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Bad Advise !!!!!

67.72.98.83
Posted on October 31, 2009 at 16:37:16
Vinylly
 I'm not sure how good the equipment reviews are on this website, BUT, I was casually reading the reviews of the Audible Illusions Mod IIIA preamp. One of the reviewers recommended using the 'Tape In' for hooking up your CD player, -he suggested there would be a great improvement.
So I tried it with my new Arcam FMJ CD36, -and it was indeed a 'shocker'. The gain was much greater, but the highs lost all its sweetness that I was so amoured over. Large orchestra pieces sounded brittle, with a metallic edge. Playing a Part with Gil Shanam, violin, the violin sounded like the scraping of fingernails across a chalk board. This has got to be the worsed of all CD sounds. The Arcam had completely lost all it's tuby sweetness and listenability.
The reviewers recommendation was educational, however, -it doesn't make any difference how good your CD player can be, a good preamp can make all the difference in the world. However, if you own an Audible Illusion Mod IIIA, be sure you use the CD input for your CD player and NOT the tape input.
Has anybody had a simular experience? If you own an Audible Illusions preamp, try it and report back what you think.

RE: Bad Advise !!!!!, posted on November 1, 2009 at 11:56:52
Ric Schultz
Manufacturer

Posts: 462
Joined: August 7, 2000
 I know the older Modulus had a 100K Roderstein resistor in series with the CD input. I assume the Modulus 3 is the same....If not, disregard the rest of this post: The Roderstein resistor would pad the gain going into the pot and, of course add the sound of the resistor. Also you are adding the sound of an extra switch and circuit traces when using the CD input. The tape input does not have the series resistor and is the shorter purer signal path. However, having a purer path does not mean you like the sonic results...obviously. The Roderstein resistor has a depressed upper midrange (perfect to get rid of glare and hardness) a slightly wooly bass, and much less info than the straight wire. It is a "musical" sounding part but not very transparent in the truest sense.

Your experience reminds me of the time I was playing with the original Hafler preamp and bypassed all the switching and ran the pot directly to the circuit.....it sounded thin and hard....this was because all the extra switches and wires and circuit board traces were rolling it off. So, I had to spend a great deal of time making the circuit have lower distortion so I arrived at a more musical sound with even more detail.

More than likely, you like a more colored sounding input in order to compensate for some distortions somewhere else in you system. Try sanding and blacking your CDs....you will get way less hard, bright and more musical sound. Do you have good tube dampers? Lots of ways up the mountain.

The Modulus preamp....the older ones that I know.....have a ton of gain...something like 26 times (2 volt CD player X 26 = 52 volts of gain, that is a lot to attenuate!!!!).....so this is why people are always complaining that they can never turn up the volume. The 100K resistor in series with the CD input was a way of lowering the gain somewhat to make it more user friendly.

RE: What You Suggest, Makes The Most Since :, posted on November 1, 2009 at 15:56:42
Vinylly
 I figured it out that the tape input has considerably more gain then the CD input. Seems it was overloading my amps into distortion. After all they are only 25 watt triods. I simply lowered the volume by several steps, which solved the problem. Now I have to do some very comprehensive listening to see if playing the Arcam through the tape inputs is better then the CD inputs. I'm having the feeling that the CD inputs are preferable, however.

My Audio Research SP-9 is similarly configured, posted on November 4, 2009 at 05:45:07
E-Stat
Audiophile

Posts: 9838
Location: Central boonies
Joined: May 12, 2000
Contributor
  Since: April 5, 2002
 CDPs typically have high output, so the CD input only provides 9 db of gain vs. 21 db for the other line inputs. You could be overloading the input. In fact, my CDP has such high output (4 volts), I don't use the preamp at all!

rw

Puzzling results., posted on November 1, 2009 at 11:42:24
Al Sekela
Audiophile

Posts: 8279
Location: Northern California
Joined: February 18, 2002
 The description and specifications suggest this preamp provides the same gain for all the high-level inputs (those not labeled "phono").

Perhaps there is a defect in your preamp or cable.

Loading issue, posted on November 1, 2009 at 07:11:13
Panelhead
Audiophile

Posts: 430
Location: Houston
Joined: September 26, 2000
 I have never lifted the cover on a M3, but have looked inside AI Modulus II quite a bit. Rather than use a rotary selector, they use relays. The tape selector is closest to the tube active stage. Using this input just passes the signal through less contacts.
If it sounds very different than a normal input it must be loaded different. The volume control is the load for the other inputs. I think it is 50k whether a pot or stepped attenuator. Some M3 models had a pot, I think all M3A had SA.
There may be a series resistor in the tape input that is making the sound hard. Changing the 3dB point from the input capacitors. Or another loading resistor on just that input.
If you own a VOM, try measuring. Select the CD input and measure from hot to ground on the RCA Jack. Then select tape in and the do the same. If they measure the same, they SHOULD sound the same.

George

RE: Bad Advise !!!!!, posted on November 1, 2009 at 05:07:33
jult52
Audiophile

Posts: 167
Location: Philadelphia
Joined: May 27, 2009
 Funny you mention this but I just plugged in my CDP directly into my Forte preamp's Aux connection and got exactly the results you heard. I imagine this preamp's Aux input was built for analog inputs?

Also a lesson in how you need to read really, really skeptically.

??? All the inputs are for analog. (NT), posted on November 1, 2009 at 06:50:32
Kal Rubinson
Reviewer

Posts: 7158
Joined: June 5, 2002

RE: ??? All the inputs are for analog. (NT), posted on November 2, 2009 at 07:31:57
jult52
Audiophile

Posts: 167
Location: Philadelphia
Joined: May 27, 2009
 Kal - I didn't write clearly. I meant analog-source inputs.

RE: ??? All the inputs are for analog. (NT), posted on November 2, 2009 at 08:54:03
Kal Rubinson
Reviewer

Posts: 7158
Joined: June 5, 2002
 I assumed so. What differences would you expect between analog inputs for analog sources and analog inputs for digital sources anyway?

Kal

RE: ??? All the inputs are for analog. (NT), posted on November 3, 2009 at 07:44:10
jult52
Audiophile

Posts: 167
Location: Philadelphia
Joined: May 27, 2009
 Kal - I don't know, but the difference in inputs in my preamp was more than a question of break-in. There was a sharp difference in gain.

RE: Bad Advise !!!!!, posted on November 1, 2009 at 04:11:17
mrod
Audiophile

Posts: 64
Location: East Tennessee
Joined: July 8, 2000
 On the M3a I use the CD input for the Sony SCD-777es, the DAT input for the Perpetual Technology boxes and the Tape loop for the Fostex CD recorder and the only difference I can hear is that which each component brings.
I also remember when I first got the M3a, reading somewhere that the tape loop was the purest sound and I tried it; really it was no biggie.
This from a 1996 Stereophile review might shed some light on a percieved difference:
"Because the line-stage flips phase, the main output of the Modulus 3 and 3A is absolute-phase-inverted. To restore correct polarity, you simply reverse your speaker cables: hot to ground and ground to hot on both channels. The Curl-designed solid-state tape-output buffer circuit doesn't invert phase."
enjoy!
mrod.

Nostalgia is history removed of the burdensome weight of reality
ding ding ding- We have a winner, posted on November 3, 2009 at 06:25:00
Awe-d-o-file
Manufacturer

Posts: 6093
Location: 2 hr. west of DC
Joined: January 10, 2004
 ""This from a 1996 Stereophile review might shed some light on a percieved difference:
"Because the line-stage flips phase, the main output of the Modulus 3 and 3A is absolute-phase-inverted. To restore correct polarity, you simply reverse your speaker cables: hot to ground and ground to hot on both channels. The Curl-designed solid-state tape-output buffer circuit doesn't invert phase."
enjoy!
mrod."""


sad to see how much bad or useless advice can from many other posts.



ET
Question "Authority", the mainstream media sucks - Go Independent and hold BOTH parties accountable instead of just the other guys!

I need music to help forget the reality of today
RE: Here I've Been Playing My AI Mod IIIA Out Of Phase For 10+ Years!!!!, posted on November 3, 2009 at 12:11:24
Vinylly
 Is there any sound difference whether it's in-phase or out-of-phase???
After reading this I switched the speaker cables. I 'think' there was a difference in gain but am not sure if it wasn't just psycological.

RE: Here I've Been Playing My AI Mod IIIA Out Of Phase For 10+ Years!!!!, posted on November 5, 2009 at 16:02:19
Awe-d-o-file
Manufacturer

Posts: 6093
Location: 2 hr. west of DC
Joined: January 10, 2004
 Sorry for the slow response. You may like it one way or another. Pick one and don't worry which one is "right".



ET




Question "Authority", the mainstream media sucks - Go Independent and hold BOTH parties accountable instead of just the other guys!

I need music to help forget the reality of today
Not familiar with the AI pre but..., posted on October 31, 2009 at 20:21:56
kuma
Audiophile

Posts: 5085
Joined: July 8, 2001
 a preamp's input performance can vary.

Once i've listened to all inputs and surprised how each one varied. ( slight to huge depending on a make )

RE: Bad Advise !!!!!, posted on October 31, 2009 at 17:39:01
rick_m
Audiophile

Posts: 2529
Location: Oregon
Joined: August 11, 2005
 That's odd. Tape in is just another line-level input on all the preamps or receivers I've ever had. What do the specifications of the preamp show?

Rick

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