Amplified music : Solid-state valve amp <--link for "Dial-A-Tube" circuit
That's a good read but there's actually no need to modify the amp design.
A current drive effect can be easily replicated by a huge BSC with a giant size inductor, a 4 ohm or 8 ohm resistor and a cap too small for treble (these materials all go parallel to each other to create the bsc. Then the BSC unit goes series to the speaker). Nothing like a huge bit of copper to replicate the sound of an output transformer. This is a simple resistor padding approach, except that an inductor is added parallel to the resistor so that most of the amplifier's power isn't wasted into the resistor.
Lack, presence, and/or amount of current drive is applicable at any size amplifier, buffer, or preamplifier.
The point?
It is likely that made-for-tube-amp speakers don't have the proper crossover elements to support a voltage drive amplifier; however, The missing parts can be added externally.
As a bonus, any "sounds like a chip" midrange audio harmonic distortion will vanish into that resistor, never to be heard.
other notes. . .
That1200 is a pretty thing but can be a little sibilant in some (not all) conditions, depending on what drives it. It may need to be either driven appropriately or bypassed.
Modulous86 is neither an integrated amp nor voiced. You'll probably be wanting a preamp for more convenience And to better suit personal tastes.
Actually, the Modulous86 product is a nice little power amp, so we need to confine our expectations to match its actual job description. There's no tone controls, it won't flip your LP for you and you'll need to add your own preamp.
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Ah. That makes me sleep a little better at night...
I actually like both. When I went from a generic but pretty darn decent solid state amp to my 300B, I found the sound of the 300B to be much more open and natural. I am guessing this is because the 300B has a relatively flat THD profile (i.e. THD vs Frequency is flat). It could also be because the 300B has mostly 2nd ard 3rd order harmonic distortion, which many report as being more pleasing to the ear. While I enjoy the 300B sound and presentation, in particular in my DG300B, I would not consider it to be precise. Especially the bass tends to be on the warm and fuzzy side. Nothing wrong with that. In fact that's why many people like tube amps...
The MOD86 is a precise amp. It's a wire with gain and that's about it... There's no coloration of the sound and its low output impedance (about 150 mOhm for R1.0 and 50 mOhm for R2.0) will control any speaker tightly. This is a blessing and a curse. If you like the precise sound, it's mostly a blessing. You will hear the grass grow on your recordings and incredible detail will be extracted. For example the cavity resonance of an acoustic guitar is cleanly reproduced. As is the detail in the fretting and picking of the guitar. Now if your speakers exhibit cone break-up in the 10+ kHz range, you'll probably find the sound a bit harsh (or precise if you like cone break-up). A tube amp will have less control over the speaker cone (higher output impedance), hence, won't excite the cone break-up as efficiently. Going from a warm and fuzzy tube bass to a precise bass, will seem like the bass goes away. Measure the SPL or listen for a while and you'll notice it's actually there. It's just very precise.
The MOD86 is now my daily driver. I really like the open and natural highs. They're like the highs of the 300B but more precise. I did miss the warmer bass at first, but appreciate the more precise bass of the MOD86 now. I plan to address The Bass Situation by building a speaker that can actually reproduce bass below 50 Hz, unlike the Dali 3A I'm using at the moment.
~Tom
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Awesome. Thank you. Yeah, I'm getting to be rather intimately familiar with the LM3886.
~Tom
The one thing I find so intriguing is the constant "obsession" - sorry!! - of audiophiles with "low bass" - in 30 years I have yet to hear this miraculous big, lower bass thing - systems with megasized drivers to me sound like only slightly more refined versions of the kid's car in the street, with the roof bulging up and down to the beat.
I have recordings with very intense, visceral bass - and this comes over extremely well with a properly working system - I never hunger for that 25" subwoofer for extra thud!!
...
Its pretty easy to warm the bass by shortchanging the in- coupling frequency to cause bass foldback distortion. Audibly, bass distortion cancels if you have an equal amount of thus and booms frequencies. Otherwise, monotony results.
I think that the ear must have both booms and thuds so as to compare thus perceive, but if you've got the in- coupling wide open (such as a dc tracker or a very huge cap value), monotonous thud-only bass results. That's very well meaning yet misses the mark just slightly. That's certainly a lot cleaner than the severely shortchanged in- coupling in the lm3886 datasheet that results in annoying blurry boom-only (and even higher pitches than that). Anyway, you need an attractive point in-between.
There IS an attractive point in-between that will "allow" you to hear a pleasantly vast variety of bass. That does exist.
A different idea is Dr. Cherry's group delay circuit http://www.epanorama.net/sff/Audio/Circuits/Pre-Amps/60W NDFL Power Amplifier.pdf
It seems similar to what I would expect since tube amplifiers have output transformers that are basically delivering current. This is an advantage when driving through Fs type impedance peaks due to system resonance. I would love to hear Tom's impression as well. (Just read it)
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Sorry if this annoys you, but basically output transformer of tube amps convert high voltage low current to low voltage high current. Some transformers have taps for different speaker impedance, and generally people end up selecting the values lower than what the speaker specs say.
still pish. Any current comes from the tubes. If you are going to quote a mechanism you need to understand some basics. There is nothing magical about a tube output transformer that causes Ohms law to go on holiday for a while and extra current to appear in the speakers beyond the turns ratio of the transformer and the impedance matching the transformer gives you.
The experience in the sense that you can see the stage, the hall, performers, audience; even smell it - IOW, if you were blindfolded, sense of smell was switched off, in both locations - would it be harder for you to say that?
This is an interesting point. I often close my eyes when listening to live performances to focus on listening. I have also noticed I perceive sound differently when watching a video of live performance vs listening with my eyes closed.
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Here do you mean people generally prefer lower impedance taps (more current) than higher (for more volt swing) ? So for example someone with an 8R speaker tends to prefer the 4R trafo tap to the recommended 8R one?
At least people here whom use tube amps with tend to select the lower value tap more often. It makes sense to me.
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