My brother gave me an old crown amp. Its been sitting in a closet for many years. This monster is too heavy to lug around to gigs, so I replaced the input jacks with rca jacks, and hooked it up to my acoustat 2+ 2's. It would sound great if it wasn't about 10 dB louder from about 2 kHz on up.
Considering my Acoustats are a real brutal load in this region, I am perplexed why.
I did not replace any caps as they all looked good. And replacing the big cans would be more expensive than I want to do at this time.
Would not replacing the cans cause this.
Also, the volume pots almost all the way up does not give the volume I'd expect from my cd player.
When using my pre amp (audible illusions) I can drive it better. So I assume that p a amps have a higher input sensitivity?
Thanks,
Paul
Considering my Acoustats are a real brutal load in this region, I am perplexed why.
I did not replace any caps as they all looked good. And replacing the big cans would be more expensive than I want to do at this time.
Would not replacing the cans cause this.
Also, the volume pots almost all the way up does not give the volume I'd expect from my cd player.
When using my pre amp (audible illusions) I can drive it better. So I assume that p a amps have a higher input sensitivity?
Thanks,
Paul
On at least some versions you can select either 20 or 26 dB gain. Check the service manual for how to increase the gain.
The bright sound may mellow as you break in the amp after all the storage time, give it maybe 100 hours to start.
http://www.crownaudio.com/media/pdf/legacy/dc300aim.pdf
http://www.crownaudio.com/media/pdf/legacy/dc300a2.pdf
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I very much doubt that, those amps are ruler flat.
If anything, maybe it can properly drive your Acoustat's
in a way none of your other amplifiers ever could ... but that's a speaker problem, not an amp defect, quite the contrary.
Many PA amps have +4dB (1.4V RMS) sensitivity ... hard or impossible task for many sound sources, but they are not meant to be directly driven, they expect a PA/Stuydio mixer out, at least a preamp.
I told you.
In fact that counts as lower input sensitivity.
These amps, DC300* are designed to produce DC voltage, for such things as throttle control solenoids, linear actuators, etc. Speakers do not like DC. So use with major care. At the minimum, make sure the source you are using has a capacitor at the output.
These amplifiers have no input capacitors and have a frequency response +-0.1dB from DC to 20kHz
I would suspect your signal input and if not that, your speakers.
I would suspect your signal input and if not that, your speakers.
Exactly what I said: 1 db down at 45kHz at the lowest load impedance. 🙄
As mentioned above, 0.1dB down at 20 kHz.
No trace of "+10 dB above 2 kHz" 😱
Hope you meant "designd to amplify DC voltage " 😉
I used to run my DC300A II with both channels on a 1.6 ohm load all day long.
Never had an issue except for heat and at full tilt the heat sensor would kick in after about 25 minutes or so as they have no fan in them.
I have let it cycle like this for many hours at a time like this and when the heat switch kicks on it just keeps pumping the power!!
And, it is still running today.
I have had mine (used) since 1996 or so and I have never had to do anything to it except spray the volume controls a couple of times.
I used to run it on my Apogee Duette's ribbon tweeter for many years, they were 3 ohm as measured.
The amp is quite a brute and shouldn't have any major problems with your ESL's.
They don't have as nice of a crisp and clean high end as my Ashley FTX2000 does, But it does perform well overall by any means though.
The last time I did a FR sweep on mine, it does roll off quite a bit as shown in the manual.
I don't have any of those graphs handy anymore.
Once I get a bigger set of ESL's I plan on just using the crown for the low end and use my Ashley for the ESL's, especially since it is a bigger amp and is designed for 1 to 2 ohm loads.
The manual states how much voltage is required to drive them to full power and your typical -10db home stuff may never drive it hard enough reach the peak voltage that it can do.
I have mine connected to my Mackie 32-8 and I have had it all of the way up lots of times.
Even though I have never actually measured the input voltage I can say the I could run up to the +10db peeks on my VU displays without even clipping the amp straight out off the mains on the board.
This level is somewhere around 6v to 9v peak I believe, and with the amp wide open.
There are three (if not four) different versions of this amp the last time I looked up all of the prints for them.
https://www.google.com/search?num=1....6.6.0....0...1c.1.57.hp..0.6.451.B_DqUjaJpr4
FWIW
jer 🙂
Never had an issue except for heat and at full tilt the heat sensor would kick in after about 25 minutes or so as they have no fan in them.
I have let it cycle like this for many hours at a time like this and when the heat switch kicks on it just keeps pumping the power!!
And, it is still running today.
I have had mine (used) since 1996 or so and I have never had to do anything to it except spray the volume controls a couple of times.
I used to run it on my Apogee Duette's ribbon tweeter for many years, they were 3 ohm as measured.
The amp is quite a brute and shouldn't have any major problems with your ESL's.
They don't have as nice of a crisp and clean high end as my Ashley FTX2000 does, But it does perform well overall by any means though.
The last time I did a FR sweep on mine, it does roll off quite a bit as shown in the manual.
I don't have any of those graphs handy anymore.
Once I get a bigger set of ESL's I plan on just using the crown for the low end and use my Ashley for the ESL's, especially since it is a bigger amp and is designed for 1 to 2 ohm loads.
The manual states how much voltage is required to drive them to full power and your typical -10db home stuff may never drive it hard enough reach the peak voltage that it can do.
I have mine connected to my Mackie 32-8 and I have had it all of the way up lots of times.
Even though I have never actually measured the input voltage I can say the I could run up to the +10db peeks on my VU displays without even clipping the amp straight out off the mains on the board.
This level is somewhere around 6v to 9v peak I believe, and with the amp wide open.
There are three (if not four) different versions of this amp the last time I looked up all of the prints for them.
https://www.google.com/search?num=1....6.6.0....0...1c.1.57.hp..0.6.451.B_DqUjaJpr4
FWIW
jer 🙂
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That 10 times the power from 2khz on up, and literally twice as loud.
Not likely unless there is something really wrong with the amp, but most likely it's a speaker issue.
It's probably not 10dB louder on top at all. It just sounds that way. What you're hearing is an increase in distortion at higher frequencies (probably above 2 KHz) which your ear is interpreting as "bright". It could also be a marginal stability issue, which will also sound "bright". ESLs are a capacitive load, which could result in either phenomenon with a class AB+B output stage.
This type of amplifier is not the best for electrostats. Turn up the bias to mitigate the rise in crossover distortion and you risk instability. BTDT, bought the T-shirt. Either way you could be screwed. The best amp topology to use with these is full comp EF2 (EF3 with careful thermal design) with a high bias. Something the DC300A is definitely not.
This type of amplifier is not the best for electrostats. Turn up the bias to mitigate the rise in crossover distortion and you risk instability. BTDT, bought the T-shirt. Either way you could be screwed. The best amp topology to use with these is full comp EF2 (EF3 with careful thermal design) with a high bias. Something the DC300A is definitely not.
I owned a pair of Acoustat 2+2s. Measuring the freq response showed a large downward shelf at 10kHz. I never liked them because of the lack of treble. A tall ribbon tweeter would be perfect to fill in the missing treble. A/B testing beside Martin Logan CLS clearly showed the missing treble in the 2+2.
I have a DC300A. I use it with a Woofer Tester Pro to perform thiele-small tests at high power. The response of my DC300A is ruler flat from 1 Hz to 20 kHz measured with the WT Pro and a 10 ohm 30 watt calibration resistor assembly.
I have a DC300A. I use it with a Woofer Tester Pro to perform thiele-small tests at high power. The response of my DC300A is ruler flat from 1 Hz to 20 kHz measured with the WT Pro and a 10 ohm 30 watt calibration resistor assembly.
DC300A was designed to drive heavy loads, but not necessarily weird ones. An amp may measure prefectly flat to 20 or even 100k, but if the distortion tails up at high frequency in just the right (wrong) way it will be drive you from the room annoying. I have one pair of loudspeakers (with ribbon tweeters) that I can't use on my Flame Linear. At all. Another amp just sounded "bright" on anything I hooked up to it. Board flat to 50k, but had a peaking rise near 100k. Increased the capacitance across the global feedback resistor to get rid of the peak. Only cost 0.2dB at 20k, but it sounded like somebody dropped 10dB off the high end and made the amp quite listenable.
It's curious that the distortion vs power, distortion vs frequency and IMD graphs are omitted from my DC300 manuals.
I found the amplifier was tedious to listen to...two of mine went under the knife. (I sold the output transistors on EBay.)
Thanks everyone for your input.
If your familiar with the acoustat 2+2, an measuring it, you may know that mic placement varies your response a lot.
It appears that after re-measuring the crown the response is more like 4 dB up in the treble. This is compared to the output with my moscode amp. Also the bass is down in midbass and lower bass by several dB.
Yes, Jer the treble is a little hashy, maybe because it is higher in output?
No, I didn't measure it but no output of dc. As this would mean a blown transistor, and the sound is quite nice with nice imaging etc.
This is an old amp. I didn't replace the capacitors, I did replace a lot of the wires, and cleaned it up a lot. Could the the up tilted frequency response be due to the old capacitors, or is this amp just not right for a highly capacitive speaker. In the manual (available online) Crown state that the amp can even drive a completely resistive load, which I think could be the opposite of what my speakers are.
I am going to take it over to my daughters house next week. I made for her a full range open baffle speaker. I'll see how it drives those.
Thanks again,
Paul
If your familiar with the acoustat 2+2, an measuring it, you may know that mic placement varies your response a lot.
It appears that after re-measuring the crown the response is more like 4 dB up in the treble. This is compared to the output with my moscode amp. Also the bass is down in midbass and lower bass by several dB.
Yes, Jer the treble is a little hashy, maybe because it is higher in output?
No, I didn't measure it but no output of dc. As this would mean a blown transistor, and the sound is quite nice with nice imaging etc.
This is an old amp. I didn't replace the capacitors, I did replace a lot of the wires, and cleaned it up a lot. Could the the up tilted frequency response be due to the old capacitors, or is this amp just not right for a highly capacitive speaker. In the manual (available online) Crown state that the amp can even drive a completely resistive load, which I think could be the opposite of what my speakers are.
I am going to take it over to my daughters house next week. I made for her a full range open baffle speaker. I'll see how it drives those.
Thanks again,
Paul
The capacitive load won't cause a 4 dB tilt up in the HF response. May cause peaking above the audio band, but its effect at 20k should be well under a dB. If you really do have a rising response there is something wrong. Old electrolytics could cause it, but it still seems weird. I'd suspect calibration isues. A falling response is more likely with bad electros.
If you are actually getting a rise in FR at the high end this could be caused from resonance peaking due to the Leakage inductance of the transformer and the panels capacitance.
The resistors in series with the primary winding is what is used to reduce this Peaking affect in ESL's.
jer 🙂
The resistors in series with the primary winding is what is used to reduce this Peaking affect in ESL's.
jer 🙂
That's not the amplifier's fault. 4dB of acoustic rise and coming out of the speaker and 4dB of peaking in the amplifier's response are not the same thing.
Can you give some examples of affordable suitable amps using this design? I did a Google search and got a total of three results with "full comp" and "EF2"
😀
»EF2« just might have done the job. There literally are tons of designs out there. The HoneyBadger is one of them.
Best regards!
Best regards!
Is it stable at 2 ohms?
I looked at a thread about quiet PA amps and the K1/K2 stood out for being fanless and being rated for 2 ohms.
Also, is the HoneyBadger a "full comp EF2" or "EF3 with good thermal regulation" design? Also, apparently with high bias.
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