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Walter Woods Amps History and Development

#41
KungFuSherrif,
That's a important piece of information for the folks who are buying these amps used. Walter was a real innovator in that light. Who else was building an transistorized solid state amplifier in 1972 that sounded better than the tube amps it was "emulating".

Ric
 
#42
Better or worse than a tube amp is a matter of personal judgment, but there's a lot to love about those little amps -- I could go on for days about the dynamic range alone.
A few years back I scored one of the "Ice Cream Sandwich" amps from a pawn shop, but definitely prefer my current amp. It also doesn't hurt that he put each MI-series amp's schematic into the chassis, so on the off chance it ever dies the circuit won't be a total mystery to whoever is asked to fix it.
Re: the stereo preamp schematics, there's no appreciable difference in layout or components to each channel, but they sound vastly different to my ears, EQ nonwithstanding. Can anyone fill me in on this?
 
#45
Uncletoad said:
Can anyone clarify the timeline and model development for me? I'm getting confused already.
Click to expand...

Phil,
If you look at a Woods amplifier there are three different logos that Walter used to identify his model changes. The Ice Cream Sandwich and the early MI's had the WW/AMP logo. Around 1993 Walter changed the logo to two art Deco W's and finally he put the Electo Acoustic logo on in around 1997.

The really cool thing that we are finding out from all these posts, is that Walter made a great deal of modifications in the Pre Amp controls from around 1992-1995. I've never seen the MI-200-8 that Kevin Kelly owns. It's really unique. Since it has sweepable lows, mids , and highs along with a crossover. That's a very cool amplifier. Thanks to Kevin for posting it.
 
#46
Subscribed.
I was pretty pissed when that old thread disappeared. It was getting pretty good! I submitted photos of my early Electroacoustic model and by comparing them to a recent model, a couple guys were able to point out the physical differences between them and how they might affect the sound. I remember the concensus was that the early Electro models had more low-end while the newer ones were leaner down there. Something to do with the new power supplies.
 
#47
VintageBT6Lover said:
I remember the concensus was that the early Electro models had more low-end while the newer ones were leaner down there. Something to do with the new power supplies.
Click to expand...
I remember that too. Changed around 2003 as I recall. For DB that leaner low end is probably better. My woods (2005) can get a little electric bass-ish with my DB as the volumes go up as it is. The decreased low end makes the DB sound more natural. Earlier ones may be better for the Electric Bass though.
ric vice said:
Walter made a great deal of modifications in the Pre Amp controls from around 1992-1995.
Click to expand...
Seems like he was heading towards his electroacoustic amp then and in '97 incorporated all those preamp changes with an increase in power. Right?
 
#48
Subscribing also. . . I had that old thread (several of them, actually) bookmarked so I could check in from time to time. Lots of interesting things there, but I forgot about it after a while. I am interested to hear more about the earlier (96-2002 I guess?) Ultra tonal differences when compared to the latest version. I had an Amber light, called the Super High power I believe, for a while that I thought was fantastic. I suppose it was a late 90's model. I eventually sold it because someone offered me $500 more than I'd paid for it and I couldn't pass it up. I'm using an Epifani UL-502 right now and I think it's a fantastic amp, love the tone with my Epi 210 NYC's. But I've never fully gotten the yearning for an Ultra out of my system. . . I don't double so I suppose the older one would be better for me (electric)?

Thanks for restarting the thread, Uncle :bassist:
 
#49
Uncletoad said:
Seems like he was heading towards his electroacoustic amp then and in '97 incorporated all those preamp changes with an increase in power. Right?
Click to expand...


Great observation UncleToad!

Thanks to others we have seen at least two totally different preamps
in the Walter's MI (Musical Instrument) Amps built after @1990.

That Stereo MI-200-8 with the vari controls for bass, mids and treble and the dual crossovers was posibly version I.

The Stereo MI-100-8 with the boost and brite switches and single vari (midrange) is probably version II (This amp was also avaliable in single or two channel mono versions)

So that would make the Electro Acoustic v III

He had bulit MI-400's and 600's with the original preamp
but they were only avaliable for a few years. I've always wondered why?
 
#50
KUNGfuSHERIFF said:
It also doesn't hurt that he put each MI-series amp's schematic into the chassis, so on the off chance it ever dies the circuit won't be a total mystery to whoever is asked to fix it.
Click to expand...

Unfortunately, The power supply section of the schematic dosen't show
anything.

KUNGfuSHERIFF said:
Re: the stereo preamp schematics, there's no appreciable difference in layout or components to each channel, but they sound vastly different to my ears, EQ nonwithstanding. Can anyone fill me in on this?
Click to expand...

KUNGfuSHERIFF
Walter actually talored the EQ of the MI channels differently!

Channel one was for Electric Bass CHannel 2 was for Acoustic Bass
 
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#51
Uncletoad said:
I remember that too. Changed around 2003 as I recall. For DB that leaner low end is probably better. My woods (2005) can get a little electric bass-ish with my DB as the volumes go up as it is. The decreased low end makes the DB sound more natural. Earlier ones may be better for the Electric Bass though. Seems like he was heading towards his electroacoustic amp then and in '97 incorporated all those preamp changes with an increase in power. Right?
Click to expand...
It occurred to me today that right when I got my Woods around June '05 I had Tom Bowlus' Woods from 2001 or 02 or something at the same time. When I A/B tested them next to each other, same source, same cab I couldn't hear a difference. Whatever the differences may have been they were small.
 
#52
I'm in here too. I wish I had been aware of the thread you're all referring to but I guess I missed it. Not sure how much I can contribute, but I have acquired three used MI series amps over the past 20+ years and they are my main sources of amplification.

In a way I have always thought that Walter has been a part of my moderate success as a performing musician, and I finally got to say that to him last year in a phone conversation when he helped recondition one of my units. Absolutely fantastic individual!

This is a great thread! :hyper: Thanks Uncletoad!
 
#54
Uncletoad said:
How bout pics?
Click to expand...

OK

th_IMG_1553.jpg

MI 100-8 Single Channel (1980)

th_IMG_1538.jpg

MI 100-8 Dual Channel (1979)

th_IMG_1563.jpg

MI 225-8 Power (1982)

I know the approximate ages of these ('75-'85) and Walter told me about his serial number/date code, but I don't want to take them apart just to get the date.

(Edited to include build dates.)
 
#55
Ric Vice said:
Jonas,
According to my "manual" for the MI-100-8 the Power Requirements are "120/240 VAC switchable, 50-60 Hz ( stepdown transformer not required for european operation). Hopefully some of our techies will enter the thread and explain this feature. There is also a switch between the cooling fins on the rear of the amplifier that provides for 200- 240 50-60 hz operation volt operation. However I'd be really careful about using it.

Ric
Click to expand...

Hi Ric,
I am in the process of finding some techies that could help me with that here...the switch was found, and switched to the european voltage, with the result that nothing happened. I used an adaptor so that I could plug in, wondering if there is a ground issue or maybe something I can't think of right off the bat. The fuse should be all right, but still no power. The step down transformer, with the switch between the fins again at the 110 setting, allowed the amp to work. And yes, I feel nervous about using anything at all until I get some solid answers. Of course, not very patiently waiting, because it just sounds so awfully good!
jonas
 
#56
Condor said:
...Walter told me about his serial number/date code, but I don't want to take them apart just to get the date.
Click to expand...
Cool photos. Thanks for posting them. The serial numbers on these amps can be seen by simply removing the four screws that hold the top panel on. The numbers are stamped into the top of the large heatsink. The last 2 digits in the serial number indicate the year the amp was made.

It's amazing how many different models Walter has made over the years, especially considering that he works completely by himself and designs and builds each and every amp (with a little help from his wife).
 
#57
robgrow said:
The serial numbers on these amps can be seen by simply removing the four screws that hold the top panel on. The numbers are stamped into the top of the large heatsink.
Click to expand...

Thanks for the tip, robgrow! Now that I know the disassembly isn't extensive, I'll be doing that and edit the dates into my post. :)
 
#58
jotabass said:
Hi Ric,
I am in the process of finding some techies that could help me with that here...the switch was found, and switched to the european voltage, with the result that nothing happened. I used an adaptor so that I could plug in, wondering if there is a ground issue or maybe something I can't think of right off the bat. The fuse should be all right, but still no power. The step down transformer, with the switch between the fins again at the 110 setting, allowed the amp to work. And yes, I feel nervous about using anything at all until I get some solid answers. Of course, not very patiently waiting, because it just sounds so awfully good!
jonas
Click to expand...


Jonas,
I don't think that you should have to use it for standard voltage 50-60 cycles from 100-120 volts. Here's what the instructions say, please read them carefully. "120v/240v switch: Incidated on the amps bottom cover, This switch must be in the "Down Position" for 100-120 volt 50-60 HZ powerlines and in the "Up" position for 200-240 volt 50-60 HZ powerlines. So normally, unless you are running it into a 200-240
volt high power line you wouldn't use it at all.

Ric

If you have any concerns here is Walter Woods us phone no.
760-347-7009
 
#59
Regarding the MI 200-8 shown in an earlier post of mine: I checked out the year of manufacture stamped on the heat sink: xxxx91.

There are also three dates written in magic marker on the aluminum flange in the top part of the chassis: xx.xx.96, xx.xx.2K (00?), xx.xx. 04. Does Walter typically do this when he does repairs, bench tests, updates, etc.?

Thanks for any input!

Kevin
 
#60
interp said:
There are also three dates written in magic marker on the aluminum flange in the top part of the chassis: xx.xx.96, xx.xx.2K (00?), xx.xx. 04. Does Walter typically do this when he does repairs, bench tests, updates, etc.?Kevin
Click to expand...

Kevin

Based on what I just found inside two of my amps, yes Walter writes the date of any work he does.

My 2 channel MI 100 has four dates along the left side and back flange, and my MI 225 has one date on the left side that I know is from last year when I sent it to him for reconditioning.
 

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