|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
67.186.133.167
Hi everyone just wanted to say thanks for all the good advice I received from this site
I have finished my project and the amps work GREAT
I used the dynaco Mark 111 schematic with a few twists
Follow Ups:
Congrats!
Abe
I like that, you hardly ever see those bullet diodes anymore. Good thing you used new electrolytic caps though. That's one area where older is not better.
Its hard not to try and use everything one has but the old caps keep biting me so I broke down and spent some money
ckeck out the pic this is how I made the 11.2
Get rid of that WW pot in the cathode circuit and just use the 10 ohm resistor. That pot is a liability. Better yet, use a separate 10 ohm resistor per tube so you can match each one independently.
The reason for the 11.1 ohm resistor is a bit interesting. In the early 1960s a precision volt meter was expensive. $10 digital meters were science fiction. The cheap hobbyist analog meters were rather inaccurate at such low voltage readings. So Mr. Hafler made the proper bias current work out to be 1.56 volts. That just happens to be the terminal voltage of a D flashlight battery so you could calibrate your meter to a fresh battery and the Dynaco bias should be the same!
Today we have precision volt meters that can be bought at an auto parts store for less than $10. So by just using the 10ohm resistor, you can easily calibrate your bias.
thanks I will do that next time I have it open
If you do put a 10ohm cathode resistor on each output tube, the voltage reading across EACH 10 ohm resistor should be HALF of what it was when both tubes shared the same resistor.
This is important as you could grossly over bias the tubes if you don't remember this.
I have made some great progress in building tube amps since we last spoke .
I have been building and learning like its a full time job!!!
I have inherited a large amount of vintage electronic parts from my dad . I thought I would sell most of it but I can't bring myself to let anything go. This was the love of my dad's life and he has saved it all for many years and he has touched every piece. The idea was to make an amp and bring back some life into these old vintage components and let dads spirit shine through. I feel that he had been grooming me for this my whole life . starting with sorting screws and resistors to playing with he soldering iron melting all his solder into large globs . While building these amps I realized how important it was to play with my erector set (I know you all had one). I can hear his voice teaching me the old lessons as I work.
Thoght you would like to know the plan for the tube amps
I have a AMX controled home theater room in my rack that is built into the wall are
6 Crest 400 watt stereo amps there are 12 speakers in the room .With the push of a button I can change the configuration of the surround sound path from listening to it while sitting watching my 8' wide screen or sit across the room and watch my 50" plasma on the adjacent wall.and have the surrond change direction. (easy with a matrix switcher) Well enough of the surround noise system. Last year I took my set of EV pro speakers and built cherry boxes of thr same cubic volume and loaded the speakers and xovers in the new (pretty) corner boxes. 24 wide x 42 high x 22 deep(see the pics)
15"" woofer 8" mid 5" horn tweeter
My wife would not allow the big black ugly EV boxes in the room. I believe that the model of EV was the same as the klipsh design at that time. Well the project was a smashing success. they sound identicle to the ev boxes .THEY DESERVE A TUBE AMP TO COMPLIMENT THEM!!!!!. They are the mains in the room and when I listen to music I only want to hear them in stereo
Your obsessed friend
.Joe P
Well done, excellent job!
Luca
ecc230
here is a look inside
everyone should build a lazy susan
That damn Lazy Susan idea (Squared) is killing me. What a great idea!
Frell! I've already built way too much iron to use in any rational way and I need this?!?!?
sigh
Very good idea! Of all the things I thought of in building stuff a Lazy Susan was never one of them.
Also, very nice job on the amps. The wiring looks well thought out and the blue iron on the black chassis makes them very esoteric.
What Dynaco Mark III circuit did you use? The 6AN8? What power tubes? They appear to be 6L6's!
6550's
UTC CVP-3 OUTPUT
UTC CG-431 POWER TRANS
UTC CHOKE
Very nice design. On both cradle and amp/
NO PLYWOOD AND OLD TV MOUNTS
THE BASE SWIVELS ASWELL
dO YOU REMEMBER GIVING ME ADVICE
i SENT YOU PICS OF 6V6 AND POWER SUPPLY
ALL PARTS INHERITED FROM MY DAD
tHANKS FOR ALL YOUR HELP
jOE p
Thanks! Yes, I remember now. Very nice work. Well thought-out layout. It's make it easy to tweak and repair. Esp with that heavy duty amp cradle.
Enjoy!
Once you get used to the sound one experiment to try is to take the choke out of the circuit. Easily done by just putting a wire across. If it hums you might have to add capacitance to the first stage unless you are using a tube rectifier. If you are then you might have to use an R/C filter after the rectifier section for extra decoupling. If it hums a little just give a listen.
One of the mods I have done to Dynaco amps that use a choke is to cross them out. Most of the time they don't hum but if they do I just put in an R/C filter using a 100R resistor and a 100UF cap for an extra decoupling stage.
I think the amp becomes more lively but you can decide on what you hear if you do it. It can easily be removed if you aren't satisfied.
Nice job and good luck!
Just FYI, the Mark 2 actually used a 50ohm resistor instead of the c354 choke. The choke was added and the resistor dropped on the Mark 3. Mark 2's alsos used EL34s IIRC.
The build features all wire pairs twisted
most of the power off to one side
These amps are 100% quiet no hums crackles pops or hiss at full volume
without an audio input signal
I plan to post all results after pro testing wattage and harmonic distortion and freq ranges a variable DBs
Did you notice the rubber gasket around every trans on the chasis cutout provides insulation and wire protection
A better practice is to NOT tie wires together as you did.
Separate wire runs, one from another, and float them in free space. No problem with the twisted pairs, but the "bundling" you did mildly degrades audio performance, it is audible.
Jeff Medwin
It all depends what is bundled together. Surely one should not bundle the input lead with the heater wires. But say bundling the b+ with the OPT leads is not an issue.
Oh really ??? I personally think any bundle is a degrade. Laws of physics...right? Or, just plain common sense.Are we enlightened??
Jeff Medwin
Edits: 07/20/12
This isn't some new invention of yours or Dennis's, is it?
.
The trouble with the Dynaco choke it that they are little miserable things without enough inductance. It looks like he is using a proper choke.
Post a Followup:
FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
This post is made possible by the generous support of people like you and our sponsors: