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Line level matching: consumer device driving a Crown D150A

ktm-don

ktm-don

AK Subscriber
Subscriber
I'm adding a recently purchased Crown D150A into my home system. It does not deliver the sound level that I expect when driven by my computer sound card or a Bluetooth to RCA box.

I researched the topic a little, and of course Crown specifies exactly what it expects on the input. The manual states that 1.19V input signal will deliver 80WPC into 8 ohms. From my research, that looks like the pro audio +4 db line input standard. I've read that consumer devices use a lower level than pro gear, I've seen this referred to as -10 db level.

I've found a couple of level shifters, which seems like a simple enough device. But the units I'm seeing cost more than I paid for the D150A, such as the Radial J+4 signal level driver for $249. I do not have a separate preamp, as I usually listen to all content from my PC, either Internet radio or lossless files that I've ripped from CD. The D150A does not have 'gain' adjustments on the back like some models did.

If anyone has experience stepping signals up from consumer to pro line levels, I'd love to hear about how you accomplished it.
 
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easy way is to just add a preamp into the mix.

If you're up for some DIY, something like this would easily do it. Need to add a power supply, which Rod also sells boards for. The one I have runs a subsonic filter and runs from a simple AC wall wart that I got at a flea market.

Minimalist Discrete Hi-Fi Preamp

ESP Project Pages - Minimalist Discrete Hi-Fi Preamp. Visit my other pages for even more!
sound-au.com sound-au.com

can leave off the input selector and probably the output pot. If the gain is too much or too little you can play with R5 to get it where you need it to be.

or honestly most any stereo preamp should be able to provide enough gain to make this work. Computers and BT modules seem to have fairly lame output, somewhere in the 0.25 volt range just based on the stuff I've worked with. I had to use an op amp deal to add enough gain to a BT module I put in a car radio. It worked fine but I'm thinking you probably want something a little better quality than a $7 Amazon board that I have paired with a $1 bluetooth module in an 80s Ford radio.
 
ktm-don said:
I'm adding a recently purchased Crown D150A into my home system. It does not deliver the sound level that I expect when driven by my computer sound card or a Bluetooth to RCA box.

I researched the topic a little, and of course Crown specifies exactly what it expects on the input. The manual states that 1.19V input signal will deliver 80WPC into 8 ohms. From my research, that looks like the pro audio +4 db line input standard. I've read that consumer devices use a lower level than pro gear, I've seen this referred to as -10 db level.

I've found a couple of level shifters, which seems like a simple enough device. But the units I'm seeing cost more than I paid for the D150A, such as the Radial J+4 signal level driver for $249. I do not have a separate preamp, as I usually listen to all content from my PC, either Internet radio or lossless files that I've ripped from CD. The D150A does not have 'gain' adjustments on the back like some models did.

If anyone has experience stepping signals up from consumer to pro line levels, I'd love to hear about how you accomplished it.
Click to expand...
Buy yourself a Henry Engineering MatchBox and be done with it. Easy Peasy, problem solved. Used by broadcasters for IHF to Pro balanced and back again.
 
Thanks to all for the useful replies. Not to start another line of comments, but I will be picking up an IC150 (exact model unsure) shortly. That will probably be all I need in my home system.

I have another application where I think the D150 would work well, another computer-based sound system in a 40 x 30 workshop. I'll look at these options. The Series II mod looks attractive, as I will probably be buying a second amp and can look for Series II. The amps seem to be plentiful on Ebay these days.
 
Being a Crown Power amp fan I also owned an IC150 and later the slightly better IC150a. My advice is look elswhere than the near 60 year old IC150.
 
FONSguy said:
Being a Crown Power amp fan I also owned an IC150 and later the slightly better IC150a. My advice is look elswhere than the near 60 year old IC150.
Click to expand...
I appreciate the advice, but the IC150 part of a package deal from a friend that makes it practically free. It may be a 150A, not sure.
 
ktm-don said:
I'm adding a recently purchased Crown D150A into my home system. It does not deliver the sound level that I expect when driven by my computer sound card or a Bluetooth to RCA box.

I researched the topic a little, and of course Crown specifies exactly what it expects on the input. The manual states that 1.19V input signal will deliver 80WPC into 8 ohms. From my research, that looks like the pro audio +4 db line input standard. I've read that consumer devices use a lower level than pro gear, I've seen this referred to as -10 db level.

I've found a couple of level shifters, which seems like a simple enough device. But the units I'm seeing cost more than I paid for the D150A, such as the Radial J+4 signal level driver for $249. I do not have a separate preamp, as I usually listen to all content from my PC, either Internet radio or lossless files that I've ripped from CD. The D150A does not have 'gain' adjustments on the back like some models did.

If anyone has experience stepping signals up from consumer to pro line levels, I'd love to hear about how you accomplished it.
Click to expand...
I use a inexpensive (at least at the time I purchased it), but has very low indicated THD+N ratings adjustable level booster from the MCM (now absorbed by Newark electronics.com for nearly 10 yrs. to boost my movie/DR/DVD OPPO BDP-103 player`s analog L/R output to better match my all day playing digital music from another OPPO , both feeding their audio into my whole house`s audio distribution setup.
It`s about the size of a cigarette pack using a SMPS wall wart.

Here is the device`s pdf manual attached for your examination .

WHOOPs ! the new A/K "super duper questionable in capacity AK Server" exclaims it`s too large to attach TO POST the small manual !

There are two model/stock numbers for this IMO/E very satisfactory 24/7/365 operating device.

MCM`s original custom stock # 50-14820, and now Newark electronics.com current stock # 2365839.

Search wherever with those numbers, and find the specs, and your best price, if interested !
Good luck to the OP`s results
 
About 15 years ago when I was using portable devices as system inputs, I had trouble driving my receivers. What I did was use a headphone amplifier between the portable device and the receiver. I could then adjust the volume of the headphone amp to the level I desired. Worked like a champ. And it improved the SQ a bunch.

it was low cost solution 'cuz I used a JDS Labs CMoy HP amp with a wall wart power supply.
 
RTally said:
About 15 years ago when I was using portable devices as system inputs, I had trouble driving my receivers. What I did was use a headphone amplifier between the portable device and the receiver. I could then adjust the volume of the headphone amp to the level I desired. Worked like a champ. And it improved the SQ a bunch.

it was low cost solution 'cuz I used a JDS Labs CMoy HP amp with a wall wart power supply.
Click to expand...
Won't work and do so properly. Follow Crown's advice, or better yet buy a Henry Matchbox if using a consumer preamplifier. Balanced line on the Crown, have to properly address the difference between -10 IHF and +4 or +8 Balanced line input/output. My solution does not involve removing the covers. Henry Matchboxes are cheap used.
 
Any consumer grade electronics, like headphone amp or preamp, will only put out a consumer grade signal of -10dB. You will need a line balancer/unbalancer to get the signal from -10dB to +4dB. I have 3 Crown XLS 402 amps in my HT setup feeding my front, rear and rear surround speakers. All driven off my HT receiver. I am running the RCA outs from my receiver into the inputs on a balancer/unbalancer and Mic cables out to the inputs of my Crown amps. I have the output gain set to max on my HT receiver and the gain knobs on the balancers all set to max. While listening at normal volume levels, I have the receiver set at about -50. I also have the gain knobs on my amps set to only the 12:00 position. My receiver volume level goes from -70 to +10. So I have TONS of headroom. Check out the ART Cleanbox Pro. It will do exactly as you need it to do to connect a consumer grade device to a Pro amp and get that -10dB signal to the +4dB signal that the amp wants.
 
KentTeffeteller said:
Won't work and do so properly. Follow Crown's advice, or better yet buy a Henry Matchbox if using a consumer preamplifier. Balanced line on the Crown, have to properly address the difference between -10 IHF and +4 or +8 Balanced line input/output. My solution does not involve removing the covers. Henry Matchboxes are cheap used.
Click to expand...
I disagree. Also, based on what I can find on the interwebs, the Crown D150A has unbalanced inputs.

The issue is the OP's sources are not driving the Crown at the appropriate voltage levels. Sure, the Matchbox will work and is a good option. But there are other options. The source needs to be amplified to a level appropriate for the Crown. A headphone amp (with an adequate power supply) does exactly that, with the HP amp proving an output level suitable for the Crown. Considering that the OP is using a Bluetooth receiver to drive the unbalanced inputs on the Crown, a HP amp is a low cost option that will give SQ commensurate with the quality of the HP amp.
 
You think you have problems think about amps with 2.5 and 3.4 volt input sensitivities. THat said I used DC 150 A's for many years driving my super tweeters tri-amped. but I was using a professional crossover, and equalizers that could give added gain if needed. But my preamps and processors were rated with 2.5 volt out put with 12 volt capability before clipping. THe are many solutions of course. Maybe you need tone controls or a program EQ that could provide the extra gain.
 
ktm-don said:
I researched the topic a little, and of course Crown specifies exactly what it expects on the input. The manual states that 1.19V input signal will deliver 80WPC into 8 ohms. From my research, that looks like the pro audio +4 db line input standard. I've read that consumer devices use a lower level than pro gear, I've seen this referred to as -10 db level.

I've found a couple of level shifters, which seems like a simple enough device. But the units I'm seeing cost more than I paid for the D150A, such as the Radial J+4 signal level driver for $249. I do not have a separate preamp, as I usually listen to all content from my PC, either Internet radio or lossless files that I've ripped from CD. The D150A does not have 'gain' adjustments on the back like some models did.

If anyone has experience stepping signals up from consumer to pro line levels, I'd love to hear about how you accomplished it.
Click to expand...
That's partly true, but the two levels are measured using different reference levels for 0dB, ie dBu and dBV.
+4dBu is 1.228 volts and -10dBV is 0.316 volts, and the difference between them is 11.8dB, not 14dB (confusingly).
You can read more about it here:

Line level - Wikipedia

en.wikipedia.org en.wikipedia.org
Anyway, there's no guarantee that your computer sound card or Bluetooth-to-RCA box conform to any particular standard.
KentTeffeteller said:
Won't work and do so properly. Follow Crown's advice, or better yet buy a Henry Matchbox if using a consumer preamplifier. Balanced line on the Crown, have to properly address the difference between -10 IHF and +4 or +8 Balanced line input/output. My solution does not involve removing the covers. Henry Matchboxes are cheap used.
Click to expand...
+4dB and -10dB refer to voltage levels and have nothing to do with whether or not the inputs are balanced or unbalanced. It's perfectly possible to have a +4dB signal on an unbalanced input.

There's really nothing very complicated that's required here. Any preamp with gain of about 10dB or more (which is practically any active preamp) will do the trick.
Alternatively, the input sensitivity of the Crown can be changed to 0.775V according to the information on this page:
www.kenrockwell.com

Crown D-150A Series II Review & Lab Measurements by Ken Rockwell

Crown D-150A Series II Review & Lab Measurements by Ken Rockwell
www.kenrockwell.com
"There's an internal jumper to increase the gain to 0.775 V sensitivity."
 
rothwellaudio said:
That's partly true, but the two levels are measured using different reference levels for 0dB, ie dBu and dBV.
+4dBu is 1.228 volts and -10dBV is 0.316 volts, and the difference between them is 11.8dB, not 14dB (confusingly).
You can read more about it here:

Line level - Wikipedia

en.wikipedia.org en.wikipedia.org
Anyway, there's no guarantee that your computer sound card or Bluetooth-to-RCA box conform to any particular standard.

+4dB and -10dB refer to voltage levels and have nothing to do with whether or not the inputs are balanced or unbalanced. It's perfectly possible to have a +4dB signal on an unbalanced input.

There's really nothing very complicated that's required here. Any preamp with gain of about 10dB or more (which is practically any active preamp) will do the trick.
Alternatively, the input sensitivity of the Crown can be changed to 0.775V according to the information on this page:
www.kenrockwell.com

Crown D-150A Series II Review & Lab Measurements by Ken Rockwell

Crown D-150A Series II Review & Lab Measurements by Ken Rockwell
www.kenrockwell.com
"There's an internal jumper to increase the gain to 0.775 V sensitivity."
Click to expand...
All great points. And duly noted!
 
rothwellaudio said:
That's partly true, but the two levels are measured using different reference levels for 0dB, ie dBu and dBV.
+4dBu is 1.228 volts and -10dBV is 0.316 volts, and the difference between them is 11.8dB, not 14dB (confusingly).
You can read more about it here:

Line level - Wikipedia

en.wikipedia.org en.wikipedia.org
Anyway, there's no guarantee that your computer sound card or Bluetooth-to-RCA box conform to any particular standard.

+4dB and -10dB refer to voltage levels and have nothing to do with whether or not the inputs are balanced or unbalanced. It's perfectly possible to have a +4dB signal on an unbalanced input.

There's really nothing very complicated that's required here. Any preamp with gain of about 10dB or more (which is practically any active preamp) will do the trick.
Alternatively, the input sensitivity of the Crown can be changed to 0.775V according to the information on this page:
www.kenrockwell.com

Crown D-150A Series II Review & Lab Measurements by Ken Rockwell

Crown D-150A Series II Review & Lab Measurements by Ken Rockwell
www.kenrockwell.com
"There's an internal jumper to increase the gain to 0.775 V sensitivity."
Click to expand...
Yep, the Series II (dark faceplate) does have provision for changing the sensitivity. I have the older 150A Silver. And I think the original 150 had gain pots.
 
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