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View Full Version : Crown DC300A-II or (2) bridged D150A-IIs?



BMWCCA
04-05-2006, 02:22 PM
(Not sure if this goes here or in "General Audio" so feel free to move if appropriate)

I posted this on the Crown forum at CrownAudio.com but they all seem to be asleep or not interested. (In fairness, Crown's David Glass appears to be on vacation.) So here goes:

I've recently added some "new" old JBL speakers to my inventory and have considered how to accomodate their power needs. I currently own an original Crown D150, (2) D150A-IIs, and a DC300A-II. According to Crown specs the D150A-IIs will put out 315w @ 8 ohms in bridged mode versus the 300's 175w/channel in stereo mode. I distinctly remember inquiring at Crown a few years ago when I considered running two 150s in bridged mode versus buying a 300 to use in stereo to power my L112s and was told to just get a 300. Given that I now have the amps to go either way, what are the benefits and/or disadvantages to one set-up over the other? I also may end up with an electronic crossover at some time, if that changes the ideal configuration.

The speakers are JBL L150A with a max-power rating of 300w. I'm currently powering a very early 16-ohm JBL 030 system (in the family since I was two-years-old) with the DC300 (yeah, overkill but it sounds 'better' than the D150! :bs: ). My original "faceless" D150 has been powering a similar-to-L150A JBL L112 pair for over twenty years with great results but who knew I could use 300 watts per side with these things? Is the DC300A-II output cleaner in stereo mode than the D150A-II in bridged? Can Crown's power specs be wrong?

Thanks.

Baron030
04-06-2006, 12:08 PM
I'm currently powering a very early 16-ohm JBL 030 system (in the family since I was two-years-old) with the DC300 (yeah, overkill but it sounds 'better' than the D150! :bs: ).

I don't know why you included that BS Smiley in your posting. I have tested several Crown Amplifiers with my old 030 system. A D-75A in Dual Mode, Two D-75A amps in bridged-mono mode, a K1 and a even a K2. And with each increase of amplifier power, the transient response improves.
I have found that my 030 system sounds best with a Crown K2 and that is no :bs:

So, there is no such thing as overkill.

Baron030

BMWCCA
04-06-2006, 07:01 PM
I don't know why you included that BS Smiley in your posting. I have tested several Crown Amplifiers with my old 030 system. A D-75A in Dual Mode, Two D-75A amps in bridged-mono mode, a K1 and a even a K2. And with each increase of amplifier power, the transient response improves.
Nice to hear your thoughts. When I bought my D-150 back in 1974 it was to replace a Fisher SA-1000 that was in need of a set of then-unobtanium RCA tubes, and some other work. The local dealer let me take home one of each Crown D-75, D-150, and DC-300 to try out. As a college student, and having paid $90 for the Fisher, I wasn't exactly flush with cash. My ears insisted each progression in Crown power made the 030s sound better. My wallet made me stop at the D-150, and one without the front panel, too. But for a quarter of a century I've remembered what that DC-300 sounded like, so I bought one a few years ago. And they are great deals these days, often going for less than the D-150s. Most everyone else told me I was nutz thinking the extra power made a difference. Nice to hear you must be nutz, too!

So, what do you think about the bridged D-150 idea? Are the power specs accurate? Other than a bridged DC-300, a bridged D-150 seems like quite an impressive amp. Why would I not want to do that and why is the 150 rated at so much more power bridged than a 300 in stereo mode? I just figured the L150A and L112s needed a bit more power than the 030s. Thanks for your help and advice. I just listen to the music.

(Just in case anyone's interested, the Crown D-150 cost $399 in 1974 [serial #D5655] and High Fidelity Showroom gave me $120 in trade for the Fisher SA-1000 which they promptly installed in their High Fidelity Antiques museum.)

Robh3606
04-06-2006, 08:18 PM
I use 2 Crown D150A-IIs bridged to power my 2235 woofers in my 4344's in a biamp set-up. I also use a bridged D150A for my center channel in my HT set-up. They work just fine and the 325 watts is accurate. Nothing wrong with having lot's of clean headroom available. The actual difference is only about 3db but why not.

Rob:)

BMWCCA
04-06-2006, 09:03 PM
Thanks. Just makes me more curious as to why Crown would have recommended using a DC-300 instead of two D-150s. I'll set it up with the two bridged amps as soon as my surround-fest is complete. :thmbsup:

DjWolfe
08-06-2009, 12:29 PM
I've come into possession of a D150A and for the life of me cannot find the proper instructions online anywhere on how to bridge to mono. Obviously you flip the switch to mono, but what is the output plugin configuration to properly Bridge to the 325W Mono?

Thanks guys :)

jcrobso
08-06-2009, 01:42 PM
I've come into possession of a D150A and for the life of me cannot find the proper instructions online anywhere on how to bridge to mono. Obviously you flip the switch to mono, but what is the output plugin configuration to properly Bridge to the 325W Mono?

Thanks guys :)
Mine dose not have any directions ether. In general to go mono mode you flip the switch, connect only one input usual input #1. Output connections in mono mode only use the red banana jacks, DO NOT EVER USE THE BLACK BANANA JACKS WHEN IN MONO MODE!

midlife
08-06-2009, 02:30 PM
You can go to Crowns website under discontinued models and view the operators manual. It covers options for mono 150 use. Also a mono use 150 does not respond well to a 4 ohm load. AE Techron is the vintage Crown repair station and they can sometimes help with these types of questions.

bigyank
08-06-2009, 03:16 PM
I've come into possession of a D150A and for the life of me cannot find the proper instructions online anywhere on how to bridge to mono. Obviously you flip the switch to mono, but what is the output plugin configuration to properly Bridge to the 325W Mono?

Thanks guys :)

As others have alluded to check here:

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

Yank

scott fitlin
08-06-2009, 03:52 PM
Thanks. Just makes me more curious as to why Crown would have recommended using a DC-300 instead of two D-150s. I'll set it up with the two bridged amps as soon as my surround-fest is complete. :thmbsup:No matter what you do, the DC-300 has a bigger transformer, and bigger filter/smoothing caps and higher voltage rails. It also has a 1.75v input sensitivity, as opposed to the 1.2v input sensitivity of the 150A, 150AII, and IMO for low end, the 1.75v input sensitivity works better.

The bigger transformer, caps and power rails make better and more dynamic sound, with better headroom, and more instantaneous peak power.

subwoof
08-06-2009, 04:38 PM
everyone is forgetting 2 items:

(1) Running any crown in bridge mode means special care has to be used on the speaker connections to make sure NEITHER touches ground for any reason at any time.

(2) The smaller crowns ( under the 300 size ) use a SINGLE output transistor for each half of an output stage. The 300 and larger amps have multiples to share the load. For example the M600 has *thirty two* overall....and is only 600 into 8. The MA10,000 has *eighty*

The older crowns used output devices that were barely powerful enough to work. the PSA2 first gen had 8 outputs each channel for a 600 watt load but the devices themselves were only 100 watts each ( 2n5631 ).

buy more 300's and use them.

btw the black jacks can be used but they carry no signal of their own..:)