Any problem with this Crown DC300A?

[pyonc]

Hi,

I tried Crown DC300A Series II, a vintage power amp that I bought on ebay, with lots of expectation. Preamp was Mcintosh C29, and Adcom GTP 500, and I tried both on my 4311 and 4343. The outcome was quite disappointing in terms of the quality and loudness of the reproduced sound, compared with Marantz (135 watts per channel) and Adcom 555 power amp (200 watts per channel).:banghead:

With the preamp C29 volume at the same level (around 11 o'clock), I turned on the Crown, with its two channels set between 12 0'clock and 1pm. At the same time, I turned on the Marantz, with the same C29. The sound from the Marantz amp was at least five times as loud and clear as the Crown. I tried Adcom 500 preamp instead of C29, and the outcome was the same. So, this is my question: Is this Crown Professional Series II, an upgraded version of Crown DC300A, inherently weak in loudness? It's at least 155 watts per channel, as I understand. Is it because of a mismatch of Crown amp and C29, Adcom preamp, instead of Crown preamp? Or is there any problem with this vintage Crown amp? If so, what should I look into for possible improvement? Thanks a lot for your guidance in advance.

[JeffW]

Turn the knobs on the Crown fully clockwise and report back.

[HCSGuy]

If you are comparing for sound quality, you should first adjust the amplifiers to have equal loudness using the same preamp and speakers, then listen for differences. If you let the difference stay, you will be incorrectly tricked into thinking the louder one sounds better - sorry, human nature. Generally, for a simple home setup you should have the power amplifier's volume knobs most or all the way up - they don't boost, but attenuate signal only, so turning them up or down won't generally affect the power amplifier's sound quality, but if you have them way down and have to use your preamp for lots of gain, your preamp's distortion will be higher. Once you've equalized the amplifier's volume, take another listen and let us know what you think.

A little more:
THX standardizes on 29db gain through the power amplifier, so you can generally mix and match THX power amplifiers in a system without detriment or having to do lots of rebalancing. Everyone else is free to choose, but the gain structure has nothing to do with sound quality, it's just an outcome of the circuit design. Furthermore, the actual output power is not related to gain structure - if you compare a pair of 500w monoblocks that have 25db gain with a 45w/ch amp with 29db gain without adjusting their input attenuators, the little amp will be louder at the same preamp volume, which again may make you think it sounds better. Of course, when the amp runs out of power, the distortion should change your mind.

So, ignore the subjective impression left by wherever you had to put the Crown's input volume knobs - turn them up and match them to the other amp and don't read anything else into it. Listen, report, repeat...

[pyonc]

Turn the knobs on the Crown fully clockwise and report back.

Sure, let me try doing what you've suggested, and report back.
I just thought this might have something to do with the decay of
the parts of this vintage amp... Thanks!

[pyonc]

If you are comparing for sound quality, you should first adjust the amplifiers to have equal loudness using the same preamp and speakers, then listen for differences. If you let the difference stay, you will be incorrectly tricked into thinking the louder one sounds better - sorry, human nature. Generally, for a simple home setup you should be using keeping the power amplifier's volume knobs most or all the way up - they attenuate signal only, so turning them up or down won't generally affect the power amplifier's sound quality, but if you have them way down and have to use your preamp for lots of gain, your preamp's distortion will be higher. Once you've equalized the amplifier's volume, take another listen and let us know what you think.

A little more:
THX standardizes on 29db gain through the power amplifier, so you can generally mix and match THX power amplifiers in a system without detriment or having to do lots of rebalancing. Everyone else is free to choose, but the gain structure has nothing to do with sound quality, it's just an outcome of the circuit design. Furthermore, the actual output power is not related to gain structure - if you compare a pair of 500w monoblocks that have 25db gain with a 45w/ch amp with 29db gain without adjusting their input attenuators, the little amp will be louder at the same preamp volume, which again may make you think it sounds better. Of course, when the amp runs out of power, the distortion should change your mind.

So, ignore the subjective impression left by wherever you had to put the Crown's input volume knobs - turn them up and match them to the other amp and don't read anything else into it. Listen, report, repeat...

Thanks for your kind advice and explanation.
Just as you suggest, let me adjust this Crown amp to have the same loudness as Marantz, using the same preamp and speakers, and then listen for differences.
I'll report back tomorrow after trying this test. Hopefully my disappointment turns into a big job...

[JeffW]

Sure, let me try doing what you've suggested, and report back.
I just thought this might have something to do with the decay of
the parts of this vintage amp... Thanks!

I think it's more to do with the heavy attenuation you've imposed on the amp. A lot of amps have no attenuation control at all, they run always at "full clockwise" as it were. HCSGuy gave a much better explanation, but if you have a preamp already in the line, just turn the Crown all the way up and see how it does. If it still sounds bad, then it might have a problem.

[BMWCCA]

Crown suggests using the input attenuators to lower you system's noise floor by optimizing the gain structure. Used properly, the attenuators will be set to where you preamp volume control is at roughly half-way to 3/4 of the way up at the system sound level where you'd normally listen. This puts your pre-amp in its sweet-spot. Of course pro amps like Crowns are designed for fairly hot pre-amp outputs. The old Mac might not be up to the task, though it should still work fine. I've used an older C20 with my Crowns for over 40 years!

Pro sound runs unity gain to the amps. Without meters, your Mac can't tell you where that is but a safe bet is somewhere around 3/4 of the way up on the master volume control's range.

Similar discussion from the Crown forum:

am assuming that you mean the D-150 level controls have to be all the way up relative to the other amplifier. I checked the specs for the McIntosh C46 preamp and it will do 5Vrms output at the Balanced jacks and 2.5Vrms at the unbalanced jacks. So it has enough output to drive the D-150 which required a little over 1V for full output with the input attenuators all the way up.

The D-150 is only rated 20 to 20K rated for 80 watts. If it's not that the D-150 is just too small in power the only thing I can think of is that there is an input sensitivity difference between the two amps. Not knowing what the other amp is I will have to assume it is a consumer amp and not a pro audio amp like the D-150. Home consumer equipment usually runs on a much lower input level - meaning it needs a lower input voltage to get to full output than pro audio gear. If this is the case than the other amp is achieving full output before the D-150 can get to full output. To fix this you will probably have to turn the other amplifier's level controls down and turn the output of the Pre-amp up. In this configuration the D-150 would get more voltage and be able to produce full output.,and this:
When working with a non-metered Preamp 3/4 of the way up, on the preamp output, is a good place to start as this is usually about the nominal output.

[scott fitlin]

With the front panel level attenuators wide open the Crown DC-300A has an input sensitivity of 1.75v. So, lowering the pot to the 12 o'clock position considerably lowers the input stage gain, and you could need well over 2v to drive the amp to full rated output.

The ADCOM 555SE has a 1.75v input sensitivity for full rated 8 ohm output, same as the crown DC-300A SERIES II.

You asked if the Series II generations are any different than the originals, and they say that by the time the Series II was in production, Crown was no longer using the same output transistor as they used with the older DC-300A.

Different generations of Crown amps did go through parts changes, and alterations of design, I can't say that this is what your hearing, though. But in any event, open the level attenuators then see what you hear and how it works. These things were talked about in the 1980,s though.

[pyonc]

I think it's more to do with the heavy attenuation you've imposed on the amp. A lot of amps have no attenuation control at all, they run always at "full clockwise" as it were. HCSGuy gave a much better explanation, but if you have a preamp already in the line, just turn the Crown all the way up and see how it does. If it still sounds bad, then it might have a problem.

Thanks a lot. If that's the case with Crown DC300A II, I'm going to turn the two channels all the way up as you suggest first, and see what happens.

[pyonc]

With the front panel level attenuators wide open the Crown DC-300A has an input sensitivity of 1.75v. So, lowering the pot to the 12 o'clock position considerably lowers the input stage gain, and you could need well over 2v to drive the amp to full rated output.

The ADCOM 555SE has a 1.75v input sensitivity for full rated 8 ohm output, same as the crown DC-300A SERIES II.

You asked if the Series II generations are any different than the originals, and they say that by the time the Series II was in production, Crown was no longer using the same output transistor as they used with the older DC-300A.

Different generations of Crown amps did go through parts changes, and alterations of design, I can't say that this is what your hearing, though. But in any event, open the level attenuators then see what you hear and how it works. These things were talked about in the 1980,s though.

Thanks for your kind explanation. Actually I didn't realize the co-relation of this input sensitivity and the input stage gain when I tried Crown. So, let me lower the two channels all the way down, instead of the current 12-1 o'clock set, and see what happens.

[pyonc]

Crown suggests using the input attenuators to lower you system's noise floor by optimizing the gain structure. Used properly, the attenuators will be set to where you preamp volume control is at roughly half-way to 3/4 of the way up at the system sound level where you'd normally listen. This puts your pre-amp in its sweet-spot. Of course pro amps like Crowns are designed for fairly hot pre-amp outputs. The old Mac might not be up to the task, though it should still work fine. I've used an older C20 with my Crowns for over 40 years!

Pro sound runs unity gain to the amps. Without meters, your Mac can't tell you where that is but a safe bet is somewhere around 3/4 of the way up on the master volume control's range.

Similar discussion from the Crown forum:
and this:

Thanks for your kind explanation and useful tip on the attenuation issue. As I'm accustomed to adjusting speaker loudness through preamp volume, the two channels on Crown DC300A II were sort of confusing. When they're set at the lowest, I can't hear anything even if the preamp volume's set at 1 or even 3pm o'oclock. Only when I turn them up, say 12 o'clock, could I hear the sound. So, for the good unity gain, I have to turn them up all the way down, above all.

[JeffW]

Thanks for your kind explanation. Actually I didn't realize the co-relation of this input sensitivity and the input stage gain when I tried Crown. So, let me lower the two channels all the way down, instead of the current 12-1 o'clock set, and see what happens.

You won't get any sound at all with them turned fully counter-clockwise.

I wouldn't worry about gain and all that just yet. Let's just see if the amp is working properly.

Turn the volume control on the preamp all the way down. Turn the controls on the amp all the way up. Start your music source. You should hear no sound. Slowly increase the volume control on the preamp. You should start to hear sound. Keep increasing the colume control on the preamp until the music is as loud as it was with the amps you said were louder than the Crown. Now adjust the knobs on the Crown until you get this same sound level with the volume control on the preamp in about the 12 O'Clock position. You're done!

[pyonc]

You won't get any sound at all with them turned fully counter-clockwise.

I wouldn't worry about gain and all that just yet. Let's just see if the amp is working properly.

Turn the volume control on the preamp all the way down. Turn the controls on the amp all the way up. Start your music source. You should hear no sound. Slowly increase the volume control on the preamp. You should start to hear sound. Keep increasing the colume control on the preamp until the music is as loud as it was with the amps you said were louder than the Crown. Now adjust the knobs on the amps until you get this same sound level with the volume control on the preamp in about the 12 O'Clock position. You're done!

Thanks so much for this step-by-step procedure! :applaud:
Now I think I can understand more about this Crown issue.
Let me try this when I get home this evening, and report back.

[BMWCCA]

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47330

[JeffW]

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47330

I know you're an advocate of setting the gain structure, but when a guy says he can't get anything but weak sound out of a DC300A, and he has the levels set to 12 O'clock, my thought is that he simply needs to turn the dang thing up. It's not going to hurt anything to try, and if his amp still sounds weak, it's faulty.

But he was having wild, confusing swings that included trying it with the attenuators all the way down. That's not going to do much of anything.

On the other hand, if he can run the amp wide open and control the volume with the preamp just long enough to see that this amp should really rock his speakers if functioning properly, then he can go back and set the gain as he sees fit.

I just couldn't wrap my head around the "my amp won't get very loud, even though I'm running it at half mast" part.

I'll grab some popcorn if running it wide open doesn't get the volume level up.

[BMWCCA]

I know you're an advocate of setting the gain structure, but when a guy says he can't get anything but weak sound out of a DC300A, and he has the levels set to 12 O'clock, my thought is that he simply needs to turn the dang thing up. It's not going to hurt anything to try, and if his amp still sounds weak, it's faulty.

But he was having wild, confusing swings that included trying it with the attenuators all the way down. That's not going to do much of anything.

On the other hand, if he can run the amp wide open and control the volume with the preamp just long enough to see that this amp should really rock his speakers if functioning properly, then he can go back and set the gain as he sees fit.

I just couldn't wrap my head around the "my amp won't get very loud, even though I'm running it at half mast" part.

I'll grab some popcorn if running it wide open doesn't get the volume level up.

I don't have a problem with a word of what you've said. I'm just sort of amazed that it takes a tutorial to use a simple vintage power amp properly, especially for an owner of 4343s. This is not the only time here, and certainly elsewhere, where the simple input attenuator controls have proven baffling for otherwise savvy hi-fi fanatics. I figured the "set the pre-amp at 3/4 volume and turn up the Crown knobs until the sound is at normal listening level" was fairly simple, too. I don't run any of my Crowns at full-open because it doesn't give me enough use of the pre-amp volume pot and can cause imbalance, as we saw in another thread. It's not "my way or the highway". All suggestions so far have been sound and helpful. It really is a very simple concept. Crank it up!!

And given that Crown is one company that goes out of their way to provide on-line forums, libraries of owner's manuals, and other good stuff for free, it really is a simple concept that shouldn't cause such confusion. If it continues to be confusing, I have a NIB set of dummy knobs in a kit supplied by Crown for installed applications that make it impossible to change the input attenuator settings, once set. I'll trade the kit for a set of normal knobs! ;)

RTFM comes to mind but I'm an understanding guy. :)

[pyonc]

Dear JeffW, BMWCCA, scott fitlin, HCSGuy,

I just want to thank you all so much for helping me out on this Crown issue.:applaud:
Although what each of you explained to me varied a little bit, I'm happy to find that
all of you share the same solution bascially, and that's why I value this forum and your insightful advice.

This evening I tried to fix the issue, according to your suggestions, especially JeffW's.
I first turned Crown's both channels way up, then turned the preamp volume down all the way. And I played CDs, and listened for any sound: NO sound from the speaker, fortunately. So far, so good. Next, I gradually turned up the preamp volume to get the loudness that I want at normal listening level (ususally 11 o'clock position). Okay, when I turned the preamp volume up to around 11 o'clock position, with the Crown channels all the way up, I got almost the same level of loudness that I got from the other amp, Marantz. One thing I noticed was LP sound was a little bit clearer with Marantz than Crown, though CD sound was almost similar in terms of clarity and loudness. Maybe this subtle difference might be inevitable, given the different schematic and specs of Marantz and Crown, right?

Now, I'm going to biamp 4343 with these two amps over the weekend, as I've found out there's nothing wrong with this Crown. Thanks again to you all, valuable members!:)

[scott fitlin]

Once you have gotten level issues out of the way, you should hear distinct differences between the amps you mentioned. Me, being a long time Crown user and fan, I like the DC-300A, although the amp is an old design it still holds it's own today. However, the DC-300 does not produce the cleanest sounding midrange you could get, it DOES produce great sounding bass, though. I have heard the Adcom 555 MANY times, it was never one of my favorites, others love it, though. Marantz amps, they are prized for their particular sonic character, as you can see on ebay auctions and what vintage Marantz amps go for. This is an area you have to decide for yourself what you like best, there is no right or wrong, just what YOU like listening to.

[pyonc]

Once you have gotten level issues out of the way, you should hear distinct differences between the amps you mentioned. Me, being a long time Crown user and fan, I like the DC-300A, although the amp is an old design it still holds it's own today. However, the DC-300 does not produce the cleanest sounding midrange you could get, it DOES produce great sounding bass, though. I have heard the Adcom 555 MANY times, it was never one of my favorites, others love it, though. Marantz amps, they are prized for their particular sonic character, as you can see on ebay auctions and what vintage Marantz amps go for. This is an area you have to decide for yourself what you like best, there is no right or wrong, just what YOU like listening to.

Thanks again for your kind comment, Scotty. I've heard, too, that Crown produces great bass sound. I think I'm going to use this Crown for bass on my 4343, with Marantz taking charge of mid and high ranges when I biamp over the weekend. Hope I can love this Crown as much as you in the days ahead...

[scott fitlin]

Thanks again for your kind comment, Scotty. I've heard, too, that Crown produces great bass sound. I think I'm going to use this Crown for bass on my 4343, with Marantz taking charge of mid and high ranges when I biamp over the weekend. Hope I can love this Crown as much as you in the days ahead...Your welcome. BTW, Crown on the low end, and your Marantz on the mid/hi, that is a combination I could get with.

If you decide to go this route, what active crossover do you have or are you planning to use? THIS is also an area you ask a question and get twenty five different answers, but you will get tons of usefule and helpful info on active XO!

[pyonc]

Your welcome. BTW, Crown on the low end, and your Marantz on the mid/hi, that is a combination I could get with.

If you decide to go this route, what active crossover do you have or are you planning to use? THIS is also an area you ask a question and get twenty five different answers, but you will get tons of usefule and helpful info on active XO!

Actually, the active crossover I've got now is Behringer CX2300, which our kind senior member PaulB offered me for a trial the other day. Are you familiar with this one? Any advice would welcome. Thanks again.

[scott fitlin]

Actually, the active crossover I've got now is Behringer CX2300, which our kind senior member PaulB offered me for a trial the other day. Are you familiar with this one? Any advice would welcome. Thanks again.I'm not familiar with that particular Behringer model, but it will work, and serve as an entry level unit to the world of biamping.

Once you decide you will stay biamped, you have to know that the active crossover has much influence on the sound, as much as your amps, and even the speakers. At that point, you could seek out a far better performer than Behringer.

You have great speakers, great vintage amps, so GREAT active crossovers, to get the best you can from your set up will be equally important.

[pyonc]

I'm not familiar with that particular Behringer model, but it will work, and serve as an entry level unit to the world of biamping.

Once you decide you will stay biamped, you have to know that the active crossover has much influence on the sound, as much as your amps, and even the speakers. At that point, you could seek out a far better performer than Behringer.

You have great speakers, great vintage amps, so GREAT active crossovers, to get the best you can from your set up will be equally important.

I see. I've read some threads on this in this forum. Do you have any specific GREAT active crossovers in mind? How about Ashly XR-1001? How does this impact on sound vary from one brand to another? As I'm new to this biamping world, I still need some more homework to do. Thanks.

[louped garouv]

I'm not familiar with that particular Behringer model, but it will work, and serve as an entry level unit to the world of biamping.

Once you decide you will stay biamped, you have to know that the active crossover has much influence on the sound, as much as your amps, and even the speakers. At that point, you could seek out a far better performer than Behringer.

You have great speakers, great vintage amps, so GREAT active crossovers, to get the best you can from your set up will be equally important.

i agree with you on this point Scott... I too think that the crossover stage has significant influence....


I see. I've read some threads on this in this forum. Do you have any specific GREAT active crossovers in mind? How about Ashly XR-1001? How does this impact on sound vary from one brand to another? As I'm new to this biamping world, I still need some more homework to do. Thanks.

before you get all wild about swapping gear, try the Behringer you have for a bit...

if you can, adjust the crossover points, and slope of the crossover...
(but do so 'safely' -- so nothing gets broken/damaged)

it may be a real eye-opener regarding just how much influence the crossover has on the overall presentation fo sound...

I did that with an old 70s era Pioneer SF series crossover a few year ago, really made me reconsider some things I was doing....

[pyonc]

i agree with you on this point Scott... I too think that the crossover stage has significant influence....



before you get all wild about swapping gear, try the Behringer you have for a bit...

if you can, adjust the crossover points, and slope of the crossover...
(but do so 'safely' -- so nothing gets broken/damaged)

it may be a real eye-opener regarding just how much influence the crossover has on the overall presentation fo sound...

I did that with an old 70s era Pioneer SF series crossover a few year ago, really made me reconsider some things I was doing....

Thanks for your advice. Let me try with the Behringer first for a taste of this biamping.
Looks like most of LH members here praise Ashly XR1001 a lot, which I want to try after this Behringer.

[Tim Rinkerman]

Now that you say you are going to put a Behringer product inline, you should have a good reference for "broken" sounding....

[louped garouv]

Now that you say you are going to put a Behringer product inline, you should have a good reference for "broken" sounding....

the way i see it, its a good opportunity to try out a new way of doing things...
and not too expensive an opportunity either...

:)

[scott fitlin]

Now that you say you are going to put a Behringer product inline, you should have a good reference for "broken" sounding....Let him learn his way through bi-amping. Once PYONC has established the benefits of bi-amping, and IF he wants to, he can go further and get into higher level gear.

My personal recommendation at this time, is Marchand, they will make you whatever you desire, you can order completely assembled or kit form, I like this over Ashly considerably. I use customized Marchands in my system, they are clean, and GREAT sounding. The Ashly is ok, but I prefer my crossover slopes shallower than 24db per octave.

When your ready, and IF you want, there are many here including myself who can guide you to getting a really good active xover, with the proper voltage drives, filter types and slopes, and correct setup and use. Not only that, the reason I recommend Marchand besides being REALLY good sounding, and the fact that Phil Marchand will custom build to suit whatever needs you have, the COST, they are reasonably priced, and work extremely well.

I have a VERY expensive pair of Bryston 10B active xovers, and I prefer my Marchand units. Phil has many models to choose from, even a premium vacuum tube active crossover.

If nothing else, here is good reading, and good info to really begin educating yourself to active electronics>>>> www.marchandelec.com.

[PaulB]

LOL... Yowzaaaa I forgot how tough the critiques here are :P

I've ran those 4343's biamped for many years, with dual DC300As, using a Levinson (bought from Mark, a personal acquaintance), a quite nice Heathkit that I modded myself for the proper Xover, and the Behringer... hmmm, I think I'm forgetting one :S

Anyway, I loaned him the Behringer (actually I think I offered it for free, as I have no use for it), so he could stick a toe in the biamping waters and sort out his other issues. It will serve him just fine as a starter unit... IMHO the last thing he needs right now is another variable to get all befuddled over. I will now don my asbestos U trou ;)

[pyonc]

LOL... Yowzaaaa I forgot how tough the critiques here are :P

I've ran those 4343's biamped for many years, with dual DC300As, using a Levinson (bought from Mark, a personal acquaintance), a quite nice Heathkit that I modded myself for the proper Xover, and the Behringer... hmmm, I think I'm forgetting one :S

Anyway, I loaned him the Behringer (actually I think I offered it for free, as I have no use for it), so he could stick a toe in the biamping waters and sort out his other issues. It will serve him just fine as a starter unit... IMHO the last thing he needs right now is another variable to get all befuddled over. I will now don my asbestos U trou ;)

Thank you, Paul, for your kindness and consideration for this novice audiophile.:)
I'm still reading this Behringer manual before I start the set-up, but let me try biamping anyway to feel any difference. I'm going to stick to Behringer until I gain more confidence and knowledge in this biamping world, though I don't have any problem with the wonderful sound of 4343 in a single amp mode.

[PaulB]

You're more than welcome... If you reallyyyyyy get into this you'll undoubtedly trade up some of your gear to loftier products but you have a plenty good setup to "cut your teeth" ;)

Let me know if I can help...

[Lee in Montreal]

Now that you say you are going to put a Behringer product inline, you should have a good reference for "broken" sounding....

Just wondering if you have tried one before. I'm asking as my own experience with a Behringer crossover is excellent, same as with one of their digital EQ. Both soundwise and reliablity wise.

[pyonc]

Just wondering if you have tried one before. I'm asking as my own experience with a Behringer crossover is excellent, same as with one of their digital EQ. Both soundwise and reliablity wise.

I agree. It works all right with my 4343, compared with JBL M552 or even Ashly XR1001.