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NAD: Acoustic 270 and B115MkII sounds...

Discussion in 'Amps and Cabs [BG]' started by yakmastermax, May 3, 2015.

  1. Hey TB!

    I've finally got my first real amp :D
    I started on an old Peavey TNT 115 and when that blew I bought a first generation Acoustic B100.

    I sold the B100 a couple of weeks ago to raise funds for this:



    I got the Acoustic 270 head for a pretty damn good deal which was nice because money is tight:greedy:
    I picked up the cab used from a GC for $140 which I'm happy with considering it is in excellent shape and has casters. All in all I'm quite pleased with the total expenditure but I'm not exactly satisfied. :thumbsdown:

    The thing is that right now the rig sounds pretty damn meh. I'm pleased with the fuzzy grit that I can get out it but the setup doesn't have a good clean sound. They're isn't much punch and the cabinet is farting on an open E at just practice volume! This is interesting because from the Acoustic website the cabinet is rated at 450 Watts RMS...

    The clean is acceptable at low volumes but as it stands right now the clean tone is not gig or even practice ready. The best clean hifi sound I could get was with the horn on, Bass and Treble at 2 o'clock and mid-range at 10 o'clock. I set the graphic up to boost lows, slight cut in the mid lows and boost the highs with the mids flat. The bass was set flat. You can see the setup in the first picture.

    Too me it sounds like the cabinet is being pushed to hard to something or the amp is being over-driven. Is it possibly my active SR500 being too hot for the amp? Also I noticed that the 12th fret sounds very very bland. You can almost hear the sinusoid, absolutely zero musical voice or overtone.

    I think the main culprit is the cabinet... Correct if I'm wrong though but I thought that these Acoustic 370/270 heads could get a pretty good mellow clean sound? So the lack of clean in my setup is the cabinet and speaker? Btw the Acoustic horn hisses something awful.

    I'm not sure if any of you guys have heard the new Fender Rumble V3 amps but They've got a killer "vintage" tone and a great clean too. That's what I really want, along with fuzzy grit I know this amp already has. I know I know, I'm asking for the cake and want to eat it too.

    Do you guys have any ideas? My first idea was to replace the 8 ohm speaker in this B115MKII cabinet with a decent 4 ohm eminence. I figured I'd open it up and get some dimensions and call eminence with that information. I'm honestly a little bummed :meh: but I'm sure this is something fixable:rolleyes:!

    Oh and I'll say it again, money is tight!

    Thanks TB
    Last edited: May 4, 2015
    GreaserMatt likes this.
  2. JacklegBass


    Jul 4, 2004
    The 270 should be able to supply plenty of clean power. At its power amp core it's virtually identical to a 370.

    I'd suggest that when you're testing for clean sound you should flip the reverb/fuzz switch to the "reverb" position and turn the level potentiometer down to 0. As the components in the 270 age, sometimes a little bit of fuzz will still bleed through even at level 0 with the switch in the "fuzz" position. It isn't likely to be what's going on in your situation, but it wouldn't hurt to rule it out.
    GreaserMatt and yakmastermax like this.
  3. billgoodwin


    Mar 28, 2011
    pairing the 270 with vintage Acoustic cab is your best bet all around. the new GC Acoustic items are farily good amp wise (had a B200 for a good while) but the cabinets are not all that.
    yakmastermax likes this.
  4. Gaolee

    Gaolee Official leathers tester and crash dummy

    A 270 should sound great. If the cabinet is farting out, something isn't right. Did you hear the amp through another cabinet? If it sounded good, then it's the cabinet you have has issues. Aside from the things that have been mentioned, you could have a tired transistor or two, or some other internal issue in the head. It's just solid state, so it shouldn't be too expensive to repair.
    GreaserMatt likes this.
  5. While the B115MKii is a cool looking cabinet, it's not a good cabinet by any means other than cheap. Any of the Guitar Center branded Acoustic cabinets will leave you wanting more. It is definitely bottlenecking your rig. I've owned both the B115Mkii and the B410Mkii. Neither were serviceable cabs in my alternative rock band.
  6. waltdogg


    May 24, 2014
    I've had amazing results with a 270 on a "pro" cab like a Marshall 1960 or Ampeg 8x10. Those amps are also super sensitive to impedance changes, when there's a mismatch up with the cab man do they lose power.
    GreaserMatt likes this.
  7. I figured it out! :hyper:
    My active SR500 was way way too hot for the amp. I turned the volume on the bass down to 2 (from 10) and turned the amp volume up to 6 (from 2) and I'm getting a pretty sweet smooth clean at decent practice volume.

    Hmm so the reverb is working well and responds to the intensity knob but it seems like the fuzz isn't working at all. With the switch on fuzz there is no change in tone as I turn the intensity knob. Also do you know what the effect is of the BRT switch and the GND/REV switch. Furthermore do you know what the foot switch jack on the rear controls? Thanks man!
    I appreciate your suggestion though!

    I'd love to get a vintage Acoustic cab but they're pretty hard to get your hands on and most importantly I don't have the vehicle necessary to own a 301 or a 408. I might be able to manage a 105 but even that is pretty damn big cabinet. Also they vintage stuff is pretty costly:greedy:, only reason I've got this head is because I landed a killer trade for it. I remember you suggesting an original Acoustic cab in my other thread though and I appreciate the input. Down the road the ideal cabinet would be a 301 (but I need a bigger car first :roflmao:)

    Do you know if there are any particular parts to replace which can aid in the amp sounding clean? I've heard murmurings about filter capacitors? And before anyone freaks out I know very well that there are capacitors in the amp which can kill me. :dead:

    Yeah it is unfortunate that Acoustic went from top of the line pro gear to big box store house brand entry level stuff. Now that I got a clean tone out of the amp I'm thinking about returning the B115MKii and buying a first generation sealed B115. They are even cheaper and I could port it to my specifications to match an upgraded 4 ohm driver. I was looking at this thread: Modding the Acoustic B115 | TalkBass.com
    5port seemed very happy with the result.


    Thanks guys!

    The acoustic 270 (and I assume 370) gets pretty fuzzy with an active bass. For a clean crisp tone turn the volume down on the bass and up on the amp.
    What does the footswitch jack on the rear control? What does the GND/REV switch control?
  8. JacklegBass


    Jul 4, 2004

    You might want to try going into front panel input jack #2 which is padded down 10dB compared to input jack #1.

    The front panel level control is a dual (ganged) potentiometer. The fuzz section of the pot might be open, or the reverb/fuzz switch could have a bad section. Most people think the 270's fuzz is nasty sounding anyway, so I wouldn't worry about it for now.

    Engaging the BRT (bright) switch is like turning the treble control way up. I never used it, too harsh for me. The GND/REV switch is a relic of days past and will trip GFCI protection in a heartbeat. I would leave it in the GND position all the time. I'll usually disable the switch when I overhaul those amps.

    Older SS amps that have a lot of hum can often benefit from then replacing the board-mounted aluminum electrolytic capacitors. In addition, the 270 has three large chassis-mounted computer grade can electrolytics... the smallest 1000uf one almost never goes bad, and the largest 7800uF is probably OK. The 3900uF/75V output cap is still pretty easy to find, so if there is a lot of raspy distortion then I'll usually change that out just because it's easy to do.
    Last edited: May 4, 2015
    yakmastermax likes this.
  9. Thanks for all the help Jackleg.

    I tried the second input #2 and there is no volume difference. There is also definitely something wrong with both the fuzz and the reverb circuitry. The reverb seems weak and doesn't respond to the intensity knob much. The fuzz is nonexistent. I'll probably take it to a tech at a later date but right now I agree that I'm probably not missing much. Seems like this guy isn't in the best of shape...oh well.

    You're right I'm not a big fan of the BRT switch on and I hear ya I'll leave the GND switch on ground.

    Now that I got the amp to sound clean I'm digging the tone pretty good. The A and D string are real tight and punchy and I can't imagine what this amp will sound like through a proper cabinet.

    One thing though is that this speaker is definitely farting out. I'm not sure if this is because the cabinet is 8 ohms or because I don't have the amp setup right. The entirety of the E string distorts and farts at practice volume and the only way I can curb it is by cutting the bass knob on my Ibanez or by EQing out the lower frequencies. When I do this the farty distortion goes away but I lose a whole of of the awesome punch and tone that the A and D strings had before. Any tips or ideas?
  10. bottomend!


    Oct 23, 2007
    try plugging a foot switch into the input marked "footswitch" on the rear of the amp. You might also try plugging in a stereo 1/4 plug only part of the way in. This may turn the tremelo on and off and/or the fuzz/reverb as well.
    GreaserMatt likes this.
  11. JacklegBass


    Jul 4, 2004
    It's not unusual for the front panel reverb/fuzz switch to flake-out in 270 amps. The symptoms you have aren't exactly typical (normally you can't turn the fuzz off), but even still you might want to have a tech replace the switch to eliminate that possibility. On the Acoustic forum I gave you a link to a thread that touched on this subject with info about a color-correct DPDT switch by Eaton that I've used successfully in the past. You should also have a tech clean both sections of that level control potentiometer.

    Of course it sounds like the amp is working fine other than the reverb/fuzz, so what you essentially have is a great working 370.
  12. kbakerde


    Jan 24, 2012
    Yup, I found this on my 370 as well. I havn't broken out my 270 in a rehearsal or gig situation yet. It's my SVT backup, but I am going to assume it's the same thing. I find that it's pretty easy to overload the preamp section of the 370 and get a pretty nasty distortion out of it. My Gibson EB despite being passive had such a high output it would crush the input on the amp. I didn't find the padded jack to help nearly as much as just turning the bass down. If you use the 370, try to make sure your bass has a Master Volume/Balance option. Makes it really easy to manage.

    My 270 (bought off another TB'er) also has a bad Reverb/Fuzz. It just doesn't work. But if I keep the pots all the way down and keep the switch on Reverb it's fine. The Tremolo works fine, and is an interesting if not usable effect. Good luck!!.
    yakmastermax likes this.
  13. JacklegBass


    Jul 4, 2004

    You might want to try having someone replace the switch. The part itself is only $4 plus shipping from Newark. Here's a post of mine containing details... Link
    Last edited: May 5, 2015
    kbakerde likes this.
  14. kbakerde


    Jan 24, 2012
    Thanks dude. I did read that and I was considering it. I am fairly handy with a soldering iron. How difficult is it a DIY job?
  15. JacklegBass


    Jul 4, 2004
    If you can solder then it's pretty easy once you get the old switch to release its grip on the chassis hole. The rear of the DPDT switch has 6 solder terminals, but wires only connect to 5 of them -- one is unused. IIRC, there may be two wires on one of the terminals. Sketch out your wire colors and take a good picture before you unsolder anything and just follow the same scheme with the new switch.
    kbakerde and yakmastermax like this.

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