I'm using all the same connections with both amps, just swapping out the amps. The other amp is nice and clear.
Well you can hear the music and also the static, I'm not sure how to define that for you. It's enough that I wouldnt want to hook it up to my DQ10's because I feel like something is wrong with it. It's enough that it interferes with your ability to really listen to the music. Sounds kind of like the radio in the car when you start loosing antenna signal.
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Since only the power transformers are shared between channels, noise in both channels
is likely to be due to independent problems such as bad connections/solder joints, or resistors.
Definitely something for a skilled tech to tackle.
Were these two amplifiers previously used in a system simultaneously, or was one a "spare"?
Could one amp have had poorer ventilation during use than the other (on the floor or stacked)?
is likely to be due to independent problems such as bad connections/solder joints, or resistors.
Definitely something for a skilled tech to tackle.
Were these two amplifiers previously used in a system simultaneously, or was one a "spare"?
Could one amp have had poorer ventilation during use than the other (on the floor or stacked)?
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The power supply and perhaps the relay on the output…
I would forget about trying to use two in mono just because you have the pair, there wouldn’t be any real benefit unless you’re running a PA system.
Great score!
Do they have Nichicon, or Rubycon caps in the power supply?
I would forget about trying to use two in mono just because you have the pair, there wouldn’t be any real benefit unless you’re running a PA system.
Great score!
Do they have Nichicon, or Rubycon caps in the power supply?
I'm not really sure, they have been in storage for like 10years. The guy I bought them from wasnt who used them, they were his father in laws who passed away and they are trying to liquidate everything.
Ok, one out of two working fine is good. Start looking for a good tech in your area with direct experience
in these amplifiers. Maybe Parasound can suggest someone.
in these amplifiers. Maybe Parasound can suggest someone.
Check for simple things first - like blown rail fuses, perhaps. If you lose a single rail, it will sound like somebody put a diode in series with the speaker. That will be on the “very” staticky side of things.
Just a “little” staticky could be bias out of adjust, or oxidized speaker relay contacts.
second that! limited role for bridging (especially with DQ-10s)
Have heard very few bridged amps that I have really liked...
fractioning the real world specs., increased wattage / no increase in current capability, influence on (reductions in) damping factor and elements of load sensitivity with complex loads...
But most importantly, I WOULD NOT EXPECT these 2 amps to have the same musical properties *unless* carefully / very symmetrically restored and rebuilt = as a complimentary pair, as I do to many amps... specifically for this purpose. Clearly unsuited to L mono / R mono set-up.
I am particular enough (OCD like, though I am not) I would drive me ..crazy.. the possible (very likely real world) asymmetry in performance properties of both these amps, used in 2 mono amp config.
Should you choose to finesse one or both amps (they are well worth the effort) you will have one to serve as reference (if needed) or to "reverse" possible changes (if needed) *This is part of why I own (3 "Hafler 500 based amps) and have heavily modified them, in different ways to compared what works best for me.
*NOT suggesting that you "want to go nuts" as I often cannot help resist... it is a lot of fun, I do like doing the work and find it extremely rewarding. Much like wrenching on my cars...
The HCA 2200 is much like a vintage / older muscle car, that with a little attention, it .is. a super amp... not so much so = as it sits. Easy stuff = New tires, lower profile wheels [reduce unsprung mass] new brake rotors, pads and brake lines, with a decent B/L flush, change the oil, top off the battery and brakes... *replace / update the expendables* Off you go [safely] for (20?) many more years.
Lastly, I would not be playing the unhappy amp, it would suck to do further damage... ENJOY the happy 2200!
Have heard very few bridged amps that I have really liked...
fractioning the real world specs., increased wattage / no increase in current capability, influence on (reductions in) damping factor and elements of load sensitivity with complex loads...
But most importantly, I WOULD NOT EXPECT these 2 amps to have the same musical properties *unless* carefully / very symmetrically restored and rebuilt = as a complimentary pair, as I do to many amps... specifically for this purpose. Clearly unsuited to L mono / R mono set-up.
I am particular enough (OCD like, though I am not) I would drive me ..crazy.. the possible (very likely real world) asymmetry in performance properties of both these amps, used in 2 mono amp config.
Should you choose to finesse one or both amps (they are well worth the effort) you will have one to serve as reference (if needed) or to "reverse" possible changes (if needed) *This is part of why I own (3 "Hafler 500 based amps) and have heavily modified them, in different ways to compared what works best for me.
*NOT suggesting that you "want to go nuts" as I often cannot help resist... it is a lot of fun, I do like doing the work and find it extremely rewarding. Much like wrenching on my cars...
The HCA 2200 is much like a vintage / older muscle car, that with a little attention, it .is. a super amp... not so much so = as it sits. Easy stuff = New tires, lower profile wheels [reduce unsprung mass] new brake rotors, pads and brake lines, with a decent B/L flush, change the oil, top off the battery and brakes... *replace / update the expendables* Off you go [safely] for (20?) many more years.
Lastly, I would not be playing the unhappy amp, it would suck to do further damage... ENJOY the happy 2200!
really hard to tell
Well said. The likelihood of the same conditions of use, is uncertain.
Well said. The likelihood of the same conditions of use, is uncertain.
Important question: is the "noise" present whether or not there is music playing?
If the noise is present only with music, then it is likely to be some form of distortion.
You do say that the output DC voltage offset is very low.
If the noise is present with or without music playing, then it is likely to be actual noise,
due to a bad part or connection.
If the noise is present only with music, then it is likely to be some form of distortion.
You do say that the output DC voltage offset is very low.
If the noise is present with or without music playing, then it is likely to be actual noise,
due to a bad part or connection.
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So I hooked up a very efficient Klipsch bookshelf horn speaker that is 8ohm and with no music playing I can hear some hum in the speaker, but not the static sound. With the music playing I cant really hear the hum (it may just be covered by the music) and the static starts.
Yeah, Im kind of thinking I'll have the unhealthy one modified since it needs work anyway and I can compare it to the more healthy one to have a good idea of sound difference.
First check the position of the stereo/mono switch on the back.
Make sure that it is in the stereo position.
The hum may subside with further burn-in time.
Update on the 'unhealthy' amp! So I pulled the fuses in the back, pulled them out of their holders, wiped the ends down, put them back in. Then sprayed a healthy dose of Deoxit into the rca inputs and sprayed some on the rca cable then plugged it in and spun it around to try to clean up inside of the jack some. I also flipped the switches in back a bunch (mono/bridged and the balanced/unbalanced).
So after doing that I turned it on and its playing with no static! I'm thinking maybe there was some oxidation inside the inputs or something like that.
There is still the low level hum but I have to be within a foot to hear it and using a very high efficient speaker. BUT, I played dead silence with a frequency CD and turning the volume all the way up and down the hum doesnt increase in volume, it stays the same. So it's not audible in the music...even with no music it's not audible after your a foot away. With my VERY inefficient DQ10's I really cant hear the hum at all.
SOOO, it looks like both amps are doing good!!! That's exciting!
So after doing that I turned it on and its playing with no static! I'm thinking maybe there was some oxidation inside the inputs or something like that.
There is still the low level hum but I have to be within a foot to hear it and using a very high efficient speaker. BUT, I played dead silence with a frequency CD and turning the volume all the way up and down the hum doesnt increase in volume, it stays the same. So it's not audible in the music...even with no music it's not audible after your a foot away. With my VERY inefficient DQ10's I really cant hear the hum at all.
SOOO, it looks like both amps are doing good!!! That's exciting!
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With such luck, maybe you should head to Las Vegas. But still, use them for a good while
before deciding on any "upgrades".
before deciding on any "upgrades".
Oh I am, I'm not in a huge hurry about that. I've been playing the 'good' one all day and now that the 'unhealthy' one has been playing on my Klipsch for a while with no issues I think I'm going to swap them and play it all evening with the dq10's.
I may open one of them up and see if I need to blow out and dust and such. Give it a visual inspection. I did read a review where someone had a hum and they found a bolt with a ground attached had become loose and tightening it up removed the hum. Gonna look for stuff like that.
I'm excited! No idea what I'll do with a second amp. I thought about using one for each channel but you guys seem to think that's not a great idea....and honestly its WAY overkill for my DQ10's.
I'm excited!
Don't blow them out. Use a vacuum only, with a soft brush attachment.
Avoid touching or moving any parts on the boards.
Avoid touching or moving any parts on the boards.
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I've only opened one so far but it has blue Richey caps? Did they not come with those?