Audible Illusions Modulus L1- Am I missing something?

[piece-it pete]

Howdy folks!

Well I got a chance to audition one of the above, probably the highest quality piece ever in my system.

Clarity. Noise floor. It should be GREAT! It has a very nice sound BUT - it seems like it, as my audio challenged SO put it!, "runs out of steam". It gets louder but never seems to have the sparkley presence I expect.

I had it checked by a knowledgable tech and it passed all tests with flying colors. I have outside confirmation of this issue, on a much better system than mine, but all reviews I find just sing praises.

Any ideas?

Pete

[dean_martin]

Hey Pete!

I'm guessing this is the tube linestage preamplifier from AI? What amp were you running with it? Perhaps it doesn't mate well with some SS amps? I don't really have a response for you, but I've considered putting together a system with a tube preamp and a solid state amp and have read that you have to be careful of matching ohms or input and output loads or something. I don't fully understand what to look for as far as specs go yet. Maybe you have some advice?

[piece-it pete]

Hello Dean!

Yep, it's a tube pre, running my super-high-end Marantz 1152dc .

It sounds like you might know more than me on this subject already, although I suspected originally ( and told the tech so) that it wasn't putting out as much whetever as it should, but he said yes it is.

The outside confirmation was a very experienced tube guy running a very very nice Yamamoto A-08 45 SET "flea power" (2 wpc!) tube amp pushing hi-e speakers with edgarhorn tops ( I like the edgarhorns A LOT - very realistic reproduction imo) and eminence woofers. We did not say what was wrong, heck that there was even a problem, and both had the same impression, on these two very different systems.

What I'd really like to do is try it in a more "normal" ss system, defined as moderate efficiency speaks (vs my very low e DQ-10s) and a better amp. Nothing I can do about the speakers, but will be trying out a couple of ss amps, don't know which ones yet, only that they'll be quite good (yay!), within the next month or so, hopefully I'll still have the L1 & try it out, I'll post.

This is getting fun! When I look back at the system I had when I signed up here (cheap Sony HT, old junk Marantz towers) I can't believe how far I've come. I also can't believe how much farther there is to go!

Pete

[dean_martin]

Hello Dean!

Yep, it's a tube pre, running my super-high-end Marantz 1152dc .

It sounds like you might know more than me on this subject already, although I suspected originally ( and told the tech so) that it wasn't putting out as much whetever as it should, but he said yes it is.

The outside confirmation was a very experienced tube guy running a very very nice Yamamoto A-08 45 SET "flea power" (2 wpc!) tube amp pushing hi-e speakers with edgarhorn tops ( I like the edgarhorns A LOT - very realistic reproduction imo) and eminence woofers. We did not say what was wrong, heck that there was even a problem, and both had the same impression, on these two very different systems.

What I'd really like to do is try it in a more "normal" ss system, defined as moderate efficiency speaks (vs my very low e DQ-10s) and a better amp. Nothing I can do about the speakers, but will be trying out a couple of ss amps, don't know which ones yet, only that they'll be quite good (yay!), within the next month or so, hopefully I'll still have the L1 & try it out, I'll post.

This is getting fun! When I look back at the system I had when I signed up here (cheap Sony HT, old junk Marantz towers) I can't believe how far I've come. I also can't believe how much farther there is to go!

Pete

There's something about the output of some tube preamps being lower than an average ss preamp and the input rating of tube amps being higher (or lower) than an average ss amp. I think these are measured in ohms and the ss amp's and tube preamp's specs will tell you whether they are a good match functionally (whether they sound good together is of course a whole other ball of wax). Anyhow, I don't know what to look for in the specs but I picked up on this while reading a review of an ARC preamp and amp in Stereophile. The reviewer said that this new model of the preamp had a different output rating from earlier models so that it would work better with ss amps. Just another confusing factor that makes this hobby so intriguing.

BTW, your friend with the SET and horns has gone pretty far!

[Justlisten2]

I have a tube preamp mated with a solid state amp. Yes, as dean_martin stated, it could be an impedence mismatch between preamp/amp. Another thing it could be is your long time listening bias. Tube equipment tends to sound smoother and richer in the midrange then solid state equipment. Solid state usually has more punch at the frequency extremes. SS will sound more 'sparkley' on highs, as you describe it. That's why folks who like tubes, like tubes. Because much of this treble information is falsely attenuated up during the mastering process, many prefer equipment which will de-emphasis this issue. No, people don't buy tube equipment for 'sparkley' high's. They buy tube equipment for the rich, enveloping midrange, which is where the music lives. Once your ears adjust to the 'natural' sound of music, you may realize that you prefer it more than the 'electronic' sound.

I find the litmus test is listening fatigue. I find that I can listen MUCH longer with tubes and vinyl than I can with digital and solid state. I have a tube cd player, phono preamp and preamp (18 tubes in all), mated with a solid state monoblocks (Class A biased).

So it could be an impedence mismatch, or it could be that you're just so used to the 'artificial' sound of music, that the 'natural' sound sounds bland. That is why recording/mastering engineers feel the need to add more 'sizzle' during recording process, for the special effects lovers. This is not meant to be derogatory. If you enjoy that whiz-bang effect, stick with what you like. Whatever better enables you to enjoy the music. That's what it's all about really, you pays your moneys, you makes your choices.

Cheers,
John

BTW, SS does have a lower noise floor, but with a good tube design, noise really isn't an issue. I find the more natural decay of musical notes more than makes up for a slightly higher noise floor. I can only hear my system noise if my ear is within two feet of the speakers and there is no music playing. What is the point of sitting that close to the speaker and not playing music though?

[dean_martin]

OK, I went back and tried to figure out what's important in matching amps and preamps and though I don't completely understand what to look for I think I found some clues. I had read some reviews of the Pass Labs Aleph 3 amp and its successor the Aleph 30. Due to the Aleph 3's "low voltage gain", it was not a good match for passive preamps (a preamp without active output). The Aleph 30's design included an increase in the voltage gain so it could be matched with not only passive preamps/controllers, but also with some low output TUBE preamps. I also discovered that some tube preamps like the Audio Research SP16L have low output levels presumably to lower the noise floor or to lessen audible "tube rush".

So, I think if you were going to match a tube preamp with a solid state (including single-ended like the Pass Labs) amp, you would need to check the amp's voltage gain and the preamp's output level. The remaining question is what are the threshhold values in amplifier voltage gain and preamplifier output level for a satisfactory match?

I'm not sure but I think I've found some clues. In the review for Audio Research's VS110 power amp and SP16L preamp (which you can find at stereophile.com in the archives), the reviewer tried the two components together and then substituted each one seperately into his system. The SP16L's output level (which the reviewer categorized as "gain") is 11.5dB. The "gain" rating for his reference preamp was 26dB. That appears to be quite a difference. When he put the SP16L in his system, he had some of the same volume problems that Pete noticed. No juice.

On the other hand, the VS110 amp from ARC had a gain of 28dB which the reviewer said was slightly higher than average, but he didn't say what average is. Therefore, the SP16L performed much better with the VS110. The preamp's lower gain was apparently for the purpose of lowering the noise floor, and its lack of juice was compensated for by the slightly higher than average gain from the VS110. So, I think you can conclude that if you were going to get the SP16L preamp for your existing amp, you should check your amp's voltage gain and make sure it's at least 28dB (or, slightly higher than average, whatever average is - maybe 26dB?)

Once again, I owe Petey thanks for providing me an oppurtunity to work through and overcome my issues.