Purist too loud in combination with Stratos Stereo

Ferdi · « **on:** 18 Dec 2004, 11:30 am »

Hi,

I am a happy user of a Purist->Stratos->Dynaudio Audience 82 but this combination has a small problem: For normal listening, only the first few "stops" on the volume control are usable.

I find that I have too high volume at the lowest level and too little resolution at reasonable volumes.

What I am wondering is this: What can I do to somehow attenuate the signal levels? Is there an obvious modification of the Purist? I know about in-line attenuators but am worried about impacting the sound quality.

Does anyone have any ideas?

Groeten,

Ferdi

Marbles · « **Reply #1 on:** 18 Dec 2004, 03:38 pm »

Do you have the Purist at the "0" gain setting?

Ferdi · « **Reply #2 on:** 18 Dec 2004, 11:39 pm »

HI Marbles, yes I have the gain set to "0". Higher would not do me any good, would it?

thanks for thinking this one through with me. I am not sure what the right answer is...

Groeten,

Ferdi

JoshK · « **Reply #3 on:** 19 Dec 2004, 09:05 pm »

Wow, I am surprised as I thought the Dyn's were relatively inefficient, like 86-89db. Do you know what the sensitivity is? What is the gain of the stratos? Last thing to check is the voltage output of the source, what source are you using?

I am pretty sure the Purist isn't the issue. I don't recall off hand what the impedance of the attentuator in the Purist is but I think it is quite low compared to a tube preamp.

TheChairGuy · « **Reply #4 on:** 19 Dec 2004, 09:41 pm »

Ferdi,

I had the same exact problem with my Purist.

It's a quiet, nice sounding, supremely well costed, well made unit...but I could never get the volume attentuated right (Norh Multiamps, AudioSource Amp3) even on the 0 gain setting. Never.

It was fed by a MSB Gold Link III DAC that doesn't have especially strong outputs. I know 'cause with preamp removed the sound was less-than-totally deafening...as it can be when you run straight into an amp without attentuation. Speakers were 87db Lineaums and 90db Vandersteens.

I'm no lover of my tubed Dynaco PAS-4 preamp, but the volume attentuation at all levels was better than the Purist. Perhaps it did nothing else but THAT better than the Purist, but I saved my Dynaco and sold my Purist partly because of this (the other part was going to an all-in-one receiver).

So, you're not alone on this one...in case you thought you were

tkp · « **Reply #5 on:** 20 Dec 2004, 12:08 am »

Quote from: Ferdi

Hi,

I am a happy user of a Purist->Stratos->Dynaudio Audience 82 but this combination has a small problem: For normal listening, only the first few "stops" on the volume control are usable.

I find that I have too high volume at the lowest level and too little resolution at reasonable volumes.

What I am wondering is this: What can I do to somehow attenuate the signal levels? Is there an obvious modification of the Purist? I know about in-line attenuators but am worried about impacting the sound quality.

Does anyone have any ideas?

Groeten,

Ferdi

Hopefully, Curt can answer the question for you.

I suspect that the gain of the Purist is non-inverting and is equal to 1 + R2/R1 so the best you can do is a gain of 1 (0 db). If this is true then the only way is to have inline attennuator with a high quality resistor. This is not as bad as you think and especially if using a high quality resistor brand such as Holco. The input impedance of the Purist is a straight 33Kohms. Another option is to have a step down signal transformer but this could get expensive and no guarantee will be better than the inline resistor.

Good Luck

randog · « **Reply #6 on:** 20 Dec 2004, 04:10 pm »

This is bizarre. I am using the same preamp/amp combo but with Ellis 1801's and have complained that I can go to full volume at 0 gain and still not be quite as loud as I would like. I first noticed this with an Odyssey Khartago and then a Stratos.

Randog

Ferdi · « **Reply #7 on:** 22 Dec 2004, 12:22 pm »

Hi all, interesting there are so many different ideas. I CAN get the system up to very loud levels so certainly no problems on the high end.

I also don't want to sound like I have a big problem. For dedicated listening, the range of volume settings is fine. Only with the current Christmas season and playing lots of background music in the Christmas spirit do I feel the need for turning down the volume lower than it can go.

I use a Sony X77ES CD player with normal output levels (not sure exactly but around 2V I would guess, too lazy to check the maintenance manual)

One solution might be to use my DVDP and the volume control of my AV receiver that is integrated into my 2ch system.

Curt · « **Reply #8 on:** 10 Jan 2005, 09:59 am »

Hi All,

This is a good thread, let me make a few comments.

The Purist at gain level zero operates like a buffered passive attenuator. The source level going in is the same level going out to the amplifier. There is no increase in the signal size.

For the volume control: Using a 24 position step attenuator a designer can make one of two decisions. To use small subtle volume steps for superior room control or some subtle steps and some large abrupt steps to get the volume all the way down in high-gain systems. I decided the subtle steps were more useful and more desirable for most people.

I also believe switches with more poles (more than 24) are difficult to get and more expensive than the already expensive 24 pos switches.

With turntables as main sources some years ago, high-gain amplifiers were needed but with today's CD sources they are not. It is unfortunite that amplifier manufacturers don't reduce their gains, it would also reduce their THD+N figures. Many companies are still using the older designs.

The next Purist release will have a new main PCB. It will be a major update. The pink noise generator will be gone. The gain control will go from -18dB to +6dB which, for high-gain systems, should make a better "Course" attenuator control leaving the "Fine" tuning to the 24 pos VC switch.

The power supply will also be reworked to reduce the Purist THD+N figure even lower than it is today. Most people don't need the power supply revision, it is being done for the high-efficiency loudspeaker customers. We have one guy with 107dB@1W1M loudspeakers! These guys need the lowest noise possible or they hear it between cuts.

Just letting you all know IRD understands this issue and is on top of it.

Rob Babcock · « **Reply #9 on:** 10 Jan 2005, 10:39 am »

Glad to see you made it thru the Tsunami in one peice!

grub · « **Reply #10 on:** 11 Jan 2005, 10:05 pm »

Curt,
Can an "old" Purist be upgraded to the revised version?
-->grub

Curt · « **Reply #11 on:** 12 Jan 2005, 08:50 am »

Quote from: grub

Curt,
Can an "old" Purist be upgraded to the revised version?
-->grub

Yes. As always every Purist can be brought up-to-date, to the latest revision.

The next revision will require a new main PCB (complete PCB replacement). This is a one day turnaround update and the cost has not been set yet.

Our plan is to support the Purist owners for the life of the product.

Nobody will be left behind unless they choose to be left behind.

grub · « **Reply #12 on:** 16 Jan 2005, 12:01 am »

Thanks Curt.
-->grub

guest1632 · « **Reply #13 on:** 27 Jan 2005, 07:10 am »

Quote from: Curt

Hi All,

This is a good thread, let me make a few comments.

The Purist at gain level zero operates like a buffered passive attenuator. The source level going in is the same level going out to the amplifier. There is no increase in the signal size.

For the volume control: Using a 24 position step attenuator a designer can make one of two decisions. To use small subtle volume steps for superior room control or some subtle steps and some large abrupt steps to get the volume all the way down in high-gai ...

Hi Curt, Well, is it possible to have just the power supply upgraded, and how much on the cost? That noise generator is a rather useful tool, and I really don't want to lose it. Are you gonna put a record out or a tape buffer in the new upgrade?Thanks.

Ray

Curt · « **Reply #14 on:** 27 Jan 2005, 09:38 am »

Hi Ray,

Your comments are important. Other Purist owners as well. I look at all the comments before I decide exactly what features to keep or drop.

Anyone else want to keep the pink noise generator? I thought it was useful but I'm not sure it ever caught on. Guess I'm still looking to see if it is being used by anyone.

When I'm ready to do the revision I will discuss my choices here at AC but I'm not prepared to comment today or to quote prices.

Thanks for your useful input Ray, here and in your e-mails.

oris98 · « **Reply #15 on:** 23 Apr 2005, 10:58 pm »

I would suggest to keep the pink noise generator. It is very useful as a tool to break in new IC and speaker cables.
Thanks.

Curt · « **Reply #16 on:** 24 Apr 2005, 02:16 pm »

Quote from: oris98

I would suggest to keep the pink noise generator. It is very useful as a tool to break in new IC and speaker cables.
Thanks.

Good point, beats restarting a CD every hour.

Thanks for your input.

Purist too loud in combination with Stratos Stereo

guest1632