Biased? | Swart Space Tone Atomic Jr

An almost-perfect amp for its intended purposes. Deserves a closer look, don't you think?
The guitar used was a Strat with Mojotone Quiet Coil ‘67s and a Suhr Thornbucker in the bridge.
Updates/clarifications:
Apparently the speaker was installed by the owner, not Swart (ribbed cone replacing smooth) and the owner installed the 6L6 - it was not broken in shipping. I misunderstood him when I spoke to him on the phone.
And here's a look at one of its big brothers:
• Swart Space Tone Rever...
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These are things I get asked about a lot :
Amp Tech Gear Used :
Hakko FX-951 soldering station
Weller SPG 80L soldering iron (chassis work)
Rigol DS1054Z digital oscilloscope
Thsinde 18B+ digital multimeters
Kester 60/40 solder
Techspray #4 No-Clean Desoldering Braid
Below are things that make this channel possible that people don’t usually think about. If any of these companies want to send me new and wonderful toys, I’m open to that. I can’t take free stuff when it comes to the amps I review, etc, but for the stuff below, bribe away!
Microphones/Audio Equipment :
Guitar Amps : Royer R-10 Hot Rod and/or Shure SM57 (noted in videos)
Voiceover Bench : sE Audio sE8 (small diaphragm condenser)
Voiceover Streaming : Shure SM57 with shockmount and windscreen
Voiceover Mic Arms : Elgato Wave Mic arms
Guitar Mic Stand : Gator Frameworks short weighted base stand with boom
Mic Cables and Guitar Cables : Mogami/Neutrik
Mic pre : MOTU M2
DAW : Logic Pro II on MacBook Pro 16 running Sonoma 14.5
Plugins : No effects other than level matching/normalization unless a recording
specifically has reverb etc added in post (rare, various Waves plugins)
Monitors : Yamaha HS7s
Monitor Stands : Gator Frameworks Desktop Clamp-On Stands
Monitor Isolation Mounts : IsoAcoustics Iso-Puck Minis
Headphones : Beyerdynamic DT 770 Pro (main)
Headphones : Sony MDR-7506 (alternate)
Video Equipment :
Camera : Sony ZVE-10 with SmallRig Cage (main)
Lens : Sigma f2.8 18-50mm (main)
Lens : Sony ZVE10 kit lens (rarely used)
B Camera : Apple iPhone 13 Pro (rarely used)
Tripod : SmallRig 71” with SmallRig Fluid Video Head
Streaming Mount : Elgato Master Mount S with SmallRig Ballhead
Bench Light : SmallRig RC 120D
Bench Light Diffusor : SmallRig Lantern Softbox
Bench C-Stands (light and overhead camera) : Neewer Pro SS Heavy Duty
Streaming Light : SmallRig RC 120B
Streaming Diffusor : SmallRig Parabolic Softbox
Streaming Light Mount : SmallRig 148CM Wall Mount Boom with Triangle Base
Various Other Lights : Neewer LED Panels with Neewer Softboxes
Video Software :
Davinci Resolve 19
Inkscape
GIMP
Because seriously, screw Adobe
Ecamm Live (streaming software)

[@PsionicAudio]

At 6:47 I said “125W coming out of the wall” when I meant 120 Volts. Dunno, was thinking about the video or what to say next. Updates/clarifications: Apparently the speaker was installed by the owner, not Swart (ribbed cone replacing smooth) and the owner installed the 6L6 - it was not broken in shipping. I misunderstood him when I spoke to him on the phone.

[@christopherjbutler]

Hyey Lyle, I agree with you that even though it is not the ideal tube matched to the design, that 6L6 DID sound cool, to my ears as well!

[@richclayton5785]

I’m ew to this stuff but doesn’t a cold biased tube overdrive sooner than a correctly biased tube? Mr. Swart is or was years ago when I bought my Space Tone known to prefer a 6V6’s.

[@richclayton5785]

BTW good of you to add clarification and update!

[@Westernroad]

I just worked on one of these myself... wound up reworking the power trans wiring in twisted pairs, power switch/fuse wiring to code, and moved the 100 ohm resistors to the cathode to elevate the filaments. I scraped the paint from the chassis and put a lug for the power cable at the can cap mount. Thank you for your work, Lyle, you are my favorite mentor !

[@PsionicAudio]

This was brand new in warranty. So I didn’t change anything. Though I would on one out of warranty.

[@christopherjbutler]

​@@PsionicAudioI think we all know you would, lyle! Heard the bit about it being new,and I immediately assumed that the reason you didn't even mention asking the customer if he wanted you to make said modifications must have been because of the warranty. But I know why (insert internet commenter peanut galley reasons here) your response to a comment thanking you for being a mentor had to clarify why you didn't do it. Getting out ahead of other subsequent commenters asking why YOU didn't do it yourself, or getting ahead of ny number of potential armchair quarterbacks in general has to be almost as tiring as dealing with NOT getting ahead of them and refuting uninformed comments / replies.

[@markmcdonald5711]

Bought this amp 3 years ago when they were still affordable. I have a G&L strat, a Fender Am Std Tele and a Gibson LP Jr, they all sound amazing thru this amp. The 8 inch Weber is fine for playing at home, fills a small room really well. Can't say enough good things about the tube reverb. Best amp I have ever owned.

[@canadiancombatwombatthe3rd782]

Idk why I find myself constantly watching you fix amps but I do, enough to give you a new subscriber lol

[@maxvockner]

Fascinating. My vote is 6L6. Didn’t expect that.

[@JAugust]

Cool video. I've got a couple of Swarts and really enjoy them a lot. Glad to see you share a high opinion of them. I personally prefer the 6L6 but both sound great, honestly.

[@GCKelloch]

Yeah, the WGS ET65 is a fairly dark/soft speaker. The 6V6GT is a bit muddy through it.

[@ricdale7813]

Played a Space Tone at Elderly Instruments a few years back. Best low watt clean I have played. Rich,Warm and Blooming Clean. Sounded incredibly well with a TS 808 slightly driving the front.

[@christopherjbutler]

Lyle, just wanted to say, my respect for you is never disappointed,; you sir, call things exactly as your judgement knowing your craft dictates. The bit about the grounding, switched neutral, and fuse arrangement was handled exactly as it should be. And it did NOT give me a negative feeling about the brand you recommended. It just showed me yet again that you are not full of ahit, and you care more about pointing out what you see than you do about the appearance of having recommended an amp that might have had more room for improvement than you initially realized before opening one (or at least this model) Bravo. And way to clarify this distinction ton with the text before the section of the video to both head off haters in the comments section, and temper the way the observations might be received by the owners of the brand.

[@bottomkitchen250]

What a cool little amp.

[@mooseymoose]

Swapped out the stock speaker for a Fat Jimmy Alnico and it’s a HUGE improvement over an already great amp. Love it, probably should run it over to the D Lab guy to make those changes you mentioned.

[@thesjkexperience]

Thanks, I’ll give that a look. I looked, I don’t see how that fits. 😮.

[@mooseymoose]

@@thesjkexperience It fit just fine, though it did require pulling the chasis, reverb and baffle. I'd send a picture, but this is YT.

[@thesjkexperience]

@@mooseymoose thanks! I’ve changed the speaker several times in my AST Pro and it’s tricky 😂 but doable. I made a 1x12 and put a blue in it. I like that sound better, but it would be fun to have a better sounding internal speaker.

[@mooseymoose]

@@thesjkexperience To be clear, mine is the AST Jr. with an 8", not the 12".

[@thesjkexperience]

@@mooseymoose You were clear previously and currently 😉. I’m lucky to have both. I really like the J Scumback in the AST, but I’d like to try that new Celestion 100 in there! The stock speaker in the Jr, after 10 years, can be a touch dull. It’s nice a few people realize we’d pay for a quality 8”.

[@JzuHax]

Like a few people here, I tend to prefer the 6L6. For all the theoretical / electronic faults of this setup, the added clarity of higher mids gives the impression of a bigger amp. Surprising.

[@andrewcichon3037]

My stealth behind the couch amp. Great recommendation. Mine also came with the little Night Light Jr. attenuator which means lush, talking volume tones. Thanks for the tip.

[@redwaveofketchup7457]

I have this amp in head form and swapped the original 6V6 for a Genelex 6L6, and when the reverb 12DW7 went microphonic Installed matched EH 12AX7 instead and this little amp roars thru my Boogie Fillmore 2x12 cab without blowing your eardrums, there was a loss of reverb but still plenty for me.I like the 6L6 but , of course...ymmv. Thanks Lyle for all you do!!✌

[@BradsGuitarGarage]

AAAAARGH! 6L6WGC-STR! Fortunately it's batch 21AJ which reportedly doesn't exhibit the issues I'm experiencing at the moment.

[@rob-french-data]

I said "Oh no!" out loud when I saw the TAD lol

[@tedmich]

whats your approximate failure rate on that "bad batch" Brad?

[@NinerFourWhiskey]

The transformer's core saturation is the limit of dissipation for single-ended amplifiers. Single-ended transformers have an air gap. Swapping the tube changes the load-line, but more current will affect the core, reduce bass response and increase intermodulation distortion (not the good kind generally)

[@joemcgraw5529]

neat little amp ,I bet it would really sound better with a 10 or 12 inch speaker ,I like how they made that possible for a extension cabinet

[@duncangoodall7108]

I have the head version and run it through their matching 2 x 12… sounds incredible…

[@diegorhoenisch62]

Damn! Despite the sub-optimal bias, that 6L6 makes a great sound. Who knew? Cheers, Alan Tomlinson

[@barthur08]

I agree

[@thesjkexperience]

Tone is all that matters! 🎉. They sound fantastic through a 2x12 with golds! 😊. He could have put a 5ar4 rectifier in with the 6L6.

[@joeappel1]

I’ve got a Swart Antares. A really sweet sounding amp. They make great stuff.

[@td7426]

I currently have a monoprice 5 watt tube amp. Love the sound with the stock tubes. I put in a Ge long plate ecc83 and it is richer sounding and has more gain and now I have more notes feeding back on my humbucker equipped telecaster squier custom. Lotta fun!

[@victorbeebe8372]

Aloha Lyle very Interesting video, especially about switching the output tubes Mahalo noi loa.

[@tedmich]

Nice balanced review Lyle! What a dirty little amp, fits the bedroom niche I suppose!

[@seansabu310]

This is the greatest amp ever created , if God had an amp this would be his practice amp

[@CerealDust-nStuff]

I think it's the second greatest amp ever made. I've had four different ones over the last 20 years. What a heck of an amp!!

[@MrStevehunter33]

A nice sounding little amp, and you reckon it's built well, but here in Melbourne Australia they are listed at $2699.00 by the local dealer.

[@grahamtaylor3093]

Got mine about 3 years ago from DG here in Melbourne. Seemed really pricey at the time Aus $1800, but now I’m glad I made the move. Great amp 🇦🇺🎸👍🦘

[@GScott50]

I had the STR model and I found the 6L6 gave a clearer, as against the more mid-focused Champ-sounding 6V6. YMMV!

[@martinreid1740]

A nice sounding well made amp, was the cabinet solid pine? as I feel in small amps it can make a difference.

[@PsionicAudio]

Yes.

[@thesjkexperience]

I’ve had one for a decade. Mines true point to point 🎉. Love mine and my AST Pro. ❤. Swarts’ customer service is the best.

[@ericreed1673]

How would you compare those 2 amps? Interested in both. Thanks.

[@thesjkexperience]

@@ericreed1673 They are actually closer than you would guess when played through the same cab. The Pro has more low end, most likely due to the two power tubes. The Jr just kills through a 2x12”. If you need headroom go Pro, otherwise the Junior does a lot.

[@EmptyChordMusic]

If I'd build amps I could not be happier if a true professional offers free advice. No idea why some people call it "mean" if you're just pointing out ways to do things in a proper way. Let me play a solemn tune on a very small violin for them...

[@Splattle101]

Regarding the sound of the 6L6 (higher noise floor, different mids, earlier breakup, etc), I wonder if we're hearing the different impedance. The 6L6 would be about half the plate impedance of the 6V6, so if the OT and speaker are matched for the 6V6 then the 6L6 will have less bandwidth won't it?

[@PsionicAudio]

Yeah, it’s a lot of things coming together. Bias, impedance, swing, OT wattage, transconductance, those are the big ones.

[@butchlauer]

Pretty cool, love a good gain story.

[@maxvockner]

Free qc service! In my day job we have outside qc on site and it it extremely helpful to have a second set of eyes to keep quality where it needs to be! As makers we have a duty to make the best product we can . It only makes business better!

[@td7426]

Most cool! I have owned the Bugera V5

[@kmetal83]

You are the best amp tech in America

[@PsionicAudio]

Thanks, but I just glued a bit of plastic back together here. I mean, that was the gig, but it’s nothing amazing.

[@052RC]

Just a general question, but when it comes to tube amps, it seems like a lot of people have trouble getting them to sound good at low volumes. Quite often, it seems like they don't understand the difference between gain and volume, but I was wondering if you can take a more direct route to solve this problem. If you have a tube amp wired in pentode or ultra linear (power tubes), why not rewire them for triode operation? That should cut the power output in half, and subjectively speaking, triode should sound at least as good, if not better. Also, would lowering the bias help? Anyway, it was just a thought. It sounds like a good idea, but maybe you'll run into problems that I'm not aware of.

[@CerealDust-nStuff]

That's not the case with this 5 watt amp... because it's only 5 watts.

[@douglasnielson8250]

You can get new octal center pin bases you glue on with RTV. They have cutouts for all the electrical pins so they go on perfectly centered. Some of the tube dealers sell them.

[@PsionicAudio]

Yeah, I have a stash.

[@markprentice7785]

If drilling a hole in the chassis wasn’t an issue, would putting an appropriate resistor in parallel with the bias resistor on a switch help to make the 6l6 sound better? Obviously there’s still the issue of the output transformer impedance.

[@PsionicAudio]

If you did, I doubt the B+ would benefit and I don’t know that the PT would be happy with the current asked of it. And if you forgot/hit it accidentally the wrong setting would nuke a 6V6. The existing circuit is the way to go. I just wanted people to know that the 6L6 option involves compromises. It’s not the free lunch players expect. Note that Swart ships these with 6V6s and says it’s safe to use 6L6s. I’m not saying Swart is misleading anyone.

[@fountainbird]

That Marine Nationale though! :)

[@motokev2727]

Had a swart AST 1x12 combo. I liked the amp, but not the controls on the back.

[@DanielleEmberley]

Every time I see one of these, I wonder if there is a good reasonable weight case suitable for local car transport that protects the knobs and power switch,.

[@PsionicAudio]

A padded cover like a Tuki does a nice job for local transport.

[@murrayguitarpickups9545]

G'day Lyle, did you see the pictures i sent you of my new amp?

[@shckltnebay]

I think the Tone King Gremlin is a better choice even though it doesnt have reverb

[@xsonicassassinx]

regarding 6v6 and 6l6, would by vht special 6 ultra (champ circuit) benefit from the mod to 6l6? i was hoping to get more high and low end fidelity

[@PsionicAudio]

I don’t know if the power transformer in that could handle a 6L6. But you would not get those benefits.

[@Splattle101]

I laughed at your disclaimer slides 07.20. 🤣 Regarding the wiring on the PT primary, I recently documented an amp from a boutique Australian brand that made the same mistakes. Beautifully made clone of a small box tweed Twin from Achillies (yes, that's how they spell it). [kzbin.info/www/bejne/aaisaYSojcmXodksi=X4Wr7chuk_6uEuNh]

[@consultingengineer5593]

Is this your real voice, you, or comp. generated? and, damn rhos hidden fasteners

[@PsionicAudio]

It was my real voice last time I checked.

[@CerealDust-nStuff]

He has a very nice radio DJ friendly voice.

[@jfiery]

It probably wouldn't be worth your trouble, but it would be interesting to see if those stage right $200 tube amps have the same problem that fenders that you warn people about do.

[@PsionicAudio]

They’ll have worse trouble. Landfill Express.

[@jfiery]

@@PsionicAudio hahaha

[@thehaughtcorner]

Wouldn't the heat cause the superglued joint to fail?

[@PsionicAudio]

That center keyed post doesn’t get hot.

[@jochemjonker3362]

Still strange Swart didn't wire to safety regulation standards.That won't drive the manufacturing costs much higher.How the chassis is mounted in the cab,doesn't look to me,very service friendly.Swart could have designed this much better and easier. Here in the Netherlands, they're quite popular but also very expensive.

[@redbarchetta8782]

Odd that it was shipped with the tubes in.

[@BobbyCulpepper.srv3fender]

What would you bias a custom pro reverb to in ma?

[@PsionicAudio]

A little bit less than I would in Connecticut. mA numbers are meaningless if you don’t know the B+.

[@oldasrocks9121]

A 6L6GA would be that much closer at 19 watts full plate disappation, the Russian ones at 20 watts and a 23 watt 5881, all would have different cold clipping sounds.

[@patrikez1]

The 6L6 will have another Transcontance.The 6V6 will be better.

[@big-ez]

why all the carbon comps?

[@PsionicAudio]

Because Swart used them. Ask him.

[@big-ez]

ah fair point! thanks for all the great content. i’m learning a ton from your channel!

[@goodun2974]

It's my understanding that STR originally meant Special Test Requirement.

[@fiddlix]

I respectfully disagree. I remember when Phillips Sylvania came out with the STR 387 and STR 415 6L6s. STR originally stood for Special Tube Request.

[@goodun2974]

@@fiddlix , Ludwell Sibley, author of "Tube Lore", an exhaustive two-volume-set dictionary containing info on tens of thousands of tube types, says STR was Special Test Requirement. Considering the amount of research that went into those books, I believe him.

[@fiddlix]

@@goodun2974 I’m just saying what was common knowledge when those tubes were released sometime in the late 70’s to early 80’s…at least that’s when they came on my radar. To be honest Special Test Requirement makes a lot more sense..

[@guypoulin8454]

I prefered the 6l6 sound

[@DrRussPhd]

Keep it simple, eh? :)

[@shckltnebay]

Not a fan of Weber or 8" speakers