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Never mind, I see them.

Maybe it is hidden in the picture or you have the input RCA jacks in a different place, but I don't see the input going anywhere.

The light blue wires may need swapped, if disconnecting the yellow and green wire removes the noise.

Not the output taps, but, if the primary leads to the transformer are connected to the output tubes backwards you get positive feedback rather than negative and lots of noise. Removing feedback altogether is a quick way to see if this is the problem. If it is, you need to swap which tubes the...

I would try de-soldering the feedback loop ( off the output transformer) as a first step. Its easy to get this switched around by accident.

From what I remember, I based this on measuring the overall resistance through the tone controls. Not wanting to add too much feedback I ended up with 120k and was happy with the way it sounded. Here is a plot taken of the response with network engaged, eq centered, and with it switched off...

On mine, I installed a switch that either engages the compensation network (within the dotted lines on the schematic), or routes feedback through a single 120k resistor. Its best to flip the switch with the power off, but it sounds great and the overall volume of the amp remains the same.

Thanks!

One other question I read that TR114 was originally configured CBE, rather than ECB. Looking at the picture in the service manual it looks like the center leg is the collector, not the base. Does the circuit board have the center leg collector, like the picture?

I too am repairing a P2200, and along with a number of driver transistors, it has one bad 2SA909. I've checked and replaced all the bad transistors and diodes, basically all from TR109 on up Can I replace just the 1 2SA909, or do I need to do all 6? If I do 6 on one side, should I do the other...

http://sound.whsites.net/valves/preamps.html Section 8, Bootstrapped Load Feedback Amplifier. I've built and used this a number of times, mostly without feedback. It sounds great.

A recently finished 175 amp, with added input buffer.

This is the method I used on a pair of 6L6 PPP amps I built. The B+ was a little high at the start, and taking the bias off a floated ground brought things right in line. It has been working great. My observation is that it lowered the noise floor as well, since it helps to isolate the first...

On this 9300, I cut off the side flanges prior to fitting the case.

Here is v2 of the splitter, with 100W resistors: The headphone jack is very handy when trying to chase down hum and grounding issues. On mine the test jig has a common ground, so it is important to not swap the + - when hooking up to the amplifier.

+1 on using Room EQ Wizard to measure response. I put together a speaker dummy load with a headphone/line level output that I use with a USB Soundcard. The soundcard needs to support both line out and speaker in, mine is an M-Audio Mobile Pre-USB. Here is the underside view of my v1...

An old timer tube tech gave me these to keep me from burning fingers.

Sounds like you got a good deal on your console. I think you are correct, I haven't seen any differences between the 402 and 403 other than the switches.

Yes, I think this is a typo in the original schematic that was carried forward to the one that was cleaned up and redrawn. The capacitors in my amp were the same as yours, 0.047u to ground, rather than 4n. I used the 3 .047u caps, plus the .020u on the EF86.

Another area is the preamp. It doesn't have a loudness control switch, but was built instead with the loudness always on. This also causes the bass to be over emphasized. There are two PEC in the unit, this one has only two wires attached, one to the loudness tap of the volume control, the...

Not sure what your plans are, but if you are doing a rebuild there are a couple of places in the console where the engineers have added bass-boost features. This would make sense if the console was fitted with the single 8 inch full range driver, but if yours has the 12 inch woofer and tweeter...

Here are a couple different schematics of the preamp. The first is the slightly older 402, and the second is the 403. The image quality is not the best and they are very similar, so you may have to look at both to figure out the component values. Here is the amplifier.

Here are another couple of ELACs to add to the picture parade. The newer is an 870, which is a hybrid idler-belt driven table. The elder a 10H with a custom walnut tone arm.