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New member Username: Tdey1618New York, NY United States Post Number: 6 Registered: Feb-12 | If I have a turntable with built in preamp, such as the AT-LP60 by Audio Technica, do I need to bother with a receiver to connect it to "powered" speakers? What are the pros/cons of connecting such a turntable to a receiver and then to a powered speaker? It seems like there's a lot of power transfer involved that is unnecessary. Lastly, I've tried various scenarios: I've connected the turntable directly to Klipsch 2.1 and M-Audio AV-40s both of which are classified as active or powered speakers. Connecting to the KLipsch gives decent volume, but the turntable barely drives the M-Audio's. So I'm curious about the details of that. Connecting the turntable to a Hitachi KS-2450 then to the Klipsch speakers gives me more power, but not much headroom in the speakers and there is particular electrical noise associated with the receiver phono stage that I'd rather not deal with. I know the speakers I've tried aren't the best in the world for hi-fi listening but I'm on a budget. The turntable directly to the Klipsch gives me the best response thus far so I guess I answered that question myself at least. |
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Platinum Member Username: Jan_b_vigneDallas, TX Post Number: 17153 Registered: May-04 | . TDey, are you still checking this thread? |
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New member Username: Tdey1618New York, NY United States Post Number: 7 Registered: Feb-12 | Yes. |
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Gold Member Username: MagfanUSA Post Number: 2696 Registered: Oct-07 | Jan? Impedance / gain issue? Here is link to AT site w/a TT w/preamp listed as 150mv in 'preamp' mode. I'd recommend a budget phono preamp and some AudioEngine A5 speakers. Forget the TT's preamp......Most powered anything would like 10x the voltage this puts out...in preamp mode. http://www.audio-technica.com/cms/turntables/9a7f42b88ee1e14b/index.html |
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Platinum Member Username: Jan_b_vigneDallas, TX Post Number: 17154 Registered: May-04 | . A powered speaker should need a line level (anywhere from a 0.5Volt to a 2 Volt) signal to drive it to full power - the ampifier section of the powered speaker that is. A phono pre amp, whether built into a pre amp/receiver/turntable or a stand alone, probably won't have quite enough output voltage to drive a power amp directly without some lessening of the amplifier's total output. But some phono pre amps have higher output than others and the built in pre amp of your AT table is on the very low side of normal. Normally I would expect to see an output voltage of about 350mV to 1Volt from a phono stage while many fall beneath even that lower spec. (Noise is generally equal to the amount of gain in a circuit so to keep their noise specs looking good many pre amp manufacturers have lower than normal output voltages.) To drive a power amplifier (without the assistance of any additional gain stages) the phono pre amp would have to be capable of outputting about 3/4 to 1 Volt (750mV to 1,000mV). It appears your table's pre amp is still meant to be run through a line level pre amp - either a stand alone unit or one built into the line level circuits of a receiver (AUX or TAPE INPUT on the Hitachi) - to make up for the low output voltage indicated by the table's on paper spec. The advantage to a powered speaker would be, among other things; you are not buying the unnecessary parts of a power amplifier (chassis, lights, switches, etc.) so cost should be somewhat lower, the cost of cables will be reduced in most cases, and, most importantly, the designer of each component should be using the combination to make for the best system approach to sound quality. The amp can be tailored to the needs of the speaker system and the speakers can make the most of the amplifier's drive capacity. The only real downside to the combined components approach would be the lack of an easy route to upgrade the amplifier. As most active speakers are unable to bypass the built in power amp, what you have is what you will live with as long as you own those speakers. There is no specific advantage to connecting the phono pre amp to a receiver and then to the powered speakers - unless the phono pre amp has such low output voltage that it cannot by itself deliver sufficiently high voltage to drive the speaker's power amp spec. Check the "input sensitivity" spec on whichever powered speakers you intend to use. Input voltage is equivalent to output voltage and the higher the "input sensitivity" of the amplifier, the higher the voltage output your pre amp will have to produce. To drive the powered speakers directly from a phono pre amp, the "output voltage" of the phono pre amp will need to be as close as possible to the "input sensitivity" of the power amp. The further apart they are, the more of a mismatch you'll have as a result. Off hand, I don't know of a power amp that could be driven to full power by the on paper spec of your table's output. I suspect one issue you're having with the two sets of powered speakers you've tried with the turntable would also come down to the electrical sensitivity of the speaker system. http://www.goodsound.com/features/2008_02_01.htm http://www.prosoundweb.com/article/loudspeaker_sensitivity_whats_a_watt_anyway/ So, after you've read those two links, you'll know that one watt of input power (2.83 volts) into a loudspeaker system will result in "X" amount of acoustic output as measured in decibels (dB). Speakers vary in sensitivity - or, in other words, how much volume they put out with each watt of input. Klipsch, as a line, are known as high sensitivity speakers - they play loud for not many watts. Other speakers trade some volume output (sensitivity) for a higher degree of accuracy. I would suspect the M-Audios are simply a lower sensitivity speaker system (and they could have an input sensitivity in the amplifier that is also higher - needs more voltage input - than that of the Klispch). That would translate into less output from the M-Audios no matter the wattage of the built in amp. Both of these systems appear to be computer speakers so they aren't going to provide much more than adequate volume levels I suppose. If you're on a tight budget, the turntable's pre amp into the Klipsch would be your best bet. But this would still be a fairly short term system when funds allow for any improvements. You'll always be limited by the very low output voltage of the AT table - if their on paper output spec is correct. (Specs are funny things that don't always transfer easily from one component to another and possibly AT is measuring their output in a different manner than most other manufacturers.) That would be the first place to improve the system as that would give you more options once you have more output voltage. If you want to stay with powered speaker systems, the AudioEngines are a good choice for a home system. If you have access to a pro music shop, powered speakers have become popular again in that market. There are a few companies which are more focussed on the home studio level of buyer which might make a decent replacement for the Klipsch; http://www.musiciansfriend.com/search/search.jsp?sB=r&question=active+monitors But the basic rules of speaker buying still exists, you'll have to make certain whatever you buy will have a speaker system which has a sufficiently high sensitivity to allow the volume levels you desire. If a (speaker) sensitivity spec isn't included in the description of the speaker system, you'll have to do a bit of research before you plonk down any cash. An audition would be even better. Each +3dB increase in speaker sensitivity is equal to doubling the output of the amp but will result in an increase in volume which is not all that noticeable. In other words, a 25 and a 50 watt amp of equal quality will only play slightly louder with the higher wattage, barely noticeable on music program. Additionally, a speaker rated at 87dB will only play slightly less loud than a speaker rated at 90dB. (Those are pretty general statements due to the amount of fudging the industry allows with specs but, for now, they'll do as a guideline.) You'll have to have an increase of +6dB at minimum to actually sense that one system plays louder than another. Make certain you have the switch on the back of the table's base set to "line". Most power amps are expecting to have about 1 volt of input to reach full power. If the speakers simply won't output sufficient volume and you've checked the input sensitivity of the speaker's built in amp, then I would suspect your pre amp just isn't going to be suitable for powered speakers without an intervening gain stage from either a pre amp or a receiver. . |
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Platinum Member Username: Jan_b_vigneDallas, TX Post Number: 17155 Registered: May-04 | . "Connecting the turntable to a Hitachi KS-2450 then to the Klipsch speakers gives me more power, but not much headroom in the speakers and there is particular electrical noise associated with the receiver phono stage that I'd rather not deal with." The Hitachi should have a "phono" input with a built in phono section. Right? When making this connection you would switch the table's output to "Phono" at the back of the table's base and plug the table directly into the receiver's "phono" input. You could also try the table set to "Line" and plug the table's output into the "AUX" or "TAPE INPUT" of the Hitachi. If you select "TAPE INPUT", switch the receiver's front panel "tape monitor" button on to listen to the table. . |
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New member Username: Tdey1618New York, NY United States Post Number: 8 Registered: Feb-12 | Jan, I tried the "Line" and "Tape" connection and the sound is much better, louder with more headroom. Thanks so much! As far as the other reply. I'm going to past that onto my laptop and go through it in detail. Good knowledge going forward. I wanted to get the Audioengine A5's, but decided to opt for the Promedia's I had lying around. Hopefully in a couple of months I can spring for the A5's. Thanks. |
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Platinum Member Username: Jan_b_vigneDallas, TX Post Number: 17156 Registered: May-04 | . Glad that works for you. Do remember that the "tape monitor" function is one that overrides all other inputs. When the tape monitor switch is engaged, no other source player will be output from the receiver. In other words, if you come home one day and want to listen to something other than your turntable, you might find you have no sound form the receiver. In that case; first, lower the volume level and then disengage the tape monitor switch. . |