once a day and then leave it on continuously.
What still worries me is the current delivered by the amp.
Now that you mention Samson brand, I have actually a Samson Servo 260 at hand that fails to give me an adequate bass response through my present speakers (old Dynaudios).
It is weak and slow, an evidence of low current from the amp.
From some photos I can see that the transformer inside the A500 seems quite more substantial and this is very good.
Do you have any idea about its VA rating ?
Looking at the specs the Servo 260 is 130W/4ohm and the A500 should be 230W/4ohm.
On the basis of your very positive opinion I strongly think that the A500 will be my next power amp.
I like very much the way how is built.

Thank you very much again for your very valuable advice.
Kind regards,

beppe
 

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GordonW

GordonW

Member
Joined 2005
rick57 said:
Are there any drawbacks to doing exaclty as Chris has done - active crossover at a lower 250 Hz - with a steep 48 db/oct?

Thanks
Click to expand...

Well... at home listening levels, it might be OK. However, the PR17/PR170 has a rather limited Xmax, so I'd be afraid of getting into intermodulation problems with excursion, at the levels I tend to use the drivers at (as in cabinets, mated with double-15" woofers and such... 105+ dB peaks)...

I tend to take Audax at face value- 12 dB/oct, 500 Hz... but, as I said, most of my installs were in the "native environment" (ie, pro audio) of the driver, where demands are greater...

Regards,
Gordon.
 
A

AndrewT

R.I.P.
Joined 2004
Hi,
to attempt to gain a whole octave below the manufacturer's recommendation by increasing the filter steepness is somewhat ambitious.

The high efficiency of the driver is partly due to low moving mass and this has been achieved by using a very short voice coil. Short voice coils will distort badly if overstroked. Driving a midrange unit this way may give a very noticeable coloration or worse to all the familiar voice sounds. i.e. horrible.
 
D

DIY_newbie

Member
Joined 2004
AndrewT said:
Hi,
to attempt to gain a whole octave below the manufacturer's recommendation by increasing the filter steepness is somewhat ambitious.

The high efficiency of the driver is partly due to low moving mass and this has been achieved by using a very short voice coil. Short voice coils will distort badly if overstroked. Driving a midrange unit this way may give a very noticeable coloration or worse to all the familiar voice sounds. i.e. horrible.
Click to expand...

Well I just ran some quick off the cuff calculations but if the manufacturer recommends 500 hz @ 12db/octave (assuming LR2) then the resulting transfer function would be:

500 : -6db
250 : -12db
125 : -24db
62.5 : -36db
31.25 : -48db

While 250hz @ 24db/ocatve (LR4) would be

500 : 0 db
250 : -6 db
125 : -24db
62.5 : -48 db
31.25 : -72 db

and 250hz @ 48db/octave (LR48) would be

500 : 0 db
250 : -6 db
125 : -48db
62.5 : -96 db
31.25 : -144 db

It would seem that the only place you would have less output with the 12db @ 500hz than the 24 would be around 250hz, below that all the steeper slopes better protect from over excursion...

I think the real question is how low can the PR170 really play??

--Chris
 
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thylantyr

Member
Joined 2001
In my quest for a high sensitivity midrange, the PR170M0
scored the highest in sound quality with the PHL1120
coming in at almost a tie. It would take you a long time
auditioning both to pick a winner as it's very close. Actually,
I prefer the PHL1120 because the design is more robust,
more xmax, more power handling, etc., at a slight sacrifice
to sensitivity. You can order those with treated cones, front
and back, I believe 1121 is the code :double check:

You can easily run those two drivers at 250hz with 8th order
slopes with no issues regarding mechanical damage.

The Focal Kelvars are pretty good, but I prefer the other brand.
The Focal W cones scored the lowest in SQ auditions.
Seas Excel is nice, but it's more of a midwoofer with much
lower sensitivity that requires more power to get any 'slam'
out of them.

Why not build a line array and solve all your
problems -> :devilr:

You can build some crazy high sensitivity loudspeakers
that way using cheaper drivers, low distortion can
be achieve by using lots of them -> :smash:
 
D

DIY_newbie

Member
Joined 2004
Thy,

Thanks for your comments. Line arrays are not really what I'm looking for...

I looked at my DCX settings and it turns out I'm crossing them at 225hz LR8 slopes.. Sounds pretty good to me.. I'm listening to Genesis: Invisible Touch on LP right now as I type this message..

However I've been want to try crossing to my H-frames lower than the current 22 so I started looking at some of the 8" PHLs and thinkin about running them 125 to 3K.. I know its pretty demanding to play such a wide range but the 2460 looks pretty good ... QTS 0.44, FS 81 and +/- 5mm xmax

--Chris
 
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rick57

Member
Joined 2002
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