[claytontstanley]

Hey everyone,

I just got into vinyl, bought a pro-ject xpression III turntable, and absolutely love it. However, I'm loving it a lot more lately, after I made a change to my wiring setup a few days ago that greatly reduced the amount of distortion I hear in the loud moments. I'm using a Phono Box II preamp, and I originally plugged the RCAs from the preamp into the tape input on my receiver. But a few days ago, I moved the wires and plugged them into the CD input on my receiver. Immediately afterwards a lot of the distortion I had been hearing in loud moments dissapeared.

I wouldn't think that such a change would make a difference, as I was under the impression that all line inputs on receivers are the same. I have a Marantz sr5002, and during the time that I had the wires plugged in to the tape input, it was actually blinking red every once in a while, telling me that the amp had hit the rails. After I moved the wires to the CD input, no more blinking red light, and much less distortion. Also, I'm bypassing the EQ for both the tape and cd inputs, so no processing is being done in the receiver.

So, it seems to be the case, that at least for my setup, the line input on the receiver that the preamp is plugged in to can affect the quality of the sound.

I'm wondering if this generally applies to all setups. That is, is there something in the specification of CD vs Tape vs DVD RCA inputs that defines different acceptable voltage ranges for these inputs? If so, this could be what's causing the distortion in only the tape input.

It may be the case that this only occurs for my setup, which is fine. I'm happy with the sound now. But if it does apply generally for all setups, I would think this would be an interesting item to discuss.

Any thoughts anyone?

Thanks for your time,
-Clayton

[neobop]

Hi,
The tape input is actually part of a tape loop with recording/playback facilities. This can be configured differently in preamp sections, but in general is the reason you're overloading that input. 

[claytontstanley]

Hi,
The tape input is actually part of a tape loop with recording/playback facilities. This can be configured differently in preamp sections, but in general is the reason you're overloading that input.

Thanks. This makes perfect sense. I can't tell the difference between any of the other inputs (CD, DVD, etc.). It's only the tape input that causes a large amount of distortion, so it 'sounds' like the tape input is the one that's not like the others. Good to get some solid theory to back up what I'm hearing.

This does raise a question though. When I move the input from tape to CD (or DVD) the distortion is reduced, not completely eliminated. This leads me to wonder if I could reduce the distortion even more if I could manually adjust the Gain of the phono preamp (push it down just a bit). I have an entry-level preamp, the Phono Box II. Are there more sophisticated preamps out there that allow me to adjust their gain, or is this something that I shouldn't be playing with?

Thanks,
-Clayton

[neobop]

Well, by decreasing the output from your phono section, you would only reduce distortion if your present levels are overloading or saturating the high level input on your amp. I think this is unlikely, but not impossible. Do you need less gain on the phono than other sources like CD? Also, having less output from phono will decrease the S/N ratio and make it more likely that the red lights will flash because the signal is too low and the amp is running out of headroom. 

Perhaps at this juncture, you would benefit more from reducing distortion from the record player. Things like cartridge alignment and clean records make a dramatic difference. Maybe a record cleaning machine would be a better investment now. At a distance, it's hard for me to know exactly.

EDIT:
After rereading your last post, I realized that I didn't answer your question. Yes there are other phono preamps with adjustable volume. They are not necessarily more expensive. It's better not to have an extra volume control if you don't need it. I'm not really familiar with it, but I've read that the one you have now is very good in its class.

[claytontstanley]

Well, by decreasing the output from your phono section, you would only reduce distortion if your present levels are overloading or saturating the high level input on your amp. I think this is unlikely, but not impossible. Do you need less gain on the phono than other sources like CD? Also, having less output from phono will decrease the S/N ratio and make it more likely that the red lights will flash because the signal is too low and the amp is running out of headroom. 

I can't tell if the phono source has more/less gain than other sources, so it's close. Hard to compare though, since I have to use different media to do it. But I do know that no more red lights are flashing (after I switched from using the tape input to the CD input), so I'm going to bet that the gain is just about right where it should be. So, it seems that the distortion left is being not being caused by the gain stage, and (like you suggested) is most likely being caused by dirty records / cartridge issues.

Thanks for your direction on this one. Probably saved me some serious cash and time in the long run.

-Clayton

[claytontstanley]

I wanted to add a few comments about line voltage range that I've learned after swapping out my preamp.

When I posted this message originally, I was using a pro-ject phono box II preamp (pro-ject's entry level preamp), a sumiko entry-level MM, and a Marantz power amp. For comfortable listening, I usually had the Marantz set at -42, and even after moving the preamp output from the tape input on the Marantz to the DVD input, the receiver would still hit the rails every once in a while (causing an unpleasant harshness in the sound).

I just switched to pro-ject's phono box SE II preamp, and the Marantz no longer hits the rails. In fact, my new comfortable listening volume on the Marantz is about -25, which means that the phono box SE II's output has a much lower gain than the phono box II.

Usually that would be a bad thing (due to S/N), but I think the phono box II had the gain set too high (or at least too high for my MM & receiver equipment), so lowering the gain a bit was the right thing to do.

Based on my experience with the phono box II, I wouldn't recommend purchasing it. I'd instead pay a little more and get the phono box SE II. The phono box really does seem like a toy compared to the phono box SE.

-Clayton

[analognut]

Noone seems to have caught this, so here goes:

The reason you had problems with your tape loop is because you were using it incorrectly. You said you switched from your tape inputs to your CD input. You should have tried the tape outputs. If you look at the tape machine as a playback device you were using the wrong side of the tape loop. Any device which can play into a CD input will also play correctly at the tape output, but most definitely won't work at the tape input! 

[neobop]

Err..... I don't think so. My video receiver died, and I happened to replace it with a used Marantz 4500. Hard to tell exactly what's going on but I think the tape input/output is pretty straightforward. I have a computer plugged into a tape input, and it works OK. Not sure if it will work at all in the tape out.

Claytontstanley,
Even though your gain was greater with the lesser phonobox, was it louder than a CD player after you switched?
The amount of headroom on the different inputs seems to vary somewhat but it's really designed for digital sound processing. The flashing red light alerts you when you're overloading the input. If subsonics or ultrasonics are present in the output of the phonobox, this could happen easily, at normal listening levels. Did you hit the ATT button when the lights flashed? This attenuates the input level by about 50%.

Whatever, good to hear that you got the better sounding unit now. Enjoy.
neo

[analognut]

I thought he was saying he had used the Rec side of the tape loop, but maybe I was wrong about that. My Yamaha CX-1 preamp has 3 tape loops with the jacks labeled Rec and Play to keep guys like me from getting confused! 

[claytontstanley]

Thanks for the help & comments.

I tried hooking it up through the tape output (my receiver only has a tape intput/output) and nothing came out of the speakers. The tape input works just fine now though, since the phono box se has a lower gain than the phono box.

But, after realizing how much the preamp actually influences the sound of the music, I stopped dabbling and just bought a Graham Slee Reflex M. This is going to be a long two-week wait!

-Clayton