How can I get more warmth out of my Music Man 210HD?

Discussion in 'Amp Central Station' started by lemmingman, Nov 24, 2020.

  1. PCollen

    PCollen Friend of Leo's

    Posts:
    3,487
    Joined:
    May 7, 2010
    Location:
    Florida
    I once owned a 212-HD130 combo with EV-12S speakers. It weighed 90 pounds and could break glass at 50 feet, figuratively.

    The PI is not considered to be a preamp section. It is the power amp driver. Many think it's part of the preamp because of the dual triode used , but it is not. If you look at a schematic that has Preamp Out/Power Amp In capability, the Preamp Out does not come FROM the output of the PI. The Power Amp In goes TO the input of the PI, the first stage of the power amp.
     
    Last edited: Nov 25, 2020
  2. That Cal Webway

    That Cal Webway Friend of Leo's Silver Supporter

    Posts:
    2,959
    Joined:
    Nov 16, 2012
    Location:
    Minot

    Albert Lea's massive old standby has JBL's in it.

    There's a big difference between those speakers and standard issue ones.
     
  3. 11 Gauge

    11 Gauge Doctor of Teleocity

    Posts:
    12,268
    Joined:
    Mar 21, 2003
    Location:
    Near BWI Int'l
    I've been mildly curious about amps like the HD130 for a few years, but never looked at a schematic until now.

    It looks like only 1/2 of the dual triode is used for a cathodyne/split load phase inverter, which simply provides the power tubes the necessary signals for push/pull, with a gain of only ~1 (e.g. unity).

    But the other half of the dual triode does look to be the actual final gain stage that dumps out after the SS preamp stuff. That's where the (global) negative feedback connection is made, and the master gain falls between it and the phase inverter.

    For whatever reason, I never would have thought that the preamp circuitry in the HD130 and similar would be primarily just op amps, although I do see that they used the old metal canister types. That would make replacement with the current common DIP8 types a pain. Also, the slew rate of the LM307s that were used look to already be on the low side, and even though it's probably counterintuitive, that's actually what tends to sound better in guitar-specific circuitry (IMO), especially if driven into clipping.
     
  4. clayfeat

    clayfeat Tele-Afflicted

    Posts:
    1,832
    Joined:
    Jan 19, 2005
    Location:
    Midwest
    10" speakers never sound warm to me. Plug in a cab loaded with a 15" speaker and get cozy!
     
  5. Mexitele Blues

    Mexitele Blues Tele-Afflicted

    Age:
    43
    Posts:
    1,727
    Joined:
    Mar 7, 2018
    Location:
    Westminster, CO
    So it lacks that je ne sais quois?

    How does one add warmth? I think we need to know what about the sound you currently don't like. Is it too shrill (turn down the treble), too sterile (turn up the gain), too thin (turn up the bass)?

    You mentioned an always on pedal. If you want to go that route I would be looking at a good compressor or a full range OD like the Timmy or Blues Driver.
     
  6. richiek65

    richiek65 Poster Extraordinaire

    Posts:
    5,029
    Joined:
    Dec 26, 2012
    Location:
    Sydney NSW Australia
    One of these should do the trick, cheap too
    images (3).jpeg
     
  7. BelairPlayer

    BelairPlayer Tele-Afflicted

    Posts:
    1,657
    Joined:
    Jun 22, 2010
    Location:
    NorCal
  8. Chiogtr4x

    Chiogtr4x Doctor of Teleocity

    Posts:
    11,136
    Joined:
    Mar 29, 2007
    Location:
    Manassas Park, VA
    This may be a non-invasive, cheap fix, and if it doesn't work- you still get a very good Fender amp emulator to use into PA as a ' backup amp'
    But checkout the JOYO American Sound pedal ( clone of Tech 21 Blonde)

    It has a great sounding ( nicely tapered) 3 band EQ, and a Voice knob to approximate various Fender amp series, plus Drive/ Level

    I use mine ( always ON) with a Tube Screamer clone ( for OD). into a SS Fender to balance EQ,

    See settings below, what I use for a general BF/SF Clean tone. I don't care for Drive past 9:00-10:00, but its sound good there, plus easy EQ shaping
    $35!
    20200913_164521.jpg
     
  9. PCollen

    PCollen Friend of Leo's

    Posts:
    3,487
    Joined:
    May 7, 2010
    Location:
    Florida
    If V1a is in fact acting as the final preamp stage , replacing it (a 12AX7 or 7025 per schematic) with a 5751 or an Ei ECC83 will add warmth to the tone.
     
  10. codamedia

    codamedia Poster Extraordinaire

    Posts:
    5,608
    Joined:
    Apr 4, 2009
    Location:
    Western Canada
    Early 70's.... that's great news, and bad news!

    Music man amps run 700+ volts on those output tubes which keep it clean for days, but "too clean" can often be taken as "sterile and cold".

    If it were a later 70's model I would suggest running the amp in LO mode... which drops that voltage to about 450 which is the range of most fenders. Sadly, the early 70's models (which are more valuable, and preferred in general) aren't as reliable in LO mode, so it is not recommended.

    Keep in mind a MusicMan is not a Fender! The look similar, but that is where it ends. They have a lot more mid range and a tighter low end, more akin to a Marshall than a Fender. Ask Marshall users how they warm up their tones.... that would be more applicable!

    Make sure it is running the correct tubes... this is not a place to skimp on a Musicman. Early 70's would be EL34's. Having the amp biased properly would be highly recommened.

    I've owned two musicman amps over my career, both had no problem in the warmth category. Solid State pre-amps have NOTHING to do with the difference!

    However, opamps wear out just as tubes can and this amp is almost 50 years old. Those amps use LM307H op amps in a TO99 form factor. They are getting hard to find and counterfeits are abundant. Another option is to buy the TO99 to DIP8 adapters... then you can source DIP8 LM307H OpAmps much easier.
     
    lemmingman likes this.
  11. 3-Chord-Genius

    3-Chord-Genius Poster Extraordinaire

    Posts:
    8,961
    Joined:
    Apr 3, 2015
    Location:
    Winchester, VA
    "Warm"? Right now I am running a 100W digital modeling head, and it sounds just as "warm" as any tube amp I've had. And I've had plenty.
     
    lemmingman and Jakedog like this.
  12. W.L.Weller

    W.L.Weller Tele-Holic

    Posts:
    956
    Joined:
    May 20, 2014
    Location:
    Queens
    I'd want to make sure that amp was working properly if I needed to rely on it. The super-high plate voltage on the power tubes is a relic of a different era. I think the best bet for currently produced tubes that can stand up to the abuse are the Sovtek 5881WXT. But I don't think working on this amp (even just swapping tubes and biasing) is for amateurs or dilletantes.
     
    lemmingman likes this.
  13. 11 Gauge

    11 Gauge Doctor of Teleocity

    Posts:
    12,268
    Joined:
    Mar 21, 2003
    Location:
    Near BWI Int'l
    Op amps are not actually wear items like tubes are. They either function or are broken.

    With guitar-specific devices, we actually tend to prefer SS stuff with considerably less than hi-fi performance (lower slew rate, less gain bandwidth, etc.), and the LM307 is probably yet another example of that.

    IMO, if the op amps have to be replaced, I'd personally get adapters for DIP8s and pop new production NJM741s in their place. They also have pleasing low-fi characteristics, and the currently produced (NJR)/NJM versions are much lower noise, compared to the old 70's stuff.

    ...If someone did want something with a more modern twist, I'd suggest trying NE5534s, but I bet that most folks would probably go back to the 741s instead.

    Something else to consider would be using an op amp that has external compensation, like the OP07, and put a 30pF cap across pins 1 and 8. If you go bigger with the cap value, you can restrict the bandwidth even more, and make it as guitar-specific as you want.
     
    Last edited: Nov 27, 2020
  14. codamedia

    codamedia Poster Extraordinaire

    Posts:
    5,608
    Joined:
    Apr 4, 2009
    Location:
    Western Canada
    Respectfully, I have had a very different experience with my two MusicMan amps.

    I agree they won't wear the same way tubes do... but noise starts to set in along with tonal anomalies and no amount of socket cleaning can resolve it. Just like tube rolling, I could chase these anomalies through the circuit (eg: 2nd channel, or reverb circuit) by simply moving the bad ones around. After replacing several LM307's with original spec TO99's.... the problems went away.

    If you say an OP amp doesn't wear, and yet I'm able to chase the offending OP Amp from socket to socket - is it possible the TO99 form factor has flaws that get exposed over time?
     
    Last edited: Nov 27, 2020
  15. 11 Gauge

    11 Gauge Doctor of Teleocity

    Posts:
    12,268
    Joined:
    Mar 21, 2003
    Location:
    Near BWI Int'l
    Yes. IMO/IME, it's more of a mechanical/construction malfunction as opposed to 'wear' within the integrated circuit itself.

    While canister-based semiconductors definitely win the award for the cool factor, I'll take transistors in a TO-92 format, or op amps in DIP8/SIP8/DIP16 formats, whenever possible.

    Semiconductor construction has obviously improved a whole lot over the years!
     
    codamedia likes this.
IMPORTANT: Treat everyone here with respect, no matter how difficult!
No sex, drug, political, religion or hate discussion permitted here.