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yell if you want other options... [message #30093 is a reply to message #30091] Sat, 08 January 2005 15:02 Go to previous messageGo to next message
PakProtector is currently offline  PakProtector
Messages: 935
Registered: May 2009
Illuminati (2nd Degree)
I won't be too far away.
regards,
Douglas

Re: yell if you want other options... [message #30094 is a reply to message #30093] Sun, 09 January 2005 03:56 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18670
Registered: January 2001
Illuminati (33rd Degree)
Hi Douglas,

Are you planning to build one of these, by any chance? My plate is pretty full right now, and while I plan to build one, it might be a little while. I'd sure like to see an actual model built and tested. Subjective listening impressions welcome; O-Scope measurements might be cool too.

Thanks again for all you've done for this project and for this forum.

Wayne

predictions and more options [message #30095 is a reply to message #30094] Sun, 09 January 2005 07:33 Go to previous messageGo to next message
PakProtector is currently offline  PakProtector
Messages: 935
Registered: May 2009
Illuminati (2nd Degree)
Hey-Hey!!!,
I have built three like it already. The first was SS rectified and had cheap-o coupling caps. It sounded really good. I built two after that with increasing complexity( like you'd expect anything else, right? ).

I have another in process which I mentioned as having a schematic in hand for. Just got the big PS choke from Heyboer, and the active load valves from Radio Electric Supply and a bunch of other stuff cleaned up from my slavage box. Top plate on Monday...

This gives me a reasonable assurance that it will sound excellent. L-C filter and tube rectifier( either hybrid Graetz-bridge or perhaps get two of the 230V Hammonds and pure valve rectifier...), are definatly an improvement on the all 1N4007 C-R-C-R-C I used at first. One could try the Cree Schottky types. 1A/600V are ~$1 from Tubebuilder in Maryland and are zero recovery time. I tried them in a full bridge amplifier circuit, and found an improvement over Fairchild's Stealth types.

The most important modification will be cascoding the active load circuit. One more gate-stopper and one more 2540 and it is done. The 'top' mosfet is the one which will need the heatsink, so leave room to add another, or swap it.

If you decide on resistive loads, you'll need a second filter stage. move the big oiler to the output end and put a 450vdc 'lytic in its place.
regards,
Douglas

Re: predictions and more options [message #30096 is a reply to message #30095] Sun, 09 January 2005 08:11 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18670
Registered: January 2001
Illuminati (33rd Degree)
You've really got my mouth watering with this project, Douglas. Now I just need to make some time...

diet Dr. Pepper please [message #30108 is a reply to message #30066] Fri, 14 January 2005 10:59 Go to previous messageGo to next message
PakProtector is currently offline  PakProtector
Messages: 935
Registered: May 2009
Illuminati (2nd Degree)
beer does strange things to me. and allows me to do even stranger ones...

The thanks are appreciated though.
regards,
Douglas


Re: diet Dr. Pepper please [message #30109 is a reply to message #30108] Fri, 14 January 2005 11:35 Go to previous messageGo to next message
colinhester is currently offline  colinhester
Messages: 1349
Registered: May 2009
Location: NE Arkansas
Illuminati (3rd Degree)
Diet Dr. Pepper it is, and lots of it.....Colin

heretic.... [message #30142 is a reply to message #30090] Wed, 19 January 2005 15:22 Go to previous messageGo to next message
PakProtector is currently offline  PakProtector
Messages: 935
Registered: May 2009
Illuminati (2nd Degree)
just spend a bit more on a Swiss Army Knife sort of PT with multiple taps and stay pure choke input. ought to burn you at the stake for suggesting such a thing. Class A stake with a-a/4 impedance....
regards,
Douglas

I know you`d like it... [message #30160 is a reply to message #30142] Thu, 20 January 2005 15:25 Go to previous message
Damir is currently offline  Damir
Messages: 1005
Registered: May 2009
Illuminati (2nd Degree)
Actually, in SE amp (1) I slowly build (long breadbording phase), I use toroidal PTs (2), "ordinary" 5V4G rectifiers (3) CLC filter (4) with MKP first cap, but electrolitic second (5), actually, 2x270uF (6), 130 Ohms 10H choke (7), even add 10 Ohms resistors between the secondary and the rectifier (8), maybe I`ll bypass electrolitics with MKP closer to the 300B (9)... Huh, I really tried, but can`t do 10 Mortal Sins in Audio...sorry.
In my defense, I use small 35VA transformer for the heater (6,3V) and filaments (2 x 5V) and separate 300VA transformer with HV 2X360V + 2 x 5V for the rectifiers. Few swithes, and I have standby function like this: main switch on - small trafo is "on" through power resistor (~0,8 Uh on the load), then standby switch "on", and both transformers are "on" - IDH rectifiers provide ~30 sec. more "slow start". In standby, HV is "off" and heaters/filaments are heated with 0,8Uh...

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