nikongod

From what I hear there is enough of the tice for both of you to share.

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When you put it together make sure that when the volume is set to minimum there is very little resistance between the 2 pins you use. Volume minimum=impedance minimum. I usually spend 3 times as long as I should thinking about this & measuring a bunch to make up for the 1 time I didnt. Once bitten, twice shy.

Balanced shunted 2 deck pot. All you need is a few 1% resistors, match them if you feel like it. Or dont, your still better off than 90% of 4-deck pots. The Pot You have now will work fine. I would start with resistors at 1/2 the nominal impedance of the pot - if you have a 10Kohm pot try 5Kohm resistors to start. There is LOTS of room for experimentaion in that. Buy some other values too (10k & 15Kohm). Its still cheaper than buying another pot. Configuration A is what everyone does. Configuration B is what I would suggest. Advantages: Minimal cost. Better phase matching. Keeps the split pot in this case. No drilling, finding knobs, etc. If the knob is switched you can keep that. Disadvantages: Its cheap CAN get bitchy with floating output transformers. Real men dont need balance controls. You loose the switches and knobs race. Depends on perspective: This wastes some gain. IMO most amps have too much gain, others disagree.

I was using a Tamron 90mm F2.8 macro lens. I have shot scarry sharp photos with it at similar ranges, I think I need to be more patient focusing and stop down further. Those were already all 3second or more exposures and I was worried about wind. I think a handheld flash somewhere above & to the side would help pretty much everything, does the consensus agree?

I took these outside of my house, what do you think?

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Thanks for the advice to add the diodes. I plan to switch these with a mechanical switch, the diodes seem more important to SS controlled gear, but I'l add them anyways. I dont think that the switching time will be very important to this. The circuit is just being used to switch the secondaries of the transformer to accommodate different headphones. I found lots of information on protection diodes, and many mentions that the diodes slow things down, but could not find any way to estimate how much. Got a link? It sounds like the diode delays the unlatching of the relay until it bleeds off the voltage spike, usually a few miliseconds. Im totally OK with that. Any thoughts on the basic circuit?

Hello Head-case I (still) have not built the amp I'm interested in here, but have a tangentially related question that I think may be of interest to several other people who have expressed a desire to use this transformer in their own amp projects. I am interested in making a fairly compact PCB to switch between the various secondaries on the transformer. To understand this you will need to download the LL1689 datasheet from K&K audio. Here is the general circuit. The general operation of the circuit is as follows: The top 2 switches put windings 3&4 in series or parallel with 2&5 and likewise for 10&7 and 8&9 The third relay puts winding 10&7 in series/parallel with 3&4 I am pretty sure that with these 3 switches I can get all 3 possible outputs as indicated in the datasheet. The bottom switch is somewhat optional. It is there ONLY to switch the headphone or preamp outputs. Maybe not appealing to everyone, but its only a nominal additional expense. I plan to control this mess with a 4-pole-4 deck switch. The switch will only be used to switch DC (at low voltages & currents) so it should not be hard to find a truly cheap unit I did consider using some sort of SS logic chip, but gave up. Anyways, I would appreciate any corrections to my circuit above. Chapter 2: Im pretty sure my circuit above is right so I drew the circuit in the EAGLE schematic editor. Here it is: I think I copied the schematic over properly into Eagle, but greatly appreciate any corrections. NOTE! The second relay is "upside down" in this schematic compared to the hand drawn one. I planned to run this board off of spare current in the heater supply on my amp. I think 2 channels will only use 100mA, so Im happy. I could not find 6V relays to match my heater supply but 5V parts are everywhere: the resistor is to drop a volt. Chapter 3 (finally) I let Eagle make me a double sided PCB. I wasnt sure how to get EAGLE to make a single sided PCB. With a bunch of trace re-routing I got the while mess on one side of the board. This whole thing now is dependant on both schematics being right... But even if not do you have any recommendations for this PCB? Im not sure how large it is (heh) or how to put holes in the corners. For size I would ideally like to have the whole thing only slightly larger than the transformers so they can sit next to or underneath them in the amp and not waste a lot of room. Thanks in advance for any help you can give

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The NYC meet just got mucho better.

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Dusty, happy 22000 posts.

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