I’ve been lurking almost daily for the last 6 months trying to absorb and soak in as much information as possible. I’ve learned a lot to the point of making the decision to join the DIY game and build some amps. The plan is start with a ACA mini, then Tokin SIT amp (when details are released) and maybe eventually a M2X. As I have read and learned I am beginning to I stand Nelson’s love of the 2nd harmonic character of his designs especially when the 2nd harmonic is a negative phase.
My question is what effect does balanced input into the amp have on the 2nd harmonic characteristic? Does the common mode rejection inherent in a balanced topography cancel this out?
Bigger picture. I started following/reading after picking up a XA30.8 amp. First time ditching tubes in 20 years and not really looking back. In the 6 months that followed a XP25 and XP22 showed up. My understanding is all of these are fully differential/balanced topographies. at the same time I remember reading that part of the change from the .5 to .8 amps was a greater emphasis on the negative phase 2nd harmonic. Would running XLR from XP22 to XA30.8 negate those changes? And further let’s say I did run XLR from pre to amp and liked the presentation would I expect a similar effect on a FW J2 using balanced vs single ended?
And lastly, would effect would running the XP25 to XP22 balanced and then single ended to the amps have harmonically/sound presentation wise? Clearly if I do build the mini ACA, Tokin SIT, and M2X I’m looking at singled ended input into those amps.
Thanks fo any input!
PS: I’ve been working on a laundry list of tools to grab for the amp building projects. If I was going to post a thread with specific questions about tools needed to complete something like M2X or VFET front end boards should I do that here since it’s Pass specific for the equipment/tools section?
My question is what effect does balanced input into the amp have on the 2nd harmonic characteristic? Does the common mode rejection inherent in a balanced topography cancel this out?
Bigger picture. I started following/reading after picking up a XA30.8 amp. First time ditching tubes in 20 years and not really looking back. In the 6 months that followed a XP25 and XP22 showed up. My understanding is all of these are fully differential/balanced topographies. at the same time I remember reading that part of the change from the .5 to .8 amps was a greater emphasis on the negative phase 2nd harmonic. Would running XLR from XP22 to XA30.8 negate those changes? And further let’s say I did run XLR from pre to amp and liked the presentation would I expect a similar effect on a FW J2 using balanced vs single ended?
And lastly, would effect would running the XP25 to XP22 balanced and then single ended to the amps have harmonically/sound presentation wise? Clearly if I do build the mini ACA, Tokin SIT, and M2X I’m looking at singled ended input into those amps.
Thanks fo any input!
PS: I’ve been working on a laundry list of tools to grab for the amp building projects. If I was going to post a thread with specific questions about tools needed to complete something like M2X or VFET front end boards should I do that here since it’s Pass specific for the equipment/tools section?
CoGT3,
There were 4 of the same post in the approval queue. Did you happen to accidentally post it that many times?
Not intentionally. Pretty sure I hit submit once.
CoGT3,
There were 4 of the same post in the approval queue. Did you happen to accidentally post it that many times?
whichever way you arrange interconnection between your preamp and amp, it'll sound similar
not exactly the same, but almost
reason for that is mainly in fact that amp which is inherently balanced, even if fed with SE signal, will act as SE to BAL converter and it'll have pretty much the same transfer characteristic for both cases
so, you're left to "just" enjoy in very low THD level, while THD Spectra is still being slightly 2nd dominant
with time I found that I really don't care anymore which flavor of amplification I'm listening to, as long it is good enough and BS level is non-existent (meaning that every part in schematic is really justified, not being result of Ego boosting of designer or Company)
not exactly the same, but almost
reason for that is mainly in fact that amp which is inherently balanced, even if fed with SE signal, will act as SE to BAL converter and it'll have pretty much the same transfer characteristic for both cases
so, you're left to "just" enjoy in very low THD level, while THD Spectra is still being slightly 2nd dominant
with time I found that I really don't care anymore which flavor of amplification I'm listening to, as long it is good enough and BS level is non-existent (meaning that every part in schematic is really justified, not being result of Ego boosting of designer or Company)
Attachments
Great. That’s what I had hoped. One on the things I have learned here is Nelson seems to go to great pains to carefully craft a sonic signature. Just couldn’t grasp if running balanced would negate some of that signature (didn’t think it would as it would seem to counteract his designs, still learning).
ZM, since you responded, questions about tools/equipment to build up some Pass DIY projects best here or equipment/tools section?
well, those are details you're grasp by osmosis, if you hang here long enough 🙂
- decent solder station with several tip sizes ; Chinese brothers are making great copies of Hakko - I have 3pcs of Baku 936D, each armed with different tip - but most important is mentioning biggest one - chisel form, 8mm wide.. that one cranked tyo max is breeze for soldering fat wires
-small tools - screwdrivers, pliers, yadayada....... SS tweezers ..... in fact - as many tweezers you can buy cheap - with time you'll toss bad ones
-DMM - good times these are - i have proper stable of UNI-T; absolutely not crying for Fluke or whatnot; had them, have them, but good times these are; buy as many you can - nice to clip in several at once, and just to glance at each, instead of frantically move probes around having one too less or just one
- avoid non-Lead solder
but - most important advice I can give you - whenever in doubt about some tech. detail - ask here on board, whatever or however stupid it feels for you; stupid is not ignorant one, stupid is one avoiding to learn; in short - ask, be given with answer, do your homework .....
- decent solder station with several tip sizes ; Chinese brothers are making great copies of Hakko - I have 3pcs of Baku 936D, each armed with different tip - but most important is mentioning biggest one - chisel form, 8mm wide.. that one cranked tyo max is breeze for soldering fat wires
-small tools - screwdrivers, pliers, yadayada....... SS tweezers ..... in fact - as many tweezers you can buy cheap - with time you'll toss bad ones
-DMM - good times these are - i have proper stable of UNI-T; absolutely not crying for Fluke or whatnot; had them, have them, but good times these are; buy as many you can - nice to clip in several at once, and just to glance at each, instead of frantically move probes around having one too less or just one
- avoid non-Lead solder
but - most important advice I can give you - whenever in doubt about some tech. detail - ask here on board, whatever or however stupid it feels for you; stupid is not ignorant one, stupid is one avoiding to learn; in short - ask, be given with answer, do your homework .....
Again, thanks for you insight.
I have been digging around the DIY store and saw the link to the EVV blog series on soldering under the Fire Metall solder. Ive been through those twice already. Seems like the Hakko FX888 would more than serve my purpose now and in the future.
DMMs-funny you mentioned Fluke. I have an ongoing search on some auction site for a 87V. Figured if I could pick up one at a decent price it would be a decent investment and then add some other less expensive DMM for lower voltage to clip in at multiple locations are you suggested. Since you brought up Uni-T, any reason not to just skip a used Fluke and grab more Uni-T? If I go far enough down the rabbit hole to start playing with tube designs and the higher voltages associated with those does that need a more robust DMM? Any specific Uni-T?
The real question I had is if I was planing on building all the currently available VFET FE boards for the future Tokin SIT version (I did grab a quad as Nelson suggested) and eventually the M2X with the 4 FE board and now a real power supply do I need an oscilloscope and wave generator? If so, for hobby purposes could you get away with a newer DSO with built in AWG? This is one of those things where I don't mind making the investment if I know it would meet my current and likely future needs. And further, I frequently see Nelson show oscilloscope tracings of a 1khz sine wave with matching distortion curve. My understanding is that the AWG is sending the 1khz sine to the amp and channel 1 of the scope for the first curve, then the output of the amp is feed to a spectrum analyzer which then feeds back to channel 2 of the scope for the distortion curve allowing tweaking of bias to shift the distortion curve as needed. If this understanding is correct (big if) do you need this level of detail to build the above or is it a luxury? If it is helpful, can a modern DSO with integrated AWG and basic spectrum analysis get you to those same curves? Or does this absolutely require an external analyzer be it a hardware or software (REW) solution?
Sorry for the barrage of questions but Santa has to get his DIYaudio shopping list set!
I have been digging around the DIY store and saw the link to the EVV blog series on soldering under the Fire Metall solder. Ive been through those twice already. Seems like the Hakko FX888 would more than serve my purpose now and in the future.
DMMs-funny you mentioned Fluke. I have an ongoing search on some auction site for a 87V. Figured if I could pick up one at a decent price it would be a decent investment and then add some other less expensive DMM for lower voltage to clip in at multiple locations are you suggested. Since you brought up Uni-T, any reason not to just skip a used Fluke and grab more Uni-T? If I go far enough down the rabbit hole to start playing with tube designs and the higher voltages associated with those does that need a more robust DMM? Any specific Uni-T?
The real question I had is if I was planing on building all the currently available VFET FE boards for the future Tokin SIT version (I did grab a quad as Nelson suggested) and eventually the M2X with the 4 FE board and now a real power supply do I need an oscilloscope and wave generator? If so, for hobby purposes could you get away with a newer DSO with built in AWG? This is one of those things where I don't mind making the investment if I know it would meet my current and likely future needs. And further, I frequently see Nelson show oscilloscope tracings of a 1khz sine wave with matching distortion curve. My understanding is that the AWG is sending the 1khz sine to the amp and channel 1 of the scope for the first curve, then the output of the amp is feed to a spectrum analyzer which then feeds back to channel 2 of the scope for the distortion curve allowing tweaking of bias to shift the distortion curve as needed. If this understanding is correct (big if) do you need this level of detail to build the above or is it a luxury? If it is helpful, can a modern DSO with integrated AWG and basic spectrum analysis get you to those same curves? Or does this absolutely require an external analyzer be it a hardware or software (REW) solution?
Sorry for the barrage of questions but Santa has to get his DIYaudio shopping list set!
Having an oscilloscope isn't needed. It is a nice thing to have though. You can use it to learn about your amplifiers etc.
Having a bulb tester is important though. The Hakko FX888 is awesome. I have one and have thoroughly enjoyed using it.
Having a bulb tester is important though. The Hakko FX888 is awesome. I have one and have thoroughly enjoyed using it.
I got it, grab a stack of reasonably priced DMM to test at multiple locations simultaneously.
Sounds like the DSO is probably a luxury also. Even though is seems like with a AWG the mini ACA would be a great tool to learn about amp design and how to use a DMM and scope.
Sounds like the DSO is probably a luxury also. Even though is seems like with a AWG the mini ACA would be a great tool to learn about amp design and how to use a DMM and scope.
Great advice by ZM. I never thought of having three solder stations stacked like that. Nice to not have to switch tips. I have three Flukes and use them daily. You need 3 DMMs. Fluke 101 is only $60 nowadays and well worth it. I love the silky feel of the selector dial. You can drop kick them and they won’t break. Good copper solder braid/wick. If you are older than 45, flip up binocular magnifiers for old eyes. Good diagonal cutters and good needle nose pliers. Use premium leaded solder from well known brand. Avoid Chinese made solder. Their irons are ok but not the solder.
Happy soldering!
Before getting DSO (useful for finding oscillation), get a good USB audio interface and REW software so you can measure the frequency response and distortion spectra. It lets you set the H2/H3 balance on amps with a dial-a-yield H2. More tips on how to make measurements here.
Happy soldering!
Before getting DSO (useful for finding oscillation), get a good USB audio interface and REW software so you can measure the frequency response and distortion spectra. It lets you set the H2/H3 balance on amps with a dial-a-yield H2. More tips on how to make measurements here.
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The 2nd harmonic character is inherent in the output stage, and does not depend on the electronics prior to the output Fets. This is true of both single ended and balanced output stages.
the DIYaudio solder is great. Also, Cardas eutectic solder is terrific as well. Flows very nicely. I use it explicitly.
Get Isopropyl alcohol for cleaning extra flux etc. Highest percentage that your local Walgreens, walmart etc has. I believe I have 91%
Diagonal cutters as mentioned. Get extras, I have three pairs. The cutting edge is generally not very durable so only use them for their intended use.
Good tweezers. Get extras if you like
There are little measuring tools for bending the leads on axial resistors. I haven't used one but some people like them.
A fan to blow the solder smoke away from your nose, doesn't need to be very strong.
Solder sucker
Solder wick
All of the above are cheap items that probably add up to $50-$60 or so.
Here are some extra little items that are good to have as normal stock items:
(there are smaller quantities of the first item)
https://www.amazon.com/gp/product/B08KXTW9PH/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1zip ties
thermal paste there are cheaper options that the below link but thermal paste takes a long time to go through so a good value that way)
(https://www.amazon.com/gp/product/B08T5ZWP55/ref=ppx_yo_dt_b_asin_title_o08_s01?ie=UTF8&psc=1)
Insulators (some insulators do not need thermal paste)
a good bench (hollow core door slab works with a couple of saw horses etc.)
organizer
shrink wrap of various sizes
Flux pen
Wire (The stuff below is very nice to work with. The insulation burns easily but super flexible and high strand count. Takes solder easily)
https://www.amazon.com/gp/product/B01M7NWX7A/ref=ppx_yo_dt_b_asin_title_o00_s01?ie=UTF8&psc=1A bunch of various sized fuses. I grabbed a multipack of fast blow off of Amazon.
A bulb, bulb socket, wire, junction box and a switch to make a tester.
Save IEC power cables off of items. They come in handy.
So I don't know if any of this is outside of the scope of your question but these are great little stocking stuffers cheap and you won't want to be without them if you forget them.
Take your solder gun apart every once in a while. The tips can get stuck in the solder sleeve, or whatever it is called.
Get Isopropyl alcohol for cleaning extra flux etc. Highest percentage that your local Walgreens, walmart etc has. I believe I have 91%
Diagonal cutters as mentioned. Get extras, I have three pairs. The cutting edge is generally not very durable so only use them for their intended use.
Good tweezers. Get extras if you like
There are little measuring tools for bending the leads on axial resistors. I haven't used one but some people like them.
A fan to blow the solder smoke away from your nose, doesn't need to be very strong.
Solder sucker
Solder wick
All of the above are cheap items that probably add up to $50-$60 or so.
Here are some extra little items that are good to have as normal stock items:
(there are smaller quantities of the first item)
https://www.amazon.com/gp/product/B08KXTW9PH/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1zip ties
thermal paste there are cheaper options that the below link but thermal paste takes a long time to go through so a good value that way)
(https://www.amazon.com/gp/product/B08T5ZWP55/ref=ppx_yo_dt_b_asin_title_o08_s01?ie=UTF8&psc=1)
Insulators (some insulators do not need thermal paste)
a good bench (hollow core door slab works with a couple of saw horses etc.)
organizer
shrink wrap of various sizes
Flux pen
Wire (The stuff below is very nice to work with. The insulation burns easily but super flexible and high strand count. Takes solder easily)
https://www.amazon.com/gp/product/B01M7NWX7A/ref=ppx_yo_dt_b_asin_title_o00_s01?ie=UTF8&psc=1A bunch of various sized fuses. I grabbed a multipack of fast blow off of Amazon.
A bulb, bulb socket, wire, junction box and a switch to make a tester.
Save IEC power cables off of items. They come in handy.
So I don't know if any of this is outside of the scope of your question but these are great little stocking stuffers cheap and you won't want to be without them if you forget them.
Take your solder gun apart every once in a while. The tips can get stuck in the solder sleeve, or whatever it is called.
Don't think I'll reach the point of 3 soldering stations but I love the idea?
I ordered a Uni-T 139C to play around with. Look like the current version of the UT890 can also be had a decent price to rapidly expand the flock of DMM.
I just hit the big 50 this year but have already been a member of the progressive glasses club for years. How do the flip up magnifiers work over glasses with progressive lenses? My initial thought was to try one of those lighted magnifying glass that attach to a table. In my day job I have a lot of experience working technically under magnification where you can't see your hands, only the instruments you are using.
Solder will be from DIY store. Got to support the home team.
I have been slowly working through the REW megathread. We do have an older laptop I might be able to repurpose for full time diagnostic purposes. If you are using something like the Focusrite USB interface can you use the signal generator in REW to feed your amp input and then clip on to the outputs back into the Focusrite for measuring?
Now that you say that, it makes perfect sense. Single ended vs balanced will only affect the the signal coming downstream from the XP22.
BTW since you responded. The statement you made at the end of your Burning Amp presentation is what got this all started. The mini ACA amp is really what convinced me to go ahead and give this a try. I became interested reading about the recent VFET amp project with multiple FE boards. I didn't throw my name in the hat for those amps but I did buy a qaud of Tokin TFH-51S from watanabetomoaki. Figured if a version of the VFET materialized that would use the Tokin SITs that would be fun amp to use as a different voice from the XA30.8. The part I was struggling with was I would need a starter amp to really brush up on the solder skills and learn how to test it appropriately. As wonderful as the original ACA is I didn't really need a full sized amp in a chassis as just a practice amp building project. The mini ACA fits that role perfectly. Should be relatively idiot proof to build and an excellent platform to practice DMM and REW measuring skills before tackling the Tokin SIT amp when available. Then if I get really ambitious I may try a M2X down the road with the added level of complexity of building a complete power supply. Sound like a lot of fun to me! Not to mention I should end of with a couple of amps with distinct voices from the XA30.8 to play with. Add a FW F8 to the stable and its party time.
This was copied in its entirety into the Notes app for shopping purposes. Time to go fill Santas stocking. Thank you for taking the time to lump that all together in one place.
Now I just need those mini ACA kits to show up in the DIY store.
I use the flip magnifiers on top of my reading glasses when I want that extra bit of magnification. The lighted ones work well although I just use one of the big LED panel photo lights to light up the ceiling above my workspace.
REW can provide the 1kHz oscillator but it won’t be ultra low distortion. It will be fine for amps with 0.01% or higher THD. If you want to do the ultra low stuff, use an Akitika 2ppm oscillator or Victor’s ppb oscillator. Focusrites work well for this.