Big Class D Recommendations

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Jump to Latest
S

Silent Screamer

Member
Joined 2012
Ok from post #15 it does appear possible although not that practical as it results in loss of power and heat in the resistor. So back to the other part of my question power the VC separately with 2 ohms, better or worse?

Edit:
Just looked at a few of the forum comments on bridging and perhaps I am chasing the wrong solution.
 
Last edited:
V

Viennatom_new

Member
Joined 2010
"Would it make any difference if I drove each of the voice coils separately with 2ohms? Since the driver in question is effectively 2 x 2 ohm voice coils."

Not really. But still I d like to know why you "love" exactly this driver so much?

"Could I add some resistance to each of the VC?"

Umm... lets say it this way: This is not really the smartest idea of the century. ;-)
 
V

Viennatom_new

Member
Joined 2010
"Ok decided to stop mucking around tapping with a smaller hammer and went to the cupboard and just bought this http://www.ebay.com/itm/Crown-I-Tech-9000HD-Amplifier-IT-9000HD-Itech-9000-HD-/370658928251
Ticks all the boxes and should drive that speaker comfortably."

This is not an amplifier - it is more a DREAM of an amplifier!

But still I don t see how they come to claim it can put out less than half 4 Ohm power into 8Ohms (usually 8Ohm power is half or slightly more than half 4 Ohm pwr):
1500 8Ohms vs. 3500 4 Ohms just don't make sense to me.

I-Tech HD Series
 
Last edited by a moderator:
V

Viennatom_new

Member
Joined 2010
Oh I see, this is not a PA system but a home theater and the low efficient transducer is used to reach the lowest octaves at medium SPL instead of maximizing SPL with less low frequency extension as is usually the case on "standard" PA or disco systems.
Just take care not to fry your voice coil. And post us how the system is working once everything is installed! ;-)
 
S

Silent Screamer

Member
Joined 2012
ViennaTom said:
Oh I see, this is not a PA system but a home theater and the low efficient transducer is used to reach the lowest octaves at medium SPL instead of maximizing SPL with less low frequency extension as is usually the case on "standard" PA or disco systems.
Just take care not to fry your voice coil. And post us how the system is working once everything is installed! ;-)
Click to expand...

Yes that is exactly the plan. I want to have plenty of head room to get the low frequencies without worrying about the amp holding it back.
That is why I decided to forget about tapping away with the XTI series and get the sledge hammer out. I am also leaving my options open on the other 2 x TC Sounds Pro 5100s I have.
With such a big sub I may not need more than one sub, but if I decide to convert the Pro 5100s and try them out as subs, I could use one sub per channel on this amp, as they are not as power hungry as the 5400.
I already have a 1000w per channel Class D Rotel RB-1092 which I am currently powering the 5100s with, and would probably use it, but this amp would be good for back to back testing of the Rotel to see if it is up to scratch.
Yet to build the sub but expect it to be in the region of 500 litres...
 
S

Silent Screamer

Member
Joined 2012
ViennaTom said:
So u got it for USD3699 right? Awesome!
Here in europe the price is "slightly" higher at EUR 6.439,— € which equals ~USD 8360 (!)

Audio Pro | Crown I-Tech HD Serie
Click to expand...

I have never bought anything second hand before as I normally buy new, but since this amp will sit unused a lot of the time and only be used for movies, I am prepared to take a risk on it to get a better amp for a cheaper price.
 
V

Viennatom_new

Member
Joined 2010
That is why I decided to forget about tapping away with the XTI series and get the sledge hammer out.

XTI6002 is still not a kids toy, but I 'd give mine away if you sent me the IT9KHD instead ;-)
I am interested in the way you set up the DSP (lowcut, EQ, X-OVR, limiter,...) and how it works. Is it a closed (non ported) sub design? Do you attempt to actively compensate for the frequency-dependant lowering of efficiency as you step down the octaves? So just how power-hungry is that 5400 thing? I don't believe it can stand being cooked by an IT9KHD at full power on the long term.
I overlooked that this was an ebay auction for used stuff, so the price is understandable. Basically, it is always better to buy used PRO stuff at reasonable cost than brand new bulls...t at the same cost.
 
V

Viennatom_new

Member
Joined 2010
Would be quite interesting to find out what is actually the "true cost" of such a unit, e. g. bill of Material plus manufacturing labor. Given that it consists of some MosFETs ($1 - $1.5 per piece, ICs ($0.2 - several dollars for the DSP / processor), electrolytics ($0.3 - $3) , coils ($2.5) and some mechanic parts like aluminum heatsinks (several $ each), fans, chassis etc..., based on what I know from the power supply business, I'd guess the cost at roughly 8 - 13% of that $80000, the most part of the sales price covering the middlemen, the tax, the patents, the cost of shipping to the dealer, the calculated cost of service over the lifetime, the cost of advertising / marketing, the cost of business managers / inventory management / customer account reps... and the like....
 
S

Silent Screamer

Member
Joined 2012
ViennaTom said:
That is why I decided to forget about tapping away with the XTI series and get the sledge hammer out.

XTI6002 is still not a kids toy, but I 'd give mine away if you sent me the IT9KHD instead ;-)
I am interested in the way you set up the DSP (lowcut, EQ, X-OVR, limiter,...) and how it works. Is it a closed (non ported) sub design? Do you attempt to actively compensate for the frequency-dependant lowering of efficiency as you step down the octaves? So just how power-hungry is that 5400 thing? I don't believe it can stand being cooked by an IT9KHD at full power on the long term.
I overlooked that this was an ebay auction for used stuff, so the price is understandable. Basically, it is always better to buy used PRO stuff at reasonable cost than brand new bulls...t at the same cost.
Click to expand...

I believe it will take 2000w for a few hours with a max around an 8000w peak, but a lot of that is predicated on you being able to get the power from the wall to drive it.

Being that we use 230-240v with 10A power points (outlet points in some countries) the amp will be more limited by the ability to get power from the grid.

The sub build thread is over here http://www.diyaudio.com/forums/subwoofers/234379-2-x-google-page-ranking-vs-ported.html now that I have a serious amp to power this driver with protection, I will be looking at a TH or BR design.
 
S

Silent Screamer

Member
Joined 2012
_henry_ said:
watts is everything for sub :)

btw this one is a finished product with DSP filter on it. PSC2.700 it has 2x700w with 1200w PSU, plug and play

https://www.hypexshop.com/DetailServlet?detailID=3470
Click to expand...

Yeah but if you compare 700w @ 4 ohm against the 5600w @ 4 ohm I am getting. I know which one is going to do the better job of driving this big driver :)

I did look at their website but nothing was really big enough for what I wanted.

Granted what I bought was probably overkill but better to have too much than too little and I can always dial the requirements back. Try to squeeze to much from a small amp and the THD goes through the roof.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Top Bottom