Little Walter Amplifiers

George Seymour · Post by **George Seymour** » 9 Mar 2013 9:25 am

JR- I sent you a pm.

Rick Stratton · Post by **Rick Stratton** » 10 Mar 2013 9:37 am

It seems the twin-50 would be ideal for steel & guitar as both sides have their seperate inputs and controls.
How do you play your steel through both?
Splitter of some kind?

JR Ross · Post by **JR Ross** » 10 Mar 2013 10:12 am

Simplest way is to use a volumn pedal such as the Hilton which has 2 outputs ..then go one to each power amp...

Rick Stratton · Post by **Rick Stratton** » 10 Mar 2013 11:02 am

Duh!
I must have not been fully awake when I asked the question!
I use the Hilton and of course, there are 2 outputs!
Thanks JR!

john widgren · Post by **john widgren** » 10 Mar 2013 12:03 pm

Question for PF please:

I am told that you prefer a particular speaker, which is rated at 8ohms. I believe the LW is rated at 4ohms output load.

If this is correct, has the resistance mis-match caused and difficulties?

Thanks. PS: you killed at city winery in NYC with the Jumpers, and you and the rig sounded awesome out front.

Very best,

John Widgren

Dan Tyack · Post by **Dan Tyack** » 15 Mar 2013 2:53 pm

I'm not Paul Franklin, but I play a Franklin on TV.

Paul likes the Peavey Black Widow 1201, which is an 8 ohm speaker. I also play through an 8 ohm speacker with my LW 50 (a JBL E-120). It sounds great, and according to Phil Bradbury, you might lose a little power, but nothing significant. Both the 1201 and the E-120 are so efficient, you probably wouldn't see any difference in volume versus a 4 ohm Celestion cabinet.

john widgren · Post by **john widgren** » 15 Mar 2013 3:00 pm

Thanks Dan,

I appreciate the info. I prefer the 1201-8 myself which is is why I asked. I am concerned about output section damage due to the mismatch more than volume loss, but if it works...great!

Best

JW

Dan Tyack · Post by **Dan Tyack** » 15 Mar 2013 3:04 pm

Phil says the rule of thumb with tube amps is not to use a cabinet with a lower impedence than the amp. Higher is OK, as long as the mismatch isn't extreme. For example, he said a 16 ohm cab would sound crappy with the LW 50.

john widgren · Post by **john widgren** » 15 Mar 2013 3:05 pm

Gracias Amigo!

JW

Ken Fox · Post by **Ken Fox** » 15 Mar 2013 8:20 pm

From the internet:

"For tube amps a lower impedance than nominal (what the amp calls for) load is safer than a higher impedance load. Neither is ideal.

A tube amp will deliver its maximum power most efficiently and with the greatest headroom when the output impedance matches the load impedance. If the speaker load is higher than the output impedance you have a greater chance of flyback voltages damaging the transformer, output tubes and other parts than when you're mismatching the other way. But a lot depends on the nature of the transformer itself."

You can research this on the internet and find the same facts about tube amp transformer mismatching by many leading tube amp experts.

Greg Cutshaw · Post by **Greg Cutshaw** » 15 Mar 2013 8:46 pm

A simple application of ohms law (with or without reactive elements l/C) with the internal impedance of a tube amp set a X ohms will show that the maximum power transfer occurs when the load impedance matches X, the internal impedance of the amplifier. All engineers learn this proof in their first electronics course and it's easy to research and prove.

If you attach NO SPEAKER to a tube amp output, the flyback voltages theoretically approach infinity. In reality though, they just get awfully high and cause all sorts of nasty transformer arcing and eventual transformer destruction by shorting across the primary / secondary windings or to ground. So higher loads than the amp's internal impedances do cause the transformer voltages to rise. The tone of the amp will change with an impedance mismatch and it might sound better or worse (the frequency response and damping characteristics will change) than with the right impedance speaker. Either way if the tube amp's internal impedance is 4 ohms, it will put out less power if mated to an 8 or 2 ohms speaker. How much less is an another easy calculation.

I should mention that very low impedance loads (relative to the power amp's internal impedance) will as stated above, result in less power TRANSFER to the load, but more power DISSIPATION in the transformer windings and therefore more heat dissipation and melting of wire shellac and insulation eventually causing transformer failure and not making the output tubes very happy along the way.

All the above does not apply to servo amps or other high tech designs that can match the load to the amp on the fly.

Higher loads develop more transformer voltage, lower loads develop more transformer secondary current, but the Product of the current x voltage adjusted for power factor will result in lower power transfer to the load with an impedance mismatch. Given the nature of perceived sound levels versus decibels, a halving of power transfer will only result in a 3db drop in perceived volume, barely noticeable. Over all the amp/load combo may sound better to your ears with the impedance mismatch or more speakers may spread out the sound more, making the mismatched setup actually project better etc etc etc. the above examples though would result in a less than half loss in power transfer.

Greg

Franklin · Post by **Franklin** » 16 Mar 2013 6:25 am

Phil doesn't subscribe to the "If an amp building expert says it, it has to be so" mindset......Phil's process is to get a room full of high level master players, show them an idea or concept and attentively listen to their critiques and requests. Phil never views this process as doing battle...He is trying to satisfy their sonic desires not to convince them to change their minds because some expert concluded it doesn't sound good.

...Phil replaces something with something else until he hits the right component combination that pleases the tonal requirements of the largest majority of great players.....His amp success has other builders scratching their heads. They believe Phil's doing it wrong according to their acceptance of other experts conclusions.

Those 8 ohm speakers sound brilliant and the power output is fine. I'll trust my ears over anything Ken says about mismatching speaker ohms all day long.....John Hughey recorded purposely with out of phase speakers. Recording engineers pegged those VU meters deep into the red on most of the vinyl we own, even though the experts who built the consoles said to never let them go in the red. Just saying most experts never really share their secrets.....What conclusions we read may be slanted towards keeping other conclusions secret.

Paul

Ken Fox · Post by **Ken Fox** » 16 Mar 2013 6:57 am

It is not "what Ken says" but what Ken quoted as a well known fact to anyone with any tube amp knowledge. A little study in tube electronics will reveal the facts about mismatching in tube amps. Not something I made up, just a fact. Over a period of time the fly-back voltages created by the mismatch at higher than rated impedance slowly eat away at the primary winding's insulation of the power transformer. Also that can result in damage to the power tube sockets (carbon tracking). Things that can help soften these effects are ceramic power tube sockets as well as clamping/fly-back diodes on the primary side on the output transformer (as often seen in the old Musicman and Peavey amps).

I am not here to argue, just to refute misinformation. Forums are here to help each other and we need to present as much accurate info as possible. Opinions can be dangerous, facts are facts.

Olli Haavisto · Post by **Olli Haavisto** » 16 Mar 2013 7:02 am

Slightly off topic:
Would it be possible/practical to convert one channel of a two channel amp like a Deluxe reverb or a Twin to an octal preamp?

john widgren · Post by **john widgren** » 16 Mar 2013 7:03 am

Thanks to all for the generous input.

JW

Ken Fox · Post by **Ken Fox** » 16 Mar 2013 7:04 am

Groove tube makes various adapters for that.

http://www.music123.com/accessories/gro ... in-adapter

Jack Stoner · Post by **Jack Stoner** » 16 Mar 2013 7:08 am

As a long time electronics tech (and one time amp tech) there are engineering and design principles that should be followed for reliability. I know there are things people do, that should not work or are iffy at best, but there are still sound and proven engineering basics.

One thing I saw in the pictures posted for the Little Walter amp for sale here on the forum. The rectifier and power amp tubes are mounted to the front of the cabinet rather than to the rear where they can get more air flow (cooling). This restricts (limits) air flow for those tubes. As the power amp tubes can run hot the potential is there for premature tube failure and the heat that cannot be properly dissipated could cause other component failures or premature failure. Heat related failures (tubes or other components) may not occur today, next month or even 6 months from now, but it will reduce the long term reliability for these components.

Tony Prior · Post by **Tony Prior** » 16 Mar 2013 7:28 am

yeas back when I was in college,( many ) I had an 12VDC > 115VAC converter, very rare, in my car, I was running a Sony Stereo 7" Reel to Reel in my car..a 67 Olds.....go figure..but it was great... Mind you, this was back in the very late 60's....

TRUTH....

This guy I knew pretty well in an electronics store told me, before he knew I had it in my car, that 12VDC > 115vAC Converters do not work in cars..you cannot run a tape deck because the frequencies are not matched and the tape speeds will vary all over the place. Now , who was I to argue with a guy who owned an electronics store...I was quite certain he was right..the theory made perfect sense...

So after a few minutes I invited him out to my car..he looked, listened..scratched his head and said..that's not supposed to work !

He probably spent the next month trying to figure out why it did indeed work with stable speed...

Ken Fox · Post by **Ken Fox** » 16 Mar 2013 8:38 am

No one said it would not work, Tony. Just a bad practice. Fact are facts. Replaced several transformers and arched tube sockets in my shop as well over such a mismatch. Point is, don't spread opinions as facts. Too many folks like to state opinions as fact with no backup what so ever.

I will not tell anyone what is the best amp, cord, pedal or whatever. That would be an opinion. I will tell you what I like. Because I like it or a "master" likes it does not make it better or best. Same goes with information about electronics in this section. I carefully research what I post, staying away from posting my opinions. My opinion or a "masters" opinion carrys no weight without being properly substantiated. It is just that, an opinion.

Franklin · Post by **Franklin** » 16 Mar 2013 9:18 am

You can't separate facts from opinion when discussing whether mismatched components are sonically better. The sound is really all any serious musician cares about.

My Little Walters have worked extraordinarily fine for two plus years. My tubes last as long as my Mesa Boogie which I have used for several decades. And those 8ohms work great and cause no power problems.

Paul

George Seymour · Post by **George Seymour** » 16 Mar 2013 10:53 am

Olli Haavisto wrote:Slightly off topic:
Would it be possible/practical to convert one channel of a two channel amp like a Deluxe reverb or a Twin to an octal preamp?

Yes indeed, my tube tech has been doing it for a couple of years, and I've got a 72 vibrosonic I just picked up that is on its way!

Sorry, FYD amps south Burlington Vermont if you want to email him on the procedure
Google it it'll show up

chas smith R.I.P. · Post by **chas smith R.I.P.** » 16 Mar 2013 11:54 am

I can't speak about Little Walters, but I have a VHT Sig:X that has a 8Ω/4Ω output switch to the speaker. If I plug in a 4Ω speaker and don't switch to 4Ω out, it blows a fuse after a short while.

Tony Prior · Post by **Tony Prior** » 16 Mar 2013 12:09 pm

Ken, my post with regard to the Tape deck in my car is not meant to be a diss in any way or fashion, I too am electronics schooled and certainly know what the books have taught me and what the laws of physics have taught us..the tape deck story is just a story...

I know what the books say with regard to impedance matching and I do not doubt for one moment that they are incorrect or that you are incorrect..in fact I think you are right ! ..but I also had this Fender amp that I had been using for over 20 years with a mismatched speaker ! 4 ohm OT to 8 ohm speaker..

I feel what Paul is saying is..doesn't matter..it works great and sounds great and to a player that is what matters...I am also quite certain that the builder of these amps took everything into consideration and leaned towards "SOUND" at the end over what our conventional knowledge would tell us to do...

It's all good ! And I can say first hand that Pauls rig sounds quite good ...I wish he would let me borrow it for a year or two...

Franklin · Post by **Franklin** » 16 Mar 2013 12:59 pm

Jack,

The LW is a completely open back amp head.......Unlike Matchless, Fender and most boutique amp heads there is no solid wood braces on the back, just a metal screen for bracing which allows the air to flow throughout the amp head.......There is more than enough air circulating around the tubes.

Tony,

Thanks for summing up my point very accurately.

Paul

Mike Sweeney · Post by **Mike Sweeney** » 16 Mar 2013 5:30 pm

I don't have a dog in this fight and I might have missed this point being brought up earlier in the thread but what I would like for Paul and some of the other Little Walter users expound upon is this question. Is it also the way the amplifier responds to the dynamics of your touch as well as the tone? The reason I ask this is, When I was about 15 I had an old 100 watt Kay bass amp that I played through, All tube no circuit boards and a 15 inch JBL speaker. It had a sound to die for. Well I wound up getting a solid state amp which I know is different technology and side by side the Kay tube amp blew away the solid state. I also compared it to a Fender amp [Pro Reverb I think] and it blew it away. I know that a lot of things factor in to the sound thing but also that old amp responded to every dynamic.
Is that a factor other than sound that you look for?

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Little Walter Amplifiers

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