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answers... [message #30999 is a reply to message #30998] Wed, 16 March 2005 18:17 Go to previous messageGo to next message
PakProtector is currently offline  PakProtector
Messages: 957
Registered: May 2009
Illuminati (2nd Degree)
The schematic will be for what is effectively the HY69 amp. Minor changes to account for g3 being attached to the filament in the 1624 and to its own pin in the HY69. I'll be drawing monoblocks, as mine is a stereo chassis( not again I can tell you that! ).

I am trying to decide between tertiary winding for cathode fedback to be run with a pentode connected final, or U-L in the traditional fashion. I also don't quite know where the u-L point exists for the 813, that is at what percentage should the tap go. A tertiary winding that is ~30% of the anode winding takes up a lot of room. I don't think of any over ~15%, like Acro's 350 and Dynaco's A441. I have a pair of 441's and they need to be better. they are acceptable, but that's about *IT*. I need a stellar one...

I think I will go with a cathode tertiary winding. It will net me ~80W without getting to nutsy with dissipation and I can put g2 right where I want to. Fortunately I have a reasonable design OPTx for both apps. I just need to decide.

On the schematic distribution. I am going to draw them tomorrow and the next day. Such things need a good proofing I can say with confiddence. Also notes on limitations, and variations. more importantly Limits are a personal requirement. Then off to the scanner and ~4 pages at ~1 meg each ought to be fine resolution.
regards,
Douglas

Thanks [message #31002 is a reply to message #30999] Wed, 16 March 2005 19:28 Go to previous messageGo to next message
Old Brown Eyes is currently offline  Old Brown Eyes
Messages: 25
Registered: May 2009
Chancellor
gotta say I'd vote for UL over cathode feedback because I see cathode feedback as being more like Mac sound, as..hmm..souless/unconnected? But then I am thinking of high wattage as doing the boogy thang at the cost of fine inner detail.

I look forward to hearing the "whys' of your final decison.


Russ

anytime... [message #31004 is a reply to message #31002] Wed, 16 March 2005 19:39 Go to previous messageGo to next message
PakProtector is currently offline  PakProtector
Messages: 957
Registered: May 2009
Illuminati (2nd Degree)
I am not going for the mac sound. Having had several of the 75's in both stereo and mono, I think I can avoid that.

I read somewherre tht the CFB, if kept to ~10% reduces third H a bit more than just that amount of nfb would from g2 current contributions. Even with the so-so Dynaco OPTx, and more than 10% it did not sound 'souless' or dry. The leakages caused some interesting behaviour with certain connections, and I decided to try something else.

Either way, it is only a pair of OPTx, probably ~$400/pr, and I may get the main plate TX wound so I can use it for both U-L @ 700V B+ or the full 1kV for pentode conection. But until I get some funding improvement( and keep the schedule open enough to build ), I am not having either one wound. I don't think I will be certain until I do it both ways anyway, so I'll probably get both done and stop wondering.
regards,
Douglas


Re: Amp schematic [message #31006 is a reply to message #30977] Thu, 17 March 2005 20:52 Go to previous messageGo to next message
cheetah is currently offline  cheetah
Messages: 70
Registered: May 2009
Viscount
Douglas,

Don't want to seem impatient!

To date I have only recieved pieces 2 & 3 of the schematic. What is the status on the rest?

Joe

Re: Amp schematic [message #31007 is a reply to message #31006] Fri, 18 March 2005 06:05 Go to previous messageGo to next message
PakProtector is currently offline  PakProtector
Messages: 957
Registered: May 2009
Illuminati (2nd Degree)
My email service fro Netscape sucks. It is giving me fits and seems to have bolluxed up what I have sent. It is a shame because the fine detail from the original drawing I made was preserved.

I am making a more complete set of schematics, and will send them to the forum projects files managed by Wayne. A bit more patience please, I will deliver this as promised. Figure Monday by thetime I can distribute the scans( even a pre-liim proof found mistakes and omisions, this must be done right the first time ).
regards,
Douglas

Re: Amp schematic [message #31009 is a reply to message #31007] Fri, 18 March 2005 15:49 Go to previous message
cheetah is currently offline  cheetah
Messages: 70
Registered: May 2009
Viscount
Hey Douglas,

Understand! Take your time. Just knowing is half the battle.

Joe

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