Dneu2011 Posted September 10, 2022 Share Posted September 10, 2022 I am selling my newly built Nelson Pass F5 amplifier along with a matching Pass Preamp. I have two preamp options; one is the Korg Nutube B1 and the other is the Amp Camp Preamp. Both in the same style chassis with 2 inputs and one output. The Korg has an extra fixed “tape” output. The F5 was built to match 6l6’s build on DiyAudio on the forum called “An illustrated guide to building the F5.” I reached out directly to 6l6 to get his recommended grounding scheme and he help me get the amp to be dead silent on my Harbeth speakers. 25 watts class A into 8 ohms and more into 4 ohm. Can also handle a load down to 2 ohms. I used 66,000 uf per rail and only military spec vishay resistors. The Mosfets were matched and I used genuine JFETs matched from DiyAudio. The chassis I made from a pair of scrap Heatsinks, perforated sheet metal painted black and a 10mm faceplate from Modushop. I put this in my main system to compare to my Pass XA25 and it really surprised me how good it sounded vs Nelson’s Passlabs amp. Asking $1250 shipped for one of the two preamps and the amp. 2 Quote Link to comment Share on other sites More sharing options...
Speakrpeepr Posted September 17, 2022 Share Posted September 17, 2022 Hi, I'm interested in the NuTube preamp and your power amp. I have a few questions. What methods do you accept for payment? Would you insure the package when you shipped it? How many hours have you run the amp? Can I assume you used all the same parts as 616 did in his build? Where would these be shipping from? Thanks in advance for your responses! Quote Link to comment Share on other sites More sharing options...
Dneu2011 Posted September 17, 2022 Author Share Posted September 17, 2022 Hello. For payment I take zelle, venmo, or PayPal F&F. yes I will insure both items. hours? Probably less than 20 on the amp. The F5 does not have any capacitors on the amp boards so there isn’t burn in needed. Only the PSU has 4 large filter caps. I just built the F5 a couple weeks ago after converting it from an Amp Camp torroidal to this F5. Regarding parts I don’t know exactly what 6l6 used as it doesn’t come as a kit. I used only military spec Vishay resistors on the amp boards along with Futaba MPC71 5 watt resistors. I also used the MPC71 on the PSU. I also have the Amp Camp Preamp as a preamp option. I am located in Houston, TX. Quote Link to comment Share on other sites More sharing options...
CWOReilly Posted September 17, 2022 Share Posted September 17, 2022 1 hour ago, Dneu2011 said: Hello. For payment I take zelle, venmo, or PayPal F&F. yes I will insure both items. hours? Probably less than 20 on the amp. The F5 does not have any capacitors on the amp boards so there isn’t burn in needed. Only the PSU has 4 large filter caps. I just built the F5 a couple weeks ago after converting it from an Amp Camp torroidal to this F5. Regarding parts I don’t know exactly what 6l6 used as it doesn’t come as a kit. I used only military spec Vishay resistors on the amp boards along with Futaba MPC71 5 watt resistors. I also used the MPC71 on the PSU. I also have the Amp Camp Preamp as a preamp option. I am located in Houston, TX. I might be interested in the Amp Camp preamp if @Speakrpeepr buys the other. Thanks! Quote Link to comment Share on other sites More sharing options...
Speakrpeepr Posted September 17, 2022 Share Posted September 17, 2022 Thanks for you replies. One last question: looking at your F5 and the heat sink area vs. that of the First Watt version it seems like there could be less on your build.I know it's meant to run hot, of course, but please confirm that the heat sink area was designed to be enough. Thanks again, excited at the prospect of owning these! If you had to characterize the sound of the ACP vs. the Korg what would that be? Have not found much commentary online about the sound of the ACP. Quote Link to comment Share on other sites More sharing options...
JohnJ Posted September 17, 2022 Share Posted September 17, 2022 14 minutes ago, Speakrpeepr said: Thanks for you replies. One last question: looking at your F5 and the heat sink area vs. that of the First Watt version it seems like there could be less on your build.I know it's meant to run hot, of course, but please confirm that the heat sink area was designed to be enough. Thanks again, excited at the prospect of owning these! If you had to characterize the sound of the ACP vs. the Korg what would that be? Have not found much commentary online about the sound of the ACP. Hope you don't mind, but... Having seen the original version this particular beautifully made one is perforated all over, that might help with the heat elimination! Quote Link to comment Share on other sites More sharing options...
Speakrpeepr Posted September 17, 2022 Share Posted September 17, 2022 I did notice that! I've never built an amp before, just worked on existing ones that run much cooler, so not sure how a ventilated case works out vs. a more closed one with chunky heat sinks, especially on an amp that puts out so much heat. My question was related to reliability, not aesthetics or build quality. I like the build! This last question is more out of curiosity and not so important but I can't really tell what the volume knob looks like in the pic of the front face of the Korg Nutube preamp--insufficient image resolution. Can you snap another pic of that? Re: the preamp, also wondering if it you could confirm that it would be easy to rewire the second input to be a second output or if I'd have to figure out another solution to send a second signal to my other amp to power the swarm subs. Seems like I could easily do this but wanted to make sure. 1 Quote Link to comment Share on other sites More sharing options...
Speakrpeepr Posted September 17, 2022 Share Posted September 17, 2022 ...and another question. Neither amp is pictured with a power cable, and the preamp seems to have a socket on the back of the case that would require some sort of wall wart or inline transformer. What's the power cord situation, especially for the preamp? Quote Link to comment Share on other sites More sharing options...
Dneu2011 Posted September 17, 2022 Author Share Posted September 17, 2022 47 minutes ago, Speakrpeepr said: Thanks for you replies. One last question: looking at your F5 and the heat sink area vs. that of the First Watt version it seems like there could be less on your build.I know it's meant to run hot, of course, but please confirm that the heat sink area was designed to be enough. Thanks again, excited at the prospect of owning these! If you had to characterize the sound of the ACP vs. the Korg what would that be? Have not found much commentary online about the sound of the ACP. With my heatsinks, I have not seen the amp go over 55 degrees Celsius with my infrared thermometer. Nelson says, if you cannot keep your hands on the heatsinks for at least 3 seconds the heatsinks are too hot and require extra fans or ventilation. I am comfortably able to have my hands on them for over 10 seconds. The Korg vs the Amp Camp Preamp - Do you also like to use headphones? - Amp Camp Preamp also has a Headphone Out - Do you prefer a warmer tube-like sound? - The Korg Nutube - Do you prefer a more clean and accurate sound? - The Amp Camp Preamp - Do you need a fixed output for recording or adding headphone amp? - I added one to the Korg Nutube to use my Whammy headphone amp with - The Korg tube can ring if you accidentally hit the chassis or move the preamp. I added dampening materials inside to help but you want to be sure you have some isolation and keep it away from your subwoofer or loudspeakers if they have a ton of bass. - The Korg has an internal SMPS filter I added because there was extra space - The Korg you can tweak the distortion if you have an analyzer. I set it to the recommended voltage on the build guide. I don't have a favorite. I like to switch back and forth... Quote Link to comment Share on other sites More sharing options...
Dneu2011 Posted September 17, 2022 Author Share Posted September 17, 2022 26 minutes ago, Speakrpeepr said: I did notice that! I've never built an amp before, just worked on existing ones that run much cooler, so not sure how a ventilated case works out vs. a more closed one with chunky heat sinks, especially on an amp that puts out so much heat. My question was related to reliability, not aesthetics or build quality. I like the build! This last question is more out of curiosity and not so important but I can't really tell what the volume knob looks like in the pic of the front face of the Korg Nutube preamp--insufficient image resolution. Can you snap another pic of that? Re: the preamp, also wondering if it you could confirm that it would be easy to rewire the second input to be a second output or if I'd have to figure out another solution to send a second signal to my other amp to power the swarm subs. Seems like I could easily do this but wanted to make sure. I have used the perforated sheet metal on most of my builds. It is easier to cut, readily available from Lowes, and it is easy to paint. So if you accidentally scratch it or damage the top you could cut a new one or just hit it with a few coats of paint. I have built quite a few amp camps like this but this is my first F5 with it. Here is the link to the knob I used on the Korg from Diyaudio. It is tough to get a good picture because the knob is like a mirror! It is a Chrome finish so be sure to select that one on the link below to see exactly what it looks like. https://diyaudiostore.com/collections/accessories/products/precision-milled-aluminum-knobs?variant=6941970268194 As for the 2nd output and easily adding one. You would want to go with the Korg. There is a fixed output on it that could be removed and just add 1K resistors across the RCAs to have a 2nd output. It would just require removing the fixed output rca wires and soldering 2 resistors. Quote Link to comment Share on other sites More sharing options...
Dneu2011 Posted September 17, 2022 Author Share Posted September 17, 2022 31 minutes ago, Speakrpeepr said: ...and another question. Neither amp is pictured with a power cable, and the preamp seems to have a socket on the back of the case that would require some sort of wall wart or inline transformer. What's the power cord situation, especially for the preamp? The F5 uses a standard IEC Power cable. I can include one if you need it. The Korg and ACP both use a 24V Triad Wall Wart which would be included. Quote Link to comment Share on other sites More sharing options...
Speakrpeepr Posted September 17, 2022 Share Posted September 17, 2022 Thanks for those answers. Heat sounds like a non issue, and I think I from what you said could use the Korg fixed output for the sub amp. I like a clean and accurate sound but I already have that with my existing preamp so it would be fun to play with the Korg, I think. I have some isolation feet that would probably work on the Korg (tenderfoots from Herbie's audio lab). So I think I want the Korg, hopefully won't feel FOMO later too much. Quote Link to comment Share on other sites More sharing options...
Dneu2011 Posted September 17, 2022 Author Share Posted September 17, 2022 7 minutes ago, Speakrpeepr said: Thanks for those answers. Heat sounds like a non issue, and I think I from what you said could use the Korg fixed output for the sub amp. I like a clean and accurate sound but I already have that with my existing preamp so it would be fun to play with the Korg, I think. I have some isolation feet that would probably work on the Korg (tenderfoots from Herbie's audio lab). So I think I want the Korg, hopefully won't feel FOMO later too much. Yea, no issues with heat on this amp and it is biased at the recommended .6V. The Korg is fun to experiment with because Nelson recommends switching the polarity of of the speaker wires on both speakers to get more 2nd harmonic distortion. My friend that has a preamp I built for him has tried both and likes to switch back and forth. The fixed would not work for your subwoofer. It is just a signal and before the volume pot. You would need to change the extra output or you will just have your subwoofer receiving a signal that is not adjustable with volume. If you decide to buy the preamp and amp, I will change the output for you (no extra charge). Yea, some extra isolation under it would not hurt. In my office setup I have not needed more. 1 Quote Link to comment Share on other sites More sharing options...
Speakrpeepr Posted September 17, 2022 Share Posted September 17, 2022 OK, a few of our Q&A's overlapped in cyberspace but I think you addressed them all and we are all set. I guess I'll use Pay Pal so please give me your info. Re: sending an IEC cord I have some garden variety ones I'm not using so if you would just send that you could maybe skip it. Interested in your thoughts about how much it matters with this amp (not to open up some can of worms with everyone weighing in!). I'd be inclined to buy a heavy duty cable with some effort put into the design (nerdy details TBD) but I'm not sure that Pass himself cares about that. Your thoughts? Quote Link to comment Share on other sites More sharing options...
Speakrpeepr Posted September 17, 2022 Share Posted September 17, 2022 That would be great if you would do that wiring! The signal to the sub amp goes through a mini DSP but it would not change with the volume to the main speakers and that would be a pita. Let me know about that last cord question and the PP info. I'm going on a hike for the rest of the afternoon but in range a while longer if you want to complete this transaction. Quote Link to comment Share on other sites More sharing options...
Dneu2011 Posted September 17, 2022 Author Share Posted September 17, 2022 5 minutes ago, Speakrpeepr said: That would be great if you would do that wiring! The signal to the sub amp goes through a mini DSP but it would not change with the volume to the main speakers and that would be a pita. Let me know about that last cord question and the PP info. I'm going on a hike for the rest of the afternoon but in range a while longer if you want to complete this transaction. If you use a MiniDSP (which I currently have in my main setup) you should not need the second output as the sub output would come out of the DSP. Sources -> Korg Nutube Preamp->MiniDSP->F5/Subwoofer(Amp)-> speakers Let me know if this would be correct and you would not need the second output. You would want the 3rd and 4th (if you have a second sub) output on your MiniDSP to be for your subwoofer. As for the power IEC. You can try it... but I use my better power cables on my sources and preamp. With an amplifier you probably would not hear much of a difference. Quote Link to comment Share on other sites More sharing options...
Speakrpeepr Posted September 17, 2022 Share Posted September 17, 2022 (edited) I wasn't running the signal to my Fritz Rev7 SE speakers through the MiniDSP because I wanted to skip that circuitry and they need the full signal for the homespun swarm system I'm trying. To the subs it's a wired connection to all three in series from a bridged, modded dual mono Acurus A250. Weird setup, 18 ohms. Need to adjust it all using Omnimic soon but As of now have just ballparked it As you know, to control the volume through the DSP the cord needs to be connected to the laptop-clunky-and the other thing is I need one knob to control them all rather than two. Edited September 17, 2022 by Speakrpeepr Quote Link to comment Share on other sites More sharing options...
Dneu2011 Posted September 17, 2022 Author Share Posted September 17, 2022 Ok. Got it. PM sent. Quote Link to comment Share on other sites More sharing options...
Speakrpeepr Posted September 17, 2022 Share Posted September 17, 2022 Thanks Dustin, please confirm receipt and send shipping info once you arrange that. I can't wait to hear those beauties! Quote Link to comment Share on other sites More sharing options...
JohnJ Posted September 17, 2022 Share Posted September 17, 2022 Congrats!! Quote Link to comment Share on other sites More sharing options...
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