I got my latest amp up and running, listened for a week, good results. Then I tore it down again.. new chassis, better layout, new input stage. Weeks without sound again, walking the fine line and telling myself I'll feel better when it's finished.mods never endwe need fun !!
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Altec 416-8B
There were so many variations on this same theme. By that, I mean the specs changed several times on this model number.
I strongly suggest, after obtaining a pair, to MEASURE them first, then build an accordingly sized enclosure. The one pair I have will need a bit more than 3 cubic feet. For another pair I have, 3 cubic feet would be just fine.
IMO they are best served with use of a subwoofer system, thereby relieving the stress of extreme excursions. But, that's just my opinion.
There were so many variations on this same theme. By that, I mean the specs changed several times on this model number.
I strongly suggest, after obtaining a pair, to MEASURE them first, then build an accordingly sized enclosure. The one pair I have will need a bit more than 3 cubic feet. For another pair I have, 3 cubic feet would be just fine.
IMO they are best served with use of a subwoofer system, thereby relieving the stress of extreme excursions. But, that's just my opinion.
I meant that without those signals below 70Hz, you cannot say you have a "high-end" system. My minimum is 60Hz for 2-way. Many people can live with minimum 70Hz or 80Hz but may be because they don't know yet... Once we have lived with low extension, it's hard to go back because we already know how each recording/music should sound like. Those recordings/musics just sound wrong without that extra lows.
ADD: My room is very small but the mode is still below 60Hz. Others with horn (like you) must have a lot bigger room.
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Hehehe may be I am lucky because the first time I heard a tube amp, I didn't like the sound. I have owned several tube amps and 100% people who heard my system preferred the tube amp, but I still prefer class-A solid state.
I think there is an OBJECTIVE formula that determines enjoyment, and there are SUBJECTIVE preferences. I think it is okay to change subjective preferences as long as the OBJECTIVE part is still maintained.
One point is that preference can be changed and sometimes it is better to do so. It is possible because many preferences are actually what we get used to. Get used to something new and the preference will change.
I think if I could do this and I really want to some day, I'd be more inclined to stay as simple as possible and make it as a two way modified version of the Altec M19.. I'd go with GM's MLTL for the 416, and use the Beyma TPL-150H along with the GPA built M19 crossovers for the whole works, with their mid/high adjustable knobs for easy room/taste tuning etc.. A modern M19 take interests me and I'm only working with 6 watts SEP anyhow etc..
I don't think anyone is considering a system that only goes down to 70 Hz. Oltos plans to use his own subs instead of duplicating my TD15-H cabinets, which are tuned to 23 Hz.
A bass reflex 2-way like the Altec 19 is simpler but is outperformed by the present approach. The MLTL may very well be way to wring the last drop of bass performance from a 416, but its excursion allows only so much.
I'm not so sure that the Beyma TPL-150H works in a 2-way with the 416. Although the manufacturer claims 700 Hz, from what I understand users report that a higher crossover is preferable. You can go higher with a 416 but there are sacrifices involved.
A bass reflex 2-way like the Altec 19 is simpler but is outperformed by the present approach. The MLTL may very well be way to wring the last drop of bass performance from a 416, but its excursion allows only so much.
I'm not so sure that the Beyma TPL-150H works in a 2-way with the 416. Although the manufacturer claims 700 Hz, from what I understand users report that a higher crossover is preferable. You can go higher with a 416 but there are sacrifices involved.
One option for the range below 70 Hz (not for otlos, but for others) could be a distributed sub system, something like the audiokinesis proposal: The Swarm Subwoofer System. Perhaps someone here can give some input about the advantages (if any) of such a system.
I will be starting with a GPA 414 + e-jmlc 600 or azurahorn, using an Emilar EA-175 (Alnico). I don't have much space right now, so I will first try the 414 and then the 416 (or both together) in the future. It seems the 414 does ok on its own, but a distributed system with small subs could be a neat solution.
I think it's Earl Gedde's idea. One sub will create some dip and peak, more dip and peak will make a smoother response. But I think 3 is optimum (unless it is a very very big room, because the sub should be positioned as far away from each other to be effective). Little improvement with the 4th sub and so on.
FWIW, I was an early adopter, so me too: http://www.harman.com/EN-US/OurCompany/Innovation/Documents/White Papers/multsubs.pdf
http://www.harman.com/EN-US/OurCompany/Innovation/Documents/White Papers/LoudspeakersandRoomsPt1.pdf
http://www.harman.com/EN-US/OurCompany/Innovation/Documents/White Papers/LoudspeakersandRoomsPt2.pdf
http://www.harman.com/EN-US/OurCompany/Innovation/Documents/White Papers/LoudspeakersandRoomsPt3.pdf
GM
Martin have you measured the the LM555 in the JMLC160? How does it compare to the Vitavox S2?
I think I'll call the new version of the amplifier the "Karna Kay", or "Karna K".
What I'm considering looks like this:
* XLR/RCA input, floating (no cable-ground connection between chassis). Already present in circuit
* input/phase splitter transformer, 1+1:1+1, amorphous or microcrystalline core. This is already in-circuit
* 6SN7, old-stock or new-old-stock, operating at 10~11 mA per section. Common cathodes may or may not be 47~100uF bypassed, depending on sonics and measurements
* Plate load: 15K or higher Mills or Ohmite wirewound plate resistors, with either a pair of current sources or a pair of audio-grade inductors between the top of the plate resistors and the 400V power supply
* 0.1 to 0.22uF coupling caps, most likely Jensen paper/oil/foil type
* 45 driver tubes will have 100K grid resistors for DC stabilization
* Driver circuit continues to be shunt-regulated with current-source isolation between input and driver section
* The existing hum-balance circuit will be removed, and replaced either by a filament-balancing multiturn pot bypassed by 10-ohm wirewound power resistors on each side (if AC heating is retained), or the Coleman DC supply
* B+ power transformers and power chokes replaced with mechanically silent transformers. Electrostatic screening is desirable on the primaries
By removing the first interstage transformer and replacing them with air-gapped SE chokes, 3rd and 5th-order distortion around the zero-crossing is reduced, and the 6SN7 has a considerably cleaner high-order spectra than the 5687/7044/7119 family.
What I'm considering looks like this:
* XLR/RCA input, floating (no cable-ground connection between chassis). Already present in circuit
* input/phase splitter transformer, 1+1:1+1, amorphous or microcrystalline core. This is already in-circuit
* 6SN7, old-stock or new-old-stock, operating at 10~11 mA per section. Common cathodes may or may not be 47~100uF bypassed, depending on sonics and measurements
* Plate load: 15K or higher Mills or Ohmite wirewound plate resistors, with either a pair of current sources or a pair of audio-grade inductors between the top of the plate resistors and the 400V power supply
* 0.1 to 0.22uF coupling caps, most likely Jensen paper/oil/foil type
* 45 driver tubes will have 100K grid resistors for DC stabilization
* Driver circuit continues to be shunt-regulated with current-source isolation between input and driver section
* The existing hum-balance circuit will be removed, and replaced either by a filament-balancing multiturn pot bypassed by 10-ohm wirewound power resistors on each side (if AC heating is retained), or the Coleman DC supply
* B+ power transformers and power chokes replaced with mechanically silent transformers. Electrostatic screening is desirable on the primaries
By removing the first interstage transformer and replacing them with air-gapped SE chokes, 3rd and 5th-order distortion around the zero-crossing is reduced, and the 6SN7 has a considerably cleaner high-order spectra than the 5687/7044/7119 family.
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Avoid the Altec 511 or 811 horn. These are far from flat and have lots of diffraction by modern standards. Keep in mind that although diffraction can be partially equalized away, the reflections in the time domain remain, and cannot be removed. According to Altec's own measurements, they also have a "pattern flip" in the 1~2 kHz region (polar pattern goes from horizontal to vertical).
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