Double Bass Walter Woods advice

[fdeck]

That's certainly an interesting schematic. The preamp could easily be replicated today, though you'll need to find a substitute for the JFET and then lay in a stock of them. Single JFETs are going obsolete. Vendor stock probably won't be replenished. This happened to the JFET that I use, and luckily I bought a lifetime supply of them before they vanished.

Each of the "gain blocks" functions like a crude op amp, albeit with different impedances on the two inputs. This principle is also incorporated in most tube power amps, where you see a resistor sneaking a signal from the output and feeding it back to the cathode of the input tube.

Implementing the circuit with IC op amps would turn it into a generic preamp. Boring. On the other hand, whether you'd want to replicate the power amp and power supply depend on how much magic you believe they contribute to the overall sound.

The power supplies will need to be clean. A source feedback amplifier has poor power supply rejection. Ask me how I know.

 

[Ric Vice]

I’ve tried to make informed decisions based on my ears and the opinions of TB players who understand that. Over the years I’ve owned a Walter Woods MI-100-8, MI-400-8, and a Walter Woods Electroacoustic Ultra. They were very unique at the time I got my first one circa 1980. At the time most of us were playing through used Ampeg B-15N’s that weighed 65 lbs. Walter’s head weighed 7.5 lbs. produced 4x the power of a B-15N, the preamp was whisper quiet, with a wide frequency EQ section that could cut or boost treble and bass 10 DB and had a midrange control. That particular design was totally Class A/B ( analog) with the exception of the power supply that was a switch mode design. It sounded and “behaved” like a tube bass amp.
Walter’s amps had no real competition until Acoustic Image Contra and MarkBass F1. which had to be discontinued because the SMPS power amp
they used became unavailable. With Acoustic Image and Euphonic Audio closing there are few if any dual channel amplifiers. Most players don’t need a two channel amp. Preamps like the Headway EDB-2 H.E., Grace Felix and Moxie are our current options other than the GR Bass AT Cube Acoustic.

 

[james condino]

Are the WW amps consistent in their sound?

I've owned six different mid 1960s Ampeg fliptops and every one is nice, but a bit different; the 1966 SB12 I have right now is majic in almost all ways above the others, but too small to gig with. My B12 XT was close, but it was crazy loud.

 

[FUCHSAUDIO]

Are the WW amps consistent in their sound?

I've owned six different mid 1960s Ampeg fliptops and every one is nice, but a bit different; the 1966 SB12 I have right now is majic in almost all ways above the others, but too small to gig with. My B12 XT was close, but it was crazy loud.

Funny you mention B-15. We're looking at maybe making a portaflex style combo for next year...

 

[Ric Vice]

I wish you well in your endeavor. If anyone out there can build a B-15N tribute it’s you folks. I actually still have mine from 1964 ( a B-15N (revision C)
Two things that make this particular amplifier give it its unique sound. As you probably already know from repairing them, they used 3 6SL7’s , Octal Tubes in the preamplifier. It’s probably not practical to even attempt using them since they’re no longer manufactured. The cabinet was also unique as it’s a Double Baffle Reflex design which is labor intensive to build. Ampeg stopped building them that way after @ 5 years.

 

[Hubert]

You say this is being repaired in Germany right now? Any idea where?
I have an electroacoustic green light and loved it, but the power supply died and no one here in the US can/will repair it. Any possibility you could find out where this one is being worked on in Germany and let TalkBass know?
This is definitely the reason to be hesitant buying a WW.
Thanks!

Hi Chilibass, sorry to hear your amp is out of order and sitting in a box. If you or a friend of yours travel to Paris, come see me and bring me the amp at home between sightseeing trips. I have repaired several difficult cases with these amps.

 

[barneybass]

Dig this.

I know the engineer who traced this. We have both owned various WW over the years, I only own a 79 green-light atm (with hypex power amp).

There is something about the older preamp that is 'somewhat' tube like.

Unfortunate that WW isn't willing to sell the company on to be continued.

WW is the Grandfather of the OG mini bass amp.

A two channel Fuchs would peak my interest FWIW.

 

[fdeck]

The "somewhat tube like" sound is likely due to the relatively low open loop gain, and clipping behavior, of the JFET source-feedback circuit. JFETs and triodes have some similarities in their characteristics, though JFETs typically operate at much lower voltage.

Here's my contribution to the source feedback preamp genre, just for grins. I was aware of WW's design when I made this, but also several other examples of source feedback and its triode equivalent, cathode feedback.

https://bassisttech.github.io/JFET-bass-preamp/index.html

 

[Ric Vice]

Unfortunately, even with a proper Schematic of the amp many of the important components Walter used to build his amps are hard to source.
There are great options out there on the market currently. If you own a Walter Woods amp, just enjoy playing it. His amps were built to last.
If it does start to have issues, move on. Just my take. Depending on a specific amplifier for “your sound” probably isn’t a wise move.

 

[FUCHSAUDIO]

I wish you well in your endeavor. If anyone out there can build a B-15N tribute it’s you folks. I actually still have mine from 1964 ( a B-15N (revision C)
Two things that make this particular amplifier give it its unique sound. As you probably already know from repairing them, they used 3 6SL7’s , Octal Tubes in the preamplifier. It’s probably not practical to even attempt using them since they’re no longer manufactured. The cabinet was also unique as it’s a Double Baffle Reflex design which is labor intensive to build. Ampeg stopped building them that way after @ 5 years. View attachment 7346590

Thanks for the kind words. I'm hoping Q12026 we can get the process started of making a few Fliptop style cabs and see what works best for the current speakers out there. I like the idea of a 112, 115 and maybe a 210. Oure new 112XL bass combo sounds so good, I may try a portaflex build and compare to see if it's worth the effort.

 

[FUCHSAUDIO]

Unfortunately, even with a proper Schematic of the amp many of the important components Walter used to build his amps are hard to source.
There are great options out there on the market currently. If you own a Walter Woods amp, just enjoy playing it. His amps were built to last.
If it does start to have issues, move on. Just my take. Depending on a specific amplifier for “your sound” probably isn’t a wise move.

I tried early-on to copy the original Woods preamp (which I loved btw). That particular Fet was extremely hard to locate and no modern equal exists. That's not to say you couldn't adapt the circuit to modern devices, but who knows if it would sound the same ? The other issue on later Woods amps remains that Walter sanded off chip and transistor markings to hide his design from the big-boys. If you don't think Peavey or Ampeg wouldn't have wanted to dissect a Woods (since at the time it was magic, long before ICE power, Stewart and digital amps in general), guess again. He was sure protective.

 

[Ric Vice]

All good points. Until the advent of the IcE power modules Walter had pretty much cornered the lightweight, high quality bass amp market.
He started build the dual channel MI-100-8’s circa 1975 his amps pretty much cornered the professional DB and portions of the EB market until
the 2000’s. Unfortunately, his production output eventually exceeded his ability to repair amps.

 

[Keithunem]

I’ve been looking at some Walter Woods amps, but not interested in spending &1,000 to $2,000 that might last and perhaps not. I’m looking for a nice clean little amp to pair with my Whizzy 112 M Line. I have PA support unless it’s just a coffee house gig. When we played larger venues and concerts I only play upright on first set.

I’ve tried my EB gear (Mesa Prodigy with 410 Barefaced), but as good as they sound for EB, they are too colored for my taste to use for URB (Upton with Krivo and Yamahiko)or EUB (Yamaha Silent Bass SLB300). I’ve been thinking about a Genzler Magellan 350 with one or two Whizzy 112’s or something like an EA Doubler, Clarus, etc…but the EA and Clarus are kinda in the same boat as the WW as far as repairs.

I’m hoping for some thoughts on clean modern day amps with 300+ watts…any and all suggestions will be greatly appreciated!

 

[james condino]

I keep hoping that someone will crack the Walter code and find a commony available substitute from period recycled parts, much like how most of the hipster pedal makers are having great success making raspy old analog delay type pedals from chips recycled from old Pachinko machines and cheap consumer electronics from the '80s.

 

[redtomfunk]

I listened to the words of warning with WW amps and kept using my Fuchs FBS-700. I have to say that I got the best sound until now coupled with a Barefaced One10. I use either a Ehrlund EAP or more often a KNA db pickup into a Red Eye preamp.

 

[Ric Vice]

I listened to the words of warning with WW amps and kept using my Fuchs FBS-700. I have to say that I got the best sound until now coupled with a Barefaced One10. I use either a Ehrlund EAP or more often a KNA db pickup into a Red Eye preamp.

RTF,
I think that your amplification setup is probably the best or at least among the best possible combination’s

 

[redtomfunk]

I tried also with my barefaced big baby but the sound is too flat (not to say boring) and the bottom is too extended.
I wonder if in relation to the one10 the one10T would add anything really with the tweeter.
Second thing I wonder is whether a super mini T would be better than the big baby with double bass

 

[Ric Vice]

I tried also with my barefaced big baby but the sound is too flat (not to say boring) and the bottom is too extended.
I wonder if in relation to the one10 the one10T would add anything really with the tweeter.
Second thing I wonder is whether a super mini T would be better than the big baby with double bass

Since I’ve never used a Barefaced Big Baby Cabinet. Based on my experiences with MAS and GR Bass cabinets I’d have to say “ it depends on
the frequency and overlap of the 10” driver in relationship to the tweeter and the sonic quality of the tweeter.

 

[logdrum]

they used 3 6SL7’s , Octal Tubes in the preamplifier. It’s probably not practical to even attempt using them since they’re no longer manufactured

Invalid Link Removed , definitely New Sensor maybe even JJ, My Frenzel guitar amp has them and I can order a bass preamp from Frenzel with those tubes and an Ampeg Baxandall inspired voicing. Will not sound like a B15

 

[Ric Vice]

Invalid Link Removed , definitely New Sensor maybe even JJ, My Frenzel guitar amp has them and I can order a bass preamp from Frenzel with those tubes and an Ampeg Baxandall inspired voicing. Will not sound like a B15

While you definitely can get JJ's they aren't quite the quality of say a set of NOS Sylvania's ( I have a set in mine) and believe me there is a difference between those tubes and the JJ's which I also used for a time. Since I don't have any experience with a Frenzel guitar amplifier I can't comment on that. What I am very familiar with are 12AX7 based Portaflex amps ( I owned a SB-12 and often played through a B-15S) they just don't have the same
character as the 6SL7's in combination with 6L6 Power tubes and a Weber Copper Cape Rectifier running into a JBL D-130F enclosed in a Double Baffle Reflex Cabinet. Just my take of course but the "proof is in the pudding", so to speak. Using the B-15N with a Double Bass.