Swart Space ToNe

[mresistor]

Swart Spa-ce To-Ne  , wondering what you guys think of this amplifier. Says it's a derivative of a 5F2/5F1 and also says that it is PTP wired, no board at all ......  true PTP, which I find to be kind of cool. The cabinet design is cool too.  http://swartamps.com/amplifiers_tweed_tone_6v6se.htm


I notice it uses a GZ34 and I'm sure there are some fans of that recto here. Minimum voltage drop. But since it's class A I wonder why even bother with a tube rectifier? Unless that's what interested buyers are looking for and it's part of the boutique thing. I guess if it's tweed vintage then there had better not be any solid state in there..  :-)

[HotBluePlates]

Swart Spa-ce To-Ne  , wondering what you guys think of this amplifier. ...

I've never seen one in person & never played it. But I did go look at the website, listened to some clips on youtube and looked up prices online.

It's a 12AX7, 6V6, and a rectifier tube (GZ34 or 5Y3, according to the site) into an 8" 4Ω speaker, with Volume and Tone controls. What I just described is 100% a tweed Princeton (5F2-A was the final version of the 5_2-series Princetons).

The sound clips I heard online sound like a tweed Princeton.

The price (typically $850) is pretty high for the amp. I only paid $450 for an actual tweed Princeton (a 5B2 from probably 1954) in okay condition back in the late 90's. Granted that was some time ago and prices were lower.

You can build your own tweed Princeton (whichever circuit version you prefer) for much less than $850. You can spend very much less if you only build it as a head (because you already have a speaker cabinet to use) or if you're not chasing cosmetic perfection.

So what do you think of the Swart 6V6SE, given the above?

... it is PTP wired, no board at all ......  true PTP, which I find to be kind of cool. ...

True point-to-point wiring won't change the sound of the amp, but will make it harder to replace parts and still retain a clean, professional-looking result.

Over time I found I like any construction method that's well-executed, be it true PTP, eyelet board or turret construction or some variant. I don't mind printed circuit boards per se, but find they're very often a pain to repair or modify.

... I notice it uses a GZ34 and I'm sure there are some fans of that recto here. Minimum voltage drop. But since it's class A I wonder why even bother with a tube rectifier? ...

I'm not gonna claim "Swart copied a Fender tweed Princeton" because I don't know that's true.

But if Swart copied a tweed Princeton, then they copied an amp that was around before solid-state rectifiers existed that were cheaply-available and would reliably rectify an amp's full power supply. So they copied the tube rectifier found in the original amp, whether or not it adds sag, etc.

(Selenium rectifiers existing at least by the mid-50's and Fender used small ones in the fixed-bias supplies of their amps. I've seen selenium rectifiers in lab-quality test equipment from the time. I presume that since they were being used in expensive equipment but Fender didn't use them in their amps, that cost was a barrier in the old days.)

[Fresh_Start]

A client of mine got a Swart Atomic Space Tone several years ago and wouldn't stop raving about how great it was. Unfortunately I never got a chance to hear the amp.

Reading the product descriptions seems like a litany of cork sniffing boo-teek guitar player goodies. All carbon comp resistors (meh), "true" point to point construction, no evil solid state (works great in some places), JJ cap can (so what?), and a pine cabinet selected after extensive testing (Seriously?).


But product reviews seem almost universally excellent.  Makes me think Swart takes classic designs and builds fine amplifiers, then markets them very well.


The chassis/cab layout is unusual to say the least:
http://swartamps.com/photos_atomic_space_tone_rear2.htm


The deep chassis with staggered pots is cool IMHO.

Respectfully,
Chip

[mresistor]

HPB -  your description is just what I was thinking. It's a 5F2 basically, with some little add-ons and some voicing.  I have actually been thinking of building a 5F2 because of everything I've heard about them. I've built a bunch of BF Champs which really are not much different except for the addition of one more tone control.    I think Swart is catering to the recent trend towards good sound in small and light packages for playing out in small venues. The little switch is interesting, he calls it a 3db feedback compression switch. I'm thinking it's to change the feedback resistance from 22k to smaller like in a BF champ? Compression?  The idea of variable feedback is interesting to me. The 8" speaker isn't anything to write home about. IMHO a 10" is way more speaker; 8" speakers in guitar amps have never impressed me. Nice cabinet tho. The one thing I prefer is to have easy access to the controls, whether they be on top or in front. Having then in back to me is strange, but this little amp is probably set it and then use the controls on your guitar. Why is there only one input?
So, now I'm thinking ... how much different is a 5F2 in sound and power out compared to a AA764 Champ? Other then tone stack? And the cathode circuit on the second half of the 12AX7 which you could also lift with a switch. Why wouldn't a person just buy a much cheaper BF Champ that is modified with a tweed switch to bypass the tone controls and a fbk/cathode bypass lift switch? Piece of cake?  Didn't FYDamps make a desktop champ with this feature? Then if you don't like your modified Champs looks you could recover it in tweed. I am currently making some 10" speaker baffles for my Champs, as the best Champ I have is a '65 with a vintage Jensen brown frame 10" speaker wound in 4 ohms. Try finding a good sounding lower power 10" guitar speaker in 4 ohms.  I imagine this little '65 would stand up to these space tones all day long. I would have just used a diode rectifier if I was building one from scratch as I don't think there is much difference in sound, if any, when compared to a tube rectifier, especially a 5AR4. With a 5Y3 or a 5R4 maybe but I doubt I would hear it with my tired old ears.

Chip  I to thought that staggering the controls looked kind of cool.      His graphics are nice and simple.

[HotBluePlates]

... The little switch is interesting, he calls it a 3db feedback compression switch. I'm thinking it's to change the feedback resistance from 22k to smaller like in a BF champ? Compression?  The idea of variable feedback is interesting to me. ...

Beware marketing and mis-naming by the manufacturer (I think we've run into the latter on a different thread).

By way of marketing, I notice the Swart "goes to 11" like Spinal Tap. Cute, but I bet the guys the amp is targeting don't realize the original Fender "went to 12".

So what about that "3dB Feedback/Compression switch"? I think it's simple than you'd imagine.

If you lift a cathode bypass cap, you typically get half-gain from a 12AX7 stage due to local negative feedback across the cathode resistor. For voltage gain, that would be -6dB, but 1/2 is -3dB when you're talking about power. I wonder if what he's really saying (indirectly) is the switch disconnects the bypass cap across the 6V6's cathode resistor.

Now, because Gerald Weber talked about "compression" all the time in conjunction with his explanation of how local negative feedback reduce the gain of a preamp stage, people have linked the 2 ideas. I think it comes from the mental picture of "more signal -> more tube current -> more voltage across unbypassed cathode resistor -> more bias voltage -> reduced tube current -> smaller plate output." Or from the idea that compression is "gain reduction" and since voltage/power gain is being reduced by an unbypassed cathode resistor, there is also compression.

I totally disagree with that terminology for this reason: compression or limiting which has the audible effect we associate with those terms also has a "release" or a transition to a non-gain-reduced state. It's the "lower gain, but only on the peaks" which sounds like "compression". If we have a Volume control, but turn it down so all signals are reduced by the same amount all the time, we don't call that "compression." And that's what we have with an unbypassed cathode resistor.

If my assumption is correct that Swart is accurately applying the -3dB/-6dB distinction of  half-power/voltage, respectively, then they're telling us the switch is for the cathode bypass cap of the 6V6. It also "increases feedback" but doesn't change loop values per se, and "results in compression" but only in what I believe is a wrong sense of the word but commonly repeated.

[HotBluePlates]

... So, now I'm thinking ... how much different is a 5F2 in sound and power out compared to a AA764 Champ? Other then tone stack? ...

Not "other than the tone stack"... The tone stack is the thing which makes them sound different.

The tweed amp uses a simple one-knob Tone control which either shunts highs to ground (on the low-number settings) or bypasses highs around the Volume control (on the high-number settings). Because it doesn't "cut all then provide adjustable 'boosting' " like the blackface Fender tone stack, there's much less signal loss. That means the tweed circuit will distort the output tube at lower Volume control settings than the blackface Champ.

The blackface tone circuit also has an overall frequency response it imposes, with a sharp mid-cut. This is part of Fender's "blackface sound" and is replicated across all amp models for that period. Once your ear is accustomed to that EQ curve, the tweed circuit sounds "mid-heavy" in comparison because the tweed 1-knob tone control doesn't/can't impose the mid-cut. The mid-cut also is a signal reduction over a portion of the frequency spectrum where much of the guitar signal is, and explains that signal loss I mentioned earlier.

Back when I had a 5B2 Princeton I also had a '67 Princeton Reverb. I did my "SRV sound" by using an A/B/Y pedal to play a Strat through both amps at the same time. At a given room-volume, the Princeton Reverb was clean and mid-scooped, while the tweed Princeton was distorting and mid-heavy.

[Fresh_Start]

Mrresistor - Weber makes mighty fine 10" speakers for a Tweed Princeton/Harvard 5F2-A. The 10A100 sounds great in my version.

I also don't like the controls on the back.

The chassis hanging 1/3 of the way down the cab just seems weird to me. Especially since the top edge of the speaker is higher than the top of the chassis. I suspect that the chassis is not a box but a bent sheet of steel. That's fine if there aren't any fluorescent lights or other electrical noise sources nearby. Personally, I always want the amp's innards shielded completely.

I put a choke plus an extra reservoir cap in the power supply before the plate node so that it filters everything. It made a significant reduction in noise - at least in my build.

The output transformer makes a big difference in this circuit. HBP is correct about the effects of the Blackface tone stack, but the bigger OT and higher voltages also are a part of the differences in tone, distortion, and feel between tweed and blackface champs. A 10" speaker and bigger OT could use an adjustable bass cut for my ears. A small, cheap OT doesn't reproduce too much bass anyway.

Respectfully,
Chip

[HotBluePlates]

... Why is there only one input? ...

I don't know about you, but I wish when I built my tweed clones that I had/used a custom chassis with a single input jack. We're not in the 50's/60's any more with multiple players sharing a single amp, so there's really no call for multiple input jacks. You can reduce cost & build time by not having the extra jacks & their associated parts. Channel switching and/or signal reduction previously performed at the jacks can be done other ways now.

[mresistor]

... Why is there only one input? ...

I don't know about you, but I wish when I built my tweed clones that I had/used a custom chassis with a single input jack. We're not in the 50's/60's any more with multiple players sharing a single amp, so there's really no call for multiple input jacks. You can reduce cost & build time by not having the extra jacks & their associated parts. Channel switching and/or signal reduction previously performed at the jacks can be done other ways now.

That's true, I really don't use both inputs just the one on the left. From what I understand the left jack was for guitar and the right jack was for microphones.
Chip what kind of magnet is on that 10A100? Is it a C type or a round affair.  The 10' speakers I have are out of a Hammond organ . 

[Fresh_Start]

Alnico speaker.  Shape?  I don't know.
http://www.tedweber.com/10a100

Chip

[tubeswell]

Not the SE amp, but the reverb trem one - These are somewhere on the web out of curiosity. Appears to have the same toob compliment as a BFPR, but without a reverb transformer. It appears that the reverb pan input is AC coupled to the AU7 side of the 12DW7 (using a brown turd cap)? (Edit actually these guts shots are from an amp with 6 pots on the front panel, and 4 preamp tubes - oh well)

[Fresh_Start]

Thanks for the gut shots!

That is NOT point-to-point in my book.  Sure look like turrets to me.

The 12DW7 capacitor coupled reverb circuit is well worth investigating.  The reverb is supposed to be very nice in these amps.

Anyone know if the Tone control is just a Tweed high cut or something more?

Chip

[bruno]

I have a swart space tone (push pull 6v6s with reverb and tremolo).

It is a very nice sounding and well put together amp, taking into consideration where most of the "boutique" brands on the market place themselves price wise, I don't think it's too bad/expensive.

But obviously a lot of us over in this forum, have some skill, and access to people with knowledge enough to put an amp similar to this one together for much less money.

The reverb is excelent sounding, but if you look at tubenit's implementation of a reverb using only one 12ax7, you will run into very similar (and good) results.

So overall, yeah they're good amps, but with a bit of time invested you can probably build your own and spend a lot less money.

[mresistor]

Very nice to see the innards of the amp. Thanks for the upload. Very interesting, it indeed is not true PTP wiring like we saw in the 40's & 50's, in Baldwin organs for instance. Does look very well made. I wonder if he is making these one at a time or has he hired a crew? I checked availability at some retailers and found waiting lists.


Very interesting reverb implementation. I too would like to know how the tone and space controls are functioning in this circuit. Is space control like a presence or raw setup?  Now we know he is using Mallory and looks like Xicon caps on the board, and modern production carbon comps. Is that a black Hammond chassis?  Note the lone ground terminal in pic two. Not connected at time of picture.

[Willabe]

I have a swart space tone (push pull 6v6s with reverb and tremolo).

Very interesting reverb implementation. I too would like to know how the tone and space controls are functioning in this circuit. Is space control like a presence or raw setup?

Yes can you tell us more?

[Willabe]

Is space control like a presence or raw setup?

I'm pretty sure that 'Space' is the verb control.

[VMS]

I think the tone control is standard fender tone control and space control is the reverb control.

I once played the amp (6v6se) in a shop and to me it sounded like the switch cuts out the nfb-loop.

I think it had a 8" weber speaker that might also be a factor for a great sound. It sounded bigger than it looked.

[Fresh_Start]

My bet is that the topology is something like this:
1st 12AX7 triode
tone control (stack?)
2nd 12AX7 triode
12AU7 triode of 12DW7 into reverb tank
12AX7 triode of 12DW7 as reverb recovery
3rd 12AX7 triode cathodyne phase inverter
4th 12AX7 triode for bias vary tremolo
push pull 6V6s, cathode biased

I can't see those photos well enough to figure out any details.  Reverb may be earlier in the circuit, especially if there's negative feedback.  Build quality looks very good.  I just don't like the marketing approach much.

Cheers,
Chip

[VMS]

If we talk about the single-end 6V6se amp you can see from the picture that it uses JJ 40+20+20+20 can cap. So it differs from champs by having more filtering.

This could also be the reason for using GZ34 rectifier.

[mresistor]

Is space control like a presence or raw setup?

I'm pretty sure that 'Space' is the verb control.

OH yeah  head in palm    sometimes brain is totally idling..   

[Ed_Chambley]

I have a Swart dealer not too far from me and have played a few different types of their offerings.  I like the amps a lot!!  Certainly it could be built fairly easily, but Swart has managed to pull off some nice marketing and as mentioned above in the Boutique market they are priced well.  I cannot find anything I do not like about any of their designs, but I have not purchased any and probably would not.


The Band of Joy, or Robert Plant however you wish to refer to his newest gig, the guitar player uses 2 and he has a very vintage tone and unusual style.  I like it for him if you know what I mean.  I have looked closely at Swart amps and if you have built a couple of amps you shouldn't have any problem building one.  They are low watt tooby sounding with a really nice verb.