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-   -   HiFiMeDIY T3 or T4 for Klipschorn & LaScala Woofers? (http://www.diyaudio.com/forums/class-d/191590-hifimediy-t3-t4-klipschorn-lascala-woofers.html)

nwboater 26th June 2011 10:44 PM

HiFiMeDIY T3 or T4 for Klipschorn & LaScala Woofers?
 
I'm going to active EQ on the 3 fronts in our 5.1 system. The L & R are Klipschorns modified from 3 way to 2 way and the center is a Klipsch LaScala also changed to 2 way. The sides are Klipsch Heresies.

The high frequency horns I believe are properly rated at 8 ohms. The Klipsch Heresies are 8 ohm and will not be biamped.

I was about to buy four T4 amps for this but then remembered that the Klipschorn woofer is lower impedance. It is rated as 8 ohms but the impedance/frequency plots show it averaging 6 ohms with dips to 4 ohms.

So I'm wondering if I should use a T3 amp for the two Khorn woofers since it's a 4 ohm amp. But then it might suffer at the higher impedance points, as I'm concerned that the T4 might suffer at the lower impedance points.

The La Scala Impedance curves average about 7 ohms, but also with some 4 ohm dips

This seems a no win dilemma or am I just being too concerned and is this perhaps typical of a lot of speakers?

Thanks for any suggestions. Also might it be advisable to try to contact HiFiMeDIY directly? Or might he be responding here?

Rod

nigelwright7557 27th June 2011 12:41 AM

A speakers impedance varies wildly with frequency.
Part of the speakers impedance is an inductance which goes up with frequency.

I would suggest you are worrying unnecasarily.

nwboater 27th June 2011 02:59 PM

Quote:

Originally Posted by nigelwright7557 (Post 2620228)
A speakers impedance varies wildly with frequency.
Part of the speakers impedance is an inductance which goes up with frequency.

I would suggest you are worrying unnecasarily.

Thanks for the response Nigel.

I'm still really wondering if the T3 would not be a better solution for the Khorn woofers than the T4 I'll be using for others.

Thanks,
Rod

Bernie7 28th June 2011 01:26 PM

Of the two, I'd get T3. It has the current to double going from 150w at 8ohm to 300w into 4ohm. This means it can drive both loads without sweat.

OTOH the T4 is weak at 4ohm, actually falling from 180w to 90w at 4ohm :eek:

Hifimediy|Hifimediy T4 2 x 180W@8ohm amplifier

I'm using T3 monos and it's fab.

nwboater 28th June 2011 01:46 PM

Quote:

Originally Posted by Bernie7 (Post 2622060)
Of the two, I'd get T3. It has the current to double going from 150w at 8ohm to 300w into 4ohm. This means it can drive both loads without sweat.

OTOH the T4 is weak at 4ohm, actually falling from 180w to 90w at 4ohm :eek:

Hifimediy|Hifimediy T4 2 x 180W@8ohm amplifier

I'm using T3 monos and it's fab.

Thanks Bernie. It really was looking like the T3 would be the better solution for the Khorn woofers.

Has anyone done a SQ comparison between a T3 & a T4?

I sure do wish we could get some distortion curves on these amp assemblies. Not just the chip manufacturer ones.

Rod

Bernie7 28th June 2011 01:52 PM

Quote:

Originally Posted by nwboater (Post 2622077)
Thanks Bernie. It really was looking like the T3 would be the better solution for the Khorn woofers.

Has anyone done a SQ comparison between a T3 & a T4?

I sure do wish we could get some distortion curves on these amp assemblies. Not just the chip manufacturer ones.

Rod

Distortion and noise performance would depend on your assembly too won't it? Prob why some kit suppliers don't provide measurements.

From hifimediy's site, T3 looks a no brainer choice to run with real world speaker loads.

nwboater 28th June 2011 03:36 PM

Quote:

Originally Posted by Bernie7 (Post 2622085)
Distortion and noise performance would depend on your assembly too won't it? Prob why some kit suppliers don't provide measurements.

From hifimediy's site, T3 looks a no brainer choice to run with real world speaker loads.

Yes on distortion and noise measurements somewhat being a function of assembly. Actually that's a bit of a spooky part of this project, but will be the subject of a later thread.

Are you suggesting that the T3 may be the best choice for all our amps, the 8 ohm ones also? The small increase in power on the T4 @ 8 ohms is not an issue for us with our super efficient horns. We just want amps that put out a good dose of power so we have plenty of headroom, but are super clean.

Rod

Bernie7 29th June 2011 12:55 AM

Quote:

Originally Posted by nwboater (Post 2622212)
Yes on distortion and noise measurements somewhat being a function of assembly. Actually that's a bit of a spooky part of this project, but will be the subject of a later thread.

Are you suggesting that the T3 may be the best choice for all our amps, the 8 ohm ones also? The small increase in power on the T4 @ 8 ohms is not an issue for us with our super efficient horns. We just want amps that put out a good dose of power so we have plenty of headroom, but are super clean.

Rod

If it's true that T4's power falls from 180w to 90w going 8 to 4 ohms, then one can draw the implications for oneself since speaker impedance generally fluctuate quite a lot over frequency. But this is at full power, and its behavior at lower power is not known, perhaps it's not as drastic. It would be interesting to plot the FR of the T4 at varying power levels and loads.

nwboater 30th June 2011 01:20 PM

Quote:

Originally Posted by Bernie7 (Post 2622762)
If it's true that T4's power falls from 180w to 90w going 8 to 4 ohms, then one can draw the implications for oneself since speaker impedance generally fluctuate quite a lot over frequency. But this is at full power, and its behavior at lower power is not known, perhaps it's not as drastic. It would be interesting to plot the FR of the T4 at varying power levels and loads.

So now I'm thinking of ordering one T3 & one T4 initially instead of the 4 amps I need to end up with in the system.

Looks like they both use the same supply.

Will probably be quite awhile before I can spend a lot of time on the project but I plan to do some testing and listening comparisons. Should be interesting I'll post here afterwords.

Thanks for everybody's good input on this.

Rod

aussiephil 1st July 2011 01:16 AM

2 Attachment(s)
Rod,

I had the same dilemma with T3/T4 for my mixed sub setup and future use with active LCR setup. After pouring over the specs and doing costings i decided the basic T3 board was the better choice with the ability to better drive 8 or 4 ohm loads making the module more versatile over time with various drivers.
Have currently got two T3's running from SMPS's at 49V. One is driving a TH with a 15" 8 Ohm driver the other runs a pair of 18" ported cabinents in parrallel for 4 ohms.
Not having the T4 to compare all I can say is i consider the T3 to be a great little module that provides great bang for buck.

You can see the TH and bins in the attached photo.
The second photo shows one of the new fronts we have built that is currently passively crossed but we ultimately be driven by multiple T3's.
As you can see i haven't yet built a case around the amp modules.

Cheers
Phil


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