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Sorry if there is already a topic on this, but I couldn't find it. Anyhow, a woman robs a bank and not only leaves her debit card, but writes the note on the back of a prescription... in her name FBI: Bank robber leaves debit card behind - Chicago Breaking News

Step away from the crack pipe dude! These idjits commenting on things they don't have a clue about drives me nuts on hf anymore. If I wasn't selling a couple things I'd have no reason to even go there anymore. At least he admitted he was wrong, instead of the usual misdirection...

Holy fucking sheet Birgir! You're a beast! Can I have the spare aluminum?

She's a doll Naaman! Congrats to you and your wife! Beautiful name as well!

Did you read your welcome PM? If not, I suggest you do so. Reks seems to be in a better mood WRT the shovel, but I'd look out if I were you...

Happy birthday Tyll!

Got the tubes today, thanks Tom. I only thought you were sending a pair I put the two pairs marked 6J6 in. The first pair was marked 105/100 and 100/105. These measured PL of 124, PR of 114. The second pair (don't recall the tester values) seemed better at PL of 136.7 and PR of 134.2 IIRC. I measured the Vf across the 4 LEDs and all were 1.63V except for one which was 1.62V. The drop across the CCS resistors was 0.93V, so this makes sense (1.63 - 0.7 = 0.93). I didn't check the Vbe across each of the BJTs. CCS is right around 56.x ohms, so ~16.6mA right now.

Brent, sorry to hear that. Hang in there, things will work out.

Yes, plenty of clearance on the bottom. I found out inadvertantly what shorting the CCS resistor to ground does... one BJT and and LED and a resistor later Winter or whenever would be great Doug. Thanks Tom. I'll have to do some listening with this after I get it cased up for safety. I played around with RMAA a bit last night. Nothing I could do would get the distortion level down so RMAA would not complain about it. I also took a look with Visual Analyzer, and yes, the THD drops quite a bit as you reduce the signal level (not surprising). I'm still fumbling around with VA however.

Conversion of RMS to peak would be Vrms * sqrt(2), or 120vac * 1.414 or ~170Vac. Still in range, or should be. Even my little $5 Harbor Freight jobbie will measure AC line at 120Vac or so.

V~200 should have been plenty. Meter <-

I was looking the PCB over to figure out where to drill some holes to install SIP pins for putting the parallel resistors in when it dawned on me... pull the 75 ohm resistors, put SIP pins in their place, and solder the 75 ohms on the bottom between the pins So that's what I did...

Happy Birthday!

I had hoped to enjoy this show, but really didn't and wound up making no effort to watch it (was usually watching a DVR-delayed Lie To Me instead).

The only time in the past that I have touched the volume control on an amp under test is if I can't get the input level low enough for RMAA. It wants to see as close to -1dB IIRC as possible. I don't know what the gain is on this amp, but it doesn't seem particularly high, at least from listening.

Doug and Tom, Thanks, I'll play around with it some more and see what I can find. I did already turn the volume down on the amp, but maybe not enough.

I think I will socket either one or both (paralleled) CCS resistors to make changing them easier. That way, my brother can decide what he likes the best and go with it. Doug: yes, I'm aware that RMAA is just a tool. Running it on my Counterpoint tube preamp resulted in much much lower distortion numbers, but it is an entirely different tube architecture. Volume (and gain) were at max for that testing as I used the THD values to bias the tubes in the line stage. Here's a sample. The M-Audio FW Audiophile is an external box, but yes, functions as a sound card. RMAA has to have a certain level range in order to function. I have control via the control panel of input levels (I presume this is input coming back from the M-Audio, so it is the output of the DUT), and output levels (I presume this is the output of the M-Audio into the DUT). I can of course also vary the volume pot on the amp. Normally, amps are tested turned all the way up (at least to my understanding). Speaking of the Counterpoint, would you be willing to take a look at it sometime Doug? No hurry, maybe this winter or something if you are up for it. Still having a slight hum problem. RMAA_test_ SA5.1_32_192k_80407_4.pdf

Yes, when I looked at the previous numbers, I thought I would see the 56 ohm numbers much higher based on RMAA bitching at me. The channel imbalnce with equal input levels (the 56 ohm CCS numbers) is ~0.7dB for the high impedance and 1.7dB for the low impedance. BTW, for 120 ohm phones, would the high impedance be the setting most likely to produce good results? Or just listen and see which you prefer? EDIT: Also, does anyone have dimensions for center on the tube holes in the top? I think I am going to use a 1 1/4" holesaw for these. I may have access to a unibit big enough as well.

OK. I got around to grabbing the two RMAA runs I saved last week, as well as running a couple more today. Last week's runs were done with 75 ohm CCS resistors. I also tried to balance the input levels between channels so these will not show the channel imbalance to the full extent. Bias (PR / PL) was 110Vdc / 130 Vdc. Runs at both 32 ohm setting (33 ohm load) and 300 ohm setting (330 ohm load): RMAA_test _ l'esp_330_load_up.pdf RMAA_test _ l'esp_load_33_down.pdf I paralleled 221 ohm resistors to the existing 75 ohm for 56 ohm CCS. I also matched the BJTs in the CCS as well. When I went to run RMAA, it was complaining that there was too much distortion. I played around with the volume control on the amp, input and output levels to/from the M-Audio box, etc., but could not get rid of it. Bias is now at 148 Vdc (PL) and 129 Vdc (PR)... yes, it got worse. RMAA_test _ l'esp_330_load_up_56.pdf RMAA_test _ l'esp_32_load_down_56.pdf I've never had anything distort so much that RMAA complained about it. THD levels don't look too good. I may pull one end of the 221 ohm and run some and see how it behaves that way. Any other suggestions?

Happy Birthday Pete!

New series on A&E. Caught the premier two episodes of this last night, though I think it is slotted for Sunday nights. Seems promising; I am going to target watching this. Rubicon - AMC

Happy Birthday Todd!

A couple of reasons: Countersunk is teh sex, at least from looking at Nate's. Check page 169 IIRC in the Amp Build thread here. These are for mounting the pair of 0.25" standoffs under the PCB in a slide-in case. Normally I would run a 1/2" or so screw up from the bottom and fasten the PCB with a nut, but since the board slides into the case, this would be difficult. Since flathead screws apparently are measured from the head, it would be easier to come up with short enough screws. 2x 1/4" panhead screws are too long; you really need something like 3/16" which aren't easily found. I ground some 1/4" down for now.

Just a crappy one from Harbor Freight. I wouldn't recommend it as it tends to lift up at the adjustable head when tightened, thereby angling your work for you Like this one 6" Jaw Capacity Drill Press Vise

^ I have a drillpress vice which can hold it. Otherwise, I usually don't have problems holding stuff by hand on a piece of wood.