[Mark Korda]

Hi Lab guys,Jake from the Tube Circle told me to try this question here.I have 2 Dyna PAM-1's.I also have some Dyna Mark 3's to go with them.I may be crazy,but I want to soup up those mono preamps with gold connectors and a Goldpoint volume pot.The Mark 3's have the octal tube plug to hook up the umbilical cord to the PAM's to power their heaters.My question to the Lab Circle is(Is there any way I can remove the tone controls and the loudness switch from the circuit? I am going to try and send the on line manual which has a big blow up pictoral and shematics and such.I'd really appreciate any ideas.Thanks so much.......Mark Korda(http://www.the-planet.org/dynaco/Preamplifier/PAM.pdf)

[avahifi]

Hi Mark,

Before you spend much money on the old PAM preamps, invest in a spray can of Deoxit D5 contact cleaner and clean all the controls, switches, jacks, and even the tube sockets.  Then make sure you have first class 12AX7 tubes installed.

The loudness control is out of circuit when it is switched off so there is no need to remove it.  Removing the tone controls is tricky because they are actually part of the line stage feedback loop so you can't just disconnect them with good results.  You need help from someone who knows the circuit and can give you good electrical advice in doing this.

Maybe someone else here can provide good info about that.

Regards, and Merry Christmas,

Frank Van Alstine

[Mark Korda]

Dear Frank, thanks for your answer.When I posted that question about the Dyna PAM's,I had a deep feeling maybe you would chime in.I was honored when you were the first name I saw to respond to it.Your answer is also very humble because I know if you weren't exactly sure how to take the tone controls out of the circuit,I don't think anyone would be able.I know next to jack about feedback,but wanted to get my soldering iron hot and have another little project to work on.By the way,the Dyna SCA-80Q,that you modded for me in the mid 80's,is still working perfectly,but in a buddy of mine's system.Thanks so much for handing out advise...sincerely Mark Korda

[Mark Korda]

Hi Frank,this guy on the Dyna Tube Forum gave me some hints about what to do and I'd like to ask your  view   on the project if it would be could  to try.I am going to try to copy and paste...wish me good luck...thanks Mark Kordahttp://dynacotubeaudio.forumotion.com/t1476-the-dynaco-pam-1-mono-preamp

[clydethecat]

I think it's pretty easy to disable the tone controls on the PAM-1.  The 47K resistor is the feedback resistor, with 33uuF in parallel for compensation.  The loop is taken from the junction between the .05uF and 0.1uF output caps, to the cathode of V2 pin 3.  Take everything else out of the circuit.  There is also 62K to ground from the junction of the two coupling caps.

[Mark Korda]

Clyde you cat,I appreciate your answer on the Dyna PAM-1,I really do!,but I'm not the sharpest tool in the shed on electronics,but I'm trying to learn everyday.I'll be 300 years old before I get Ohms Law down,but I'm not quitting.What I'm trying to say is that I can solder,look at the manual,am still  learning schematics,but some of your terms are going over my head.The loop,for instance,to me that is the completion of the circuit?Clyde,I need step by step instructions to get those controls out of the PAM's circuit,like Frank VanAlstine does with his kit instructions,like Dyna did,make it simple enough so a Geiko Caveman could do it. If you could do that and re explain your idea I'd go wild! One other guy on the Dynaco Tube Forum named Peter Capo,who belongs to  the Audio Circle gave me his idea,and I would like you to see if that would go or not with your oppinion...thanks so much Clyde...sincerely Mark Korda

[clydethecat]

I've erased removed components, the blue line is the jumper wire you'll have to add to complete the circuit.

[avahifi]

This should work, leaving you with a flat line stage with a gain of about 10 and no tone controls, an improvement,but still a pretty lame circuit with an inadequate power supply and no capability to drive a modern solid state amp input impedance well.

Still a step in the right direction.  When I have time I will make some suggestions to help it a bit more.

Regards, and Happy New Year,

Frank Van Alstine

[Mark Korda]

Hi Clyde and Frank,you seem to have come to some agreement with the Dyna PAM-1 tone control removal.That you guys got back to me is fantasic!I got 2 other freinds on the web that have an idea too,one Pete Capo is on the Dynaco Tube Forum,which you guys must join,Bob Latino has brought Dynaco back to life,as you always have done Frank.I know you had to move on and do your own thing because you could do better,thats what America is supossed to be.I butchered Clyde and Frank,a Dyna PAM -1 to make a passive preamp project,with 6db gain,from these transformers that I read in AudioXpress,Electroprint.I know you hate passive preamps Frank,but I would like to show you both some pics.By watching American Resoration,seeing Bill Thomas's Dyna rebuilds,trying to learn tube stuff thru Van Valkenburgh's Navy training books,the one's that show baseball players throwing around electrons,and in respect to David Hafler or Ed Laurent,I must complete this project,which I will photograph in steps,like Bill Thomas.I can't complete this without the smarts of you mugs!I'm going to wait a little until you are in total agreement,and Clyde,to see what you erased?,I'll look at that against the diagram or schematic.I have already found the electrolytic capacitor needed at Antique Radio Supply,as it even said in the description that it was used for the Dyna PAM-1.Frank,I will never use these with a solid state amp,their power comes from the Mark 3's with that plug,I knew you knew that.The tone controls are 400,000 and 700,000 ohms.I can't find any.The volume control is 500,000 ohms.I can find that,without a loudness tab,and on/off switch on the back of the pot.I don't need that as the on/off switch would be on the Dyna Mark3's.If I could spray all the recomended  switches,pins,pots like you told me,and put in some gold jacks,eliminate the PAS-3 spacial control,would'nt I have some thing special?Remember,this was the preamp I bet that DJ's used in 1958 to play some good ole rock and roll...Clyde and Frank I always look forward to your e-mails.......thanks Mark.

[Mark Korda]

Frank and Clyde....pics I hope

[Mark Korda]

The stuff

[Mark Korda]

Inside the chassis

[Mark Korda]

[Mark Korda]

The last shellac finish,from the same hobby store where I got U-Bar for my Grado Longhorn,almost 30 years ago

the last pic

[Mark Korda]

Hi Clyde the cat,I had a hard time figuring out your answer until I finally got some new ink for my printer.I made a physical copy of the manual and could finally see what parts you erased comparing the schematic and diagrams.Thanks so much.To me it seems as if I just cracked the German enigma machine code.I am now ready to precede with the project.Frank,you agreed with the cat,but if you get this note,what does (a gain of 10 mean),I don't know what the 10 is,(hz,db,all your fingers,or a perfect score)?You guys rule for helping me,thanks so much.....sincerely...Mark Korda

[clydethecat]

Gain of 10 is 20dB.  So 1V AC input signal will generate a 10V AC output level.  In the old days, +20dB was a "typical" gain for the line stage of a preamp, although these days with digital sources it's sometimes more convenient to have a line stage with 0dB ("unity") gain, to +6 or +12dB.

[Mark Korda]

Hi Clyde,thanks for that super fast answer....Mark