get*set*go pictures

[TomMcNally]

I took a bunch of pictures of a get*set*go 6B4G SET amp with an updated
panel from Front Panel Express. We moved the RCA jacks to the back,
added a volume control, moved the power switch to the front,
and the speaker jacks are now side by side in the back.

http://mcnally.cc/gsg

click on any pic for a larger version

[TerrySmith]

Nice work Tom! I can't wait to build one of these.

Where is a good place to buy Sovtek 6B4G or 6A3 tubes? I like the mono plate construction better than the old double plate types.

On a different note, what if you paralled both sections of a 6BL7, 6BX7 or a 6AS7G and used it for the output tube?

[TomMcNally]

I got my Sovtek 6B4G's from TubeDepot ...

http://www.tubedepot.com/so-6b4g.html

I'm not sure you'd have enough filament current with paralleled tubes,
this amp is designed around the Dynaco PA-774, which has two 6.3 VAC windings, and the cathode resistors are part of the DC filament circuit, so it would get complex.

[Shannon Parks]

In a different note, what if you paralled both sections of a 6BL7, 6BX7 or a 6AS7G and used it for the output tube?

I'll try this out today.

[TomMcNally]

Terry -

Sorry, I misread what you said and was thinking paralleled tubes (Double Darling on the brain) ... paralleled sections is another story.

... tom

[lth1]

I have a suggestion on the layout. I would move one set of output connectors over near the RCA's. Move the choke towards the center which would give more room for the right speaker outputs and rca's, do not like the length of wire run from right OPT to right speaker terminals, also reduces run of speaker cable.

Lee Hankins

[TomMcNally]

Hi Lee -

I don't like the thought of the output connectors being close to the input connectors. The RCA's were originally up front, which people don't care for much these days. They were moved to the back to allow for a volume control up front. Moving the choke to the center would put in under the power transformer, which would mean it would have to be mounted with countersunk screws, and would be subject to magnetic coupling to the power transformer.

The Front Panel Express file for the top plate will be available for download, and their free software allows you to easily modify and upload it for manufacture, so users will be able to customize it very easily. Future versions may be bigger, so it will be easier to open things up as you suggest.

Thanks for your thoughts.

... tom

[lth1]

Hello Tom,

I do not like to see the long run of unshielded wire running in and around the AC lines, understand your concern about the closeness of the input and output connectors, and I definitely agree. It is rather foolish on my part to just look at a picture and try to redesign the plate.

Is there any hum with the get set go. I have not been able to eliminate hum in my eiclones, and with my lack of knowledge really do not know how to go about reducing or eliminating the hum that I have. It really isn't too bad, just not as low as my Paramours and Paramounts, so it becomes noticeable. A problem when using high efficient speakers.

Lee Hankins

[TomMcNally]

Hi Lee -

The get*set*go's are dead quiet with ear next to speaker. My way of thinking is this ... keep the input wires, which are low level, away from anything ... you'll see that in the pictures. Speaker leads don't pick up hum, so it doesn't matter if they are close to AC wires, BUT they can radiate audio, so they need to be kept away from anything that can pickup audio - like input and grid leeads. You'll see that the AC wires are all twisted, which is a hum reducing technique. The AC wires are in the back of the amp, which is the power supply, which isn't affected by AC.

Lead dress and grounding are very important, AC lines should be twisted, and kept away from inputs, attention needs to be paid to every detail. Do you amps hum when inputs are shorted and nothing else is connected ?

[jduffy]

Great pictures as usual. I like how you take them outside. Natural light really shows the details. It also gives me the feeling that electronics is a part of nature, not just some man-made invention.

A part of nature if you would.

[lth1]

Tom, I have looked everywhere and did not notice a posting of the top plate size, want to get a head start on the base.

Yes I do have hum with the input grounded. There is more hum with just the heaters on, and the hum is reduced when B+ applied. The hum is not as noticable on the Cornwalls, very noticable on the Super 12's. They were both suspose to be 98dB efficient, go figure.

Lee

[TomMcNally]

The top plate isn't posted yet - the boards will be here in a few weeks, and at that time all of the documentation and current parts lists, etc. will be ready.

[EWBrown]

I see that The Tube Depot also has the Sovtek 6A3s, so if one is a true- blue 4-pin tube phanatique then those are an alternative to 6B4G. I'd SWAG that it is the same glass and metal bits, just joined to a different base. :o

I just sent off for a pair of the 6B4Gs, might as well not rock the boat too much Yellow_Light_Colorz_PDT_01 Yellow_Light_Colorz_PDT_04 Yellow_Light_Colorz_PDT_08

BEsides I have some used but still good Ken-Rad 6B4Gs probably a LOT older than I am, and I can do a comparison. Yellow_Light_Colorz_PDT_11


/ed B in NH

[TomMcNally]

I have one NOS Sylvania 6B4G, I'm looking for a mate, or will
swap it if someone has one and needs one. Doesn't it look like
the JAN was scraped off ? hah