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Measuring Amplifiers - Page 8

post #211 of 1917
Thread Starter 
Quote:
Originally Posted by FlashJim View Post

Chuck, thanks for all of your work on this.


Your welcome! It is fun for me now that I do not do it for a living anymore
post #212 of 1917
Quote:
Originally Posted by chasw98 View Post

Using the QSC, you will not get as much headroom and you will not get the flexibility to turn off some cabinets when you are watching I Love Lucy reruns.

I had to snicker a little on that one

The four subs are all in one cabinet. Each sub has two voice coils. Each coil is 4 ohms. The subs are rated at 1000 watts RMS each, but I have personally put a lot more power to them, and they have taken it without problems. They are the Rockford Fosgate Power DVC 15's that I have owned for over 6 years. They have great bass, and take TONS of power....without distorting too. I would rather buy four used speakers like these for $800, than one super duper 15" sub for $800...which will easily be blown away by the four, but back on topic..

The eight behringers will add more complexity, but only for the one day they are installed. I will have them setup where only one amp will be running 95% of the time, but when I have that master and commander, or behind enemy lines DVD, I'll turn them all on. Yes the QSC's will probably be easier to setup, and sound almost as powerful as the Behringers...but they will be working at 100% duty to do what the behringers would be doing at 50% duty. We are talking about doubling the power here, so I don't see any cons going the behringer route. And remember....the distortion starts to go up significantly when you hit that 100% duty mark...on ANY amp.

I'm also sick of waiting to buy something, so I'm getting something tomorrow.
post #213 of 1917
Thread Starter 
Quote:
Originally Posted by staffcurtis View Post

I had to snicker a little on that one

The four subs are all in one cabinet. Each sub has two voice coils. Each coil is 4 ohms. The subs are rated at 1000 watts RMS each, but I have personally put a lot more power to them, and they have taken it without problems. They are the Rockford Fosgate Power DVC 15's that I have owned for over 6 years. They have great bass, and take TONS of power....without distorting too. I would rather buy four used speakers like these for $800, than one super duper 15" sub for $800...which will easily be blown away by the four, but back on topic..

The eight behringers will add more complexity, but only for the one day they are installed. I will have them setup where only one amp will be running 95% of the time, but when I have that master and commander, or behind enemy lines DVD, I'll turn them all on. Yes the QSC's will probably be easier to setup, and sound almost as powerful as the Behringers...but they will be working at 100% duty to do what the behringers would be doing at 50% duty. We are talking about doubling the power here, so I don't see any cons going the behringer route. And remember....the distortion starts to go up significantly when you hit that 100% duty mark...on ANY amp.

I'm also sick of waiting to buy something, so I'm getting something tomorrow.

Sounds like a plan. You might want to pull some extra 20 amp circuits to the location of the amplifiers. I have found that running at full wattage you can only put 2 of them on a 20 amp circuit. I currently have 2 of them on a 20 amp circuit that also has a light and a digital clock on the circuit and on very deep, loud bass notes the lamp will dim and the digital clock will reset itself to 12:00! Show us some pictures when you have it installed.
post #214 of 1917
I will have four 20 amp circuits run into that location. I know power will be a major concern, and I'll have my bases covered. I plan on getting the behringer DCX2496 module to manage timing and pre-out levels. I am having to redo my subs to have 8ga wiring so there are no weak links in the chain. This setup will be complete within the next 2-4 weeks. I will post pictures when it's done for others to see. I will probably have even more questions for everyone then.

Thanks for all!
post #215 of 1917
Thread Starter 
Quote:
Originally Posted by staffcurtis View Post

I will have four 20 amp circuits run into that location. I know power will be a major concern, and I'll have my bases covered. I plan on getting the behringer DCX2496 module to manage timing and pre-out levels. I am having to redo my subs to have 8ga wiring so there are no weak links in the chain. This setup will be complete within the next 2-4 weeks. I will post pictures when it's done for others to see. I will probably have even more questions for everyone then.

Thanks for all!

I have a DCX2496 and a DEQ2496 that I am getting ready to use in a project myself shortly. Watch the gain settings in the DCX!
post #216 of 1917
I have only heard good things about the DCX. This will be uncharted territory for me, so I'm very excited!
post #217 of 1917
I just found this thread. Very interesting. You have tested all the amps I have that would be worth a look at. Except the Behringer A500, I have running my subs.

Hmmm... the map to Margate looks like a 6-7 hour drive...

Great thread. Great stuff to give out to the community.
post #218 of 1917
Chuck,

I'm building a new sub and will be ordering an amp shortly. I am going to order either an OAudio 500 BASH or a Rythmik A370. It will take me a while to build the box so I'd be happy to ship the amp to you if you want to test it. Any interest?

Joe
post #219 of 1917
Thread Starter 
Quote:
Originally Posted by soho54 View Post

I just found this thread. Very interesting. You have tested all the amps I have that would be worth a look at. Except the Behringer A500, I have running my subs.

Hmmm... the map to Margate looks like a 6-7 hour drive...

Great thread. Great stuff to give out to the community.

Ahhh, but you have Arvo's that I am starting to build! Maybe meeting halfway, no that won't work, ummmm, lemme' think about this!
post #220 of 1917
Thread Starter 
Quote:
Originally Posted by JoePerri View Post

Chuck,

I'm building a new sub and will be ordering an amp shortly. I am going to order either an OAudio 500 BASH or a Rythmik A370. It will take me a while to build the box so I'd be happy to ship the amp to you if you want to test it. Any interest?

Joe

I will be glad to test any amplifier. I know that lots of people use both of those amps so it would probably be of interest to others that come around here. Not sure how we would work it out but I am sure it could be.
post #221 of 1917
Cool. Once I get the amp we can make arrangements. I can ship it to you and then give you my UPS account number to ship it back on or I could send a call tag. We'll figure out what works best for you.

Any opinion on these two amps before I make up my mind?

Thanks,
Joe
post #222 of 1917
Thread Starter 
Joe:
That sounds like a plan. I have worked with the Oaudio and it seems OK. It worked well with an AE15 in a ported box that ssabripo and I made. But I am real impressed with the Rhythmik gear. I have heard crackyflipside's (Chris) 12" unit and it sounds very, very good. I would tend to go with the Rhythmik. No solid scientific reason, just gut instinct from what I have heard.
post #223 of 1917
chasw98, is it worth tossing the sometimes flimsy pwr leads that come with power amps and hardwiring in somthing heavier and bypassing that extra connection point as well? l have'nt heard of many people doing it so l'm just curious as to whether it would help with peak power delivery at all, l'll be interested to hear what you and others thoughts are on this .

Ken
post #224 of 1917
Thread Starter 
Quote:
Originally Posted by kesa32 View Post

chasw98, is it worth tossing the sometimes flimsy pwr leads that come with power amps and hardwiring in somthing heavier and bypassing that extra connection point as well? l have'nt heard of many people doing it so l'm just curious as to whether it would help with peak power delivery at all, l'll be interested to hear what you and others thoughts are on this .

Ken

This question can lead to the snake oil boutique power cord discussion which can go crazy. I took a common sense approach. If you want to bypass the SJE connector built into the back of the amp and make your power cord 'permanent' so that it cannot be unplugged, yes, it will be according to numbers a better connection than a pluggable connection. Will it be an audible difference? Highly unlikely.

I went so far as to buy Belden power cords that come under the 'Volex" name and are available at www.carlton-bates.com. Model 17604 is 3 cond, 14 gauge power cord. I then cut the end that plugs into the amplifier and replaced them with Schurter brand connectors. The cords are around $8-$9 each and the connectors are $4-$5 each. Shipping will kill you if you order one at a time.

So to answer your question, I tossed the flimsy power cords but kept the input connectors on the amp. Now realize that all of this doesn't mean squat if you are hooking this up to a 20 amp circuit with a wall plug rated at 15 amps and the internal house wiring is 14 gauge. I bought 20 amp Hubbell hospital grade outlets and wired 4 dedicated circuits with 10 gauge wire and run no more than 2 amplifiers per circuit. All my low level equipment is powered by a 2.5kw Balanced Power Transformer to cut down on noise.

In the end, does it make a difference? I believe all the little tweaks I have done to my power system add up to an audible difference. If you take each one by itself, they help and build a good foundation. Hope this helps.

Chuck
post #225 of 1917
Thanks for the reply chuck, l'll go ahead and replace it then as it's not going to cost much anyway , l have just one dedicated 20amp/240v circuit , but l only run my tada9000es, ep2500 and a pioneer969 universal player off it , l'll check out my outlets as l'm only running standard atm , it'll be an easy job replacing those as well...........it can only help things and dont cost much , yeah l'm not a great believer in the snake oils either mate

Ken
post #226 of 1917
chasw98:

I just bought eight EP2500's, and am having someone wire my house appropriately. Do you remember the current draw on the EP2500 at full load? I know you had it for the ep1500.

Thanks
post #227 of 1917
Thread Starter 
Quote:
Originally Posted by staffcurtis View Post

chasw98:

I just bought eight EP2500's, and am having someone wire my house appropriately. Do you remember the current draw on the EP2500 at full load? I know you had it for the ep1500.

Thanks



Yeah, average current draw running the amp wide open at full power "playing music" is a little less than 10 amps. Using a steady state 1000 Hz sine wave I was able to pull 17 amps. I just read your thread about mounting the amps in the closet. Make sure you have room for the air to circulate behind it! You might need to force feed some air behind the amps with a large auxiliary fan.
post #228 of 1917
So Chuck, any chance of making the Cinenova sweat on that test bench there?
post #229 of 1917
Thread Starter 
Quote:
Originally Posted by crackyflipside View Post

So Chuck, any chance of making the Cinenova sweat on that test bench there?

I actually have a reason to pull it out of the rack and use it in another scheme I am cooking up. But it is so heavy. If a really strong guy with an interest came over one afternoon, it would be much easier!
post #230 of 1917
Quote:
Originally Posted by chasw98 View Post

Yeah, average current draw running the amp wide open at full power "playing music" is a little less than 10 amps. Using a steady state 1000 Hz sine wave I was able to pull 17 amps. I just read your thread about mounting the amps in the closet. Make sure you have room for the air to circulate behind it! You might need to force feed some air behind the amps with a large auxiliary fan.

I would like to suggest the best air circulator for keeping the EP2500s healthy. It is silent, draws only 70w.
http://www.vornado.com/products/circulators/733b.htm
post #231 of 1917
Quote:
Originally Posted by chasw98 View Post

I actually have a reason to pull it out of the rack and use it in another scheme I am cooking up. But it is so heavy. If a really strong guy with an interest came over one afternoon, it would be much easier!

I'll see if I make it this Saturday or Sunday. I'll confirm it over PM.

You still trying to talk Sherv into testing his K2?
post #232 of 1917
Thread Starter 
Tonight for your listening pleasure we have an 'OAudio 500' BASH plate amplifier. I would like to thank JoePerri for sending me his brand new amp to test. Thanks Joe! I will have to say from the start that I like this plate amplifier. It can be bought for $229.00 + $10.00 shipping from www.oaudio.com and packs a lot of punch for the price. This was the plate amplifier that was used in ssabripo's first DIY subwoofer that we built together. That being said, here are some specs and test results.

Controls


Close up controls


Rear PC Boards


Closeup Rear PC Boards
post #233 of 1917
Thread Starter 
Now here are the specifications and the tests.

Specifications page 1


Specifications page 2


Test results


Oscilloscope and current reading at full power
post #234 of 1917
Thread Starter 
Let's see..... the first thing I'll hear is 'It doesn't even meet specifications' and 'Those aren't great numbers'
and 'It doesn't have flat frequency response.'

You're right. It also only weighs less than 10 pounds soaking wet and costs $239.00 delivered. If you look at the controls, you will find features that don't exist on comparable PE plate amps. The quality of assembly and components used are very good. Yeah, it's made in China and OEM'ed to OAudio but it has good quality and decent specs.
It has a soft clip circuit that reacts when a steady state sine wave (or music) is applied and brought up to full power slowly. I could crank it up quickly and watch it peak without clipping but I could not get it to run at a steady 80 Hz at full power. You could see the waveform being 'adjusted' electronically. Now, for a 500 watt plate amp, this is a good thing. You can see from the current reading in the last image that I am drawing 4.94 amps. The fuse is rated at 5 amps. (I got tired of buying fuses and just put the current meter in line to monitor the draw.)
The fact that I have heard this amp work in a well built cabinet with a great 4 ohm 15 inch driver is what I base a lot of my praise for the amplifier on. This amp was run right with sherv's old SVS Ultra and it bested that sub easily. So, even though it only gets close to meeting specs, it has some power behind it. And it's efficient. For a plate amp, this is one of the better ones. Thanks again to JoePerri who shipped this to me from California so that I could test it.

Chuck
post #235 of 1917
Judging by the photo of the test equipment, the whole room must have been shaking!
post #236 of 1917
I agree watt per dollar is good. I also think that the 6db rise in the frequency response as you reach down to 10Hz is probably a designed feature rather than a fault. Remember this is an amp dedicated to be used as a sub amp.
I've seen a low frequency boost built into other plate amps. They even suggest or will allow circuit changes to be made to gain that 6db rise.
I'll bet if you examined the amp's circuitry you'd find a Linkwitz Transform or an ELF as part of the design.
post #237 of 1917
Great work Chuck!

I am very pleased with the results. It's certainly not a pro amp but for $239 I'm happy! This amp is for my first sub build. (build thread is over here. ) I don't expect to ever push it to max output as my neighbor wouldn't be too happy. I really liked the inclusion of the parametric EQ and the sub-sonic filter. When I first pulled the amp out of the box I was a bit worried as it was so light and there didn't seem to be much to it. I thought I might be asking for a refund after Chuck finished his testing but the results are perfectly fine for what I'm trying to do and for staying within my budget.

Thank you very much Chuck for taking your time and using your expertise to test this amp! This is a great thread you have going that is sure to be a reference for any DIY'er looking into amp choices. I really appreciate it, thanks again!

Joe
post #238 of 1917
Thanks Joe, for sending the amp to Chuck! The more amps he gets to test, the better for all of us. And even before I read Chuck's thoughts, I thought the results looked dang good and matched up to the specs pretty well (from what I could tell).
post #239 of 1917
Sounds about right Chuck! well done!!!

indeed, it didn't quite seem to meet specs, but for $230, it is a bad little bugger....it more than drove that AV15, quite handsomely I might add.

Chuck has a buncha stuff going on in the next few weeks, but there is a Crown K2 ready to be tested as soon as time permits!
post #240 of 1917
Chuck,

Thank you for doing this for all of us here... I just wish I had a different amp to send you
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