Weak Phono Output?

[CapZark]

I have a big Pioneer reciever from the 70s that is realy loud when you plug a CD or tape deck into it, but you have to turn it up twice as much to get the Phono outputs to sound just as loud. The power needles dance around a lot more when using the turntable as well. Using an external phono pre-amp through the Aux produces the same result, but a CD player through Aux is loud. If I plug the turntable into another reciever the phono output is fine. I had it serviced and the guy said it checked out OK. Does anyone have a clue what might be going on here? Thanks in advance for any advice. PS - the sound is sweet, it's just not as loud as my other components.

[Islander]

CD players and sources like them put out "line voltage", which is around 1-2 volts. Turntable cartridges put out much lower voltage, maybe 2-5 milli-volts for a moving magnet and as little as a tenth of that for moving coil cartridges.

With my 2005 Yamaha receiver, I listen to CDs at -25 to -35dB volume settings, DVDs at -21 to -28dB, but records at -10 to -20dB, with a Shure MM cartridge with 4mv output. This is normal. You just have to remember to turn the volume back down after listening to LPs.

Your second receiver may have a phono pre-amp with a lot more gain than the one in your Pioneer, which would explain the difference.

Are you using an MM or an MC cartridge? If it's an MC cartridge, you'll need a higher-gain phono pre-amp. MM pre-amps often have around 40dB of gain, while a typical MC pre-amp would have more like 60dB.

[CapZark]

Thanks, Islander. It sounds like my reciever is OK, which is a relief. I'm using a Shure MC cartridge. I've seen some phono pre-amps with a volumn knob. Is that what I would need to increase the level without cranking up the volumn control on the receiver? Also, would something like that wind up distorting the signal? It sounds like if I go to a MM cartidge that would makes things louder as well. Do MM cartidges sound better than the cheaper MC cartidges? If any of this is true can you recommend a reasonable (under $200) phono-preamp and/or MM cartidge? Thanks.

[DoubleJ]

CapZark:

I'm running into the same exact problem you are experiencing.

My BBX is in Mark's hands to see if there are any issues with its Phono section.

The TT (MusicHall 2.1) works fine connected to my Scot 299c but when it's connected to the BBX LOMC, I have to crank the volume and the gains all the way up just to get an audible sound. A CD/DVD player hooked up to the BBX works fine.

It's frustrating and I'll keep you up to date on my progress as I go along.

JJ

[seti]

You could get a higher gain cartridge or a step up transformer.

[andyo5]

A Shure moving coil cartridge? Are you sure (no pun intended)?

I was unaware that Shure ever made any cartridges other than moving magnet.

What model is your Shure cartridge?

[LarryC]

I don't know of any Shure MC cart, either. Yeah, which model of Shure do you have?

What's the model of Pioneer receiver that you have, and what's the brand/model of receiver you said worked just fine? Those results are contradictory.

Current Shures range from 4 to 6 mv output, which is hefty and should be plenty for any receiver's phono input.

It sounds like your repair person was wrong about the phono input being OK. I wouldn't run around buying anything to "help" until you solve that puzzle. An MC phono stage and perhaps a transformer may not be suitable.

[CapZark]

My apologies, it's a MM cartridge (M97xe). I also have a Audio Technica AT440MLA. They sound about the same. The Pioneer SX-1980 has the weak phono, but sounds really good. I'm not sure why the power meter needles bounce so much either. If you engage the 15hz cut-off button that issue goes away. The other reciever is a Pioneer SX-650 that is as loud as all get out, but not nearly as sweet sounding as the SX-1980. Loud and harsh is the best way to describe it. I just wish the 1980 had a stronger phono stage, then it would be all around fantastic. I will say that since it's been serviced it sounds better than ever, just weak when using a turntable. Any ideas or suggestions would be appreciated.

Here's an update - I just went and really cranked it up (about half way) and the needles really bounce around. On top of that, if you depress the 15hz cut-off the needles start to run away and there is a large loud growing rumble in the subwoofer. If you disengage the 15 hz cut-off things sound better, but still weak for were the volumn is. At this point, my needles are showing between 1 and 10 watts a side. If you engage and then disengage the tone control switch you can get the rumble to come and go. It sounds to me like the phono pre-amp section of my unit is messed up, but I am just a novice when it comes to electronics. As I mentioned, using an external phone pre-amp on the AUX doesn't help much either.

[Islander]

I'm not sure why the power meter needles bounce so much either. If you engage the 15hz cut-off button that issue goes away.

Sounds like you're getting a lot of rumble, but if you can make it nearly disappear by just pressing a button, it's not really a problem. Using the rumble filter may also free up some power to give you a bit more volume. Have you noticed this?

Using a step-up transformer should give you more volume, but it might add a bit of noise. I have no experience with them, so I won't recommend any one in particular.

BTW, I'm using the same cartridge as you, so are those volume numbers I mentioned seeming similar to what you're experiencing?

Hmm, just read your update. Now I'm not sure what to suggest...

[CapZark]

Islander, -10db on my system is about 2 oclock and I've never gone that far with it. With a CD player I can't really bare anything beyond the 10 oclock position. I'm afraid that if I went to -10bd the rumble would blow my beloved Belles to smitherines.

[LarryC]

The Shure M97xe and the AT440MLA both have 5 mv output, and should produce about the same loudness level. (I'd expect the Shure to sound better.)

The two receivers have identical phono sensitivities, 2.5 mv, whatever that means (the specs don't give the gain for either the phono or line stages). So, there shouldn't be a big diff there, either.

I can't figure the needles bouncing around, except I don't think the phono input is working right for the Pioneer SX-1980 because of that plus it produces such a weak signal. Since the 15 Hz filter kills the bouncy-bouncy, I wonder if there's a bad connection at either the phono jack on the receiver or the phono leads from the turntable. Jiggle the leads and jacks while watching the meter needles, and jiggle it where it comes out of the turntable or base of the tonearm. TURN DOWN THE VOLUME when you do this. Maybe if you're lucky, you'll find a bad solder or mechanical joint in the leads.

Which reminds me -- what's your turntable? Are the little (VERY little!) pins on tight at the back end of the cartridge? Don't jerk or pull on 'em. Again, keep the volume turned down or kill the phono input when you fiddle with these.

[CapZark]

Larry, I'm running a Technics SL1200MK2 direct drive turntable. I think all the connections are okay since it seems to work fine with the SX-650. My sub-woofer makes the rumble much worse as does the introduction of any tone controlled bass. Being somewhat of a novice, I don't understand why my external phono pre-amp produces the same results? For some reason this animal likes 1 to 2 volts a lot better then 5 milli-volts regarless of what input I use (Tape, AUX, or Phone). Perhaps, I should try a different turntable as this one my be producing a poor output with lots of rumble, but that still doesn't explain why it cranks loud on the 650. Or could it possibly be the amp section of the 1980 and not the pre-amp section? My tech said the unit is putting out more than 270 watts a side as advertised. I believe that using line voltage, but not even close with a turntable.

[LarryC]

Or could it possibly be the amp section of the 1980 and not the pre-amp section?

I'm not sure how well I'm tracking this, but --.

The amp section is unchanged by any of this and doesn't warrant further discussion.

The pre-amp section would consist of a "line stage" which is fed directly by "line sources" such as CD player, tuner, aux, etc. It's also fed by a separate phono stage, if there is one, if phono is switched on. Thus, the phono stage precedes the line stage.

Moreover, if there is a separate moving coil stage, it precedes the phono stage!

Thus, there is the following daisy chain if you're switched to phono:

• Moving coil electronic pre-preamp stage or transformer (if you have one), leading to the --
• Moving magnet phonostage (if you have a phono input), usually leading to the --
• Volume control, inserted just before the line stage, leading to the --
• Line stage, leading to the --
• Amplifier or amplifier section.

Based on this (I couldn't find a simple diagram to illustrate), you would not expect to find that the line stage is responsible for something screwy with only the phonostage, because any linestage problem would affect ALL sources in the same way.

Thus, the problem pretty clearly is in the phonostage of the SX-1980 or possibly whatever precedes it (like the connections between the turntable and the phono inputs). From what I read, that's the only place you have a problem. Not the linestage or amp section. Unless your other TT works just fine in the SX-1980 .... If it does, we start over.

[CapZark]

Unless your other TT works just fine in the SX-1980 .... If it does, we start over.

Larry, I doubt that a new turntable will change anything, but if I get my hands on one I'll try it. One thing I don't follow is the volumn control in front of the line input. If the volumn preceeds the line input, how is the line input volumn controlled? I don't know if I will ever solve this problem. If I really want to crank up a tune, I record it to a tape deck and then blast it back that way. All the rumble is gone at that point and I can set the record level a litte higher to compensate for the weak phono level. In the end this reciever produces a really nice sound (similar to tubes). I also get a wicked lower end, just not with the phono stage and I guess I can live with that. Everything else works to my satisfaction.

[LarryC]

I erred, you've only mentioned one TT I believe. No, I don't think a different TT will change anything.

How do you record it to a tape deck? Are you saying that the Shure signal makes it through the receiver's circuitry to record on the deck via the "record out" jacks on the back, but not to the speakers? If so, that's a real curiosity, and maybe the problem is in the connection to the phono stage even though the tape deck connection is OK.

I suggest you get some contact cleaner (Deoxit?), pop the top, and spray the heck out of the backs of all the selector switches -- the ones that choose phono/aux/tuner etc. ALSO the one labeled "tape monitor" on the front panel! Then, work all the switches back and forth. Maybe some dirt will come off and everything will work OK. That seems more logical than finding some faulty little transistor by expensive trouble-shooting.

One thing I don't follow is the volumn control in front of the line input. If the volumn preceeds the line input, how is the line input volumn controlled?

It's irrelevant so maybe I should've left it out. As I understand it, the switches for the line inputs (one each for the left and the right) usually feeds the selected signal directly to the volume control without active circuitry. The linestage amplifier is next in the chain after the VC.

If there is a phono stage, it usually precedes the volume control. Thus, the VC controls the volume by controlling the gain of the linestage. If you want a real workout, look at the diagram below! See if you can trace (separately) the TV and phono inputs through the MONOPHONIC Marantz preamp below. The out to the amp (it's only a preamp, not a complete integrated amplifier or receiver) is at the bottom, "To Amplifier." Tube V1 (V1a and V1B) appears to be the only phono stage tube. The signal then goes to the Volume (labeled on the long dotted line), and THEN to the line stage, which is V2 and V3 combined. Note that the treble, bass, and loudness are naturally worked into the line stage, since those apply to all inputs across the board.

Anyway, sorry for the complicated pic. As I said, I couldn't find a simple block diagram.

[CapZark]

Thanks, I see how that works in the diagram. In regards to the recording, the phono output has always made its way to the speakers, it's just not as loud as the line signal. I can record the phono stage and just boost the recording level with the tape deck. When I play the tape, I get the higer gain (although it's probably a bit distorted, it still sounds fine). All the rumble as noted earleir in the thread disappears since the signal is now coming from a tape and not the TT. For some reason my TT produces a lot of rumble, but again, I think its the way the reciever is processing the milli-volt signal (rumble and reduced gain). I'm just not sure were that problem is occuring, but my guess is that its in some circuit board somewhere since everything else works fine and my tech couldn't find anything wrong with the phono stage. In addition, some of my controls were cutting in and out, but my tech fixed all that when it was serviced. There are no issues with any of the controls now.

[LarryC]

Maybe not likely to do any good, but I'd still consider spraying the switching controls front and rear with a contact cleaner like Deoxit from Radio Shack. Sorry you're having this trouble.

[CapZark]

I appreciate the help, Larry. Thansk for the diagram too.