This,5881 = 6L6GC = 6P3S-E Tubes. Lot of 8. Tetrode. RARE - eBay (item 330437063970 end time Sep-22-10 12:24:44 PDT) has become a popular tube to some. I might like to play with some. Would 8K be to lite a load? I've seen reference from 5K up to 7K6. I Understand the decrease in distortion and wattage, but unsure if this is going to be a little to much. Thanks
I've used those in an old ST70 and eventually they found their way to a Mac 240. They're all right. I like the look of them.
8K is too light a load. 6K is best, 5K (much more common) works well if you lower the rp of the tubes by operating at lower (375-380) volts and higher (60-65mA) current. At 7.6K they'll start to sound a little pinched.
That's an okay price, about what you used to be able to get them for.
Poinz
8K is too light a load. 6K is best, 5K (much more common) works well if you lower the rp of the tubes by operating at lower (375-380) volts and higher (60-65mA) current. At 7.6K they'll start to sound a little pinched.
That's an okay price, about what you used to be able to get them for.
Poinz
There are four, all 6GK5. The primary impetus for the new-driver-device search was the difficulty in finding dual devices that were matched well enough to make a lo-distortion diff-amp. I was very fortunate in finding an orphan teevee front end tube that also gave me 20% lower Zout, 60% higher gain and substantially greater linearity. How fortunate? I bought over 350 of the things! Great way to get 0.5% quads :^)
Aloha,
Poinz
AudioTropic
Aloha,
Poinz
AudioTropic
Let me see if I understand this correctly; you have two old low-line output transformers which are of an incorrect load reflection, one of which is dead. You are, nonetheless, determined to use them for an amp upon which you will spend scores or hundreds of hours of your labor, and the price of associated hardware.
Why?
P
Why?
P
OK, maybe I was unclear. Much like you, say 10 years ago, I'm experimenting and using what is available to me. While you have since moved on, using boutique transformers, another generation is learning using old gear.
I do not plan on using a dead transformer. I got the iron for pretty much nothing. If mass is any indication, the Eico OPTs are significantly more well built than some of the very expensive Lundahl gear.
I am not expecting an amplifier that I build out of old parts to better my F5, or my F3, but I do expect to learn something. And hopefully have fun doing it. I'll stop posting in this thread though, as our goals don't seem to be aligned.
Just wanted to kick this up to the top one more time and see if anyone that has built this amp happens to have some nice high resolution shots of the underside. I'm shamed to admit that this project is still on the back burner for me, but as it will be my first p2p wired project, I'm hoping to get some ideas. For those that commented earlier in this thread that they were building this amp, did you end up getting it done? Am I the only slacker?
I don't have any photos of the underside of the Music Machine amp that my daughter built, but you could take a look at the turret methodology used by Pete Millet in some of his amps.
Try laying out your parts on a board to see how they fit together or use a program such as Visio to do it virtually. I usually find that I need more room than I originally thought.
You might also consider the tag boards and turret boards that you can get from AES.
ray
Try laying out your parts on a board to see how they fit together or use a program such as Visio to do it virtually. I usually find that I need more room than I originally thought.
You might also consider the tag boards and turret boards that you can get from AES.
ray
These are of the latest iteration. Big photos. One of the power supply side, and two (one from the front, on from the back) of the audio circuit. I don't have time to label everything right now; trace 'em out.
http://audiotropic.net/Demo/mmACf.jpg
http://audiotropic.net/Demo/mmACr.jpg
Aloha,
Poinz
http://audiotropic.net/Demo/mmACf.jpg
http://audiotropic.net/Demo/mmACr.jpg
Aloha,
Poinz
Pointz-
Thanks for the pictures!
I really like my MM that I built a few years ago, and an 'updated' MM like the one discussed here is 'on the list' for 2011. (I'll also route the HV and heater wiring separately next time, not in one routed channel.)
Thanks again for a great design and lotsa help online!
All the best for 2011.
John
Thanks for the pictures!
I really like my MM that I built a few years ago, and an 'updated' MM like the one discussed here is 'on the list' for 2011. (I'll also route the HV and heater wiring separately next time, not in one routed channel.)
Thanks again for a great design and lotsa help online!
All the best for 2011.
John
Poinz:
I can only second what was stated above; great design and an INCREDIBLE willingness to help out those of us new to the journey. Not many out there that would provide the info/details that you do for a product that they sell commercially. If I had the dough I'd just buy straight from you and be done with it (but then I'd miss out on the adventure of building it myself).
Anyway, MUCH appreciated.
P.S. I'd still love to see what some others have done just to get a better handle on how I want to attack mine.
I can only second what was stated above; great design and an INCREDIBLE willingness to help out those of us new to the journey. Not many out there that would provide the info/details that you do for a product that they sell commercially. If I had the dough I'd just buy straight from you and be done with it (but then I'd miss out on the adventure of building it myself).
Anyway, MUCH appreciated.
P.S. I'd still love to see what some others have done just to get a better handle on how I want to attack mine.
I tried to copy the Pointz-style chassis pretty closely, but I made it a bit larger.
As a beginner, I found it easier if I had a bit of 'spare real estate' to work with.
John
I found something interesting with the 6GK5. I had 10 of them sitting here for a Musical Machine project, and used one as the first stage in a simple guitar amp. This amp has an elevated heater supply due to a direct-coupled cathodyne PI and I had problems with hum from the 6GK5. The solution was to connect the internal shield (pin 6) of the 6GK5 to the voltage divider supplying the elevated heater voltage. (The voltage divider feeds 2 x 270R resistors, one goes to each heater wire.) Just for info...might help someone somewhere someday. Fortunately I did not lose any hair over this one, but I could have 
I do not have pins 1 and 7 (cathode) tied together, I forgot to try that and the amp is now bolted into its cabinet.
I do not have pins 1 and 7 (cathode) tied together, I forgot to try that and the amp is now bolted into its cabinet.
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