jwc Posted May 8, 2018 Share Posted May 8, 2018 Why are these DIY amp chassis so freakin" huge? Does anyone know of a supplier with a more visually appealing chassis? Quote Link to comment Share on other sites More sharing options...
richieb Posted May 8, 2018 Share Posted May 8, 2018 --- many of these builds are Class A circuits so they run hot, some very hot so they require many square inches of heat sinks. Look at all the Nelson Pass First Watt chassis - they are all identical and large with lots of heat sink and a lot of empty space inside. All Class A, all run hot. 1 1 Quote Link to comment Share on other sites More sharing options...
Guest wdecho Posted May 8, 2018 Share Posted May 8, 2018 As Richieb B said all are class A requiring huge heatsinks. In class A/B the transistors idles at minimum setting till needed to be turned up so smaller heatsinks can be used. In class B the transistor is cut off till a signal comes in. In class A the transistor is wide open going full speed all the time. It is call the biasing of a transistor. The more output transistors running wide open the bigger the heatsinks required for adequate cooling. Very inefficient but the most linear of all types of amplification. Mostly for purist wanting the best. Quote Link to comment Share on other sites More sharing options...
Full Range Posted May 9, 2018 Share Posted May 9, 2018 8 hours ago, jwc said: Why are these DIY amp chassis so freakin" huge? Does anyone know of a supplier with a more visually appealing chassis? Heat sinks for class A amps need to be large enough or components will burn up So the casing is made to the size of the heat sinks Quote Link to comment Share on other sites More sharing options...
jwc Posted May 9, 2018 Share Posted May 9, 2018 I get it. I couldn't tell the size of the heat sinks relative to height of the case. But maybe a case that is a little more attractive. Just Curious. I don't want to steer too much off topic....thanks Quote Link to comment Share on other sites More sharing options...
Guest wdecho Posted May 9, 2018 Share Posted May 9, 2018 Perhaps more attractive but the original, not diy. Quote Link to comment Share on other sites More sharing options...
justinsweber Posted May 9, 2018 Author Share Posted May 9, 2018 The true F6 casework/ first watt casework is much better than the DIY stuff. Quote Link to comment Share on other sites More sharing options...
justinsweber Posted May 9, 2018 Author Share Posted May 9, 2018 On 5/5/2018 at 4:54 AM, wdecho said: I've built both and like Full Range I prefer the M2 over the F6 with horns. The sweet part of building a Firstwatt clone is that you can now just purchase the M2 boards and stuff them and replace the F6 boards for very little money. Slightly over $100 being higher than some of the other designs because of the input transformer used in the M2. There are no culls in the Firstwatt line for diy'ers. All are great sounding class A amplifiers designed by the premier designer of amplifier circuits. Whether you would prefer the M2 over your F6 can and does depend on the music you enjoy. There is a new project designed around the M2 but not using those hard to find and expensive J-fets you may want to read about. It is hard to just build one. http://www.diyaudio.com/forums/pass-labs/321925-diyaudio-watt-m2x.html The M2s I've seen used Encore transformers. Ive had a been time with time more than once... its a non starter for me. Ive heard my fair share of pass amps... I put the ACA and the F6 and Alph right up there. I went F6 for use use of input transformers. If selecting Firstwatt DIY projects, Id always recommend ones without feedback as they are a more forgiving sound :-). Quote Link to comment Share on other sites More sharing options...
richieb Posted May 9, 2018 Share Posted May 9, 2018 --- granted the the F3 is mid-way in the line of F-series amplifiers and only one of two to use JFET power transistors but Pass himself extols the virtues of JFET's "the sound is absolutely extraordinary. The F3 is by far the best single stage audio power amp on the planet, a testament to the potential of power JFET transistors". And it does sound awfully darn good. Even with a Pass Labs XA25 sitting next to it I have no plans to sell it. They are both superb in their own way, its a nice problem to have. Quote Link to comment Share on other sites More sharing options...
Guest wdecho Posted May 10, 2018 Share Posted May 10, 2018 5 hours ago, justinsweber said: The M2s I've seen used Encore transformers. Ive had a been time with time more than once... its a non starter for me. Ive heard my fair share of pass amps... I put the ACA and the F6 and Alph right up there. I went F6 for use use of input transformers. If selecting Firstwatt DIY projects, Id always recommend ones without feedback as they are a more forgiving sound :-). A respected member on the diyaudio forum Zen Mod who is tremendously talented loves the M2. He is called Nelson's adopted son and gets to see all the new schematics of all the new amplifiers. He flew in from a country that use that was part of the USSR, forget name, to the Burning Amp Festival last year and returned with all the parts to build one of Nelson's new amplifiers. He still considers the M2 the best of the best with his horns and has nothing but praise for it. I love mine but it is not my favorite child. A worthy addition for someone that likes to build clones. I still favor the BA-2 with the BA-3 front end. https://www.zenmod.in.rs/ Quote Link to comment Share on other sites More sharing options...
Guest wdecho Posted May 10, 2018 Share Posted May 10, 2018 4 hours ago, richieb said: --- granted the the F3 is mid-way in the line of F-series amplifiers and only one of two to use JFET power transistors but Pass himself extols the virtues of JFET's "the sound is absolutely extraordinary. The F3 is by far the best single stage audio power amp on the planet, a testament to the potential of power JFET transistors". And it does sound awfully darn good. Even with a Pass Labs XA25 sitting next to it I have no plans to sell it. They are both superb in their own way, its a nice problem to have. I like my F3 as well. There is a newer version that uses J-fets called the J2. The official schematic has not been published but I doubt many will be built when it is available for diy'ers. The reason being that it uses NOS J-fets made by SemiSouth that has went out of business. When one finds them for sale they are terribly expensive. Quote Link to comment Share on other sites More sharing options...
justinsweber Posted May 10, 2018 Author Share Posted May 10, 2018 On 5/8/2018 at 10:33 AM, jwc said: Why are these DIY amp chassis so freakin" huge? Does anyone know of a supplier with a more visually appealing chassis? Short answer... no. Most look like lab equipment. There are some Jeff Roland clone chassis around... those look amazing. Quote Link to comment Share on other sites More sharing options...
justinsweber Posted May 10, 2018 Author Share Posted May 10, 2018 Is there a version of the M2 not using edcor iron? Quote Link to comment Share on other sites More sharing options...
justinsweber Posted May 10, 2018 Author Share Posted May 10, 2018 Does the M2 use an Opp amp? I thought I eyeballed on in a pic? Quote Link to comment Share on other sites More sharing options...
Guest wdecho Posted May 10, 2018 Share Posted May 10, 2018 I believe there are a number of input transformers that will work, some maybe better. It would take some reading of the M2 thread at diyaudio to find answer. Another solution is just post the question at diyaudio forum M2 thread. After posting I found this answer at the forum, Just use a Jensen with the right turn ratio.I think voltage gain of amp is around 6. No op amp, 4N35 optocoupler. As far as feedback, post 1435 by Nelson. http://www.diyaudio.com/forums/pass-labs/281520-official-m2-schematic-144.html http://www.diyaudio.com/forums/pass-labs/281520-official-m2-schematic.html Unique circuit even the best minds one the forum could not figure out how the function of diodes in conjunction with optocoupler worked. Nelson revealed the answer via Zen Mod in the thread. The M2 was preferred by Nelson with horns when introduced. Page 5 and 6 will answer some of your questions about transformers and function of optocoupler and diodes. http://www.diyaudio.com/forums/pass-labs/281520-official-m2-schematic-5.html As far as the correct number Jensen post the question on the thread and you will not have to read complete thread. Quote Link to comment Share on other sites More sharing options...
jwc Posted May 10, 2018 Share Posted May 10, 2018 On 5/9/2018 at 11:05 PM, justinsweber said: Short answer... no. Most look like lab equipment. There are some Jeff Roland clone chassis around... those look amazing. Where is the listing for just his chassis? Quote Link to comment Share on other sites More sharing options...
justinsweber Posted May 11, 2018 Author Share Posted May 11, 2018 http://r.ebay.com/qX4NCMhttp://r.ebay.com/RWQeLJhttp://r.ebay.com/Q4vuOshttp://r.ebay.com/mrCEtEhttp://r.ebay.com/lkU0CBhttp://r.ebay.com/yjzQDMhttp://r.ebay.com/y6f9Q3http://r.ebay.com/zJUbBLhttp://r.ebay.com/HIn13Zhttp://r.ebay.com/RN76drhttp://r.ebay.com/PjJszK Quote Link to comment Share on other sites More sharing options...
jwc Posted May 11, 2018 Share Posted May 11, 2018 Wow. Those look good. There are even more than listed. Thanks Quote Link to comment Share on other sites More sharing options...
jazzmessengers Posted May 11, 2018 Share Posted May 11, 2018 @justinsweber why wouldn't you recommend the DIYAudio store chasis? I was considering one for a build because with their PCBs it would be pre-drilled. I don't have the tools to do that myself and places like FrontPanelExpress charge a decent amount for that. Quote Link to comment Share on other sites More sharing options...
Guest wdecho Posted May 11, 2018 Share Posted May 11, 2018 One is not going to beat the deal for an adequate heatsink chassis' at diyaudio.com. I use this one myself but one must drill and tap the holes. https://diyaudiostore.com/collections/chassis/products/dissipante-4u For a ready to use, holes already drilled with back panel already cut and drilled go with this one in steel. https://diyaudiostore.com/collections/chassis/products/deluxe-4u-amplifier-chassis-steel Aluminum one is a few dollars more. https://diyaudiostore.com/collections/deluxe/products/deluxe-ultimate-amplifier-chassis The price includes shipping which one is not going to get from Asia. I have searched for better deal many times without beating these deals. Before they were made available I use to buy the heatsinks and build my own case from https://www.heatsinkusa.com/ Not a easy task I would want to do anymore with the cheap prices diyaudio store has now. Quote Link to comment Share on other sites More sharing options...
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