crown dc 300a power amps

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11-05-2005, 07:46 PM
gene

crown dc 300a power amps

hello do any one know how good or bad are crown dc 300a amps are.this guy name joe put an ad in the washington post. selling old tube and solid state eq.he is some kind of audio nut like my self, but you would not belive all the audio eq this guy have. from altec lansing jbl mac sansui tube klipsh fisher marantz the list goes on and on. I ask him why not go to lansing heritage and sell all this stuff his reply was to much of a headache . any way he selling all this stuff dirt cheap. he told me he is not in this for the money, but he lives for good eq. but back to my quesiton how good is this amp I got 2 amps for 50 dollars each thanks gene
11-05-2005, 07:56 PM
scott fitlin

The DC-300A, some say this was the best sounding amp crown ever made! I say it is good for bass, if its enough power for your speakers, but most of todays speakers need considerably more than this amp can give. Still, has a certain sound on the bottom that I think is good.

Up further into the mids and highs, I always thought the DC-300A was a bit grainy sounding, it will work though, not as refined as I like in the mids and highs!

Hook em up, listen to them, and see what you think!
11-06-2005, 09:03 AM
pelly3s

I just got my DC300A for $60 in mint condition :applaud:
11-06-2005, 12:29 PM
gene

crown dc 300a

scott I have two dc 300a amps .I am going to used mono blocks. one left and one right. thats 300 rms. my speakers are custom jbl. 12 cubit ft cabinet 18 inch 2245h/ 2202h mid bass/ 2425h with 2344a biradial horn and a 2404h high freq driver crossover at 250 hz to 1200 and 5000 khz. I hope 300 watts rms is enough power
11-06-2005, 01:43 PM
Ian Mackenzie

DC300a= bullet proof

Actually,

You might be better of leaving them stereo and biamping a the 250 hz crossover point.

As a result of the biamping at this crossover point (thereabouts) you get a effective 6 db increase in power to the speakers. ie 180 x 4 per side.

Using a passive crossover will result in power losses and damping. The 2245 prefers to be biamped. it will most probably sound better.

Great speakers, post some images if you like.

Ian
11-07-2005, 06:27 PM
pentictonklaus

crown/amcron DC 300 a

The dc 300 a are all I use after many years of dealing with the expensive stuff. I use the for JBL 4350 and 4435. The crown stuff is very reliable, but take the drivers along when they go due to DC output. I am still working at some DC preventer curcuits to avoid damage to expensive drivers, but time,,
time.. time is like JBL's. You can not get enough.

Klaus
11-07-2005, 06:44 PM
scott fitlin

The DC-300 still sounds good after all these years! I have to agree with Ian on bi-amping, its better, and safer than bridge mono!

That old amp still has a sound on the bottom, Im told this is the work of the " Direct Coupled " design, and its lack of interstage coupling capacitors.

As for reliability, they are very reliable, and pretty bulletproof!

Let us know how they sound to you!
11-07-2005, 06:57 PM
speakerdave

Quote:

Originally Posted by pentictonklaus

The crown stuff is very reliable, but take the drivers along when they go due to DC output.

A Crown DC amp can be fatal to speakers even after it has been blown, disconnected, unplugged and put up for sale. Take it from me--do not hook up an unknown Crown or other Direct Connected amp to a good speaker. It can fry a voice coil instantaneously, making a horrible but very brief noise and little curls of smoke rising slowly from the scene of the crime. See it work on the seller's speakers, have it checked out by a technician, or hook it up to a dummy load and check the output for DC voltage before trying the amp with a speaker. (I think this last is a good way to check, but I am not a technician.)

David
11-07-2005, 08:11 PM
Ian Mackenzie

Well its one of the problems with amp that has gain at DC rather than unity gain. (who cares for square waves to 5 hertz)

Personally I think its a dumb arse idea when one can design with suitable time constants to avoid dc floating down the signal path using audiophile capacitors like BC N series.

In the case of compression drivers I would always a/c couple using a hi quality film foil capacitor (charge couple if you like) .

Also, with any pro amp you buy SH, get the output stage serviced before use. The power output devices do age and fail and this is the prime reason for such reputaions. Better still...buy a new one..they are cheap enough these days.

Ian
11-08-2005, 06:38 AM
duaneage

Quote:

Originally Posted by pentictonklaus

The dc 300 a are all I use after many years of dealing with the expensive stuff. I use the for JBL 4350 and 4435. The crown stuff is very reliable, but take the drivers along when they go due to DC output. I am still working at some DC preventer curcuits to avoid damage to expensive drivers, but time,,
time.. time is like JBL's. You can not get enough.

Klaus

Old Colony Sound Lab sells a speaker protection circuit kit for 40 bucks. It is made by Velleman. If your going to run Phase Linears, Crown , or any other straight through amp this is manditory to have.

http://www.audioxpress.com/bksprods/kits/kv-k4700U.htm

Cheap insurance for a 200 dollar cone kit. I have worked with PL amps before and they can be bad little boys. Took out two JBL E140 drivers for a friend of mine.
11-08-2005, 08:47 AM
louped garouv

how do these things work, and how do they effect the sonic signature of the amp?
11-08-2005, 02:18 PM
scott fitlin

Quote:

Originally Posted by duaneage

Old Colony Sound Lab sells a speaker protection circuit kit for 40 bucks. It is made by Velleman. If your going to run Phase Linears, Crown , or any other straight through amp this is manditory to have.

http://www.audioxpress.com/bksprods/kits/kv-k4700U.htm

Cheap insurance for a 200 dollar cone kit. I have worked with PL amps before and they can be bad little boys. Took out two JBL E140 drivers for a friend of mine.

Yes, Flame Linear can be a bad amp! Matter of fact, Flame Linear is more dangerous than the DC-300!

But, there are guys that love those old 700B,s!
11-08-2005, 07:33 PM
gene

crown dc300a

thanks duaneage. i went to audio xpress . I will order the two channel loudspeaker protection kit first thing in the morning:bouncy: thanks gene
11-09-2005, 05:05 AM
Fred Sanford

Quote:

Originally Posted by duaneage

Old Colony Sound Lab sells a speaker protection circuit kit for 40 bucks. It is made by Velleman. If your going to run Phase Linears, Crown , or any other straight through amp this is manditory to have.

http://www.audioxpress.com/bksprods/kits/kv-k4700U.htm

Cheap insurance for a 200 dollar cone kit. I have worked with PL amps before and they can be bad little boys. Took out two JBL E140 drivers for a friend of mine.

Why does that item say 220V supply voltage? The search wasn't too helpful on that site, maybe there's another model...

je
11-09-2005, 05:56 AM
Ian Mackenzie

Quote:

Originally Posted by scott fitlin

Yes, Flame Linear can be a bad amp! Matter of fact, Flame Linear is more dangerous than the DC-300!

But, there are guys that love those old 700B,s!

I think any amp can he dangerous if not used correctly or maintained.

You have to ask yourself why would it break....Carver was not an idiot!

But some idiots like shorting the outputs and turning them on and off in the wrong sequence, cooking them or clipping them from an overloaded desk for days on end ......the odd failure is hardly surprising when they turn up clapped out on Ebay to the un suspecting buyer.

My 700 B series 11 was used in a Clair Bros system Touring around Aust for years powering S4 's before I got it and it never missed a beat. I owned a 400 for about 10 yrs and it never missed a beat either.

I called the tech who serviced them before I bought them because his ph was on the back.

Common sense applies.
11-09-2005, 06:16 AM
Earl K

Flame Linear

FWIW :
- The first generation 700b(s) deserved the moniker that they received from the SR industry . It was the drive cards that for some reason would arc / flame / & eventually turn into carbon. Someone said that it was due to the use of Germanium transitors in the area / but I've long stopped caring if that was true .

Also;
- The chassis of these amps were tragically underbuilt for the weight of the massive power supply. These amps would literally rip themselves apart over long haul road trips. I had a few that had obviously seen too many tours. I still have one on the bench waiting for my attention ( it needs a complete mechancal rebuild ). Also, I punted my Crown 300(s) decades ago for being masked sounding and offering nowhere near the necessary wattage .
- Clair, like any pro Sr company from that era used lots of these amps (700b ) , since these were the only game in town offering big watts. Everyone who wanted their amps to continue performing put a lot of thought & effort into making sure they didn't mechanically self-destruct.
- The emergence of the Carver company and its model PM1.5 was welcomed by most who wanted big watts with some structural integrity. Of course , the use a switching type power supply ignited the debate over "iron & weight" for PS supplies that continues to this day. My allegiances ? Well, I use Crest amps on subs ( only ) for this very reason ( the beefy supply ) . QSC, Carver & small Brystons are used in other areas.

Cheers
11-09-2005, 11:26 AM
pentictonklaus

DC preventer

[QUOTE=Fred Sanford]Why does that item say 220V supply voltage? The search wasn't too helpful on that site, maybe there's another model...

Velleman is a manufactor from Belgium. All there stuff is rated 220 V 50 Hz.
I have used some of their other kits ( Multiplexer ) and the quality was very high. There was however an older version of these DC preventers available that did not need an external Voltage supply. Part No. K 4701 A up to 30 watt max
and K 4701 B 300 W max. But I could not get the 300 w version in Canada.
220 Volt supply is not necesarry a problen in North America ( Think laundry dryer ) as long as the unit will not use the 50 Hz for some whatever and can operate on 60 hz.
The old version was once advertised at www.qkits.com ,Kingston Ontario.
I suspect that the newer version will use the 220 volt thru a transformer
to a lower voltage and rectifier to DC.
I will order the kit as well and see what's up with it. It would be easy to replace the trafo with a cheap 110v version, since power demand can't be high.

P.S I still do have a bag ( 9 pieces, one as a spare ) original output transistors for the DC 300 a. The amp it's for now puts out 55 Volt DC since all 8 transistors are shortened. I bought the amp cheap on a flee market and DID NOT use it before checking out well. Would have been recone for 2x 2234's.

Will keep info up after kit's arrive.
11-09-2005, 12:23 PM
scott fitlin

Quote:

Originally Posted by Earl K

FWIW :
- The first generation 700b(s) deserved the moniker that they received from the SR industry . It was the drive cards that for some reason would arc / flame / & eventually turn into carbon. Someone said that it was due to the use of Germanium transitors in the area / but I've long stopped caring if that was true .

Also;
- The chassis of these amps were tragically underbuilt for the weight of the massive power supply. These amps would literally rip themselves apart over long haul road trips. I had a few that had obviously seen too many tours. I still have one on the bench waiting for my attention ( it needs a complete mechancal rebuild ). Also, I punted my Crown 300(s) decades ago for being masked sounding and offering nowhere near the necessary wattage .
- Clair, like any pro Sr company from that era used lots of these amps (700b ) , since these were the only game in town offering big watts. Everyone who wanted their amps to continue performing put a lot of thought & effort into making sure they didn't mechanically self-destruct.
- The emergence of the Carver company and its model PM1.5 was welcomed by most who wanted big watts with some structural integrity. Of course , the use a switching type power supply ignited the debate over "iron & weight" for PS supplies that continues to this day. My allegiances ? Well, I use Crest amps on subs ( only ) for this very reason ( the beefy supply ) . QSC, Carver & small Brystons are used in other areas.

Cheers

Earl, I agree with you, even though the 700B DOES have a great sound, especially for bass, and the reggae guys LUV the 700B, many people destroyed their speakers, and their PH amps, consistently!

Thats said, I love my DC-300A,s for driving Altec 15,s, but they havent enough balls for any other woofer, especially any of todays pro 15,s running them in stereo mode!

Way back in the day when my dad and uncle were first putting together our big system, we had every amp of the day in here! BGW, McIntosh, PH, Crown, and the Altec 9440,s!

Mc and Crown were the only ones that held up in here, worked every day no problems, and we loved the tight and punchy bass Crown became famous for!

The BGW,s used to thermal, these were amps around 1975, the Altecs blew up first weekend of use, we blew ALL our 15,s at the time with PH, Mc was too big and heavy, and expensive at this particular time and the Crowns lasted, and did something we liked!

By the time amp makers had perfected things, we were hooked on Crown! And to this day, they run fairly trouble free!

Crest, also runs consistently trouble free, I have some of the last generation 8001,s and 7001,s! But I also remember the Crest saga of the 90,s! They had a bad run of something, and their amps were blowing up on turn on! It happened to me, it happened to alot of people I know who were switching to Crest at the time! originally, I had bought one crest 7001 around 1997, I wasnt into the macro techs, and wanted the power, with an amp that had a healthier power supply, Crest was the recommended amp! Got it here, installed it, I liked it, and it had a beefier bottom than the Crown 2400! The only problem was the next day when we turned things on, about 2 minutes later there was a little curl of white smoke coming out of the front vents, POOF the amp was gone! I took it out, opened it up, it looked like a bomb exploded inside! All the emitter resistors were blown up, bits of ceramic waste everywhere! They fixed it, and sent it back to me, but I was not sure of them after this! And everyone was having the same problems, 9001,s sound great, but they were blowing up on turn on! They did solve their problem with their amps, but I think this really hurt Crests image in the marketplace. The ones I have now, are reliable, and work trouble free.

But my favorite sounding sub amp, even though its not enough power, is and always was, and will probably always be the Crown PSA-2!

Im out to lunch on Bryston, and I own three Bryston 4B ST,s 1 Bryston 3B ST, and a Bryston 2B!

Of everyone I know using QSC, they are very reliable and stable, and sound good, punchy and fast! Everyone likes them! They seem to work day after day after day.................. I went to listen to some a few weeks ago, and I thought they do have a nice taught, rythmic sound on the bottom!
11-09-2005, 05:39 PM
Earl K

1 Attachment(s)

Crests ?

Hi Scott,

- Yeh, I seem to remember something about that series of big Crest amps going nuclear. Up here in the "territories" we never saw much of that series / just too expensive for the Cdn consumer. My CA12s are from a newer / cheaper series that to my knowledge are pretty stable ( knock on wood ).
- I remember now that I acquired some Crest 3500s but flipped them quite quickly after a brief listen .

- Brystons ? The only model I've kept around ( & will continue to ) is the 2B-LP. I just love how this amp sounds with the rest of my gear. I sold off my 3Bs & 4Bs years ago. I never liked them very much ( IMO - not a titanium friendly amp - though I guess I should listen to the SST series ) . I've stayed away from the newer Brystons lines for various reasons. Interestingly; all Brystons models, past & present, have their schematics posted in pdf form at the Bryston website. All models except the 2B-LP that is. That makes me wonder since this particular topology is about 16 years old .

- My thoughts on amps ? Luckily I own a lot of sound gear which enables me to find a combination of components that please my palate. After my last 2.5 year exploration on the "sound of caps" / I'll offer up that a lot of the trading of amps for newer/older models is actually people just exchanging the "sounds" of input, coupling and power caps for something different . The 2B-LP doesn't look to be capacitor coupled in the front end. ( I was recently poking around inside one trying to find out why I like it so much. ) It's balancing / unbalancing circuitry seems to follow a discrete form of the following topology ( this .gif is from a 5235 ). You can see their are no dc blocking caps inline in the circuit before the balancing opamps. There is just a single large value interstage or coupling cap after the signal has been unbalanced . From what I have seen, both the JBL crossovers and the Bryston 2B-LP used Philips MKC caps in these positions.

Cheers

ps : Scott, you're likely a 715P ( Sprague; Orange Drop ™ ) or MKC sort of guy / given everything you've said about the "sounds" of things . This is "Capacitor-Profiling" of a regular poster . It's a new hobby of mine . :p
11-09-2005, 06:23 PM
gene

crown dc300a

I want to thank all of you guys for your input on the crown 300a.I here differnt stories not enough power , drivers being blown etc. I have other speakers that I can hook this amp up with. what you guys can help me with. I love jbl speakers and I want plenty of bottom deep bass smooth silky highs and laid back mids. I need some input on a good amp thats not only sound awesome but have the power to run my speakers, I have a 12 cubit ft speaker jbl 2245h/2202h/2425hand 2404h, crossover at250 1200 5000khz. also i need the amp to have huge caps and transformer. I dont like any of that light weight stuff no balls at all in the bass deparment. or at low volume. thanks gene
11-09-2005, 06:26 PM
scott fitlin

Quote:

Originally Posted by Earl K

Hi Scott,

- Brystons ? The only model I've kept around ( & will continue to ) is the 2B-LP. I just love how this amp sounds with the rest of my gear. I sold off my 3Bs & 4Bs years ago. I never liked them very much ( IMO - not a titanium friendly amp - though I guess I should listen to the SST series ) . I've stayed away from the newer Brystons lines for various reasons. Interestingly; all Brystons models, past & present, have their schematics posted in pdf form at the Bryston website. All models except the 2B-LP that is. That makes me wonder since this particular topology is about 16 years old .

Cheers

ps : Scott, you're likely a 715P ( Sprague; Orange Drop ™ ) or MKC sort of guy / given everything you've said about the "sounds" of things . This is "Capacitor-Profiling" a regular poster . A new hobby of mine . :p

You have hit on something! The Brystons arent aluminum friendly either! Made my JBL 2441,s sound metallic and bright! Irked my nerves. They say the 3B SST has a more relaxed sound in the upper mid/HF due to use of different output transistors, but I dont know, havent heard em!

Sprague orange drop caps? There is some Sprague orange colored caps in my modified urei crossover, ( they look like orange chiclets? ) and they also used these big Sprague caps in the power supply as well! I copied the mods into another urei 525, and used different brand, same type caps, same values, and I thought it sounds good, works like my original one, but doesnt quite have that certain little something in the midrange that the original one does!

So, Earl, what coloration is that my profile is leaning towards? :D
11-09-2005, 06:29 PM
scott fitlin

Quote:

Originally Posted by gene

I want to thank all of you guys for your input on the crown 300a.I here differnt stories not enough power , drivers being blown etc. I have other speakers that I can hook this amp up with. what you guys can help me with. I love jbl speakers and I want plenty of bottom deep bass smooth silky highs and laid back mids. I need some input on a good amp thats not only sound awesome but have the power to run my speakers, I have a 12 cubit ft speaker jbl 2245h/2202h/2425hand 2404h, crossover at250 1200 5000khz. also i need the amp to have huge caps and transformer. I dont like any of that light weight stuff no balls at all in the bass deparment. or at low volume. thanks gene

Just try the 300 on your speakers and see how you like em! A dozen people can give you 24 opinions and you still have no idea of how it sounds or what you like UNTIL YOU hear it for yourself! As long as the amp is in good operating condition I wouldnt fear them frying your speakers! Have you had them looked at by a professional to to confirm the amps are in good and stable operating order?
11-09-2005, 07:43 PM
boputnam

12 cubit ft speaker jbl

Hey, gene...

Got any pictures of those DIY'ers? I'm feeling cabinet envy comin' on... :)
11-09-2005, 10:30 PM
duaneage

Quote:

Originally Posted by louped garouv

how do these things work, and how do they effect the sonic signature of the amp?

They don't affect the sound at all. The outputs go through relays so it is a straight connection from input to output until it sees DC then it trips the relays. A SCR "looks" at the output for a DC voltage and then triggers. Input impedance on the SCR is way above anything that the driver is so it does not interact with the speakers network or anything like that. It would be hard to even measure the impact let alone hear it.

Of course those with golden ears will discuss how the relays affect the sound, but I digress.

If they save a pair of woofers who cares really?
11-13-2005, 05:58 PM
Mike Caldwell

Hello

What vintage of DC 300 do you have. There were about five different era's of the DC 300. From the originals that had the big black knobs to the last version that has the grayish black face. Let us know what your looks like and we can place it in the Crown time line as to age. I had many of the black face series and never had single problem with them. As the others have said they will pass and amplifiy a DC voltage. I would at least have a high pass filter on the inputs not only for the DC protection but they also help clean up the low end of a system and help prevent over excursion of the speakers from frequecies below there tuning cutoff.
If it matters in your system all of the Crown D and DC series amps do not have balanced inputs. I would have thought by tht time the black face series came out in the late 70's early 80's they would have changed that.

Mike Caldwell
11-17-2005, 06:37 PM
gene

crown dc 300-a

Hello my amp has a silver face silver knobs and a black leather strip close to the bottom of the amp with the numbers 300a written in white ink. the edge of the knobs are gray if thats any help to you.14411 looks like the serial# 1200 watts and 10 amps
11-18-2005, 03:01 AM
gerard

http://www.audioxpress.com/bksprods/kits/kv-k4700U.htm

Thanks duaneage :bouncy:

Very good info specially where you leave far from suppliers .
I will buy a couple of it .

Gerard
11-18-2005, 05:51 AM
Mike Caldwell

Quote:

Originally Posted by gene

Hello my amp has a silver face silver knobs and a black leather strip close to the bottom of the amp with the numbers 300a written in white ink. the edge of the knobs are gray if thats any help to you.14411 looks like the serial# 1200 watts and 10 amps

Hello
I would say your amp is from the early 1970's since you did not mention that it
had any IOC lights by the level controls. If the Crown name and DC300 are in a script written type of print that would also indicate a early 70's amp. In the later 70's they went to block letter type of print for the name and add the IOC indicators.

Mike Caldwell
12-05-2005, 01:59 AM
MartinM

Got a pair of DC-300A's I used for years in my sound co. never a problem. Now they will be the bottom end amps of a tri-amped HT/audio sytem driving each of a pair of 2245's in bridged mono 600W mode. Top end is 130A's in gutted, ceiling flown L200 cabinets, with the Hartsfield folded plate Horn/Lens combo outboard on top pushed by 2445 ferrites.

I'm hoping for some floor standing B460 cabinets for the 2245's, but open to other suggestions. Anyone?
07-15-2009, 05:59 AM
jpmoss

what about the crown psa2?
07-15-2009, 02:35 PM
jbl_daddy

When the PSA2's were new they were great, as they age they develop problems. High speed fans running for no reason, inconsistant turn on sequences, and when they blow up you can nolonger get ourput transistors. I have owned two until they both blew up in the same week. I replaced them with a pair of Crown K1's about five years ago. :)

Ps. I also have four DC300 Series 11's and love all of them.
07-16-2009, 03:08 AM
Sootshe

Quote:

Originally Posted by gene

I want to thank all of you guys for your input on the crown 300a.I here differnt stories not enough power , drivers being blown etc. I have other speakers that I can hook this amp up with. what you guys can help me with. I love jbl speakers and I want plenty of bottom deep bass smooth silky highs and laid back mids. I need some input on a good amp thats not only sound awesome but have the power to run my speakers, I have a 12 cubit ft speaker jbl 2245h/2202h/2425hand 2404h, crossover at250 1200 5000khz. also i need the amp to have huge caps and transformer. I dont like any of that light weight stuff no balls at all in the bass deparment. or at low volume. thanks gene

If you want to hear some real bass.....get yourself a Krell! :)
07-20-2009, 09:47 PM
powerd

DC300 blown

Guess what? My much loved and trusty old Crown - I think it is from the late 70s or early 80s - has blown one channel. And taken the my ESS Heil AMT3 with it(now there's a histroy lesson for you). Thankfully th eHeil driver is OK, but speaker gone open circuit.

My trusted tech has the amp and has ifentified the p[roblems, but can't find replacements or listed substitutes for two of the tansistors - I gather others have had problems with this. Does anyopne have a circuit diagram for the output stage he might be able to look and and identify the appropriate items to use?

For identication purposes, mine has a silver front, with a black strip with Crown DC300A along the lower part, and two big black gain knobs.

BTW, I am not technically literate - I believe electricity works on voodoo, so leave it to those who know black magic - so please keep any replies in layperson's terms!

I would very much appreciate any help you can give.

Cheers
powerd
Canberra, Australia
07-24-2009, 03:36 PM
subwoof

schematics

all the old crown schematics are online ( well almost ) be SURE to match the board with the one you have. there are at least 9 versions.

And all the transistors are available ( or the modern eq ) from crown. If the transistors are substituted in the output stage, you will need to replace whole banks unless you find some that are used ( I have a stash )

what are the numbers?

http://www.crownaudio.com/gen_htm/legacy/legacamp.htm