For the Amp techs. I recently was able to find an old Crown DC300A that came out of a recording studio. It powers up fine but one of the channels has a slight hum. I suspect that one or both of the filter capacitors are bad. Do you know if you can still get parts for this amp and where? This used to be a powerhorse for the industry-Mostly PA's.--Thanks
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Crown DC 300A tech. question
- Thread starter kew48
- Start date
Parts that can be used in the DC300A are readily available however the modern parts such as caps will be dramatically smaller in size. You should be aware that the DC300A is obsolete in every way. The amp also had a reputation of failing and outputting one of the supply rails across the speaker terminals killing any system connected to it.
If you are capable of repairing the amp yourself is one thing. If you have to pay someone to repair the amp don't bother.
Paul
If you are capable of repairing the amp yourself is one thing. If you have to pay someone to repair the amp don't bother.
Paul
Thanks BassmanPaul,
We used these years ago and they are built like a tank with no problems-dropped them-abused them in every way and they still performed. I am aware that they have at times failed and put out dc voltage and killed cabs but there is a protection scheme for this. They are still sought after amps for sterio buffs. Do you know where to buy spare parts?
We used these years ago and they are built like a tank with no problems-dropped them-abused them in every way and they still performed. I am aware that they have at times failed and put out dc voltage and killed cabs but there is a protection scheme for this. They are still sought after amps for sterio buffs. Do you know where to buy spare parts?
The tech at a studio I worked in back in the mid 80's altered our DC300's to filter our subsonics as he claimed they would reproduce very low freqs on the bench; believe he did this with a capacitor change as I don't remember any outboard gear; it did make the JBL studio monitors last much longer both in terms of wear and tear as well as blown drivers
At a different studio we once AB'd a DC300 against a QSC, a Bryston, and an old Peavey CS400 in Urei Time Aligns
While the Peavey was the weakest, it wasn't THAT bad and the Bryston was the winner, but only by a small margin; first time all 3 engineers ever agreed on the same thing
Crown sounded decent and was the oldest design
BTW, if you ever blow a logic trasnsistor in an MCI 24 track deck, there is a transistor in a DC150 that is close enough in value to get the deck up and running and make it through a remote... don't ask me how I know
At a different studio we once AB'd a DC300 against a QSC, a Bryston, and an old Peavey CS400 in Urei Time Aligns
While the Peavey was the weakest, it wasn't THAT bad and the Bryston was the winner, but only by a small margin; first time all 3 engineers ever agreed on the same thing
Crown sounded decent and was the oldest design
BTW, if you ever blow a logic trasnsistor in an MCI 24 track deck, there is a transistor in a DC150 that is close enough in value to get the deck up and running and make it through a remote... don't ask me how I know
I've got all the schematics and repair info for the old Crowns of that time... and a nice little piece of paper saying (truthfully) that I have been factory trained to fix the amps and the Crown tape decks....(oops, you guys wouldn't know about them). I don't recall too much now, as I doubt I have fixed more than a dozen DC300 and DC300A ever..... they didn't fail often. I worked for a warranty repair joint in the 1970's
Anyway, as far as I remember the power supply was one for both channels in all the Crowns of that era until the M600 came out. So hum in one channel is less likely to be caps. I could look it up.
Anyway, as far as I remember the power supply was one for both channels in all the Crowns of that era until the M600 came out. So hum in one channel is less likely to be caps. I could look it up.
Thanks Jerrold, it would be great if you could!! There are two huge filter caps and my first guess was that one was going bad on a circuit. I've learned that you can still buy these huge capcitor cans from Crown and they are not that hard to change out. They actually bolt on the amp with connections. As far as protecting speakers from DC overload-- It seems that you could place a HP filter in line with the speaker circuit as a protective circuit. This thing was a beast in it's time with the ability to amp. such low frequency-thus the DC term. They are still used extensively and sount great.
svtb15
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I used a DC300A for years in the mid to late 70s on my bass rig then a pair for a Clair S4 cab. it was sick..
It traveled on plane , train boats, truck.. Not one failure... Its way under powered compared to today's rigs/ size but if you run it in mono you can get a few hundred whats.. Great sounding amp.. Mine was stolen so i got the next new crown at that time the PSA2. that PSA2 was the best amp EVER used. Way faster and punchier than the beloved BGW at that time.. and way more audiophile.
Your Crown is a workhorse though.. not bad for playback in a home studio
It traveled on plane , train boats, truck.. Not one failure... Its way under powered compared to today's rigs/ size but if you run it in mono you can get a few hundred whats.. Great sounding amp.. Mine was stolen so i got the next new crown at that time the PSA2. that PSA2 was the best amp EVER used. Way faster and punchier than the beloved BGW at that time.. and way more audiophile.
Your Crown is a workhorse though.. not bad for playback in a home studio
Used them in a college production course; must have been a dozen of them; of course, that was when you edited audio with a razor blade!
With your reminder and my recall, I don't have to look it up.... two caps, one for +DC, one for -DC, one power supply for both. Must have been tired last night.
Hum one channel may be something silly like a shielded wire with a bad ground. Or not. You could see if any Crown warranty folks even remember those units. Very unlikely you can do anything significant to repair it yourself.
Though realizing this discussion is somewhat dated, so is my DC300-A.
My sick little plan is to ditch my valve gtr combos, buy a UAFX Enigmatic to do Mesa clean/three shades of Dumble overdrive; pair it with a UAFX Ruby (Vox in a box), and run them a/b as stereo sources (which they are) into the Crown, thence to a pair of TL806 cabs bearing EVM-12L drivers.
My sick little plan is to ditch my valve gtr combos, buy a UAFX Enigmatic to do Mesa clean/three shades of Dumble overdrive; pair it with a UAFX Ruby (Vox in a box), and run them a/b as stereo sources (which they are) into the Crown, thence to a pair of TL806 cabs bearing EVM-12L drivers.
