Using an Integrated as a Power Amp thru RCVR

[nhpm510]

Can I use an integrated as my "amp" for my main channels in the same fashion one would use a power amp when hooked up through a receiver (Denon AVR-2805)? I know it would create dual volume controls. Any restrictions which should be adhered to?(jk--Other than not taping the vents)

That is Part I of this question..

Part II will invovle a smoking, flaming Cambridge Audio 640A

Thx for the input

 

[markw]

I'm pretty sure the Denon 28o5 has preamp ous, right?

My 2802 does, and I doubt they would take away that feature.

Can you separate the preamp outputs from the power amp inputs on the integrated amp? If so, simply use the "main in" jacks. If not, then using a high level input will simply force the signal through the integrated's preamp section, which I don't think you want to do.

 

[Seth=L]

(jk--Other than not taping the vents)

Hey some people like putting tape on the ventilation, no sense in telling them otherwise right?

If indeed the Denon has preouts, then it will work fine. Once you set it up properly you won't however need to adjust volume on both units each time you adjust the volume.

 

[j_garcia]

What MarkW said - if the amp has main in, you should be able to do it just fine.

 

[nhpm510]

Pre-out vs main in

The Denon 2805, doesn't have a "main in", but I have pre-out ins. (I believe I had "main in" on my old AVR-2500.) Aren't they the same?

Well, to make a long story short, I was using the CA 640A via the pre-out in and boom! Blue flash, small fire and black smoke Scared the $%V* out of me!!!!

I was running the volume on the integrated at about 75%, and the Denon volume was about 25%. I had it on for about an hour and 30 minutes when all of a sudden BOOM, followed by a Small fire, and black smoke. The unit was WELL ventillated before the incident, as it was sitting on top of a non-functioning secondary subwoofer. Prior to the incident, I would say that the CA was the most open and nicest SS amp I've heard for SQ.

The weirdist thing is, IT STILL WORKS. I am not exactly sure what it says for build quility

CA Customer support said I may have blown the "input rail" (but the unit still allows me to change sources responsively.) They said I should not have been operating the volume past 50%, if using the amp in the aforementioned configuration.

At no time did any of the 5 vaunted CA "protection features" flash. The amp didn't even feel hot prior to the explosion.

Any one have any thoughts? Maybe I just got a bum unit? It really did sound great.
Signed,

 

[Seth=L]

Hold on, no more experiments!!!

 

[Seth=L]

OK, what inputs does the cambridge audio have on it, best yet tell us every label for each RCA jack.

If you saw sparks them something is wrong, where did the sparks come from?

On the back of the Denon, above the binding post speaker connectors are the "Pre-Outs" not pre-out ins. On the right side there is the "Ext. In", for now you are going to ignore that particular set on inputs, which is exactly the same as "main in". The ouputs of the Denon will be the ones labeled "Front L/R".

Post back on the RCA jack labels and we should be able to come up with a solution.

 

[nhpm510]

Configuration In/Outs

Thx for the tech support.
Above my speaker terminals on the Denon, it says "Pre Out".
(I have my universal cd player pluged into the ext ins)

It has the following Pre Outs listed:
Front x 2, Center, Sub, Surr back/Zone 2, Zone 2.

On the back of the Cambridge(from left to right):

Pre Out,Tape In, Rec Out 1, Rec Out 2, AV, DVD Tuner, CD, Aux
(A great pic is show at http://www.cambridgeaudio.com/gallery/rear/640A-v2-rear.jpg)
--
When looking at the amp from the front, the small fire occurred in the middle of the unit, nearer to the rear of it (approx 1 inch from the back of the case.)
----
I had the Denon fronts pre out pluged into the CAmbridge's "AV" rca jacks.

I appreciate the interest in this one.

 

[Seth=L]

That is a conundrum, all the connections you say are fine. Maybe one of the caps is damaged.

You up for taking it apart to see where the damage is?

 

[nhpm510]

Damaged my caps?

If it wasn't under warranty, I'd do it in a flash (pun intended). I just bought her on Sunday 11/12. Looks like Tweeter (retailer) will have to mail it back to China. If I do get another one, I certainly won't use it in the same fashion. The SQ is awesome.

Forgive my ignorance, but what fuction does a cap (capacitor) perform?

 

[Seth=L]

I would definitely return it, even if it seems to work fine.

The capacitor is a storage device that looks like a can, they are usually black. They store energy, measured in microfarads (microfarad symbol: uF). They work on a similar principle to a battery, only they can be emptied and filled very fast. They also don't have the same capacity as a battery. The purpose is to filter and give energy to the transistors when it is demanded.

The signal path goes from the Power supply (transformer), filter capacitors, and output stage. This is of course a very basic path as there are many other small functions carried out during the process.

When you turn on the amp or most amps and receivers, you will hear a primary click when you first turn it on. Moments later there is a second click. The second click means the capacitors are full and ready to go. Larger amplifiers and receivers take longer for the secondary click because they have more capacitance.

When a cap goes bad it can cause numerous problems. First of all it is dangerous, it could start a fire. Some people leave their amplifiers on all day when they are not home and a bad capacitor could just burn the hose down, though it isn't common for this to happen. The power output will also go down as the power transformer will have to work harder to acheive the same levels of output as it did before. You may not even notice your cap is bad untill one day your power supply dies because to much was demanded of it.

Capacitors are also the most dangerous component in an amplifier. Even with the amplifier unplugged the capacitors still hold a charge that if released into your body while you are grounded could cause your heart to stop, and ultimately kill you if no one is around to revive you. Capacitors are usually connected the board and access to the lethal contact points is limited and you would have to touch the - and + at the same time to get spiked.

So, again I say, you should return the amplifier and get another. I don't want to see your house burn at the hands of one sub $1000 amplifier.

 

[nhpm510]

Yikes!!!!

Seth,
Wow, you seem to know a thing or two about electronics. I always wondered what the start up clicks were.

Fear not, I am going to return it. Would you have any concerns about the CA's build quality, or was I asking the caps to do too much because the volume on the amp was turned up so high?

Thanks again on behalf of the audiophytes on the forum.

 

[Seth=L]

I would think that they are reliable, at least they have the reputation of being reliable. I think you just got a dud. Protection circuitry would have likely kicked in if you were driving her to hard, what happened to yours sounds more like a fluke.