Rekindeled an old flame.

[Jerry]

I hope this topic is OK to post here on my diary? If its not I guess the editor will remove it?

a while back there was some talk here about tube amps. At the time Iwas extreamly busy and I wanted to share my lifes expirience with tube amps but would would not alow.

I been spending much time digging out my 40X60ft home shop. Over the years the acumulation of stuff just maid it imposable to use the shop eficiently. Dryer weather was the motovation to excavate all those years of pack rating, get rid of just to much junk, build some shelves for the stuff I keep and so on. This monumental task has removed me from the discusions here and will most likely keep me from the board this sommer?

Its just like christmas when you dig back all those years and find the neat stuff you allmost forgot you had. Its allso nice to find those very special things you thought you had lost forever.

My pasion for audio and electronics started in 1958. I was a fifth grader. I lived in a small coutry town. Thjat sommer my grand parents gave me an old Crosley radio and I ain't been right since.

By the 60s I was fully involved building tube type amplifiers and on into the 80s. Then I started building monster solid state amp. I mean moster in the 10 to 15 KW range. Thats no type O (KW).

Befor opening The Audio Source of Salem car stereo I was build and servicing tube type Guitar amps.

Theres a problem with being pasionate about electronics while allso being a pack rat.

As you ca imagin my shop has more then its share of electric stuff. I come to me like I was a magnet?

After a mounths hard work on the shop I just couldn't stand it any more. I eeked out a littel time here and there and started to assemble a few small tube type amps.

I was building some special solid state mic preamps for a costomer anyway?

This first amp is stereo 15 watts per chanel, the other started unit is about 25 watts per chanel. I've allready layed out parts and such for a 500 watt 2 channel tube type and 2 mono blocks amps using the WW2 GE 211/VT4-C these are very large 9" coke bottel size triodes. These amps will be single ended.

The finnaly will be an OTL of the Futterman design. And amist all this KAOUS I still want to build more motor conversions and dual rotor machines? Why does the clock have to go so fast? LOL

Heres a picture of the littel 15W X 2 power amp. I'll be using a 1958 stereo Leak preamp, or my Fischer 400c or one of my home built tube preamps?

This amp is using PP EL84/6BQ5 audio out, 6AN8 as first AF and phase inverter and a 5U4 as the rectifier. I really prefure a solid state rectifier for tube amps but the voltage from this transformer mached the 5U4 and SI diodes would have made to plate voltage way to high. I could have used a choke input filter with the diodes but I prefur capacitor input filltering.

If anyone wants I may post progress on the other amp projects. If not and this post gets scrubed I'll just buildem and enjoy the music.

                         JK TAS Jerry

[willib]

Hi Jerry , its your diary..

i cant see why anyone would want to scrap a diary

in the late sixties, i think it was , i built a tube amp from plans and parts my dad had hanging around , it was great fun , although i think i musta misconnected something because there was more 60 hz hum than music, comming out of the speaker

[hiker]

hey jerry..

my dad got me started back in the 50s with a crystal radio kit..

been hooked ever sence..i collect the 70s stereos and speakers-pioneer-sony-maranzt-harmon kardon..

you get the picture..still hit the thrift shops for old records--sorry -just can"t stand that flat sounding digatal music---back then it was all about quality..[not saying yours aint]

i know what you mean about the shop--been trying to clean mine out for the past 2 weeks. hard to throw stuff away --even thou you never used some it for years..

well later...hows the e truck holding up??

[12AX7]

Hello Jerry!

I think the EL84 is a FINE sounding tube!

Due to it's lower power, you need the right speaker.

If your looking for advice on what amp/project to take on You need to supply us with more complete info!  

flutterman?  heard they were a bit unstable.  

fisher?   heck..  a known winner.

211s?   hummm..   sounds like power hungry monsters.

why not a nice pair of WE300bs?

a collection of 'stuff'..   sounds real nice.  

keep an eye on dan..   thinks he's hoarding all "the fisher"s stuff.

that's a nice looking amp,  what have you been putting through it?

oh lord,  not rap?

guys..   warm up  your heaters...

Jerry,  post it all!

ax7

[iFred]

Hey Jerry, I think that every single electronics tech I have met that was serious in the field and a bit older seems to be a major pack rat, i have been in spring cleaning mode for the last 2 months, so much electronic stuff and all the tools I lost and have now found! which was a bonus. Just box's and box's of parts, equipment and older projects too sort through. It took over my house, since the garage was full, I could hardly walk in anymore.. LOL, sorting it is a major pain but seems to be also be therapy. So I can sympathize with your condition, but remind you that it produced a high end technician and all the good `ol memories.  Enjoy and revel in you cleaning..LOL

- oh yea, kind of amusing when you find those missing things!

ifred

[oztules]

Please don't stop on my account Jerry, I will look forward to your forthcoming stories.

..............oztules

[Bruce S]

Jerry;

   That is a think of beauty!!

How do you handle finding multi-tap caps? I have several older units that have dried caps that now have thins horrible 60cycle hum coming through the speakers.

IMHO No Solid State can match the rich sound of a good tube radio, not to mention the beauty of the glowing tubes in a dark room:--)

Thanks for the inspiration, I've been trying to find time/parts get an old tyme tube radio back in working order.

Cheers

Bruce S

 

[Jerry]

Hi Willib.

There are a few things that could have caused the hum. Tube amps are very high impeadance devices and as such are very ceceptable to stray capactance.

Because of this lay out or parts placement is critical. Also if ac is aplied to the heaters this can be an entry point for hum. a cernter tap on the filliment transformer or at least one side grounded. If no center tap is avaialable then 2 resistors of equal value can creat the same affect as the tap.

Also it help to aply a small + dc voltage to the CT. This will make the filliments + in referance to the cathodes and it has a small null effect on the hum. This + voltage is sometimes harvested from the output tubes cathode bypass resitors if cathode biasing is used. If negative grid bias is used then a voltage devider group of resistors on the B+ supply can be improvizred.

Also helps to keep sensitive grid circuts away as much as posable any ac sources under the chasis.

Also good filtering in the B+ supply is a must.

                          JK TAS Jerry

[Jerry]

Hi Hiker

The crystal set thing brings back a bunch of memories. As a kid we lived on 3 acers.

There were 2 fir trees 100 tall each about 200 ft apart. One was close to the house the other was out by the barn.

I streched out a long wire antena at the 75 ft mark on the trees. This antena realy brought AM annd shortwave from all over the world. It was plenty of antenna for even my home brew crystall sets and my built from stratch one tube radios.

                                JK TAS Jerry

[Jerry]

Hi 12ax7.

Every time I see you post as 12ax7 I think I'm older so I should post as the older version (6SL7)LOL.

The speakers I use on these tube amps are very eficient. I've allways wanted to build a Futterman. So we'll see how stable it is. The thirory of OTL sounds very apealing.

I have in my collection 2 Dynaco A-441 25 LB 240 watt max output transformers. These have extra tretory cathode winding simuar to McIntosh. Also a matched pair of UTS CVP-5, 300 watt multi tap output transformers.

The Dynacos are 2200 ohms plate-to-plate to match PP parelell EL34, 6CA7, KT88 ect.

I'm goint to use the UTCs with 4 807s each at 3,000 P-to-P perelell. That amp will have 750 volts to the plates, 300 v to the screens, There will AC balance adustment and seperate bias ajustment per 807. This monsters gona be heavy and big.

As far as the 211s are concerned. They were in my collection so I'm going to use them.

I want to make the amps that I can out of the stuff I have without spending much money so  its a use what I got kinda plan.

The amp in the picture is not finished yet. No parts under the chasis yet. I'll post the #s after its been benched.

                               JK TAS Jerry

[Jerry]

Hi Ifred.

I know what your saying about the shop. there was no way I could walk in a straight line in any direction.

                           JK TAS Jerry

[redeyecow]

 

 Jerry, Yup that's what happens when you stay in the same place way too long.  I'm pretty well buried in really cool stuff that people now call antique but just needs a bit of TLC to get it happening.

  Anyway I've got a quite a few Guitar type tube amps, but I'm also plauged with the dreaded AC buzz.  I use a little 400 W  sq wave Eliminator which works fine for everything else but not the tubers.  My favorite is a little Harmony with a couple of 6V6s and 12AX7s. My electonic knowlege is pretty sparse, that is I keep things clean and replace things that are smoking. I also have an old tube tester that solves most of my problems. Wondering if there is a standard fix to filter out the buzz. It's amazing how the old tube tech was completely purged from the music business in the 80's, but now they're desperately trying to acquire original equpment, even the studios. It just sounds better.  keith  

[willib]

is there a lot of flourescent lights nearby?

that may be a sourse of the buzzing

[richard]

  Look at www.midnightscience.com  richard c c c

[jimjjnn]

Bad filter capacitors are things I ran into on some olde tyme circuits. You are right about filtering the B+ supply. That'swhere most dried out olde tyme caps were in days gone by.

[jimjjnn]

My crystal set antenna took a good lightning hit one time. Even melted one ceramic insulator and blew the one on the tree to rternity. Surpisingly, the crystal set survived.

[Jerry]

Hi Bruce S.

I tryed to respond to you this morning but but when i hit the post button a screen poped up and said I had maid to many post so it was removed. First time I've had that happen.

That was iratateing cause I only have one typing finger and itr takes me a long time to write out a whole paragraph of misspelled words.

I was trying to respond to every one at that time. I had to stop cause my narrow window of time to respond was gone along with every thing I wrote to you?

sometimes the cyber god don't like me LOL. I'll try again.

About the multi tap caps. there are a # of suppliers the still offer replacement caps.

The cap in the picture is from the heating & airconditioning shops dumpster.

The seem to toss a bunch of these and I've never found a bad one. Normal i use these caps on my battery desulfater/pulse charger.

I have a couple scots the bring me a 5 gal buket of them one a month or so.

I use the oval shaped caps on the pulse chargers and the round on the tube amp.

These cap come in single and dual and have AC voltage at either 370 vac or 440 vac.

You can used these caps on much higher DC voltages.

The cap in the picture is rated 370 vac at 50UF and 5 UF. The 50 UF part will be the first or main filter the 5UF will be downstrem of the main cap by the way of a 5K 5 watt resister. This is the point where the first AF and phase inverter gets there power. I also take power from this poin for the external pream.

If you can't find multi tap caps you can use axial lead tubular caps under the chassis.

If you can't find high enough voltage on a cap you can sires 2 and double there voltage rating but the UF will be half. Its normal if you do this to place balancing resistors accross the caps. This help keep voltage equal on the caps. Around 220 K or so will work.

The motor run cap mentioned above will handel twice there ac rateing in DC volts. These caps will outlast electrolytic cap many times over.

                         JK TAS Jerry

[Jerry]

Hi Hiker.

Forgot about your question on the E-car. Its great, I'm going on my second year on the new batteries and there SG is as high as the first day I installed them.

I'm using the Cap pulse charger on them every day. Its a 120 volt system (20 X 6 volt golf cart batteries). Normaly when the batteries would be charged the total bank voltage would be 144 v. I typicaly read 151v to 156 v. and the batteries are cold but the liquide is realy perkulating.

I'm either pluged in here at home or pluged in at the store. Its my daily driver and all over town gofer car. I love it.

                             JK TAS Jerry

[12AX7]

Hello 6sl7!

My old standby RCA tube manual must be hidden under the mess here (a collection of stuff)..So I had to grab my Sylvania.   Didn't know about the 6sl7...  being the "first version" of the ax7..   by the specs..   looks like it could be!

and speaking of the ax7..  Let me step forward and suggest any/all (of us with lots of stuff..  ) to take a quick look and make sure that none of their ax7's be Mullards! or any ax7 made in holland.  as all us "tube nuts" know..  that the ax7's made by Mullard have been know to cause cancer (but only in the state of ca.)  the've been also known to cause spontaneous pregnancy in white rats and daughters.    They need to be rounded up and disposed of by me.    If any are located..  please email me for arangements.

ahem..

 Jerry,  I've been baby sitting a pair of IPC AM 1026.    The parents want em back,  but I got them well trained,  and I feel I should hang on to them or else they may get out of control.

They have (their mono blocks) a pair of 807s.  Peerless outputs.   Very very sweet sound.  I think that the output was rated at 60W.   but based on other power amps I've had here I know it's another case of..  it's not how much you have, it's HOW you use it.

On one of the shelves..  I've a pair of Dynaco Mark III.   They really can't hold a candle to the IPCs..   however they will blow the doors off of just about any SS amp made 30 years older than them.

There are many tube peps out there that aren't real fond of the Dyanaco audio output transformers.  After hearing a few peerless and utc's (I've been told that utc made dyans?) I've come to think that the Dynas don't have the bottom end.

I've an copy of an old dyanco transformer ref. sheet.   I don't have a listing for the 441.   it shows a 440 but it's 4300 ohm and 24lbs.   The 450 is 2200 ohms and 240 watts.  I'm thinking that the copy of xformers I have may not be complete.

If you got em..   get working on building them.

You have the 807s?  I think Oztules..  knows that tube better than he may let on!

okay,  807s..   driven by what?  

and if I may ask something a bit more personal,   what type of music do you play through your tube amps?

DC on your heaters!

ax7 ECC83..7025

[willib]

here is some data on the new toyota camry hybrid

"a 105-kW electric motor and 244-volt battery pack that delivers a peak of 45 hp. The battery pack consists of 34 nickel metal hydride modules, each of which contains six 1.2-volt cells. "

imagine being able to walk into a junkyard and scooping up those batteries?

[commanda]

This is my tube amp.  It's only mono, and the distortion figures are far from hi-fi.  It used to be a 2 channel bass/guitar amp (Apollo 80) before I rebuilt the front end a-la Marshall (master volume cct).

And here's the speaker box. No tweeters, No crossover; But it all sounds sweet with the flying Vee or the les Paul and the volume cranked past 11.

Amanda

No playing "Stairway to Heaven" or "Smoke on the Water" in this shop.

[12AX7]

Hello Commanda!

Thats a nice looking amp, a pair of 6ca7s?

most speakers with out crossovers have a nice sweet sound, as well as great imaging (you  just need another amp and speaker to prove it).

If there's no stairway to heaven for you.. or your water is smokey in color....(and if they are el34s/6ca7) might I suggest taking a few moments and try running your outputs in "triode" mode.   The improvement may suprise you.

it's a very easy mod.   You would have less output power..   but sometimes it's not all about the "power".  

ax7

[commanda]

Output's are EL34's. Pre-amp & phase splitter are 12AX7's. When I re-built it, it didn't at first quite have the raunchy rock n roll sound that the Marshall master-volume amps are famous for, until I replaced the 12AX7's with brand new Sovtek's.

Less output power is not an option.

Amanda

I want everything louder than everything else. Ritchie Blackmore.

[Jerry]

Hi 12AX7.

For me is a mood thing. So that encumpises a largew viriety. Its kinda like food sometimes it bacon & eggs or a whopper double or meatloaf or lemon meragnue or ice tea or you get it.

As my customers alwas say when they come into my car stereo store "I just want something that sounds good".

On ocasion depending on the customer i might respond something like this.

Well Mr customer you are in the majoroty because every customer I've met since 1975 has always asked for "I just want something that sounds good". And I've never had one ask for something that sounds bad.

But I also point out thats very simular to going to Denny's and asking the waitress.

Waitress I just want something that tastes good. I bet she'll pick out something she likes.

What feels good, smells good, tastes good, looks good is a diferant thing for all of us but as I tell my wife, kids freinds and such, Hey if you want to know whats good just ask me LOL.

I like Glen Miller, Josh Grobin, Chet Atkins, Alabama, Chicago, Losharos Indos, Oh hek the list is endless.

Its like food I like most of it as long as its good.

                            JK TAS Jerry

[DanB]

Very cool Jerry!

It can get tricky to stick with the fun habit of tube amps with a home powered by windpower but I use it as an excuse to just keep building bigger windmills.

I just sold off my old McIntosh 240 on ebay and picked up a new one locally off craigs list cheap.  My new one definitely does a better job of heating the shop and I've not really quite figured out how loud it goes yet ;-) - but it sounds sweet and it's lots of fun.  Till this one I've always had old stuff (I really like old Fisher stuff) but it's fun to see that good stuff can still be had brand new.

My new one is a Jolida 801A, its about 4 years old and it's incredible.  Sure heats the shop and eats batteries fast though...

It's compliment is 1 12AX7, 2 6NS7GT's, and 4 KT88's.  Lots of fun!

[12AX7]

Hello Commanda..

I'm unsure,  when you say it didn't "quite have the raunchy rock n roll sound"

I'm confused if it's that ear splitting sound levels one hears at live concerts, or the buzz/hum/hiss you might also hear.

But,   what ever that "raunchy" sound your speaking of is..... it sounds like you achived it when you switched over to the Sovteks ax7s?

Less power isn't an option?  

I've seen some of your posts,   the fact you "rechassied" an old marshall I know you know your way around a soldering iron.    It would take you 10 min or less to make the triode mod (if it's possible for your amp).   If you have an "open" mind...  I'd suggest you give it a try.    Just like doing the mod to triode..  switching it back could be done just as quickly.  Ya do the mod..  listen to some of your favorite tunes and you could swtich it back in as little time as it took you to select the tunes you listened to.

Is your output tranny ultralinear?

enjoy your tubes..  and tweak your cd player!

ax7

[12AX7]

Hello Jerry

I understand!   did service/sales work at a hi fi video store in the mid 70s

talk about "strange people".   L

I suppose the question should have been..   "what kind of music does your wife let you listen to?"   enough said!

So..  you have a circuit in mind?   (for your upcomming amp project)

Don't touch them glowing bottles!

ax7

[commanda]

listen to some of your favorite tunes.....   and tweak your cd player!

I think you missed the point; it's a guitar amp.

Is your output tranny ultralinear?

Not sure off-hand but I doubt it.

Amanda

[12AX7]

Good Morning Commanda

at least it is here..

Perhaps I did misunderstand.   I DO understand that it's an guitar amp, I just assumed that you were using it for your music system.  

An ultra linear transformer will have leads (in addition to the plate taps) that connect to pin four of the el34's.

If it is an ultraliner tranny,   all  you need to do to convert it to triode is to disconnect the leads to  pin 4.  Then install an 100 ohm resistor from pin 4 to ground.

If it your using the amp for a bass guitar,  then I'd leave it as is.

I'm NOT a music person,  and haven't spent much time with guitar amps but..  it may be possible to switch from el34's to 6550s.   The 6550 does not have the sweet sound of the el34s..  but it does have higher output (if it's that loud raunchy sound your after)

Many a moons ago I did do a slight mod to a fender amp (sp?)  for a friend,  he had lost a finger in an accident..   So he moved his amp from the basement to his living room.

Made a nice addition to his sound system.

crank er up.. and smile.

ax7

[12AX7]

Hello DanB

thats a pretty amp ya got there.  Gave up your mac?  awww..

(was never a mac fan myself)..   but they did keep the others on their toes!

Wouldn't mind seeing some pics of your "The Fisher" collection!

ax7