Another get*set*go finished!

[TerrySmith]

After being side tracked for the last month doing "honey-do" projects, I finally got time to finish my GSG.

I went with the black Hammond chassis and black transformers to give it the old look, like it was made in the 1930's. The outputs are 6A3's, maybe one day I may mod it to try 300B's.

[TomMcNally]

Nice job Terry ! I guess everyone knows I like the look of those
Hammond chassis - and they are easy to work with too.

Have you tried both the 3.5K and 5 K Taps ? I built mine with
the 5K and didn't experiment.

... tom

[jduffy]

Very elegant looking.

I like the way the tubes sit on the PCB. What size standoffs are you using?

[TerrySmith]

Those are 1/2" standoffs, so the sockets would be flush with the top. Also the reason there are no terminal blocks is Mouser was out of the 4 and 5 terminal size when I ordered my parts, and I didn't want to wait for a backorder. Yellow_Light_Colorz_PDT_46

[Shannon Parks]

Very vintage looking - I love it! The black on black with the DHTs is a perfect match. Where's the WE badge? Now you just need to get some muratic acid on a rag to wipe off those red stars to complete the vintage look. Yellow_Light_Colorz_PDT_12

How does it sound? Not sure if you used the 3.3k, 3W cathode resistors for a 1100 ohm cathode resistor network, but lowering this closer to 900 ohms can help the Sovteks some. To my ear the original 1100 ohms sounded fantastic, FWIW.

[TerrySmith]

It sounded ok at first startup, but after 10 or so hours it really sounds awesome! Funny how just 3 watts can make that much sound. The 6A3's have a nice blue halo at the top. Yellow_Light_Colorz_PDT_11

The only problem so far is a slight popping noise in the speakers during warmup, can be in either side, and only lasts for a couple of seconds. I ain't gonna worry about it unless it gets worse or it lets the smoke out of something! Yellow_Light_Colorz_PDT_44

[Shannon Parks]

I think the popping is the Sovtek construction, and nothing to worry about. I hear it from my Sovteks but not my old stock. But those monoplates are sooo cool and worth it!

[gogzhad]

Love the black on black look - very retro and understated.

What size is that Hammond box?

[TerrySmith]

That's the 12x10x2 steel box. AES seems to have the best price on them at $19.95.

Next I need to find a 17x10x2 box for my super-duper PPP EL84 amp that is in the works. Yellow_Light_Colorz_PDT_06

[EWBrown]

If you want to drop the 1100 ohms to (almost) 900 ohms, a nice easy "no sweat" way to do it is to connect a 4700 ohm resistor (2W or more) across each of the existing 3 X 3300 resistor array.

No desoldering needed, and it is easily reversible, if you so choose. Assuming that all the resistors are exact value (they rarely ever are) this yields 907 ohms, which is more than close enough for government work Yellow_Light_Colorz_PDT_01 Yellow_Light_Colorz_PDT_02 Yellow_Light_Colorz_PDT_04

Now all I have to do is make the wooden base for mine and it will be 100% complete! I wasn't toally goofing off lately, I managed to finally completed the Bottlehead Paramount II "enhanced iron" kits last weekend. Yellow_Light_Colorz_PDT_06

FWIW, that design uses 1100 ohms as the "cathode" resistor for the 2A3, but in a "split rail" power supply design, so that the positive B+ rail runs around 322 VDC, and the negative rail runs around -59VDC. The filament goes directly to ground through the hum balance pot.
A similar scheme is used in the 30 watt amp in the back of the RCA tube manuals.

/ed B in NH

[TerrySmith]

This amp has played flawlessly for about 3 years now except the power transformer is getting noisy! It can be a dull hum or a noticeable buzz. The trans is a Triode unit date coded 06-2006.

I may replace it with an Antek 1T300 and move the innards to a nicer chassis such as a Parmetal 12x12x2 which I have.

[Quad]

FWIW - the Antek 1T300 in my amp runs a bit hot and
B+ is about 20V low and consequently, the amp is a bit
shy on low end punch.
I wanted to try a few experiments for the B+ :
reduce or short out R17, or add a couple of boost windings
to the toroid to increase B+, but never got round to it.

[nyazzip]

This amp has played flawlessly for about 3 years now except the power transformer is getting noisy!

i noticed one of the flourescent grow light ballasts in the basement (no, not for that stuff) has developed a nasty hum too. why/how can transformers start to make more mechanical noise as they age? is this a harbinger of doom?

[Ty_Bower]

why/how can transformers start to make more mechanical noise as they age?

Sometimes it is not the fault of the transformer. Your local utility company might make changes in their service which affects the line quality. Noisy power lines can manifest themselves as buzzing power transformers.

[EWBrown]

Another thing to try is to tighten the long bolts and nuts through the power tranny lams (holding on the end bells) that sometimes quietens things down. Also make sure that it isn't the choke which is vibrating / buzzing.

I see that you already have the ICL CL-90 installed in the primary circuit. That can sometimes help to tame the buzzing beast.

A "messy" and noisy AC power line can also make for noisy trannies, as mentioned previously. Also, check your line voltage, it may be higher then the modern "standard" 120-123VAC.

HTH

/ed B