# Tube amp DIY general discussion **URL:** \ **Category:** DIY Audio & Modifications\ **Created:** [August 2, 2020, 2:00pm UTC](https://forum.headphones.com/t/tube-amp-diy-general-discussion/7751 "2020-08-02T14:00:25Z")\ **Posts on this page:** 20\ **Page:** 4
**Author:** ![lost33](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.headphones.com/lost33/32/6850_2.png) [@lost33](https://forum.headphones.com/u/lost33)\ **Post date:** [August 26, 2020, 12:19pm UTC](https://forum.headphones.com/t/tube-amp-diy-general-discussion/7751/61 "2020-08-26T12:19:59Z")
> [@M17XR2B](#): > > Unless the circuit is dead neutral which none really are the resulting amp/6SN7 is what we’re hearing, not the tube itself This is a very interesting statement. How would you determine if a tube or any circuit is dead neutral? You put a sine wave in and vary the frequency at a certain amplitube and plot the freq output curve. Most modern day circuits seem to be pretty flat from 20-20khz. Is this neutral? Many post pix of the sine wave input compared to the sine wave output that shows the “faithful” reproduction and amplification of the input…checking for ringing, crossover distortion etc… Really curious how one can tell if a circuit is indeed neutral? And how is this “defined”? Alex ---
**Author:** ![Nick\_Mimi](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.headphones.com/nick_mimi/32/5998_2.png) [@Nick\_Mimi](https://forum.headphones.com/u/Nick_Mimi)\ **Post date:** [August 26, 2020, 11:20pm UTC](https://forum.headphones.com/t/tube-amp-diy-general-discussion/7751/62 "2020-08-26T23:20:57Z")
Oh man…i wish i had not run across this thread, awesome stuff here. I’m drooling again. ---
**Author:** ![Paladin](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.headphones.com/paladin/32/15903_2.png) [@Paladin](https://forum.headphones.com/u/Paladin)\ **Post date:** [August 29, 2020, 7:06pm UTC](https://forum.headphones.com/t/tube-amp-diy-general-discussion/7751/63 "2020-08-29T19:06:55Z")
![maple amp with meters](https://us1.discourse-cdn.com/flex016/uploads/headphones/original/3X/e/5/e57f3f91354f7622dba50e9a2babce2eb3f8aabf.jpeg) ![maple 2](https://us1.discourse-cdn.com/flex016/uploads/headphones/original/3X/1/7/17a70870978c08a6ff96c0186e358839c2bb332d.jpeg) These are not meant to stack especially but I am running out of space. Birdseye Maple and ebony. Final testing and meter adjustments then it is done. ---
**Author:** ![PaisleyUnderground](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.headphones.com/paisleyunderground/32/15919_2.png) [@PaisleyUnderground](https://forum.headphones.com/u/PaisleyUnderground)\ **Post date:** [August 29, 2020, 10:12pm UTC](https://forum.headphones.com/t/tube-amp-diy-general-discussion/7751/64 "2020-08-29T22:12:12Z")
Nice! Did you split one amplifier into 2 boxes? And if so, what was your reasoning, and what goes into which box? ---
**Author:** ![Paladin](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.headphones.com/paladin/32/15903_2.png) [@Paladin](https://forum.headphones.com/u/Paladin)\ **Post date:** [August 29, 2020, 10:55pm UTC](https://forum.headphones.com/t/tube-amp-diy-general-discussion/7751/65 "2020-08-29T22:55:25Z")
I had built VU meters into an amp before but the gentleman wanted two identical boxes in a light colored wood and he chose the maple. I built each box totally separately to the same specs but the are pretty exact so they can stack. I had done VU meter boxes before and he kind of liked the idea of an outboard unit that he could plug into anything. Amplifier with pre-amp out in the amp box, on the VU meter box there is also a pre-amp out set of RCA’s so that the pre-amp out is not lost. This can go direct to an amp and the volume control, controls both. You can remove your headphones and hear the speakers. Dual pots on the amp, I prefer that as does @FLTWS ---
**Author:** ![M17XR2B](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.headphones.com/m17xr2b/32/14936_2.png) [@M17XR2B](https://forum.headphones.com/u/M17XR2B)\ **Post date:** [August 31, 2020, 4:39pm UTC](https://forum.headphones.com/t/tube-amp-diy-general-discussion/7751/66 "2020-08-31T16:39:31Z")
I still have no idea what true neutral is, in my quest to find the type of signature I wanted I must have listened to hundreds of combinations of tubes on dozens of amps including high price tag solid state on every headphone I could find. No one knows what neutral is and I don’t want to go into this silly debate of numbers. Once I took it slow and compared one to one I got a feeling of how colored an amplifier is and gained a few insights. Out of a multitude of qualities an amp has, frequency response coloration or lack of is just one part in a great whole. You can EQ an amp/headphone combination to be neutral but then what about: soundstage depth/width/height, low end impact, microdetail, air, speed, imaging etc. Because of how screwed up this industry is I didn’t know what I was missing even with raved 15K+ setups on head-fi. Getting back to the neutral question, at the summit of headphone amps, comparing side by side it was plain to see the the Cavalli LG was less coloured than the WA5, Stratus was less coloured than the Cavalli Liquid Glass, the Teton less so than the Stratus, Stellaris less so than the Teton and now going into DIY and playing with components I’ve tuned my amp to be less colored than the Stellaris. Even so I think there are a few _enhanced_ frequencies yet at this level I stopped to care about it, I’ve already chased the 99.9%, I’ll leave the 0.1 for a braver soul. So the DNA Stellaris a super amp is coloured in my opinion but who cares when it sounds as it does, it’s not the neutrality that differentiates the wheat from the chaff but small minded people think that’s the case and ranked amps according to this single parameter leading wanting consumers regardless of budget on a dark path. There’s something fishy about the flat 20-20khz thing, again, using EQ you can get an LCD-4 to mirror the Utopia and they won’t sound anywhere near the same. Another point, amp measurements are taken with a dummy resistor, not real headphones that have a frequency based impedance curve. In addition different headphones have different base impedances, this creates a voltage divider and the amp specs change e.g. how much current it can deliver into a specific headphone is different than another, this can lead to subtle frequency emphasis perceived as coloration. The industry has forgotten some basic formulas and goalposts, audio isn’t really that complicated for headphones yet prices are going up and consumers are less informed on how it works leading the way to snakeoil and biased impressions and reviews from journalists and the vast majority of forums. ---
**Author:** ![lost33](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.headphones.com/lost33/32/6850_2.png) [@lost33](https://forum.headphones.com/u/lost33)\ **Post date:** [August 31, 2020, 6:39pm UTC](https://forum.headphones.com/t/tube-amp-diy-general-discussion/7751/67 "2020-08-31T18:39:47Z")
Very interesting thoughts, comments and observations… Thanks for sharing… Alex ---
**Author:** ![perogie](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.headphones.com/perogie/32/13801_2.png) [@perogie](https://forum.headphones.com/u/perogie)\ **Post date:** [August 31, 2020, 7:41pm UTC](https://forum.headphones.com/t/tube-amp-diy-general-discussion/7751/68 "2020-08-31T19:41:40Z")
> [@M17XR2B](#): > > There’s something fishy about the flat 20-20khz thing, again, using EQ you can get an LCD-4 to mirror the Utopia and they won’t sound anywhere near the same. That’s another area of great confusion. Using FR curves as a sole means of technical evaluation of a headphone is inadvisable IMO. Commentary about how the thing actually sounds is always needed to accompany an FR. FR are also potentially fraught with issues due to the lack of standardization between how measurements are taken/ displayed and issues with measurement rigs. I applaud those who are actually trying to perform consistent measurements and working to improve the data while providing subjective context. Anyone who throws up a FR and simply says this is how this sounds isn’t helping anyone. ---
**Author:** ![laughing\_psychonaut](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.headphones.com/laughing_psychonaut/32/16979_2.png) [@laughing\_psychonaut](https://forum.headphones.com/u/laughing_psychonaut)\ **Post date:** [September 3, 2020, 7:28pm UTC](https://forum.headphones.com/t/tube-amp-diy-general-discussion/7751/69 "2020-09-03T19:28:00Z")
This is so great. I did not know who Andy Grove was, now I want to read everything he’s written. Huge thanks for posting! ---
**Author:** ![bpcarb](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.headphones.com/bpcarb/32/16496_2.png) [@bpcarb](https://forum.headphones.com/u/bpcarb)\ **Post date:** [September 3, 2020, 7:59pm UTC](https://forum.headphones.com/t/tube-amp-diy-general-discussion/7751/70 "2020-09-03T19:59:30Z")
You’re welcome! I believe there are some videos on YouTube also. Here’s a link to other articles. Welcome to the community! [https://www.audionote.co.uk/articles](https://www.audionote.co.uk/articles) ---
**Author:** ![Paladin](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.headphones.com/paladin/32/15903_2.png) [@Paladin](https://forum.headphones.com/u/Paladin)\ **Post date:** [September 11, 2020, 3:46pm UTC](https://forum.headphones.com/t/tube-amp-diy-general-discussion/7751/71 "2020-09-11T15:46:47Z")
![walnut-basswood](https://us1.discourse-cdn.com/flex016/uploads/headphones/original/3X/3/4/34c3833ebe992d2798591d27226de645eb73ce42.jpeg) most likely my last amp build for a while, walnut and basswood, assembly soon to follow. ---
**Author:** ![bpcarb](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.headphones.com/bpcarb/32/16496_2.png) [@bpcarb](https://forum.headphones.com/u/bpcarb)\ **Post date:** [September 11, 2020, 3:56pm UTC](https://forum.headphones.com/t/tube-amp-diy-general-discussion/7751/72 "2020-09-11T15:56:16Z")
Nice color and grain. Incubus whales in the wild. ---
**Author:** ![frkasper](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.headphones.com/frkasper/32/9408_2.png) [@frkasper](https://forum.headphones.com/u/frkasper)\ **Post date:** [September 12, 2020, 3:11am UTC](https://forum.headphones.com/t/tube-amp-diy-general-discussion/7751/73 "2020-09-12T03:11:07Z")
Great work. It also comes with a red “carpet”, as I can see. 👏 👏 👏 ---
**Author:** ![Paladin](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.headphones.com/paladin/32/15903_2.png) [@Paladin](https://forum.headphones.com/u/Paladin)\ **Post date:** [September 12, 2020, 12:57pm UTC](https://forum.headphones.com/t/tube-amp-diy-general-discussion/7751/74 "2020-09-12T12:57:55Z")
That is just a temporary small paint booth, also known as a cardboard box lol. I finish the amp today, and begin the final testing and listening. ![walnut basswood 2](https://us1.discourse-cdn.com/flex016/uploads/headphones/original/3X/1/5/159980f7cb2b5312eb6bc27e6bb2449d71e6b2ca.jpeg) ![VT 192](https://us1.discourse-cdn.com/flex016/uploads/headphones/original/3X/5/7/57ac592761331e0e785305e429f0f15ffc29b70a.jpeg) I want to try out some VT-192’s that are the military version of the 7A4, single triode Loktal versions of the 6J5. Two of those equal a 6sn7 which is dual triode. ---
**Author:** ![M17XR2B](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.headphones.com/m17xr2b/32/14936_2.png) [@M17XR2B](https://forum.headphones.com/u/M17XR2B)\ **Post date:** [September 12, 2020, 10:10pm UTC](https://forum.headphones.com/t/tube-amp-diy-general-discussion/7751/75 "2020-09-12T22:10:13Z")
12 hours of non stop work of soldering and installation today, 40 hours total the ultra amp PSU is ready. Voltage testing is always exciting but thankfully everything was on spec from the first go. For any DIY starters, double and triple check grounding and always use bleeders to drain the caps. Employed a dual cascaded switch again, one for the heaters, the other for the rectifier and HV, everything on its own transformer, no exceptions. There’ll be plenty of time to build a shell, for now just the bare frame will be perfect. ![20200912_230131](https://us1.discourse-cdn.com/flex016/uploads/headphones/original/3X/3/1/31a3cda4ecccd2dd955aba9f5ec71bb18d543fe6.jpeg) ![20200912_230150](https://us1.discourse-cdn.com/flex016/uploads/headphones/original/3X/e/a/eac1c45000b86905b35df2ae569258da946e3ea9.jpeg) ---
**Author:** ![Paladin](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.headphones.com/paladin/32/15903_2.png) [@Paladin](https://forum.headphones.com/u/Paladin)\ **Post date:** [September 12, 2020, 10:53pm UTC](https://forum.headphones.com/t/tube-amp-diy-general-discussion/7751/76 "2020-09-12T22:53:34Z")
Those orange connectors, here we call them Phoenix connectors, screw down type of connectors. Were those part of a kit? ---
**Author:** ![M17XR2B](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.headphones.com/m17xr2b/32/14936_2.png) [@M17XR2B](https://forum.headphones.com/u/M17XR2B)\ **Post date:** [September 12, 2020, 11:12pm UTC](https://forum.headphones.com/t/tube-amp-diy-general-discussion/7751/77 "2020-09-12T23:12:29Z")
That’s how that particular company does all their single phase transformers including custom orders. ETE in the UK. Quite handy actually. My idea is all the primarys on the 4 mains transformers in the psu are adjustable from 220 to 250V, this way I can fine tune and the screw connectors make life easier. The HV one is a vintage C core in oil FW and choke input. ---
**Author:** ![Paladin](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.headphones.com/paladin/32/15903_2.png) [@Paladin](https://forum.headphones.com/u/Paladin)\ **Post date:** [September 13, 2020, 1:02pm UTC](https://forum.headphones.com/t/tube-amp-diy-general-discussion/7751/78 "2020-09-13T13:02:11Z")
Those do appear to be quality parts. It looks like wire wrap as well. I guess here we just do more point to point wiring and soldering. ---
**Author:** ![M17XR2B](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.headphones.com/m17xr2b/32/14936_2.png) [@M17XR2B](https://forum.headphones.com/u/M17XR2B)\ **Post date:** [September 17, 2020, 5:07pm UTC](https://forum.headphones.com/t/tube-amp-diy-general-discussion/7751/79 "2020-09-17T17:07:38Z")
The first turn on, eagerly waiting the high voltage rise on the multimeter, buthole clenching, finger on the off button to keep the magic smoke in. It’s alive, a spud parafeed DHT, tungsten fillament, current feedback choke input heaters, diode bias, directly heated choke input rectifier with split choke filtered psu, a mouthful. ![20200917_175113](https://us1.discourse-cdn.com/flex016/uploads/headphones/original/3X/0/2/029b67a9c1f6c6ff11ce83993360d781533c50e2.jpeg) This amp is possible due to the hot XLR output of the wavedream signature, 20Vpp so I don’t need an input tube. Can’t get any simpler than this, just on tube no trickery. It has to burn in a few days before sounding its best yet it’s already something very special, this is tube magic built in a shed. ![20200917_175135](https://us1.discourse-cdn.com/flex016/uploads/headphones/original/3X/a/f/af59013e08238f7a64ecb57b66cd95e3eb4758a6.jpeg) ---
**Author:** ![bpcarb](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.headphones.com/bpcarb/32/16496_2.png) [@bpcarb](https://forum.headphones.com/u/bpcarb)\ **Post date:** [September 17, 2020, 5:37pm UTC](https://forum.headphones.com/t/tube-amp-diy-general-discussion/7751/80 "2020-09-17T17:37:53Z")
Nice. Which of your cans do you think will pair best? Let us know if/when clenching disengaged. [Previous page](https://forum.headphones.com/t/tube-amp-diy-general-discussion/7751.md?page=3) [Next page](https://forum.headphones.com/t/tube-amp-diy-general-discussion/7751.md?page=5)