Got it home half an hour ago. Looks like it has seen the world and some rough dudes. But seems ok. Haven't tested yet. Serial Nr. 100379. Built october 3, 1979.
Best
Sidecar
Best
Sidecar
Enjoy the benefits of a premium membership!
Upgrade Account
-
TalkBass has been independent since 1998. Add your voice.
Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
Join free Log in
Want zero display ads or expanded classifieds tools? Compare plans.
Double Bass Walter Woods Amp MI 100-8
- Thread starter Ayeleeex
- Start date
Ok folks. Quick at-home test. Connected to a 4 ohm MAS26.
channel one performs as advertised. Sounds REALLY great. Punchy, powerful, loud and clean. Very effective EQ, especially the mids and the boost/cut switches. Some serious low end going on. Easily one of the best sounds if not the best I have heard from my hands and bass with any amplifier/cab/combo.
channel two is wonky, reacts to the touch of the knobs (buzzing, sound changes in the lows), and apparently oscillates when pushed a little, or when there is more than just a little treble. Treble boost on that channel almost immediately sets the oscillation buzz free, at least when played above soft levels.
so there's some work ahead, but it's absolutely a keeper! Haven't compared it to my other amp yet, but so far it seems like a more powerful version of my Lehre amp, with much more extreme eq.
best
sidecar
channel one performs as advertised. Sounds REALLY great. Punchy, powerful, loud and clean. Very effective EQ, especially the mids and the boost/cut switches. Some serious low end going on. Easily one of the best sounds if not the best I have heard from my hands and bass with any amplifier/cab/combo.
channel two is wonky, reacts to the touch of the knobs (buzzing, sound changes in the lows), and apparently oscillates when pushed a little, or when there is more than just a little treble. Treble boost on that channel almost immediately sets the oscillation buzz free, at least when played above soft levels.
so there's some work ahead, but it's absolutely a keeper! Haven't compared it to my other amp yet, but so far it seems like a more powerful version of my Lehre amp, with much more extreme eq.
best
sidecar
I, too, had one of these amps and now I wish I could try it again with the great new speakers out there...
I did ONE jamsession with a WW 100-8 amp (electric bass) years and years ago, and the feeling stuck with me.
I kept mine, and am looking foward to trying it with a MAS 4/5someday. What I've observed is, as speaker cabinets have improved, the paring with a Walter Woods is even better sounding.
Ric
Last edited:
Other observations- the amp is not really noise-free at all. It's IMO clearly something of the olden days of comparably low-bandwith 15 inch-speakers, where it was important to be able to dial in REALLY much treble for the speaker to reproduce it, and the noise on top would go unnoticed. Modern cabs reveal that there's indeed serious hiss- well, serious under the condition that, if you use the treble boost, or crank the treble, or heaven forbid even both, you'll notice and possibly be annoyed. Since I find that sound to be useless anyway, I can safely ignore this.
It has SERIOUS preamp gain, I can use the Ehrlund without preamp even though the input impedance is not optimal (1M in the Woods compared to 5.7M in the preamp). With the preamp, there is clearly noticeably more bottom end, but the EQ of the Woods can easily take care of that.
When doing it the "recommended" way (crank the master all the way up, adjust playing volume with preamp gain), the amp can get crazy loud cleanly (before break-up). Very tight sounding and great impulse/punch. With the MAS26, more volume than I'll ever need for double-bass.
It's legendary for obvious reasons. If I try to imagine this little thing and the players' reactions to it in 1979 when it was built- nobody was even remotely doing what walter was doing back then. The man was simply decades ahead.
Best
Sidecar
It has SERIOUS preamp gain, I can use the Ehrlund without preamp even though the input impedance is not optimal (1M in the Woods compared to 5.7M in the preamp). With the preamp, there is clearly noticeably more bottom end, but the EQ of the Woods can easily take care of that.
When doing it the "recommended" way (crank the master all the way up, adjust playing volume with preamp gain), the amp can get crazy loud cleanly (before break-up). Very tight sounding and great impulse/punch. With the MAS26, more volume than I'll ever need for double-bass.
It's legendary for obvious reasons. If I try to imagine this little thing and the players' reactions to it in 1979 when it was built- nobody was even remotely doing what walter was doing back then. The man was simply decades ahead.
Best
Sidecar
As I've said here many times, "Think SPL, not watts!" Keep in mind that going from 100 to 500 watts yields a 7-dB increase. That still leaves speaker sensitivity as a substantial concern. With regard to headroom (as properly defined), it is entirely unaffected by the relative position of the master control. Take a look at the explanation here. As described here, the setting of the two controls allows for optimization of distortion and signal-to-noise ratio. Placing the master gain control at maximum invites noise. It is, generally, not a good practice.
Most amps I have seen schematics of (in fact, "all" amps I have seen schematics of, but certainly not "all" amps) have a master volume that is a simple voltage divider/attenuator between preamp out and power amp in. So, the master potentiometer in its full on position acts like it's not there, while all the other positions send part of the signal to ground. The MI100-8 is completely common in this respect.
Way back when I bought my Lehre amplifier (1991, does not have a master volume, only "volume"), and I was young and foolish, I asked the builder about why he wouldn't include a master volume. His answer: "Master volume is needed when one wants to drive the preamp stage into clipping but without experiencing hearing loss at the same time, so you attenuate the preamp signal before entering the power amp. That's not what I was going for in my design". Which is along the lines of what many consider "recommended use of the MI100-8 preamp gain/master volume".
Best
Sidecar
The principle applies, as MrSidecar explained. Actually, there is good reason to have a master control. As I mentioned, it can be used to optimize signal-to-noise ratio.
Last edited:
Update on my MI100-8:
I cured the channel-two issues myself. The fault seemed to be something mechanical, as it (reread my older post for a description of the issue) was worse when the amp was placed on top of the cab.
I figured curiosity might be better than fear, and unscrewed the bottom plate. Playing that way, and upside down, there was almost no problem, so I started touching channel two's parts with my fingers, and quickly found the culprit: a pretty much totally unsoldered, at least VERY loose, capacitor in the midrange control. Soldered the connections to the PCB properly, closed the amp, bang- issues gone. Nothing to pay €100 in repair for, let alone $600 flat fee to the master himself.
About the channels: Contrary to what others have reported, are hearing or maybe even measuring (?) in their amp, the two channels on the (or THIS exact) MI100-8 are exactly the same. There were some opinions about maybe channel two being the one to use for double-bass, while channel one is for electric. At least on my amp, I do not hear a difference, and the schematic shows clearly that the midrange sections (where the difference was supposed to be) and the rest of the eq are 100% identical, they're using the same parts. I figure that a) there might be different voicings in the preamps of newer WW amps, and/or b) any difference in this design is due to tolerances in parts specs. Correct me if I'm wrong.
What fits the picture here is this: At least on my amp, the phase switch works ONLY for channel one. It would be strange (to say the least) to add a phase switch, which is utterly useless on electric instruments (as there is no resonance of the body or instrument sound to be in phase or out of phase with), to the ELECTRIC channel only.
best
Sidecar
I cured the channel-two issues myself. The fault seemed to be something mechanical, as it (reread my older post for a description of the issue) was worse when the amp was placed on top of the cab.
I figured curiosity might be better than fear, and unscrewed the bottom plate. Playing that way, and upside down, there was almost no problem, so I started touching channel two's parts with my fingers, and quickly found the culprit: a pretty much totally unsoldered, at least VERY loose, capacitor in the midrange control. Soldered the connections to the PCB properly, closed the amp, bang- issues gone. Nothing to pay €100 in repair for, let alone $600 flat fee to the master himself.
About the channels: Contrary to what others have reported, are hearing or maybe even measuring (?) in their amp, the two channels on the (or THIS exact) MI100-8 are exactly the same. There were some opinions about maybe channel two being the one to use for double-bass, while channel one is for electric. At least on my amp, I do not hear a difference, and the schematic shows clearly that the midrange sections (where the difference was supposed to be) and the rest of the eq are 100% identical, they're using the same parts. I figure that a) there might be different voicings in the preamps of newer WW amps, and/or b) any difference in this design is due to tolerances in parts specs. Correct me if I'm wrong.
What fits the picture here is this: At least on my amp, the phase switch works ONLY for channel one. It would be strange (to say the least) to add a phase switch, which is utterly useless on electric instruments (as there is no resonance of the body or instrument sound to be in phase or out of phase with), to the ELECTRIC channel only.
best
Sidecar
And yes, that's true for this amp as well, and maybe especially so with modern cabinets. The highs on the woods amp can be somewhat noisy (there is TONS of them), which might not be an issue when the amp is hooked up to a single 15inch speaker, but a cabinet with tweeters exposes the noise clearly, and using the master and preamp volumes in combination and wisely (and not like "crank the master and carefully adjust the preamp volume to fit your volume needs"- even though this assures that you get away without preamp overdrive/fuzz), can minimize this problem.
best
sidecar
Mr Sidecar,
I hope you are enjoying your MI 100. Cold solder joints are a common problem of course, and Walter hand soldered your amp 30+ years ago. Glad this was a simple repair. The phase reverse switch works on channel 1 as you found. (Early dual channel MI 100-8's do not have a phase switch.) There have been some previous discussions of the differences between the two channels on WW amps. I've had a few dual-channel MI 100-8's here, and the channels all sounded different to me. I have come to the conclusion that no two WW amps are exactly alike, as they have all been hand made, one at a time, and Walter has been constantly changing things as he went along. I have had three Electracoustic models here, and they each sounded quite different. The channels sounded different on the same unit too.
I hope you are enjoying your MI 100. Cold solder joints are a common problem of course, and Walter hand soldered your amp 30+ years ago. Glad this was a simple repair. The phase reverse switch works on channel 1 as you found. (Early dual channel MI 100-8's do not have a phase switch.) There have been some previous discussions of the differences between the two channels on WW amps. I've had a few dual-channel MI 100-8's here, and the channels all sounded different to me. I have come to the conclusion that no two WW amps are exactly alike, as they have all been hand made, one at a time, and Walter has been constantly changing things as he went along. I have had three Electracoustic models here, and they each sounded quite different. The channels sounded different on the same unit too.
Rob,
you bet I am! I sure can see why these amps were so sought after, and still are surrounded with considerable "hype". They still are great, and certainly, seeing as the last time Walter has serviced the amp was in 1989, a loose solder joint on a capacitor is peanuts. And I can only imagine the impact this design must have had when it was new. Decades ahead of the times.
Thanks for sorting that out, I had most certainly never heard any mention of that.
It might be tolerances in the specs, or maybe he built this particular one I have to have to identical channels because of a customer wish... Whatever the reason, I have no troubles with how my amp behaves, as the amp works GREAT for electric and upright. It didn't take me long to find a really outstandingly amazing tone for my '51 precision, ... Once again (like many others stated), the midrange is the powerful knob to twiddle. The difference between noon and 1 o'clock is quite huge already.
I am quite positive this amplifier is the one I'll play until it absolutely cannot be repaired anymore. This is not going to be anytime soon, I suppose, since the really special parts like the SMPS nowadays can be replaced. Until that day, I won't need or want anything else.
Best
Sidecar
Mr. Sidecar,
Glad to hear that you are enjoying you're newly refurbished Walter Woods. I saved up my gig money and bought a MI-100-8 in 1980, at that time, virtually the only other DB friendly amp was an Ampeg B-15N which weighed 85 lbs. Until Acoustic Image, Tecamp, and Euphonic Audio, built
their SMPS amps there was nothing comparable on the market, unless, you went with a separate pre amp/power amp setup. With my particular MI-400-8 there is a subtile difference, between the two channels.
Little update.
I have now used the Woods with some different cabs, and most notably in the old school ones (some old Laney stuff, and an unknown 2x15), the somewhat drastic EQ makes perfect sense: Suddenly the amp is not as noisy as I thought, and the Treble boost makes most cabs sparkle and sing very nicely. That might be old general knowledge, but for me, that opened my eyes to the tremendous versatility the MI100-8 has: It can sound great for electric and upright on all the cabinets I've tried so far. And never once has it run out of steam yet.
Pretty good track record for a 1979 amplifier.
best
sidecar
I have now used the Woods with some different cabs, and most notably in the old school ones (some old Laney stuff, and an unknown 2x15), the somewhat drastic EQ makes perfect sense: Suddenly the amp is not as noisy as I thought, and the Treble boost makes most cabs sparkle and sing very nicely. That might be old general knowledge, but for me, that opened my eyes to the tremendous versatility the MI100-8 has: It can sound great for electric and upright on all the cabinets I've tried so far. And never once has it run out of steam yet.
Pretty good track record for a 1979 amplifier.
best
sidecar
See/hear an old Woods single channel in action with an Avalon as the house amp at the NEA 2015 Jazz Awards show. Great show, BTW.
Last edited:
Eric,
I listend to Carla Bley, George Coleman, and Joe Segal videos. Sorry But I can't a link to the concert you're referring to on that particular page. I located it here
[Invalid or Expired Link Removed]
Ric
Just proves that an Avalon U5 is the shizzle. It can take virtually any pickup and
make it sound incredible. I fear that if we really could hear what the Woods sounded
like into that Hartke 410 cab, we'd probably cringe. Steve Swallow uses a MI-100-8 for his rig, so my guess is that the only folks who actually heard the Woods were the onstage musicians when he was playing with Carla. The Avalon was most likely used as the out to the board. The DB players had a very nice large diaphragm mic, so my take is that Steve was the only player using the woods. Nonetheless it was very nice to see a MI-100-8 used for that concert. You're right it's a fine listen.
Ric
Last edited:
