Double Bass Manual for Walter Woods MI 100-8

[Freddels]

Freddels,
When I bought mine in 1980 Walter had a two page flyer that told about the different models he had at the time. He had the MI-100-8 and the MI- 225-8 had just become available. I saw that same ad on my copy of the Rufus Reid book, so I wrote him a letter and he sent me the flyer. His shop was in Sherman Oaks then and I think that he actually had someone else working with him at the time. He also sent a T Shirt along with my amp.

Ric

I think I got the t-shirt too but as a college student I probably wore it out.

 

[robgrow]

+1 to Bob for jogging our memory. There was also a 200 watt stereo version of this amp with controls that look like you could vary the center frequency of the treble and bass controls as well.

There are actually four generations of Walter Woods amps including the original Mini Amp (MI 100-4, aka Ice Cream Sandwich) and the current Electracoustic amps. The MI 100-8 amps are from the two middle generations. With the exception of the original MI 100-4 Mini Amp, there are multiple versions in each generation.

 

[robgrow]

I got out my old copy of Walter's sales brochure it's "a switchable signal booster for increased sustain". So that's what the "bst" position is for, but I still clueless as to what the "mix" position is for or what changes in the mix position. It might be the Mix positions "mixes the two inputs", but that's unclear from Walter's little flyer and I'm not sure that's what it does.

Ric

From looking at the schematic diagram, it appears that, in the Boost position, the switch adds a 2nd gain stage (Preamp Volume 2) to the signal path for higher gain. This feature is unique to the single channel version of the MI 100-8. Interestingly, adding the 2nd gain stage (Boost) also inverts the phase of the signal (phase reverse).

 

[fdeck]

testing the ability to post attachments
Our Thanks to Freddels for the schematic scan

Looks like a basic flat amp.

 

[Mike Tatt]

Just bought a WW Mi 100 8 - 1st generation (anodised front panel) here in London yesterday. Paid £800 UK for it, which is a huge sum for me, but then I have been ringing Walter and looking for a 2nd hand one for 26 years now - exactly half my lifetime!
Thanks to all for the info - elgecko for the manual. Freddels - would appreciate a copy of the schematic if you could.

 

[macteacher]

On my green light amp from the same period I have one of these switches that I've never used.

Is this short for Mono/stereo mode?

I also have an xlr connector on mine that I've never used.

Is this for a microphone input, and if so which channel does it go with?

Also can this amp be bridged?

Thanks.

There were two different generations of Walter Woods MI 100-8 amps. The 1st generation MI 100-8 has a red anodized aluminum control panel and uses an all discrete transistor preamp section with no IC's. These were made from the mid 70's through the late 80's. The 2nd generation MI 100-8 has a control panel with a textured finish similar to the current WW Electracoustic series amps. They use IC Op-Amp-based preamp sections, and were made in the early to mid 90's, when they were replaced by the current Electracoustic amps. These amps are sometimes referred to as "Sweepers," as they added variable midrange center frequency controls (VARI).

The schematic posted above is for a 1st generation single-channel MI 100-8, while the manual is for a 2nd generation MI 100-8.

Here is a 1st generation MI 100-8:

Link Removed

And here is a 2nd generation MI 100-8 from the early 90's:

Link Removed

 

[Ric Vice]

On my green light amp from the same period I have one of these switches that I've never used.

Green Light Amps with Red Tops are true stereo units, unless it's red on top it's not a stereo setup as far as I can remember. If your amp has a standard black top then the Mon/Stereo switch simply divides the pre amp so that it's running stereo. You have to connect a power amp to Channel 2 at the Line Out.

Is this short for Mono/stereo mode?

Yes

I also have an xlr connector on mine that I've never used.

The XLR is a line out to send to a sound tech running the P.A.

Is this for a microphone input, and if so which channel does it go with?

Definitely not, see above.

Also can this amp be bridged?

Yes they but you have to use a very simple cord that Walter recommends.

Thanks.

If anyone has additional or better info
please chime in.

 

[robgrow]

On my green light amp from the same period I have one of these switches that I've never used.

Is this short for Mono/stereo mode?

I also have an xlr connector on mine that I've never used.

Is this for a microphone input, and if so which channel does it go with?

Also can this amp be bridged?

Thanks.

The "MON STR" switch allows the input channels to be summed together for mono or used independently for stereo operation. You will need a separate power amp for stereo however, since your amp only has one mono power amp. At one time Walter sold a slave amp for this type of use.

The 5-pin female XLR input was primarily intended to be used with Alembic bass guitars that used this type of connector.

Your amp cannot be bridged, since it only has one mono power amp.

Make sure to take a look at the Walter Woods Amps History and Development thread on the BG side, which covers a lot of this and much more.

 

[macteacher]

Thanks very much guys.

I actually did go through that BG history thread but didn't see the XLR information for this amp or which amps can be bridged and which couldn't.

So the definitive answer on the XLR is that it is an input rather than a line out to the board?

I happen to own an Alembic BG and would be intrigued to use this input.

I imagine since the alembic is a stereo instrument that I would use the amp in mono "summed" mode?

Finally, can the XLR also be used as a microphone XLR input and if so, would it dominate both channels or could the other be used for a piezo?

Thanks again.

 

[kaybass1952]

I have a green light (90's) With a balanced output XLR -on the RIGHT side of the amp.Great sound for for studio recording ,or live situations .
There is a thumbnail photo from macteacher (a posts up) that shows an XLR on the LEFT side of the amp ,near the 1/4 inputs ,this I assume might be for input use- like the Alembic.

 

[robgrow]

The 5-pin female XLR connector seen on the left hand side of the thumbnail is a special input meant to be used with Alembic type BG's of that era, and is not a balanced mic input. (3-pin male XLR connectors used on some Walter Woods amps are line outputs.)

You can see the 5-pin XLR output connector next to a standard 1/4-inch output jack on a vintage Alembic BG Link Removed. Thanks to KUNGfuSHERIFF for additional Alembic info. See below.

 

[macteacher]

agreed, 5 pins vs. 3 pin.

For some reason I was stuck on XLR connector and not the detail of the pin count...

I do happen to have an older alembic with that patch cable.

Guess it was meant to be....

Thanks again for all the guidance.

 

[KUNGfuSHERIFF]

Alembic has always and continues to use the five-pin "Cannon" output jack on its' Series 1 and 2 instruments. mac, if your Alembic is a Series instrument, you should be able to plug directly into your Woods' five-pin jack and forgo the Alembic's outboard power supply. I know that Jimmy Johnson owns a similar Woods and uses it with his Alembic for gigs when he needs a small amp. You found a rare one, pardner. Meant to be, indeed.

 

[shwashwa]

i just bouth this exact amp. its the tone ive been looking for! i cant figure out what the bst/mix knob does. i read that bst is boost, but what is mix? both the inputs work regardless the position of the switch. also, regardless which input you're connected to, both preamp volume controls affect your volume. you'd think that from the way the panel is layed out that each control affects the volume of the input that its next to, but that's not the case. they both work, regardless which input you're in. it seems that i'll have to be very conscious of my gain staging between these 2 and the master volume. can anyone explain this to me?

Here are a couple of pics of my WW.

As you can see, I still have the name tag from Walter on it.

 

[gawfshot]

+1 to Bob for jogging our memory. There was also a 200 watt stereo version of this amp with controls that look like you could vary the center frequency of the treble and bass controls as well.

This one's labeled MI 100-8, but I think it's what you're talking about....

(apologies for reviving a dead thread, but for the WW aficionados)

 

[robgrow]

There aren't many absolutes with Walter Woods amps, but...

Pilot light color indicates power level:

Red = Low Power (usually about 100 watts)
Green = High Power
Amber = Super High Power
Blue = Ultra High Power

Power levels for the green, amber and blue light amps have varied over the years. The green light MI 225-8, for example, developed around 200 watts @ 8 ohms, while the green light Electracoustic M300 develops about 350 watts @ 8.

 

[James Mitchell]

Anyone selling their MI 100-8 or MI-225-8 WW amp? I'm in the market for a tour. Already asked Jeff Scott about his here at Talk Bass. I'm new here and in search of one of the WW amps (like so many players I'm guessing). Thanks for any info...

 

[Feral Feline]

Welcome to TB and Good Luck in your Hunt For WW!

 

[James Mitchell]

Welcome to TB and Good Luck in your Hunt For WW!

Thanks for the welcome, FF!!! Kinda figured I'm not alone in the search..but gotta try!

 

[Ric Vice]

Anyone selling their MI 100-8 or MI-225-8 WW amp? I'm in the market for a tour. Already asked Jeff Scott about his here at Talk Bass. I'm new here and in search of one of the WW amps (like so many players I'm guessing). Thanks for any info...

James,
I'm sending you a Private Conversation with regards to Walter Woods.

Ric