Why have we been so quiet? Because we were busy, making a few adjustments on our Purist preamp. Let me share what has happened at IRD and to the Purist over the past few weeks ...
The Summary - So how does Purist rev(1.01) sound?
The same definition and detail as before with improved attack transients, reverberations, and decays. Very good tonal balance and accurate timber, piano is superb - slightly more real than before. Very alive sounding with liquid textures, smooth extended upper frequencies, no signs of strain at any volume level or gain setting. Very fast and transparent.
This revision makes the Purist experience more exciting and involving. Notes hang still in the air above the instruments reverberating nicely as they decay away. I don't remember this being so vivid before.
The soundstaging seems a more defined with excellent layering, maybe a little larger, and rock solid stable at any gain/volume setting (no shifting at all between gains). When sitting in front of the preamp changing gains (to see if the sound stage shifted) I was absolutely on center stage (very cool) with the band just in front of and all around me. Gave me goose bumps.
One more thing, while testing I became even more aware of how nice a step ladder VC is. To have such precise channel tracking has become a must have for me. To change volume levels and have the image remain rock solid is addictive, I don't believe I could never go back to pots.
The Whole Story:
It's been an interesting month here in Thailand. Just when we thought the Purist preamp was at its best we have managed, with the help of golden ear Purist owners, to raise the bar a few more notches.
I recently helped a few customers gain match their high-gain/ high-efficient systems, with our Purist preamp, by devising a gain reduction modification (called Mod #1) for them. Shortly after Mod #1 was implemented I received some interesting feedback, I was told that that Mod #1 not only lowered the gain but also improved the soundstaging at the 0dB setting. That the Purist sounded better at the 0dB gain setting was to be expected but that it effected the soundstaging was a surprise.
I was told the higher gains remained unchanged but the new 0dB gain setting definitely offered an improvement, a more laid back soundstaging, less forward. I had to experiment around before being able to reproduce this effect. With the right speakers and music material it became easy to reproduce this in our listening room. The effect could be subtle to moderate depending on the system configuration but it was definitely there.
I kicked off a series of critical listening and serious measurement sessions here at IRD. The new 0dB gain setting was what we were currently using but I had not done any serious switching back and forth (gain), A/B testing. I was able to hear the effect reported but could not measure any differences. Don't you just love high-end audio, you really have to trust your ears.
After a few days of simulations, lab work, and listening I discovered that the 0dB gain position had revealed a subtle interaction between the DC servo and the precision gain stage.
The servo was also slightly loading down the precision gain stage, just enough to be heard when in the +6 & +9.5dB gain setting positions. The gain stage was just starting to strain and this effects the sound. This was what was causing the difference reported when listening at the new 0dB setting.
To get to this start to strain point produces the least amount of system noise but if the sound is effected backing off just a little does no harm and adds very, very little noise, not even measurable.
I decided to standardize on 0/+6/+9.5dB gain since +12dB is rarely if ever needed then re-balanced the new gain settings with the DC servo and listened some more. I tweaked the precision gain stage loading by ear until I thought I was getting everything the gain stage could give; I was quite happy with how well everything integrated together at the lower gain settings.
We re-designed the silk-screen and made new faceplates. This revision is now our standard production model and is called Purist (rev 1.01). We will have stock, by air, in Charlotte in 10 days.
All existing Purist owners can update their Purist for FREE (new faceplate included) in Charlotte NC and internationals in our Bangkok Thailand factory.
Let me add that our goal is to produce fine audio components for music lovers and if changes or revisions are required to advance our components from time to time we will make them, every chance we get. We are not afraid to do this and welcome the opportunity to improve our components. And, no customer will ever be left behind, everyone (new or second hand owner) will always be offered an upgrade path when possible. This may also help those, with resale value, who decide to change gear.
Also, a special thank you to TKP and Richard George for their very helpful inputs that made these changes happen so quickly.
