The 12AT7 has a Mu of 60. The real world gain with a resistive load is more like 30. That is the reason for the CCS load in the SSE baord. 30 isn't enough to drive a KT88 to full tilt from a CD player. The second stage in the SPP is a split load PI which has no gain. All CD players aren't created equally as are all CD's. The SPP and the SSE can hit clipping with a variety of CD players on the majority of the CD's that I have. I still have a few CD's that can be played at full volume on both amps without seing any clipping on the scope. I have an old Toshiba DVD player that will rarely clip these amps with any CD.
Reducing the gain may cause the same effect with some of your CD's unless you have a hot CD player or really efficient speakers that don't need or want all of the amps power. If this is the case I would try a 12AV7 first. Some tweaking of resistor values may be needed.
Sherri put together 10 parts kits for the Simple P-P last year when she was here. At the time I ordered enough parts for 25 kits and enough small parts for 100. It took most of last year to sell those 10 kits and there has been no requests for more until this week. I have recently received several requests for kits, so I counted the remaining parts (I robbed some to make my own amps) and made some more kits. The people who already emailed me will get first choice and then the rest are up for grabs.
I have put together 7 parts kits since they seem to have become rather popular in the last week. The only Item that I am short on is the 39 ohm resistor that is only used in the 6CW5 version built without a power supply choke. I have 2 of them and I will get more next time I order parts. So there are 2 kits with everything, and 5 more that don't have the 39 ohm 5 watt resistor. Someone expressed interest in building a 6CW5 version so the complete kits should go to that person.
All of the parts were purchased last year before the prices went up on electrolytic caps, so I will still sell them for $65 each (same price as last year). Boards are $35 each. I can put 1 board and 1 parts kit in the small flat rate box which I can ship inside the US for $8. Anything bigger than that requires the medium flat rate box which I can ship for $13.
The remnants of tropical storm Emily blew through here yeaterday afternoon with strong winds and rain today as well. My power and internet have been intermittent most of today, but seems OK now.
PM me or email if you are interested. If there is sufficient interest I can get more parts. There are only a few items missing.
I can no longer answer Tubelab email from work and I don't get home until late, so sometimes I may not answer until the next weekend.
I have put together 7 parts kits since they seem to have become rather popular in the last week. The only Item that I am short on is the 39 ohm resistor that is only used in the 6CW5 version built without a power supply choke. I have 2 of them and I will get more next time I order parts. So there are 2 kits with everything, and 5 more that don't have the 39 ohm 5 watt resistor. Someone expressed interest in building a 6CW5 version so the complete kits should go to that person.
All of the parts were purchased last year before the prices went up on electrolytic caps, so I will still sell them for $65 each (same price as last year). Boards are $35 each. I can put 1 board and 1 parts kit in the small flat rate box which I can ship inside the US for $8. Anything bigger than that requires the medium flat rate box which I can ship for $13.
The remnants of tropical storm Emily blew through here yeaterday afternoon with strong winds and rain today as well. My power and internet have been intermittent most of today, but seems OK now.
PM me or email if you are interested. If there is sufficient interest I can get more parts. There are only a few items missing.
I can no longer answer Tubelab email from work and I don't get home until late, so sometimes I may not answer until the next weekend.
.
I have a pair of Silver Iris drivers mounted in old console radios. They are 96 db efficient with 15 inch woofers. One of my SPP's had a noticible hum in one channel. There was no hum audible at all on my 87db Yamahas even with my ear to the speaker.
The hum cancellation in a P-P amp depends on perfectly balanced output tubes and an output transformer with identically balanced windings for each half of the primary. Since neither of these exist in the real world, there will always be some hum.
I noticed that the hum followed the tubes. I have about a dozen JJ EL84's so I played musical tubes until I found a set that doesn't hum.
My OPT's were obtained on Ebay about 10 years ago for $16 each. I bought lots of them. Obviously they are far from perfect, so I got lucky and found some tubes that had complementary imbalance. On amps like the red board I must set the idle currents about 10% different from each other to minimize hum and distortion with these transformers.
The hum cancellation in a P-P amp depends on perfectly balanced output tubes and an output transformer with identically balanced windings for each half of the primary. Since neither of these exist in the real world, there will always be some hum.
I noticed that the hum followed the tubes. I have about a dozen JJ EL84's so I played musical tubes until I found a set that doesn't hum.
My OPT's were obtained on Ebay about 10 years ago for $16 each. I bought lots of them. Obviously they are far from perfect, so I got lucky and found some tubes that had complementary imbalance. On amps like the red board I must set the idle currents about 10% different from each other to minimize hum and distortion with these transformers.
George:
late consolations on the family loss, and good to have you back at whatever level of participation you're able to maintain.
once I was able to get some help diagnosing problems with flaky rectifier , my SimplePP has been working like a charm - personally I love the sound of the Psvane EL84s and 12AT7s in this baby
cheers
late consolations on the family loss, and good to have you back at whatever level of participation you're able to maintain.
once I was able to get some help diagnosing problems with flaky rectifier , my SimplePP has been working like a charm - personally I love the sound of the Psvane EL84s and 12AT7s in this baby
cheers
Hi,
I have a couple of questions regarding the Simple PP board:
1. Do I need one or two for a stereo pair?
2. Was a schematic ever published?
3. I get the sense that this is fundamentally different than the 6L6GC AB2 circuit. Correct?
I admire your work greatly, George.
Thanks and regards,
Rob
I have a couple of questions regarding the Simple PP board:
1. Do I need one or two for a stereo pair?
2. Was a schematic ever published?
3. I get the sense that this is fundamentally different than the 6L6GC AB2 circuit. Correct?
I admire your work greatly, George.
Thanks and regards,
Rob
hi I have a stupid question from this schematic\
http://www.diyaudio.com/forums/atta...d1251770100-tubelab-simple-p-p-simple_p-p.pdf
what are those tubes will be? if i want to use EL84 tubehttp://www.diyaudio.com/forums/atta...d1251770100-tubelab-simple-p-p-simple_p-p.pdf
thank you to be such a nube
nate
http://www.diyaudio.com/forums/atta...d1251770100-tubelab-simple-p-p-simple_p-p.pdf
what are those tubes will be? if i want to use EL84 tubehttp://www.diyaudio.com/forums/atta...d1251770100-tubelab-simple-p-p-simple_p-p.pdf
thank you to be such a nube
nate
simple pp uses 12at7 and el84.
um other questions. well ya now have the schematic, bom is posted on the site. its a stereo board.
As far as different, It does use some massive caps by old standards, but hey 10,000uf caps are cheap compared to 60 years ago so you might as well take advantage.
um other questions. well ya now have the schematic, bom is posted on the site. its a stereo board.
As far as different, It does use some massive caps by old standards, but hey 10,000uf caps are cheap compared to 60 years ago so you might as well take advantage.
Condolenses
George,
I have been moving backwards through the forum and just noticed that Sherri's mother has passed. I know for lurking here and on the Tubelab site that this has been a long struggle for the both of you. My condolences go out to both of you. May you find comfort during your time or mourning, be it through God, meditation, or you own spiritual devices.
My Best,
Alan
George,
I have been moving backwards through the forum and just noticed that Sherri's mother has passed. I know for lurking here and on the Tubelab site that this has been a long struggle for the both of you. My condolences go out to both of you. May you find comfort during your time or mourning, be it through God, meditation, or you own spiritual devices.
My Best,
Alan
2x 12at7 4x el84
If you really want you can do the tube rec, sand rec is optional on the el84, but required with the other variant. id spend my $20 on something else like a motor run cap.
Heres my plug for a coupling cap:
http://www.parts-express.com/dayton-film-capacitors.cfm
If you really want you can do the tube rec, sand rec is optional on the el84, but required with the other variant. id spend my $20 on something else like a motor run cap.
Heres my plug for a coupling cap:
http://www.parts-express.com/dayton-film-capacitors.cfm
3A slo blo in mine - after replacing a defective rectifier tube that randomly blew mains fuse about 3 months ago, it's been running 3-8hrs every day with no issues.
You can easily use SS diodes in place of the GZ34, saving quite a few dollars and reducing the thermal load on filament supply.
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