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RE: Amps for eminent technology LFT8bs

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In Reply to: RE: Amps for eminent technology LFT8bs posted by Satie on September 17, 2016 at 11:44:52

In his case, the hardware is still the same, so if clipping was not happening with CD/DVD's, then it won't happen with (volume adjusted) Blu-Rays. This assumes similar dynamic range of the program material and the same nominal setting of the SPL level. It's not a "not optimal" configuration assuming you haven't violated a gain structure limitation in some way. Recommending expensive active preamps to solve a simple issue like this is what's "not optimal." :)

A software volume control like MPC or VLC or similar probably only has +6db maximum adjustment, so if peaks in the program material are below -6dbFS, it's impossible to generate clipping. This is not an uncommon gain structure issue even with audio-only program material. You can find numerous audio sources where peak levels are recorded well below 0dbFS and maximum settings of volume controls will not yield enough SPL. Normalizing and/or Replaygain are options too, but those require extra steps and complication.

Dave.

Follow Ups:

RE: Amps for eminent technology LFT8bs - Satie 16:54:51 09/17/16 (8)
Can't say that I am familiar with BD audio mastering practice. I was curious after you gave the suggestion and looked up what the possibilities are. Most player software would peak limit, . That is not to say that if nothing is recorded above-6db there would be any of that going on.

I don't believe in limited gain and have yet to meet an amp that didn't need a preamp before it. More so tube amps than SS but those too. I tried LDR and passive and the dynamics always come off constrained if you don't have well above 2V output capability. My preamps do 40V tube, 20+V hybrid and 10V SS single ended.
- RE: Amps for eminent technology LFT8bs - Davey 17:28:53 09/17/16 (7)
  You need to understand gain structure a bit more. There are many instances where a system sans preamp will work really well.
  Much depends upon other variables other than power amp voltage gain. Speaker efficiency, source maximum hardware level, level of the recorded material (which is what we're talking about here), etc, etc.
  
  A high maximum voltage capability from a preamp does not (inherently) assure improvement to "dynamics" or myriad other subjective characteristics. All other things being equal, it's just wasted capability that has no use in the overall system gain structure. It can also create problem issues such as hair-trigger volume controls, increased idling noise, etc, etc.
  
  Dave.
  - RE: Amps for eminent technology LFT8bs - Satie 20:33:44 09/17/16 (6)
    The preamps generally have useful vol control to fit with their gain, I didn't really meet a hair trigger vol control issue. The extra headroom is very useful for passive line level crossovers.
    
    We tried the PS Audio DS as a preamp and it was dynamically limited and grey that way. The extra voltage is useful for analog more so than CD since analog has a higher transient content that often requires tapping into the power amp's dynamic headroom for less than a millisecond unless you put in a really powerful amp relative to your average listening level. .
    - RE: Amps for eminent technology LFT8bs - Davey 05:07:44 09/18/16 (5)
      Grey?
      Analog doesn't (inherently) have any higher transient content than CD.
      You're posting speculative nonsense.
      
      Passive line-level crossovers might indeed require the extra analog voltage because of their inherent insertion loss. However, you're changing the subject and that's a completely different topic than we've been talking about here.
      
      Dave.
      - RE: Amps for eminent technology LFT8bs - Satie 06:45:57 09/18/16 (4)
        
        In Reply to: RE: Amps for eminent technology LFT8bs posted by Davey on September 18, 2016 at 05:07:44
        
        Grey = lack of tonal contrast or :"vividness".
        
        The analog formats are inherently better at preserving short sharp transients in the sub millisecond range that can not be reproduced in CD but can be partially reproduced in 24/96 and rather well captured in DSD. In CD you can engineer a representation of the transients but not actually reproduce them.
        
        http://www.themasterdiskrecord.com/.../ask-the-engineer.../
        http://www.themasterdiskrecord.com/.../ask-the-engineer.../
        http://www.themasterdiskrecord.com/.../getting-the-most.../
        http://www.themasterdiskrecord.com/.../getting-the-most.../
        
        Though these are not up to date entirely, the references experiments and discussion are worthwhile.
        
        http://www.bodziosoftware.com.au/Attributes_Of_Linear...
        http://boson.physics.sc.edu/~kunchur/align.pdf
        
        RE: Amps for eminent technology LFT8bs - Davey 08:00:10 09/18/16 (3)
        
        In Reply to: RE: Amps for eminent technology LFT8bs posted by Satie on September 18, 2016 at 06:45:57
        
        It's easy to cherry pick stuff that agrees with what you believe.
        Do you remember what I told you a few months back about believing everything you read? You're running off on a tangent again.
        
        Anyways, you're connecting the dots from your previous statements. Explain how a preamp with 40V capability has any more inherent transient ability than a preamp with 4 volt capability.....all other things being equal. Keep in mind most power amplifiers are driven to their limits with less than 2 volts input. And don't respond with some strawman justification based on subjective characteristics.
        
        Dave.
        
        RE: Amps for eminent technology LFT8bs - Satie 10:23:02 09/18/16 (2)
        
        In Reply to: RE: Amps for eminent technology LFT8bs posted by Davey on September 18, 2016 at 08:00:10
        
        Depending on design, power amps have headroom for various length transients beyond the 2V for max rated power (driving a sine wave into a fixed impedance load), which is occasionally provided in the amp's specs as 20 or 200ms dynamic power rating. Some amps deliberately limit high voltage inputs and don't reproduce them. Most audiophile designs don't do that and no tube amps and hybrids I know of do that. So the 20 (or 40) V output preamp will provide the transients into the power amp and then some - in my amps the 10V output was plenty to deliver transients from my LPs, but they were marginally more distinct from the 6922 tube outputs rated 20 and 40V preamps, The main advantage beyond transient reproduction is for tube amps with minimal gain structures where gain may be as low as 22-24 db.E..g. some SETs with only input and driver may require up to 5 V for full rated power. As an aside, I have used tube phono preamps that had saturated the line inputs on my SS line stage momentarily. Didn't do so with tube pre at the setting for the same vol output..
        
        Class D amps apparently have a hard limit.
        
        RE: Amps for eminent technology LFT8bs - BDP24 13:49:33 09/18/16 (1)
        
        In Reply to: RE: Amps for eminent technology LFT8bs posted by Satie on September 18, 2016 at 10:23:02
        
        In case anyone is wondering, the Music Reference RM-200 Mk.2 power amp works very well with ET LFT-8's. It has an input sensitivity of 1.1V for full output, but I don't recall it's gain. It puts out 100W into 8 Ohms from just two KT88/6550 tubes per channel, and not by running them hot or driving them hard. If you bi-amp the LFT's, the M/T drivers present a 12 Ohm/very even impedance load to the amp, a breeze to drive. If you don't bi-amp, the RM200 provides tighter-than-average bass for a tube amp, as good as many SS amps---Roger makes great output transformers. The amp also has a lower-than-normal for a tube amp output impedance, therefore doesn't roll off the top end of the tweeter.
        
        Edits: 09/18/16 09/18/16 09/18/16
        
        RE: Amps for eminent technology LFT8bs - Davey 17:02:48 09/18/16 (0)
        
        In Reply to: RE: Amps for eminent technology LFT8bs posted by BDP24 on September 18, 2016 at 13:49:33
        
        JA has done a full test on that amplifier. Click link below.
        
        No doubt a 40 volt preamp will yield much better performance from it though. :)
        
        Dave.
        http://www.stereophile.com/content/music-reference-rm-200-mk (Open in New Window)

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