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Walter Woods Amps History and Development

#841
Oldtimer said:
I think it's a channel select switch. I fooled around with it yesterday and I didn't hear either a change in tone or gain! I used to run it in "mix" when I had 2 basses plugged in (one was a fretless). Interesting that I have the original 2 page manual and there is no mention of the mix switch or its uses. I also have the original schematic tucked inside the amp. If you have a bass plugged in to channel 1 and have the switch set to channel 2, you get no sound.
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That makes sense that the function of the Mix switch works differently on the two different models going by their respective physical locations on the amp.
 
#844
breadbaron said:
Does anyone have any info on whether Walter is still servicing amps? When was the last time someone had contact with him? I sent him a physical letter ~6 months ago and have been calling regularly since then, but no luck.
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Someone says they talked to him a few pages back.

I tried his number many times last year but couldn't get through to him. It's been a long time since anyone I know has spoken to him.
 
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#846
barneybass said:
Hopefully this will help someone keep these legendary old amps going. Also you can see how the mix switch works on the MI100.

After Christmas I’ll post pics of my old 79’ green light WW I refurbished with a bridged hypex amp/psu @1000w.

I sold my blue light ultra many moons ago to fund an overseas holiday when they were going for crazy $.
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@barneybass I'd love to see this amp with the Hypex! I've got an old 100-8 2 channel that seems to have a fried power amp. The preamp section is still working fine.

Also, does anyone know what BST means on the one channel BST/MIX switch? I thought it was boost, as in that would be the series preamp situation. Wish I could follow all the tech speak here!
 
#847
dylanjohnson said:
@barneybass I'd love to see this amp with the Hypex! I've got an old 100-8 2 channel that seems to have a fried power amp. The preamp section is still working fine.

Also, does anyone know what BST means on the one channel BST/MIX switch? I thought it was boost, as in that would be the series preamp situation. Wish I could follow all the tech speak here!
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The power amp is easy to repair for a qualified, experienced tech.
 
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#849
dylanjohnson said:
Any recommendations? Nobody near me can do it.
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I'm no longer recommending service shops (in general), I don't know any of them well enough anymore, and frankly many that I have had to deal with on the support side of my job have been pretty underwhelming as the older pros have retired.
 
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#850
To start I think Walter is a genius and the creator of the original mini bass amp. I owned a blue light 1200w for a few years but ended up selling it when they were going for silly money. I was inspired to purchase it after seeing all my heroes play them for years, as well as on a mid 2000’s NY trip I saw Will Lee play at the Bitter End through a blue light he unpacked from his gig bag.
But I always thought the earlier ones had a sound I preferred, for me as a doubling bass player anyway. YMMV.

So around the same time I picked this unit up from eBay, description said working but output is scratchy. It arrived and it had no output devices installed….. I thought it was an early 100W but it was one of the early class d power amps, MI225.

I’m very lucky to have a close friend who is a very accomplished bassist but also a very talented EE.

He worked out the class D timing circuit was locking up. It then sat on my shelf for a few years as the dollar was not in my favour to send it to Walter to repair a class D 200W amp from 1979.

Then one day I saw a hypex module
that fit the size perfectly. The same EE designed the go between board and the amp has been in use ever since.

The amp is stamped 79, it had a red texter mark 93’ or 97’ but it’s kind of rubbed off now which I assume was a trip back to Walter.
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#854
That's a very nice modification. Even if you could have gotten in touch with Walter, He said long ago that he could no longer repair the MI-225's. They two 100 watt power amps ganged together
and he could not source the parts to execute the repairs. Anytime Walter repaired an amplifier, he would mark the date on the edges of the chassis like you described. Since he used "magic marker" it would
eventually wear off. Cheers
 
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#855
When I installed it I had planned on making an L bracket to connect the heat sink plate of the NC502MP to connect to Walters heat sink but in testing I found the hypex plate connected to the aluminium bottom plate is ok. Gets warm but not hot to touch so I haven’t followed up the L bracket. Amp is running in BTL 1000W@4 ohms, 1200W@8 ohms.

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Of note is the quality of parts Walter used and the design. The jacks are all tight and all the pots still work well, I haven’t needed to clean them yet. I love the sleek design and the cable hooks on the back. The only thing I don’t find useful is the bass and treble boost switches. They boost and cut bass and treble respectively to max or min. Not sure when that would have been useful?
 
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#856
barneybass said:
Of note is the quality of parts Walter used and the design. The jacks are all tight and all the pots still work well, I haven’t needed to clean them yet. I love the sleek design and the cable hooks on the back. The only thing I don’t find useful is the bass and treble boost switches. They boost and cut bass and treble respectively to max or min. Not sure when that would have been useful?
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I always have the bass switch on. I love it!!!! I think it just changes the center point. I must confess I never use the treble switch or the eq switch.
 
#858
Can anyone here verify the specs of the potentiometers of the Walter Woods Electroacoustic? Mine has a two-channel preamp (so sixteen pots) and a mono power amp; a number of the pots are scratchy, and one even is intermittent: as it's turned there's no signal at a certain spot, then lots of signal a bit further, then no signal, then max signal. Spraying DeoxIT in them and working the pots (Walter's suggestion, years ago) improved some of them a bit, but hasn't eliminated it. For me, replacing all the pots would be worth it.

I think I recall Walter telling me that all of the pots are the same value and taper (I have to search whether I wrote those specs down somewhere); is that correct? Does anyone here know those specs? I suppose a repairperson can just measure them, but I'd save them that trouble if I can.
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#859
barneybass said:
I have spare interface pcbs that go between the preamp and hypex.

Will get back to you after the hols and post pics of my amp.
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Hi Barneybass,
Just curious, what is the interface yr talking about?

I have an old 225-8 Walter in which the amp/psu died 20 years ago. So I had all of that removed and just kept it as a preamp.. It's a great preamp, love the sound of it, for my Framus electric double bass.
Been using it with a QSC amp in a rack, quite heavy.
So I've always wanted to put some sort of power amplifier module inside the Walter case ... plenty of space there.
Yr mod looks like it works pretty well and the prices of those amp and psu boards are pretty reasonable. Keen to do same with my Walter. Cheers.
 

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