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I’m finishing up a KX200 for my nephew from a complete rebuild and wondering if anyone has done a tone bypass circuit they can share for this amplifier? I did leave out the high filter PEC and replaced it with a 200k resistors in place of it.

Raise your drink please. To a man who is so rare. And to his wife who is so fair. May your life together see much flair. And your tubes have no glare. Congratulations.

Maybe use a wall wart to keep the voltage low also to compare.

Just found this if you wanted to try this formula. Like Mr. Gillespie had mentioned the OPT would still be under the voltage it would normally be taking using your 125v wall socket. Turns Ratio = V in (to the primary) / V out ( measured in the secondary) e.g. if we apply 5 Volts AC and we...

Hello Tom and welcome to the forum. I left the .47 capacitors in my 400 so far and I like the the way it is preforming so maybe in yours you can try both. I did go with 220K resistors because one original was bad and I had the others. The biggest sound change to my ears came from all the mods...

I’m thinking you were probably grinning as much as he was if not more. 6 hours of music so far and you still have a few decades worth of music variety to go. Sweet.

Got to listen to Béla Fleck and the Flecktones and a Keb Mo CD today on the fisher 400 playing through Cornwall speakers and a Denon 2910 combo Blu-ray CD player. Have a little buzz coming out of right speaker but not going to be an issue for this listening session. I have the bass and treble at...

Well it looks like my lack of knowledge of understanding testing procedures had me self doubt my parts swapping ability. Each channel was tested separately and when I bypass the variac I will pick up at least 20-25v more B+. No I do not have any means to measure distortion. I had adjusted the...

Thank you Mr. Gillespie for correcting my mistake on my calculation error on the transformers. So before I hooked the B+ back up to the transformers I took readings again and they are staying consistent as long as I hook it up the right way. Looking at the Fluke 175 manual and if I’m...

Larry, you’re right thanks and so far I haven’t nailed myself or destroyed anything yet well at least that’s my story.

It might be time to find a new hobby. Had the right side hooked up wrong and had pin 5 attached instead of pin 9. So when I have both clips on the transformer leads I get close to the same reading as the left side. 3.768 squared equals 14.197824 x 16 = 227 rounded off.

Okay I keep forgetting about all that stuff in the weeds so to speak. The right OTP came out with 26.5 so I got 11.236. The left OPT came out with 3.789 so rounding it off I got 230.

150. mv division setting at .1. Same as last post last picture trigger ch 2. 285. mv division .2 same layout with order of pictures. Two more pictures at 1.930vrms and .2 mS and .5 mS sweep

Scope settings are set with the sweep setting at .2 mS. Trigger is in P.P auto mode and then using A&B INT to switch between channel 1 and channel 2. The division settings are adjusted in accordance to volume voltage reading taken at output transformers. Also switching between right and left...

Good question about the weird clipping, instability so I went to see if I could replicate it. Pictures below. About measuring the impedance of the transformers I measured the ohms between the blue and the blue with the tracer and then from the center tap to each blue wire. Left side is. 273...

Sorry, yes the readings are at the onset of clipping. With the tubes bias set at 27 mA about 4 minutes warm up time the B+ is at a resting 419v and also 419v at OPT CT and the screens are at 304v. With the power turned up to onset of clipping the OPT CT is at 402v and the screens are at...

Far as scope not syncing we can call it operator error, all left channel pictures will have trigger INT set to B. Tubes are all used pulls, but the ones that are in the amplifier now have a range from 15 to 29 mA with the EFB pot. With 27 mA and the C-56 B+ at 406v the output watts went from...

Thank you Mr. Gillespie for your remote help to assist me in finding my blunder or blunders. Also I will try not to assume that you can read my mind. So if I may I will reference that alsome schematic that you and Luis put together and l believe it to be the last version. I will put the voltage...

Mr. Gillespie your suspicion that the sine wave source may have been bad was wight on. I downloaded a sound generator app and the single looks much better on the scope. First one with no power to amplify.

My apologies for not verifying some pertinent information. The OPT are T1020-116-1AX and T1020-116-2AX. And did use the 4 ohm tap with the new feedback. Also other than then the mod from everything around the 12AX7 (phase inverter) tube I rebuilt the B+ and - power supply so far. I have two...

Some underside pictures of both right and left side of the 12AX7. So in the past I have missed the obvious so please if you have any suggestions they will be welcomed. Thanks to all in advance.

Okay adding the 4 - 10 ohm resistors I have ether 0.21 or 0.22 volts on the power tubes cathodes. But have not been able to find the instability on the right channel. Have disconnected the parts that make up the feedback loop to check value and they check good. Also checked that the 100 pF/27K...

Thank you Mr Gillespie for your quick response and your guidance to helping me resolve my issues. But I will be detained for a week or so before I can devote some more time to working on the amplifier. So thank you again and I shall return hopefully with some great news.

Thank you Mr Gillespie for your complament and leading me straight to my problem. And that’s Why I should be measuring every resistor instead of half of them or of course learning the code better. Having 118v ac going to amplifier I’m getting 394v B+. My AC and DC filament voltage is 6.34 and...

Test picture of the MOSFET with the gate and drain unhooked from circuit. Also in all of the test pictures the red test clip is number 1 green number 2 and black number 3.