Vintage Crown Galore

I use UREI Studio 3 way electronic crossovers for the front two speakers and the center is bi-amped for the HT system. the rears are now bi-amped and the sides are full range using Urei Professional modular crossovers. . Thats why I have two Mcintosh MC 207 Power amps. I guess I should replace the Urei pieces, but I just love the smooth non fatiguing sound when used in combination with the Mac amps. I also used them with the Crown amps when I just had a Stereo system.
 
Blue Shadow said:
Dual amp:

1) mono each amp, one per channel, mentioned above, it is in the manual

2) bi-amping as Phil mentions, one channel for highs and one for lows in a speaker, using the Crown VFX-2 electronic crossover instead of speaker crossover.
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sidetracked with the fuse issue for the past week or so, but now that the amps are working stably, want to re-focus on the dual amp setup.

I was running system #1 (single DC300a) into the IC150, then splitting out the the output into the 4 speaks.

For system #2, I am running the two "main" outputs of IC150a into the inputs of each of the two DC300a's, and the outputs from those into a pair of speaks as "R" & "L" channels. The "mono" setup, but in stereo mode as the that signal is being processed within the IC150a.

I do not want to go the electronic crossover option at this point, but may do so depending on the functionality of the OC150a, which is the next task at hand

Would love to hear some thoughts on bringing that unit into the current setup, especially for people that have an OC150a. Unfortunately, I have not spoken to the original owner as to how he ran this system, so a bit of a mystery. He is apparently still alive and I may ask his son/grandson to arrange a phone call to find out more about why he chose the OC150a as part of this stack, and what component was originally in this empty case that came with it
 

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John Spiro said:
The "mono" setup, but in stereo mode as the that signal is being processed within the IC150a.
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What?

You are running IC-150a Output 1 Left to one DC-300a input and the other Output 1 Right to the other input on that same DC-300a and each of those has a speaker connected? Similarly done for the Output 2 and the second amp?
 
The OC-150a is just a routing, metering, speaker connection device. Get the manual and read about it. It isn't as versatile as I would like and doesn't need to be hooked up to my main rig most of the time.
 
Blue Shadow said:
What?

You are running IC-150a Output 1 Left to one DC-300a input and the other Output 1 Right to the other input on that same DC-300a and each of those has a speaker connected? Similarly done for the Output 2 and the second amp?
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yes, thats how it is hooked up now
 
Blue Shadow said:
The OC-150a is just a routing, metering, speaker connection device. Get the manual and read about it. It isn't as versatile as I would like and doesn't need to be hooked up to my main rig most of the time.
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Blue, yes I have read it and maybe should lower my expectations ... I dont see how it was intended to run dual amps in tandem ... i cant wrap my mind on why this is part of this stack - which is how it was configured by the original owner in the mid 1970"s
 
If you wish to eventually go the DC-300 mono configured route, be advised that when you do configure a DC-300(A) they don`t like to operate into 4 ohms speaker load in mono, as the 8 ohm load across both channels splits to effectively 4 ohms per side which is their minimum rated ohm load per channel for this amp in stereo !

And trying to operate into a 4 ohm load while configured in the mono mode will trigger the amp`s internal protecting current restriction circuitry and needlessly run the amp at stressful elevated temperatures along with an increase in distortion.
 
Bill Ferris said:
If you wish to eventually go the DC-300 mono configured route, be advised that when you do configure a DC-300(A) they don`t like to operate into 4 ohms speaker load in mono, as the 8 ohm load across both channels splits to effectively 4 ohms per side which is their minimum rated ohm load per channel for this amp in stereo !

And trying to operate into a 4 ohm load while configured in the mono mode will trigger the amp`s internal protecting current restriction circuitry and needlessly run the amp at stressful elevated temperatures along with an increase in distortion.
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Hi Bill, thanks for your comments...that's the kind of feedback I was looking for, as a dual power amp system is all new to me

Do you know of a good resource (Crown?, AK) that covers what I'm attempting to do here? Is there additional equipment/cabling that would be ideal hookup for the single preamp two power amps going into a quad of 8 ohm speaks?

Again, want to factor out the OC150a for the time being until I get the basic amplification set up correctly
 
John Spiro said:
Hi Bill, thanks for your comments...that's the kind of feedback I was looking for, as a dual power amp system is all new to me

Do you know of a good resource (Crown?, AK) that covers what I'm attempting to do here? Is there additional equipment/cabling that would be ideal hookup for the single preamp two power amps going into a quad of 8 ohm speaks?

Again, want to factor out the OC150a for the time being until I get the basic amplification set up correctly
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The very thoroughly detailed DC-300(A) owner manual that`s available on line somewhere (as they say Google is your friend) will inform you of all the specifications, and connection/mono/stereo configurations.
You can look in A/K`s digital docs section to see if any Crown manuals are residing there.

Though I still own, but not using OC-150/A anymore for yrs., and never ran more than one amplifier out of it`s 2 sets of outputs at anytime when I did, I don`t see why it couldn`t drive 2 Crown amps at the same time without any issues, if its circuitry is properly functioning.
Until 2006 from the very early nineties, I operated (2) DC-300s in mono configured in my bedroom`s system driving 8 ohm Mc. XRT-18 speakers with zero problems even when I ran the stereo cranked up for hrs. But being an electronic tech for decades I made sure they were checked out on my bench and met all factory specs before installing and using them.
 
John Spiro said:
Hi Bill, thanks for your comments...that's the kind of feedback I was looking for, as a dual power amp system is all new to me

Do you know of a good resource (Crown?, AK) that covers what I'm attempting to do here? Is there additional equipment/cabling that would be ideal hookup for the single preamp two power amps going into a quad of 8 ohm speaks?

Again, want to factor out the OC150a for the time being until I get the basic amplification set up correctly
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Bill Ferris said:
The very thoroughly detailed DC-300(A) owner manual that`s available on line somewhere (as they say Google is your friend) will inform you of all the specifications, and connection/mono/stereo configurations.
You can look in A/K`s digital docs section to see if any Crown manuals are residing there.

Though I still own, but not using OC-150/A anymore for yrs., and never ran more than one amplifier out of it`s 2 sets of outputs at anytime when I did, I don`t see why it couldn`t drive 2 Crown amps at the same time without any issues, if its circuitry is properly functioning.
Until 2006 from the very early nineties, I operated (2) DC-300s in mono configured in my bedroom`s system driving 8 ohm Mc. XRT-18 speakers with zero problems even when I ran the stereo cranked up for hrs. But being an electronic tech for decades I made sure they were checked out on my bench and met all factory specs before installing and using them.
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I have the Crown DC300 manual, but the version I have does not address dual amp configurations. I did use it as a guide for the first Crown single amp system before I got all these new components

System #1 was setup for the IC150 running into a single DC-300 amp, and then into the same four 8 ohm Community's. The two +/- amp outputs were split out into R & L speaker pairs (parallel I guess) . The preamp output is presumably "Stereophonic", and the amp was set to "Dual" mode and . I followed the Crown manual exactly for a single amp setup - except for the speaker split.

I followed the same basic hookup for System # 2 but eliminated the speaker splits so each of the four amp outputs goes to a specific dedicated speaker. Seemed safe since there was still one 8 ohm speaker for each output channel.

I'm not going to risk turning it on again if this hookup is wrong (lol)
 
John Spiro said:
I have the Crown DC300 manual, but the version I have does not address dual amp configurations. I did use it as a guide for the first Crown single amp system before I got all these new components

System #1 was setup for the IC150 running into a single DC-300 amp, and then into the same four 8 ohm Community's. The two +/- amp outputs were split out into R & L speaker pairs (parallel I guess) . The preamp output is presumably "Stereophonic", and the amp was set to "Dual" mode and . I followed the Crown manual exactly for a single amp setup - except for the speaker split.

I followed the same basic hookup for System # 2 but eliminated the speaker splits so each of the four amp outputs goes to a specific dedicated speaker. Seemed safe since there was still one 8 ohm speaker for each output channel.

I'm not going to risk turning it on again if this hookup is wrong (lol)
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Don`t concern yourself with the 4 speaker (one per amp channel) 2 amp connection scheme you`re desiring to do, as there is nothing risky with that configuration.
When I was a sound man for a rock band, I ran 2 DC-300As, and 2 D-150As 6 nights a week for the loud as hell stage monitors for 5 or 6 hrs. a night with no issues !

The OC-150 preamp should drive both amps (4 channels 2 left, and 2 right with no problems, just power plug them from all into the same AC source (power strip, etc.) so as to not create a audible hum causing "ground loop that you will hear out of the speakers.

8 ohm speakers will be fine for all output connections to the amplifiers as their safely rated down to 4 ohms.
Just make sure all your speaker connections are clean and tight so as to not have accidental stranded wire shorts at the speakers or amplifier speaker connectors.

Enjoy the music, John Spiro.
 
John, please specify your gear and manuals correctly.
so far you have done well with the gear, old IC-150 preamp with DC-300a power amp as #1 and IC-150a with 2 DC300a amps as #2.

I'm concerned about the manual, you stated DC-300 manual and that manual is not for your amps which are DC-300a models, BIG difference. The correct model numbers help us know you are looking at the right documents and we know if we can help. Crown reused most of the model numbers of these early units by adding a an and the unit can be way different.

But you are moving along just fine on your journey figuring this gear out.
 
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Hey Bill & Blue: Really appreciate your interest in my system #2 project and great advice!!

The manual I am referring to is for the DC300a which I pulled off the Crown web site

I dont know a lot about Crown "pro setups" but have seen those Crown DC300a's stacked up in musical and club settings so know people use them this way

I want to keep the integrity of this great original stack, and I think the next step is to tie in the OC 150A switching unit. There is a manual out on the Crown site but it it is confusing as the the second (or third) amp setup they lay out is not really the dual amp configuration I envision. Maybe I'm overthinking this too much.

I think I'll try to patch in the OC 150 since the system is stable and sounds good so far. No overheating or distortion that I can detect even at 12:00 which is pretty f*cking loud.

Also seriously thinking about trying to reach the original owner. After all he bought all this **** for a good reason (lol)

I'll keep you posted ... John
 
Hey friends, Took a little break from all things Crown, but ready to tackle patching the OC 150A into the IC150A preamp and dual DC 300'A's amp setup, driving the dreaded quad Community CSX35 church speakers

the manual from Crown is here but too big to attach, and doesnt really talk about what I want to do:


The most logical hookup in my mind is to feed the DC300A outs into the Amp 1 and Amp 2 inputs of the OC 150A, then running new cables to the Community speaks. {image below}

I really don't understand the functionality of this hookup since it is only vaguely addressed in the Crown manual.

Does this sound like a reasonable starting point? I'm afraid to flip the switch on impulse since the OC 150is still in "untested" original condition ...John
 

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That hook up will allow you to view power meters for both amps but only allow you to use speaker selection with amp 1. Amp 2 is just going along for the ride. But it should work.

Are you running the amps in mono? I believe the OC-150a has isolated black connectors for each amp, not combined (common ground). Common ground cannot be used with a bridged to mono amp.
 
The OC-150a has three amplifier connections. A1 allows metering and individual switching of three sets of speakers. A2 allows metering and switching of two headphones jacks only. A3 allows metering only, no outputs.
 
Appreciate you weighing in Blue and Dex!!

It appears to me that the Amp 1 and Amp 2 inputs and outputs on the OC 150a are dedicated. I dont see anything specifically marked for "bridging", but I suppose that would normally be done thru cabling anyway. The terminal strips are also specific for either Amp 3 or the Headphone circuits so yeah, "isolated" on this model.

Both DC300's are in the "mono" setting, and came that way from the original owner. As I mentioned above, the original cables and documentation were lost in the move, and I havent talked to the original owner so cant confirm the original setup.

So I hear you correctly Blue, I would want to split the Amp 1 speaker output to the four Communities (?). This was the essentially same setup I had with System #1 (single DC300a).

Is the second DC300a completely out of the loop when using this switching unit?? John
 
John Spiro said:
I dont see anything specifically marked for "bridging",
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John Spiro said:
so yeah, "isolated" on this model.
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Isolated means that the left black connector for amp one is completely independent of the right black connector for each amplifier input. If not and you connect the mono'ed amp to left channel and other mono'ed amp to right channel you will damage the amps. They will be electrically connected through the ground.

I think the manual talks about whether they are isolated. you can check with an ohmmeter reading between them.

All the manuals for this gear is available on line and you have it. Rely on the manuals on using the OC-150a.
 
Ok Blue...just to get on the same page here I attached a crude drawing of the current set up for the preamp and two amps

Using both "Main" (Amp 2 and Amp 1) output channels of the preamp and, and the amps are set to "Mono" , then I think the the signals are independent, as I understand the concept

However, if using only the Amp 1 output for the mono setting, then I definitely have it wrong presently

Both amps have the Dual setting, which complicates it further, but first things first...

Not even ready for the OC 150a yet

really appreciate your patience walking me thru this!! John
 

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