AX84 BBS Recent Posts as of Sun, Apr 26th, 2015 @ 17:42:48 http://ax84.com Amp Parts and KitsDoberman Music Products, LLC offers a variety of parts and kitshttp://shop.dobermanamps.com RE: Under $50 Over-Ear Headphones(by Douche Baggins) Beats without the bloat and expense of an Endorser. I started out looking for $100 and under headphones and came across this site: <a href="http://headphones100.com/ " target="newwin1430084571">[link]</a> . I was about to pull the trigger on the AKG K240 Semi-Open Studio Headphones for $69 but, after further investigation they are no longer made in Austria and there are several complaints about the ones made in China. Sun, 26 Apr 2015 17:42:01 -0400 http://ax84.com/bbs/dm.php?id=490362 RE: Resistor Clearances(by David Staepelaere) I would worry that a component lying in loose contact with the board might be possibly buzz in sympathetic vibration in some odd case. I don't think I've actually had it happen, but I try to avoid it all the same. For bigger components, like p/s caps, that touch the board I'll usually bed them down in a dollop of silicone adhesive.Sun, 26 Apr 2015 15:30:50 -0400 http://ax84.com/bbs/dm.php?id=490361 RE: Turret Wiring(by David Staepelaere) No huge insight here... I tend to drop component leads in through the top. For hook up or jumper wires, I wrap around the turret with a 180 degree (semi-circle) bend. For under-board connections I drill a hole next to the turret and then connect on the top-side -- this makes it easier to trace the connections later on and avoids the problem of wires falling out during rework after the board is installed. Sun, 26 Apr 2015 15:19:04 -0400 http://ax84.com/bbs/dm.php?id=490360 Turret Wiring(by lkrasner) How do you guys recommend wiring to turrets? I generally try to stick the leads of components in the top, then wrap any wires around the base. However, this falls apart when there are multiple thick-leaded components. I also like the idea of sticking wires up through the turret and hooking over the top, but this takes up all the inside space as well.Sun, 26 Apr 2015 15:19:04 -0400 http://ax84.com/bbs/dm.php?id=490359 RE: Under $50 Over-Ear Headphones(by tedmich) Nice find! I'll check them out. They kind of look like Beats eh? Other well regarded (<$50) over the ear phones: Sony MDR-V55 Samson SR850 Pioneer STEEZ 808 SE-MJ751 Sennheiser HD203 Panasonic RP-HTF600-S JVC HARX500 Sun, 26 Apr 2015 14:20:07 -0400 http://ax84.com/bbs/dm.php?id=490358 RE: Poweramp Cathode Bypass W/ Bias Check Resistor(by lkrasner) <div class="quoteblock" >On 04/25/2015 @ 18:25, Paul Fawcett wrote : <div class="quoteblock" >On 04/25/2015 @ 12:53, Alva Goldbook wrote : : You don't need to use a 1 ohm resistor with cathode bias. The only reason a 1 ohm is used is so you can measure the bias in a fixed biased amp. If you're going to cathode bias the amp with say a 150ohm resistor (a common value for EL84's) then you measure the bias through the 150 ohm resistor. You may find these videos helpful. : : </div> : : Well, yes, but a one ohm resistor could still be handy, since 1mV = mA. It avoids the necessity to do math, and if external bias points are being provided, the measurements on these will conform to standard expectations. Also, the 1R resistors used are often 1% or better parts, so you will have higher confidence in the reading than you would with a 5% or 10% part (you could always measure the actual resistance of course). : : It doesn't matter if the bypass cap goes around the 1R resistor or not, do what is convenient. -- </div> Exactly, I do it for the simplicity, and I use a .1% resistor for accuracy. Just makes things easier not having to pull out a calculator to do the math. ThanksSun, 26 Apr 2015 12:44:17 -0400 http://ax84.com/bbs/dm.php?id=490357 RE: Custom chassis(by SX4Amps) Great news! I've been buying from Watt's Audio. A little more expensive that Ddawg's but not too bad. Sun, 26 Apr 2015 10:14:07 -0400 http://ax84.com/bbs/dm.php?id=490356 Under $50 Over-Ear Headphones(by Douche Baggins) Just purchased a Status Audio HD One headphone <a href="http://thestatusaudio.com/ " target="newwin1430084571">[link]</a> last week. I researched a lot of under $50 headphones before deciding on this one. There are several reviews on line, almost all are positive and mine is as well. Very neutral stock setup and need EQ to bring them to life. When EQ'd properly sound great with very good passive noise cancellation. What tipped the scales compared to others in it's price range is that they are made in the USA..Brooklyn, N.Y I have no affiliation with the company in any way. Sun, 26 Apr 2015 17:42:01 -0400 http://ax84.com/bbs/dm.php?id=490355 RE: Hookup Wire Choices(by Douche Baggins) I want to apologize to other members here for stating "we" in my second post to the OP. I should have used "I" instead, as it was my sole statement and not anyone else. I want to apologize to the OP for crossing a personal boundary labeling him as a pud. I hope the OP understands that during replies to his future posts that he should take all with humility and graciousness. Sat, 25 Apr 2015 20:49:08 -0400 http://ax84.com/bbs/dm.php?id=490354 RE: Poweramp Cathode Bypass W/ Bias Check Resistor(by Paul Fawcett) <div class="quoteblock" >On 04/25/2015 @ 12:53, Alva Goldbook wrote : You don't need to use a 1 ohm resistor with cathode bias. The only reason a 1 ohm is used is so you can measure the bias in a fixed biased amp. If you're going to cathode bias the amp with say a 150ohm resistor (a common value for EL84's) then you measure the bias through the 150 ohm resistor. You may find these videos helpful. </div> Well, yes, but a one ohm resistor could still be handy, since 1mV = mA. It avoids the necessity to do math, and if external bias points are being provided, the measurements on these will conform to standard expectations. Also, the 1R resistors used are often 1% or better parts, so you will have higher confidence in the reading than you would with a 5% or 10% part (you could always measure the actual resistance of course). It doesn't matter if the bypass cap goes around the 1R resistor or not, do what is convenient.Sat, 25 Apr 2015 18:25:47 -0400 http://ax84.com/bbs/dm.php?id=490353 RE: Hookup Wire Choices(by KenInVic) <div class="quoteblock" >On 04/25/2015 @ 15:10, Douche Baggins wrote : So is Apex Jr. considered option C or D?,,lol...pud. -- </div> Will give you credit for your choice of nicks. You definitely are. It will be immensely enjoyable ignoring you. Seen way too many of your type, bitch.Sat, 25 Apr 2015 15:24:24 -0400 http://ax84.com/bbs/dm.php?id=490352 RE: Hookup Wire Choices(by Douche Baggins) So is Apex Jr. considered option C or D?,,lol...pud.Sat, 25 Apr 2015 15:10:43 -0400 http://ax84.com/bbs/dm.php?id=490351 RE: Poweramp Cathode Bypass W/ Bias Check Resistor(by Alva Goldbook) You don't need to use a 1 ohm resistor with cathode bias. The only reason a 1 ohm is used is so you can measure the bias in a fixed biased amp. If you're going to cathode bias the amp with say a 150ohm resistor (a common value for EL84's) then you measure the bias through the 150 ohm resistor. You may find these videos helpful. <a href="https://www.youtube.com/watch?v=L3rRk3eSTnA " target="newwin1430084571">[link]</a> <a href="https://www.youtube.com/watch?v=w9B0Rhr_Y-E " target="newwin1430084571">[link]</a> <a href="https://www.youtube.com/watch?v=pjKYiSr497w" target="newwin1430084571">[link]</a> Sat, 25 Apr 2015 12:53:20 -0400 http://ax84.com/bbs/dm.php?id=490350 RE: Hookup Wire Choices(by lkrasner) This is what I'm using right now: <a href="http://www.ebay.com/itm/100-Ft-20-Awg-Silver-Plated-SOLID-CORE-600V-Mil-Spec-M16878-4-Teflon-Wire-AMP/181725313388?_trksid=p2047675.c100011.m1850&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D30002%26meid%3D4ebaf344eee14f158cd6685aa8598106%26pid%3D100011%26rk%3D1%26rkt%3D6%26sd%3D171700291415 " target="newwin1430084571">[link]</a> Sat, 25 Apr 2015 12:50:52 -0400 http://ax84.com/bbs/dm.php?id=490349 RE: Hookup Wire Choices(by lkrasner) I'll second (third?) Apex jr. You can get their wire on ebay as well, which may be cheaper depending on shipping and what you need. I use PTFE solid core 20ga wire for everything except the mains connection, which I use 18 ga stranded for. The PTFE insulation is a pain to strip, but it doesn't burn and looks nice. Even stranded PTFE wire will hold its shape better than normal PVC insulation. PTFE insulation is also much thinner. Generally 20 gauge is fine even for the heaters unless you have multiple power tubes that draw a lot of current.Sat, 25 Apr 2015 12:43:15 -0400 http://ax84.com/bbs/dm.php?id=490348 Poweramp Cathode Bypass W/ Bias Check Resistor(by lkrasner) When putting a 1 ohm resistor in series with the bias resistor to facilitate checking of the bias current, should the bypass cap fully bridge BOTH resistors, or is it ok to leave it only across the larger bias resistor?Sun, 26 Apr 2015 12:44:17 -0400 http://ax84.com/bbs/dm.php?id=490347 RE: Using an old SE transformer(by DaveW) That's what I suspected. Shame.. its a great bit of kit. Guess the paperweight is the best option. Thanks, DaveSat, 25 Apr 2015 07:50:05 -0400 http://ax84.com/bbs/dm.php?id=490346 RE: JCM 800 voltages(by steve25) If you tap the wiper terminal /center of the treble pot do you hear a light pop out thru the speaker?Sat, 25 Apr 2015 07:41:09 -0400 http://ax84.com/bbs/dm.php?id=490345 RE: Using an old SE transformer(by steve25) Yup, that's what it is made for, driving long speaker lines with 100 volts! I would say that unfortunately you just have a nice paper weight there unless you build something with it for clean playing only and get the needed transformer to place inbetween that OT and whatever regular 8 ohm speaker you want to use! If you do such a build I would use a TRS type output Jack and wire it so that any normal TS Jack will not power up and feed the possible speaker on the other end as even 60 volts will blow most speaker right quick!Sat, 25 Apr 2015 07:35:52 -0400 http://ax84.com/bbs/dm.php?id=490344 RE: output section(by Mitch Markin) Yes the middle lug in the input jack is connected to ground. That's the switched contact. When nothing is plugged into the jack the switched contact is connected to the signal contact. That keeps the amp's input grounded and quiet if nothing is plugged into the jack. When you plug in a guitar cable the switched contact is opened, the input is no longer grounded and the guitar signal gets fed to the amp. Thanks for the kind words about my SEL. The heater wires at the back were just twisted together with a power drill. The wires going to the impedance selector and output jacks are bundled together with cable lacing. The AC wires and power transformer wires too. Cable lacing is an old way to bundle wires together. Not used much these days because most people just use nylon cable ties. Cable lacing looks neater though. It's sort of like flat string. It's waxed to help it stay where you tie it and you can run a series of connected loops along the entire length of the bundle. Sat, 25 Apr 2015 05:29:03 -0400 http://ax84.com/bbs/dm.php?id=490343 RE: P1 (EX Sort of) on a record!(by Frank Tone) Thanks Stephen, I had a hard time putting that song last(Fix), but it seems like such a good song to close the album with. It was funny to me that I recorded a lot of tunes, but ended up with a mostly acoustic EP! Hmm.. I don't have a schematic handy, but I could poke around inside the amp and take a quick stock of things to post. Something that may be worth mentioning is that I played the guitar on that track(keep the good times coming) through an open back 8" speaker cab, with an old "oaktron" alinico speaker from the early 60's. It mates nicely with the amp and It's easy to get a great room sound with it. It has a felt dustcap which I usually don't care for, but with this amp just works. <div class="quoteblock" >On 04/24/2015 @ 16:13, Stephen Keller wrote : Nice. The acoustic "Fix" is my favorite of your tunes. : : Do you have an as-built schematic of your P1-eX variant that you'd care to post? : : Stph -- </div>Fri, 24 Apr 2015 21:15:51 -0400 http://ax84.com/bbs/dm.php?id=490342 RE: Hookup Wire Choices(by Dave C) As far as the Tube Store is concerned, I have dealt with them and have been very happy. To be honest I have had good service from all the suppliers I have used .. AES, Tube Store, Apex Jr wire and for fellow Canadians don't forget Just Radios in Toronto. Dave is excellent to deal with and they have a great stash of Caps and Resistors with great prices and the shipping is lickety split. Too bad they don't carry the carbon film resistors I am usually after but their E cap inventory is deadly. Also great coverage in the poly cap inventory as well.Fri, 24 Apr 2015 20:21:27 -0400 http://ax84.com/bbs/dm.php?id=490341 RE: Seeking long 1/8" / 3.5 mm stereo jack(by BC Walter) Good to feel useful :) I hope they work outFri, 24 Apr 2015 19:38:33 -0400 http://ax84.com/bbs/dm.php?id=490340 Using an old SE transformer(by DaveW) I have been given an old partridge transformer. As far as I can tell it is a single ended unit and looks to be quite high power. It has one secondary which has a resistance of 44.8 ohm, the primary has a resistance of 413 ohm tapped at 376 and 265 The unit it came from originally had two EL34 valves and looked like a PA chassis (homebuilt). If I put 7.6V AC to the secondary I get 59.8v across the full secondary. This calculates to a ratio of 7.83 so a 16R speaker would give a 998 ohm anode impedance. Is this a bit low for a pair of EL34s? Could it be a 100v output transformer? I would like to use this any suggestions what valve/valves would this work well with? Thanks, DaveSat, 25 Apr 2015 07:50:05 -0400 http://ax84.com/bbs/dm.php?id=490339 RE: P1 (EX Sort of) on a record!(by Stephen Keller) Nice. The acoustic "Fix" is my favorite of your tunes. Do you have an as-built schematic of your P1-eX variant that you'd care to post? StphFri, 24 Apr 2015 16:13:01 -0400 http://ax84.com/bbs/dm.php?id=490338