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Old 30th September 2009, 06:10 PM   #111
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L_FB-2 and R_FB-1 seem to tie directly to ground. I'm guessing those aren't actually feedback connection points? Or am I missing something here?
These terminals work the same way that the Simple SE works. The L_FB and the R_FB are both two terminal screw connectors. The secondary of the OPT is connected to them. In order to close the feedback loop, you need a connection to the cold side of the OPT secondary (the terminals you referred to) as well as the speaker tap 9the other terminals in the same connector).

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any thoughts on whether the circuit would be a good match for small beam tubes, such as the 6V6GT or 6AQ5?
Yes, and Yes. I built test amps with both the 6AQ5 (since I have several hundred of them) and the 6V6. Email responses strongly favored the EL84, so that is what I used here. I have another test amp with 6AQ5's and 6AU6's (all pentode design) that works very well, who knows, maybe next year.
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Old 4th October 2009, 03:02 AM   #112
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Just wanted to see if there was anything new on the Simple P-P? How have things been going with testing?
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Old 4th October 2009, 01:45 PM   #113
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How have things been going with testing?
Not much testing going on. I have been building boards (4) and taking pictures at every opportunity. I have about 500 pictures so far. I have started the process of sorting through the pictures and processing the ones that will be used in the manual.

I have about 1 more week before I have to travel. I don't have any exact plans yet other than an apointment for my mother in law in Pittsburgh on OCT 19. I should have all of the pictures and other data necessary for compiling the construction manual during the trip.

There are thousands of components (many still in unopened boxes) piled up that need to be organized before the "bag of parts" kits will be ready. I am guessing that everything could be ready by early November, but I can't forsee all of the "stuff" that seems to happen.

There are 5 boards in this picture. The 2 in the front row are being assembled for the pictures. The two in the second row are both completed working boards. The one in the back row is being partially assembled to shoot detailed pictures of specific components. The assembly line:
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Old 4th October 2009, 09:02 PM   #114
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I've been wanting to build a pp 6bq5 integrated amp and have had my eye on this design as it has developed. I'm wondering, would this little amp be driven to full output with a CD/DAC or does it need to be used with a preamplifier?
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Old 4th October 2009, 11:45 PM   #115
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I'm wondering, would this little amp be driven to full output with a CD/DAC or does it need to be used with a preamplifier?
At this moment, I don't own a working preamp! Yes it works fine connected directly to a CD player, DVD player or iPOD.
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Old 7th October 2009, 04:38 PM   #116
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If I recall correctly, the Simple P-P will require 12AT7's in the front end. Any suggestions for brands to look for?
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Old 7th October 2009, 04:54 PM   #117
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I have a few different types and have tried them all in the SimpleSE. They all sound the same...I can't tell any difference. Maybe due to the active plate load, which the SimplePP doesn't have. I can sort-of tell the difference with the VTA-70 board on the Dynaco, at least in the input position.

JJ's are inexpensive, the quality has been consistent for me, and they sound fine to me. To each their own, of course.
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Old 7th October 2009, 05:33 PM   #118
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My favorite 12AT7 is the Sylvania 6679.
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Old 7th October 2009, 09:42 PM   #119
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Any suggestions for brands to look for?
I have a big bunch of Sylvania 6201's so I have been using those. I have tried at least a dozen different US made military surplus versions and they do sound similar. There are about 4 different constructions with very slightly different sound characteristics. The only real outlier is the new production JJ. It looks like it was made from leftover 6DJ8 parts. It has a different sound than all of the US made versions and it measures slightly lower in distortion. Many people prefer this sound, but I keep putting the 6201's back in.
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Old 7th October 2009, 10:27 PM   #120
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Originally Posted by SigloOne View Post
If I recall correctly, the Simple P-P will require 12AT7's in the front end. Any suggestions for brands to look for?
My budget picks are:

-GE 5-star 6201's (triple mica gray plates)

-Mullard CV4024 (later production)

Don't have any Sylvania 6201's, but I've never heard anyone say they didn't like them.

Jeff
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