amp choices for active speakers - AVS Forum
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post #1 of 44 Old 06-18-2010, 05:39 AM - Thread Starter
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I am going to need 6 channels to power three 2 way active econowave type speakers (LCR)

Drivers are the AE TD12M, the CD is still undecided.

I am going to be using my Onkyo 875 as the pre. The DCX will most likely be the xover.

I am leaning more towards pro amps.

My only criteria is that it has gain controls for each channel. unless there are cheap stand alone gain/volume controls that can be placed in the chain.

Fanless cooling would be a plus too, but not a deal breaker.

I dont mind using multiple amps so it doesnt have to have 6 channels in one.

So far the Rane MA-6 seems pretty good for the price.
Also how about multiple Behringer A500s?

How many wpc should I be looking for?

No real budget. Obviously the cheaper the better.
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post #2 of 44 Old 06-18-2010, 05:44 AM
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I use the A500 to drive my TD12Ms and I recently found a Hafler amp for my CDs (BMS4550 or Radian 475B)

I definitely like amps with VC so that I can adjust the gain structure through them.

How many watts you really need depends on your listening distance and SPL requirements.

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post #3 of 44 Old 06-18-2010, 05:51 AM
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I remember reading something about someone doing tests on the A500 in a lab and finding numerous flaws with it. One being very high THD. Take it with a grain of salt but if someone finds the link I'm talking about please post it.

I would look at the EP2000/4000, EPX 2000/3000 amps or how about the emotiva UPA-2 amps as a cheap fanless solution.

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post #4 of 44 Old 06-18-2010, 06:06 AM
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Emotiva amps will not have VCs. There are VC options online.

A link to the A500 tests would be great.

The new Peavy 1600 is another good choice. Measured well and even the listening test from Chuck says its a worthy low cost amp. Its my next choice.

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post #5 of 44 Old 06-18-2010, 06:17 AM
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The A500 has problems using the VC at anything other than full, so I don't know if the A500 presents a suitable VC option. Whats wrong with adjusting the gain on the DCX2496? I adjust mine all the time without issue.

http://www.youtube.com/watch?v=RWj5CUl7rio

Makes me very weary of getting one.

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post #6 of 44 Old 06-18-2010, 06:20 AM
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Quote:
Originally Posted by DL86 View Post

The A500 has problems using the VC at anything other than full, so I don't know if the A500 presents a suitable VC option. Whats wrong with adjusting the gain on the DCX2496? I adjust mine all the time without issue.

http://www.youtube.com/watch?v=RWj5CUl7rio

Makes me very weary of getting one.

Mine is on the TD12M and I have never used anything but 100% VC. I should try it out.

Adjusting gains on the DCX will not remove the hiss of CD driver (about 60dB for most at 1 inch, DCX adds about 6dB more too), only through amp gain structures can you lower the noise floor enough.

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post #7 of 44 Old 06-18-2010, 06:21 AM - Thread Starter
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Is that the PV 1600 you are referring to?
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post #8 of 44 Old 06-18-2010, 06:29 AM - Thread Starter
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Yeah Penn pretty much summed it up.

Not all my listening is at reference levels. So a 60+ db hiss on the CD will bug me to no end.
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post #9 of 44 Old 06-18-2010, 06:34 AM
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Its the IPR-1600

measurements here
http://www.avsforum.com/avs-vb/showt...2#post18534472

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post #10 of 44 Old 06-18-2010, 06:53 AM - Thread Starter
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Wow 7 lbs.

I usually use weight as a judgment of quality. I guess that doesnt apply here.
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post #11 of 44 Old 06-18-2010, 06:59 AM
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Quote:
Originally Posted by DL86 View Post

The A500 has problems using the VC at anything other than full, so I don't know if the A500 presents a suitable VC option. Whats wrong with adjusting the gain on the DCX2496? I adjust mine all the time without issue.

http://www.youtube.com/watch?v=RWj5CUl7rio

Makes me very weary of getting one.

Who adjust the gain in real time though?

Also the econo wave's could even be run off of a gainclone at ridiculous spl levels. You will probably never put more then 30watts through them.
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post #12 of 44 Old 06-18-2010, 07:01 AM
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Those amps are cool.

How loud are they? (fan)

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post #13 of 44 Old 06-18-2010, 07:03 AM
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Quote:
Originally Posted by stgdz View Post

Who adjust the gain in real time though?

Also the econo wave's could even be run off of a gainclone at ridiculous spl levels. You will probably never put more then 30watts through them.

I remember putting 1 watt into my CD and that wasn't very pleasant to my hearing just to test its efficiency.

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post #14 of 44 Old 06-18-2010, 07:06 AM
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Quote:
Originally Posted by Hot Grits View Post

Wow 7 lbs.

I usually use weight as a judgment of quality. I guess that doesnt apply here.

Weight only matters in Class A or B designs. Class D, Class H quality has little to do with weight.

I have a Sunfire amp that does > 300Watts into 5 channels and its about 35lbs...its a $4K amp.

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post #15 of 44 Old 06-18-2010, 07:10 AM - Thread Starter
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Quote:
Originally Posted by DL86 View Post

Those amps are cool.

How loud are they? (fan)

According to the measuring amps thread the fan noise and blue LED are the only drawbacks.

I suppose we could swap out the fan for one of those quiet Noctua fans. It would void the warranty I suppose. But its only a $300 amp, so I am not too worried bout that.
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post #16 of 44 Old 06-18-2010, 08:19 AM
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For the horn - crown D-45 or D-75. Low power (25w & 35w/ch), gain controls with adjustments in the range you'll need them, fanless, 106db s/n ratio, made in the USA.

I use two D-45's and a D-150sIIa in a uber high sensitivity three way horn system with a digital dbx crossover and they do great.
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post #17 of 44 Old 06-18-2010, 11:32 AM - Thread Starter
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Anyone have an opinion on the Rane MA-6. http://www.rane.com/pdf/old/ma6dat.pdf

Seems like a real cheap option.

I could bridge channels 1 & 2 and 3 & 4 to the TD12Ms and use 4 & 6 for the CDs.

This would take care of the mains. These will be built first. After some listening I may not even use a center.

Anything wrong with this idea. What are the specs I should be lookin at, S/n ratio, thd?
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post #18 of 44 Old 06-18-2010, 06:16 PM
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The 8-channel Rotel RMB-1048 (if you can still find one) has worked well for me. Rotel also makes a 6-channel amp with more power.
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post #19 of 44 Old 06-19-2010, 05:54 AM
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Quote:


Anyone have an opinion on the Rane MA-6.

I don't but I would love for you to get it and then tell us how good it is

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post #20 of 44 Old 06-19-2010, 07:35 AM - Thread Starter
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I think I will do that. Maybe I could send this thing to ChasW for testing while I build the enclosures.

It's definitely cheap, but the S/N ratio doesnt seem too good. It is spec'd at 96 db, but that is at 100 watts. Most manufactures seem to state the S/N ratio at 1 watt. If my math is correct 96 db S/R would correspond to a 70-something db at 1 watt. Plus it says it is also an A-weighted measurement which also probably makes it look better than what it is.

I really dont fully understand how this all translates to real world usage. but it doesnt seem too good.

Anyone feel like giving me a quick lesson as to what these numbers mean?
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post #21 of 44 Old 06-19-2010, 05:18 PM
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ep2000.

only downside is the fan noise. you can fix that.

i'm kind of surpised that there is not a diy version of this amp with massive heat sinks in order to remove the fan noise.

hey...maybe you could be the first. copper is only $3/lb, so perhaps a 33 pound heat sink could be a $100 option. i'd jump at that!

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post #22 of 44 Old 06-19-2010, 05:41 PM
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Quote:
Originally Posted by LTD02 View Post

ep2000.

only downside is the fan noise. you can fix that.

i'm kind of surpised that there is not a diy version of this amp with massive heat sinks in order to remove the fan noise.

It could be done but the layout of the internal PCBs and original heatsinks would mean a large enclosure and a vertical orientation, ie PC tower shaped case might work very well.

Quote:
Originally Posted by LTD02 View Post

hey...maybe you could be the first. copper is only $3/lb, so perhaps a 33 pound heat sink could be a $100 option. i'd jump at that!

That's raw cost. Shaped cast or extruded heatsinks tend to be a lot more expensive.
[Conrad Heatsinks]

Another alternative would be water cooled if you had a dedicated room and the ability to run the plumbing to a recycled car radiator outdoors. Several people have used this approach for high power class A SS amps. The output devices can be bolted to a flange soldered onto standard copper water pipe and water flow controlled by a small electric pump like a pond pump that could also be placed outdoors. This approach would be especially efficient for those who used a rack of amplifiers which could all be on one water cooling system.

Similarly, for even less work, those with a rack of amps could employ a remote ducted fan to draw air through all of their amps and remove the fan noise to another room etc.

William Cowan in his Unity build has the amps suspended under the floor of his room so fan noise is barely audible even when listening for it directly over them. Couple of hole for wires and a 12V remote relay control to turn them off and on. As basements are common in many US homes, this would be very easy I would think.

Lots of possible alternatives, but most people don't look past the obvious ones.
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post #23 of 44 Old 06-19-2010, 05:47 PM
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Quote:
Originally Posted by DL86 View Post

I remember reading something about someone doing tests on the A500 in a lab and finding numerous flaws with it. One being very high THD. Take it with a grain of salt but if someone finds the link I'm talking about please post it.

Nope. Power is a bit overstated but otherwise it looks good. I was going to buy a half dozen of them to power my speakers before I started scoring the Yamaha's cheap secondhand.

Audioholics A500 thread
The Audio Critic test measurements
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post #24 of 44 Old 06-19-2010, 06:05 PM
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i hear you alpha niner...

there is no reason why several fans blowing low cfm across a large copper heat sink can't cool a very high power amp. that's my gripe...

sh_t, i have no training, but i could probably work out the math.

heck, kick the fans into high gear if ambient goes north of 80. but at 68...come on....

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post #25 of 44 Old 06-19-2010, 07:49 PM
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Quote:
Originally Posted by LTD02 View Post

i hear you alpha niner...

there is no reason why several fans blowing low cfm across a large copper heat sink can't cool a very high power amp. that's my gripe...

Sure it's possible and Cu heatsinks wouldn't add anything much to performance except a modest reduction in size.

However with your example of using the EP series, these units are designed to be used in a rack where weight, size and cooling efficiency in that useage need to be considered. It would be easy to take the guts out of an EP amp and make it convection cooled but the market for these sorts of amps is either audiophile ( ∴ expensive) or pro where noisy forced air cooling is not an issue.

DIY builds or mods of existing amps get around the commercial issues and can provide the end user with what they actually need. But we are a very small niche market.

Quote:
Originally Posted by LTD02 View Post

sh_t, i have no training, but i could probably work out the math.

heck, kick the fans into high gear if ambient goes north of 80. but at 68...come on....

The maths isn't hard and there are several online calculators to do the hard work, usually around a specific manufacturer's product, but easily transposable to other sinks.

For the designer and QA engineers of commercial pro amps, they have to balance the issues of fan noise (not typically a big deal) with the performance of the amp in intended use and it's function over it's lifetime. The fan speed sensors are connected to the heatsinks and are set to come in at a temp (not ambient) the designer feels gives good working performance and reliability of the product, and a bit cooler is not a bad thing. It keeps the transistor cases at a safe temp and inside SOA and reduces secondary radiation of heat inside the case to other components such as caps, especially the big PS electros and other semiconductors and passive components.

Every few degrees increase in temp of an electronic component reduces it working like and MTBF.
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post #26 of 44 Old 06-19-2010, 09:36 PM
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Originally Posted by A9X-308 View Post

Nope. Power is a bit overstated but otherwise it looks good. I was going to buy a half dozen of them to power my speakers before I started scoring the Yamaha's cheap secondhand.

Audioholics A500 thread
The Audio Critic test measurements

Explain this

http://www.youtube.com/watch?v=RWj5CUl7rio

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post #27 of 44 Old 06-19-2010, 09:41 PM
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Quote:
Originally Posted by DL86 View Post

Explain this

http://www.youtube.com/watch?v=RWj5CUl7rio

Got no sound on the PC ATM so I'll have to download it and look at it at work later.

I do tend to trust measurements from someone with an AP than some random net post though.
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post #28 of 44 Old 06-19-2010, 11:40 PM
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Got no sound on the PC ATM so I'll have to download it and look at it at work later.

I do tend to trust measurements from someone with an AP than some random net post though.

Agreed, but the person performing those tests in that video basically shows that you will get quite large THD at anything other than the volume gain knob set at 100% on the amp.

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post #29 of 44 Old 06-20-2010, 12:15 AM
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i hear what you are saying alpha niner...good points. i'm just dissappointed in the market not providing an "in between" solution. the fact that we are discussing it though...probably means that it is on the way! gotta love the free market...

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post #30 of 44 Old 06-20-2010, 12:18 AM
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|sidebar|

dl86, did you ever get your horn sub time aligned? i'm curious to know if after time alignment if it adds much beyond your direct radiating 18 sound sub.

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