Pro-Ject Phono Box MKII - How do I turn down the gain?

[Chris R]

One or two of you might have read the recent thread on the issues I was having with my Rega P3 turntable, phono amp, M-Audio sound card, computer, etc.

When the dust settled it turned out the problem was the Pro-Ject Phono Box Mk I. So I was upgraded to the Pro-Ject Phono Box Mk II at cost and was happy.

The first LP needled drop through the new phono amp was Steve and Kevin's recent Nat King Cole After Midnight 2 LP set. Turned out very nice, though I noticed on a couple of songs that the audio peaked over zero. Wasn't sure why. So I just left it.

Next up, I attempted a Capitol Canada stereo Twist And Shout LP needle drop. Every song was "pinging" into the red in Cool Edit Pro. :eek: (Input thru Windows 2000 and the M-Audio Revolution sound card was/is set to the lowest levels.)

I thought something must be wrong. :confused:

I began an E-mail dialogue with Kurt Martens, president of Essential Audio Corporation, the Canadian distributor of Pro-Ject.

At first Kurt thought I might have accidently set the box to MC (moving coil) position. That actually was the first thing I checked when I noticed the hot levels. The box is correctly set to MM (moving magnet).

This morning I sent two screen captures from Cool Edit Pro of The Beatles - "I Should Have Known Better", stereo U.K. LP needle drop to Essential. The first cap is from a needle drop through the original Phono Box MkI, peaking around -4, -3, from about a year ago. The second cap was from a needle drop this morning, peaking between I'm guessing +1, +2, even higher. Think about the screen cap Steve showed us of the difference between the analogue and digital RHCP new album. Well, it's not quite that severe. :)

When I arrived home this evening, I found this E-mail.

Dear Chris,

Thanks for sending the screen captures. This showed us exactly what is going on :

The gain (amplification factor) of the new Phono Box Mk II is 40dB for the MM input (see technical specifications on the Pro-Ject website or in your user manual). The previous model Phono Box (Mk I) had a 32dB gain for MM. This means that you now have 8dB more gain than with the previous model (as shown clearly on your screen captures) which explains why it plays considerably louder.

There is therefore nothing wrong with your Phono Box Mk II. It performs exactly according to specifications. The higher gain is actually one of the improvements that was incorporated in the new design because it provides better compatibility with a wider range of cartridges and the line inputs of most current receivers/amplifiers/preamplifiers (which it is designed to be used with).

If your recording software or soundcard does not allow you to adjust the recording level any lower than it is right now, I'm afraid there aren't that many options.

The only other possibilities would be to either change your cartridge to one with a lower output (I don't know which cartridge you are using right now and what its output is), or change to another phono stage with less gain. Within the Pro-Ject range your options would be either the Phono Box SE (36.5dB gain on MM, M.S.R.P. $349.00, applicable taxes not included) or the brand new Tube Box Mk II (32dB gain on MM (which is the same gain as your previous Phono Box Mk I), M.S.R.P. $399.00, applicable taxes not included).

I hope this information was helpful...
______________________________

NIce to know the new Phono Box is working to spec, which was kind-of what I thought was going on. I also spoke to Dave the owner of Loyalty Sound where I purchased the box and he thought the same. Is 40dB really better? I thought "louder is better" was only used by some current CD mastering engineers.

Can't afford to upgrade to the Phono Box SE or the Tube Box Mk II. Dave/Loyalty suggested I purchase a pre-amp. Don't have the big bucks. I supposed I could run the Rega P3 thru the Phono Box, thru to my Nak BX-2 cassette deck and then into the sound card. I could control the input level thru the cassette player. Not a great solution though. :sigh:

BTW, the cartridge on the Rega P3 turntable is red Bias 2.

Is there a way to turn down the record input level in Windows 2000 or thru the M-Audio card, or configure the sytem differently so I can control the input level to the computer? Or maybe I can find a decent inexpensive pre-amp somewhere. :help:

Thanks.

[AudioEnz]

When you're recrding into a analog-to-digital convertor, you need some way to control the level going into the ADC. Otherwise you're risking going over zero (distortion and clipping) or having the level too low.

I have a M-Audio usb device (I think it's called Audiophile) in house and had the same problem as you. I eventually had to use the pre-outs on my Plinius integrated amp to control the level when doing needle drops.

I also have a Griffin iMic, which is almost certainly not as good as the m-Audio Audiophile, but at least its gain can be controlled through a prgram such as Audacity.

You really need something like a preamp to control the gain. Otherwise you will always have problems with your cmbination of equipment.

[Curiosity]

Actually, there is a simple answer to this. What you need is a 10 K dual ganged potentiometer, some screened wire and 2 x 2 phone sockets. You use the wire to connect the first pair of sockets to the ground and middle contact on each section of the potentiometer. That is for the input. And do the same thing but this time between the upper contact and ground of the potentiometer to the second pair of sockets (output). If you're feeling like it, put it in a small plastic box. What you have made is a variable output control which will allow you to set the output level of your phono box to suit the input sensitivity of you PC's sound card.

I use one all the time because my Williamson-Hart K1450 phono stage has a 2 -3 volt output which is great for my Rotel amp but too much for my Sony Minidisc's line input.

Problem solved.

Regards,

[dgwalizer]

I solved this problem by purchasing a preamp from TDL Technologies (http://www.tdl-tech.com/index.html) that is made specifically to drive a computer's sound card. They have RIAA versions as well as versions for setting proper equalizations for 78s and older (pre RIAA) LPs and 45s. I find the variable output control to be a necessity for getting just the right signal to my sound card. I have also used the preamp in my audiophile sound system and am extremely impressed. This is a very high-quality piece of equipment!

[serendipitydawg]

If I were in your shoes I would investigate the possibility of turning down levels within Windows. I don't have direct experience of Windows 2000, but I know for a fact that it is possible to do so in Windows XP