Phono gain for AT95 pickup?

[Cobra Dave]

I have a Project Phono box S and AT95e pickup.

According to the phono manual a recommended input gain for MM pickup is 40 dB.

I tried this, and then 43 dB instead, and I thought it sounded better. Not only louder, but fuller. I then tried 60 dB and the sound got even better. No problem what so ever with background noise, high clicks or pops, the music just expand through the room and sparkles.

When I change back to 43 the sound gets thin, and if I increase the volume on the amplifier the music just get annoying loud!

I thought that it was best to not pressure the simple phono too much, and let the amplifier (Boazu) do the amplifying job instead. But the gain setting on the phone does not only change volume, but sound quality too according to me.

Have someone experienced the same with this phono/pickup combination, or can someone explain the reason for this?

All best!

[lejonklou]

That's an interesting one, Cobra Dave!

I have no experience with this particular phono stage, but if it has a gain that can be varied, there's usually one setting that sounds best and the others will sound worse. That is often regardless of cartridge and simply an intrinsic property of the circuit of the phono stage. It's been tuned to (or it happens to) sound best at one particular gain and the others were added later.

60 dB is a lot for an MM cartridge, so the volume on your Boazu should be 20 steps lower to keep the volume the same (compared to the 40 dB setting). Does that seem to be the case?

If there's no distortion (overload) in the phono stage, it makes sense from a theoretical perspective to make the amplification early in the chain. So I say Rock On! But be prepared there might come a record where the phono stage hits its rails, which will sound like a crack or a plop or simply like a note was cut off.

[Ron The Mon]

Cobra Dave,
Are you currently talking about your Axis with AT95E or your new LP12 with AT-VM95E?

The older AT95E body (for over 30 years) has an output of 3.5mv. The new AT-VM95E (for past 13 months) has an output of 4.0mv.

If you are talking about the older version, be prepared for a shock when the new one arrives. One-half a millivolt doesn't sound like much but in context of your hi-fi, it is a lot louder!

Fredrik Lejonklou is correct; setting your phono stage as loud as possible before audible distortion will result in best performance.

Ron The Mon

[lejonklou]

Fredrik Lejonklou is correct; setting your phono stage as loud as possible before audible distortion will result in best performance.

I didn't say that. I say that there's one gain setting that will sound best and that's an intrinsic quality of the circuit in the phono stage. Cobra Dave found that the loudest setting is the best one in this case, but it doesn't have to be. In a different phono stage it could be another one. That it happened to be the loudest is probably a good thing.

I've had a number of requests from vinyl freaks for a specific gain that they think will suit their system. It's been both lower and higher than the fixed one that I use. Recently a guy wrote that he wanted to order a Slipsik 7 with a gain of 40 instead of 41 dB and a while back another guy wanted a Gaio with 50 instead of 40 dB.

Each time I tell them that it's not a problem for me to change the gain, but it will not sound the same. There are two ways to decrease the gain - by decreasing some of the gain already present in the circuit or by adding a step that lowers the signal - and both makes the phono stage loose dynamics and sort of holds the music back a little. It becomes boring. To increase the gain I can simply add some more in one or several parts of the circuit, but that will make the music nervous and more focused on attack than decay, which is tiresome to listen to.

Every circuit has a balance and the gain is one of the parameters that establishes this balance. If the goal is optimal musical performance, it can't be set arbitrarily without changing many other things at the same time. This is why SINGularity and Entity has such a high gain (which makes them unsuitable for cartridges with more than 0.4 mV of output) - the circuit required that to sound at its best.

To make the gain variable without negative consequences, one needs to design the circuit specifically for that task. I would call that a volume control.

[Cobra Dave]

60 dB is a lot for an MM cartridge, so the volume on your Boazu should be 20 steps lower to keep the volume the same (compared to the 40 dB setting). Does that seem to be the case?

Yes, that is the case indeed. Earlier I had to crank up the volume on the Boazu when played LP compared to digital music, now it is the other way around. With the 60db setting on the phono I use about 20 levels of lower volume on the Boazu.

I think this is interesting because I have never really tried but just got in to Tune dem. And now suddenly with the 60db setting on the phono I can stand in another room and suddenly on very low volume "hear" how good a song is. It has happened several of times the last days with songs that I have never heard before. And songs that I do have heard a lot of times before suddenly sounds more pleasant, as if the pickup picks up more music. I think and hope that this is a combination of phono setting and new player (Linn Axis instead of Linn Basik). And I am confident that I will experience even more of this when I get my Majik LP12 delivered. :)

[Cobra Dave]

Cobra Dave,
Are you currently talking about your Axis with AT95E or your new LP12 with AT-VM95E?

The older AT95E body (for over 30 years) has an output of 3.5mv. The new AT-VM95E (for past 13 months) has an output of 4.0mv.

If you are talking about the older version, be prepared for a shock when the new one arrives. One-half a millivolt doesn't sound like much but in context of your hi-fi, it is a lot louder!

Fredrik Lejonklou is correct; setting your phono stage as loud as possible before audible distortion will result in best performance.

Ron The Mon

It is still my old AT95E, the new AT-VM95 has not been delivered yet.
Thank you for heads up about AT-VM95 beeing louder. I might set it down to 43 again when the AT-VM95 arrives, but as I am experiencing better sound quality not only louder volume I think that I will use the 60 db setting if possible. I really like Lejonklou's comment that it could be that the phono sounds best at this setting, and that everything else is a compromise.. There is actually a 63 db setting too, I might just rock on all the way there.

[Ron The Mon]

Fredrik Lejonklou is correct; setting your phono stage as loud as possible before audible distortion will result in best performance.

I didn't say that...

Fredrik,
I agreed with Cobra Dave, adding you were correct; I will be more careful in my framing of words.

...There are two ways to decrease the gain - by decreasing some of the gain already present in the circuit or by adding a step that lowers the signal...

There is a third way; which Cobra Dave's Pro-Ject uses.

The Pro-Ject is an op-amp MM/MC stage which uses DIP switches for gain adjustment and loading. Pro-Ject recommend the 40db setting for moving magnet. The capacitive and resistive loading of the this circuit is adjusted independent of gain.

The three gain DIP switches only affect the second (of two) amplification stage. They simply increase the feedback resistance, increasing amplitude. There should be no overload in the phono amp itself. Each op-amp device probably has 40db of gain, leaving a lot of headroom. What's interesting to me is what Cobra Dave has heard. The first DIP switch turns on and off 43db, the second turns on and off 63db. The third DIP switch disconnects a parallel resistor for a 3db trim allowing the 40 and 60db settings.

I would guess 63db sounds best (as that is how it was originally designed), then 43db, then 60db, and lastly 40db. Usually, the less switches, the better the music.

You may be more familiar with this design than you think. Pro-Ject stole the circuit design from Clearaudio. About 15 years ago, Pro-Ject made a through-hole circuit board version where they copied it wrong and it sounded terrible. They also used really cheap low grade components and a wall-wart power supply. And it still sold and was popular! Cobra Dave's model is a really well built surface-mount version with loading options.

Ron The Mon