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Ran my Streamliner at 16 ohms tonight -- a revelation

Discussion in 'Amps and Cabs [BG]' started by bobcruz, Mar 11, 2018.


  1. bobcruz

    bobcruz

    Mar 10, 2004
    CA
    For around the last 5 years, I've been using a Streamliner 900 into a pair of 8-ohm 12's I built as my rig at church. Running at 4 ohms, the Streamliner has more power than I need and I've always been nervous about blowing up the 12s. This week I built a pair of flyweight 10's with Eminence Basslites, rated at 150 watts thermal handling each. I wanted to try them at church since the 12s are overkill there. I would have been even more nervous about overpowering the 10s, so I decided to create a series cable and run them in series for a 16-ohm load. I figured the Streamliner might produce around 300 watts into 16 ohms and the power would match the speakers' thermal capacity exactly.

    It worked very well. Of course I had to turn up the master volume, from around 11:00 when I ran it into 4 ohms, to almost 3:00. What I didn't expect was the additional tubey-ness that would result. The amp seemed to have the exact same bouncy feel as my Walkabout. I've enjoyed that feel and would have said previously that the Streamliner was close, but not quite as tubey. Now it's all the way there, a dead even match in tubey-ness. I couldn't be happier about that. It's also nice to just play without constantly holding back to control transients. Happy camper here! :thumbsup:
     
  2. The electrons passing through both speakers have to work twice as hard, because they have to make sound twice.
    This makes them extra strong. It's like lifting weights. The more you do the more you can carry. And since we all know the low end is where the heavy lifting goes on, that's why two speakers in series sounds better than two in parallel.

    Anyway, after that tale, I'm just checking in to say I'm glad to hear you found a unique solution to a problem you didn't know you had. :thumbsup:
     
    Loring, musicman666, JRA and 8 others like this.
  3. Cool! Sounds like it worked out well for you.

    Depending on your eq and input signal, 3 o’clock on the master volume might be “wide open”. I had one amp I used with a 4 ohm cab, and very little eq tweaks from flat. I set the input stage hot, but not clipping. The power amp side of the amp would clip with master volume at 1 o’clock. I was shocked. I thought I had a lot more volume left on tap - but I was feeding full wattage in to that cab. (In my case the cab’s thermal rating was near twice the amp’s max rms wattage.)

    Oh - you said you made a special cable, but you could probably have wired up the backs of the cabs to connect in series.
     
  4. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    Correct, you are driving the power amp harder (higher output voltage, lower output current), so you are entering the Streamliner's output tube emulation circuitry earlier. A lot of effort went into the algorithms that control this feature. While it can be scaled much more effectively than the Walkabout, it doesn't get as sloppy and over the top when you don't want it to. This is a more interesting and challenging balancing act than you might think.

    So Bob, if you were participating in a double-blind test, do you think you could reliably identify the Streamliner as a class D amp with a Switchmode power supply? I ask this question because I already know the answer, having participated in a few with this amp as we were developing the 3DPM circuitry in it.

    This is actually an aspect of solid state power amps that I have spent a considerable part of my design career on, specifically controlling how, and what happens when a power amp (doesn't matter what type) begins to transition from linear to non-linear operation. There are a lot of landmines to avoid in order for an amp to be able to be slammed hard, WELL beyond rated power, yet hold up both tone/sonic AND with bulletproof reliability. IMO, this aspect is kind of the elephant in the room when it comes to separating the man amps from the boy amps. There are some designers who do a good job with this and there are also some who "kinda don't get it".

    I am working on some new products that I think advance this "state of the art" with regards to what happens to cone control and (acoustic) system Q under both low drive as well as very high drive conditions. No promises, no hints, no time frame, but if this R&D works out the way it appears to, there could be a new plateau available in the future that might appeal to some of you who are more subtle aspects of tone, feel, and a higher degree of refinement. Development and refinement of new technologies doesn't ever stop, I'm working on things years in advance, which is one reason why I value your collective TB opinions even if they may appear to be a little off topic... because in many cases the topic is not yet well defined, or as well defined as you might imagine.

    Hope this helps.
     
  5. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    Cute bedtime story ;)

    Fortunately, the amp is just loafing at 16 ohms. Fewer electrons are necessary, though there is a relationship between voltage and current, there is also a complex and (potentially) interesting relationship between what signal processing effects can occur to the voltage in one part of a circuit based on the current in another part.
     
  6. bobcruz

    bobcruz

    Mar 10, 2004
    CA
    I'm glad you chimed in. I was thinking I had finally hit the 3DPM threshold and I love it. I like having a lower-power option for this amp. There's no way I could pick it out blindfolded as class D with SMPS since it already feels exactly like my class A/B Walkabout with a traditional power supply, and both feel like my previously owned tube power amp. It just took me a few years to get here. I'm eager to see what the future holds! :)
     
  7. bobcruz

    bobcruz

    Mar 10, 2004
    CA
    LOL. I'm glad I found a way to tame the massive power in this amp with series wiring--this could be useful for other high-powered amps I'm interested in but wary of since I just don't need all the speaker-busting power they put out....
     
    BadExample likes this.
  8. BadExample

    BadExample

    Jan 21, 2016
    Injiana
    I'm glad you asked Bob! I'm on nearly the same project, 2 150W 8's, and was wondering the same. I didn't even think of the tubey amp section circuits. SL600.

    So Andy, with the SL600 rated at 600/4 Ohm and 375/8 Ohm, do you expect half of the 8 Ohm rating at 16 Ohms, or a bit higher?

    Got a wild guess at the mechanical power handling of the Shuttle 8T extension cab? Not going to crank the bass knob so much and probably play low B.

    So, I can hear it in action without more hearing loss :D It's about time that circuitry get off it's butt and work for me :D
     
    singlemalt and bobcruz like this.
  9. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    At 16 ohms, I would expect the Streamliner 600 to be around 200 watts RMS. This should fit well with a Shuttle 8T cabinet but with the Shuttle series it would be slightly higher due to the way the HPF's are implemented in each amp.
     
    RedVee and singlemalt like this.
  10. I’m jealous! This just sounds like so much fun.

    I warn you ahead of time that one day I WILL own one of the amps you have designed! As my pension limits me I’ll have to wait until the lottery gods are good to me again! :)

    Maybe this week! :D
     
  11. murphy

    murphy

    May 5, 2004
    Toronto, Canada
    Oh Boy
     
    /\/\3phist0 likes this.
  12. bobcruz

    bobcruz

    Mar 10, 2004
    CA
    If you're going to make a series cable for the two cabs, I recommend the rubber insulated toaster/clothes iron wire I used. At 16 gauge, it's plenty of copper for this lower power application and the rubber jacket makes it very flexible. That helps where you have to splice a connector into the positive-side wiring. If I hadn't left my cable locked up with my amp at church, I'd post a picture of the cable I made--the excess loop of negative wiring where I made the splice wraps nicely along the Speakon connector and is held there with two zip ties for a very neat result. I've seen some pretty ugly series cables with the regular (round) insulating jacket and a lot of heat shrink tubing--it's hard to make that kind of cable look un-amatuerly made. I know, I care too much about appearances! ;)
     
    BadExample likes this.
  13. BadExample

    BadExample

    Jan 21, 2016
    Injiana
    Interesting. I'll probably wire the cab(s) series. Unless I ever get a smaller amp. I thought I would need to but was going to test first. No need to test now!
     
  14. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    You can also use some 4 wire cable for a series speaker cable.
     
    Balog, Gabbs, AstroSonic and 2 others like this.
  15. Omega Monkey

    Omega Monkey

    Mar 8, 2015
    Seems like a splitter box would be a bit neater than a homemade cable. Just find an old donor ABY box for a few bucks and rewire as necessary.
     
  16. BadExample

    BadExample

    Jan 21, 2016
    Injiana
    Thanks Andy! You might guess what I'm up to. Top secret :D It will be a while...
     
    agedhorse likes this.
  17. singlemalt

    singlemalt Supporting Member

    Dec 15, 2007
    White Salmon, WA
    So, I’ve got a Streamliner 600 and a couple fEarful 12/6 cubes I built. The cabs are 8 ohm each.

    I find I like the how the amp behaves better with just one cab.

    If I hook up both and drop to 4 ohms, it’s wonderful, loud and punchy, but the good gooey is gone. I figure if I need that kind of volume, the subtle stuff has already gone by the by.

    You guys seem to be saying I could make a new speaker cable or two, (I have some heavy four wire cable) and I could use both cabs in series for a 16 ohm load. This would reduce overall output but give me more of the tube goodness I’m just starting to get with one cab at 8ohms.

    Or did I just whiff on this?

    If this is indeed the case, how exactly do I build the cables to put the two cabs in series? Four pole speakon connectors on everything. Go slow, or pictures would be great.

    I’d love to have another gear on this rig. It gets too loud before the goodness gets really good. Even with just one cab. Maybe I just need to experiment more with the gain stages and the master.

    I’d also be interested in the cabs the OP built. Bob, are these plans available? I’m always looking for an excuse to build cabs!

    Thanks!
     
  18. SactoBass

    SactoBass A retired civil engineer who likes all-tube amps! Supporting Member

    Jul 8, 2009
    Sacramento CA
    Very.....very.....*V-E-R-Y* interesting! I will be keeping my eye out for such developments! :thumbsup: :thumbsup: :thumbsup:
     
  19. bobcruz

    bobcruz

    Mar 10, 2004
    CA
    Your understanding is correct. With about 200 watts at 16 ohms, you may or may not get the volume you need from the 3012LF speakers but you won't know until you try. The "cabs" I built are heavily modified Fender Rumble 40 combos that I picked up in mint condition for pocket change and modified with Basslite speakers, new port tubes, felt lining, a jack dish and jacks to interrupt the wiring from the combo's amp to the internal speaker and custom covers made by my sweet spouse. The modding details are in this thread: Fender Rumble v3 40 - First Impressions and some pictures of a similar mod of a Rumble 100 are in this thread: Fender Rumble V3 mod: separating amp and speaker. In each case, my out-of-pocket is about the same as buying each combo new ($199 street) and I have built-in redundant amps if needed. I could save another pound or two by removing the amps but I'll actually use one of the combos as a combo for quiet rehearsals. They only weigh 17 pounds with the amp left in place.

    I'll let others post about series cable construction until I can get to my cable and take a picture of it. I also have a series box as mentioned by Omega Monkey but that requires three cables and the box compared to my all-in-one series cable and I had the cable connectors just laying around so I made the cable.
     
  20. singlemalt

    singlemalt Supporting Member

    Dec 15, 2007
    White Salmon, WA
    Thanks! A pitcher is worth a thousand words.

    A couple pitchers and we’d be here all night.
     
    Loring and BadExample like this.

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