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Tubelab Discussion and support of Tubelab products, prototypes and experiments

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Old 3rd April 2018, 11:27 PM   #1
riven67 is offline riven67  United States
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Join Date: Dec 2012
Default Another SSE is Born!!

My SSE has been built and has undergone initial checkout, I am now letting it play for a few hours using cheap Chinese el34's.

I will probably roll some other tubes in after Im more secure in my work. lol

But I have to say George your amp sounds ssooooo ggoooodd!! Thank you for taking the time designing it so even us noobs can enjoy building a great sounding amp the first time.

Hell they even made these Bose 201's sound decent, I used them because I only paid $1.00 each for them at a garage sale!! haha

I will attach my ADC 404's later and see how they sound.

Thanks to everyone that gave me advice and help.
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Old 4th April 2018, 02:33 AM   #2
PDL is offline PDL  United States
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Join Date: Jan 2010
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Careful with the cheap chinese el34's. I've had them self destruct and take out the the cathode bias resistor and cap.

Luckily, George overbuilt the board and no PCB traces were harmed during the fiasco.
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Old 5th April 2018, 12:04 AM   #3
DaMuffinMan is offline DaMuffinMan  United States
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Location: Plant City
Need pictures or it didn't happen..
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Old 8th April 2018, 03:39 AM   #4
riven67 is offline riven67  United States
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Well it survived the cheap chinese el34s and ive rolled a set of 6l6gt's, sovtek 5881's and EH 6ca7's i think the 6l6's are my current favorite.

I will load some photos tomorrow of the test bench setup, and again as the chassis is built and populated.
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Old 8th April 2018, 03:33 PM   #5
Lee from Chitown is offline Lee from Chitown
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Riven67, in tube rolling, I found in my SSE the 12at7 tube made a huge difference in the sound.
I started with a Jan/Phillips then Mullard, Telefunken, and RCA black plate. All nos.
Power tubes I’ve tried el34s, kt77s, and kt88s.
Fun.
( Led Zepplin on kt88s, with Telefunken was too much base. ?)
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Old 9th April 2018, 07:40 PM   #6
riven67 is offline riven67  United States
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Quote:
Originally Posted by Lee from Chitown View Post
Riven67, in tube rolling, I found in my SSE the 12at7 tube made a huge difference in the sound.
I started with a Jan/Phillips then Mullard, Telefunken, and RCA black plate. All nos.
Power tubes Iíve tried el34s, kt77s, and kt88s.
Fun.
( Led Zepplin on kt88s, with Telefunken was too much base. ?)
I've got a boatload of 12at7's all makes and a few equivalents as well,
I'll try em as soon as I get the chance to dig them out as they are still in boxes from the move.
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Old 28th April 2018, 12:18 AM   #7
riven67 is offline riven67  United States
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Default Help needed with some final details for my build!

Ok so all the tests worked fine no magic smoke came out of the amp during testing, so I'm very happy with the way it works and sounds.

So onto the final design of the finished amp.......this is where I need some help with some of the things I'd like to do.

I love the "Man Cave" version of the SSE from this thread Man Cave
I'd like to add some of his ideas into my final design, though my chassis will look nothing like his.

Some of the things he's added intrigue me but I'm not sure how to duplicate them. So here's my issues I need help with.

1. VU meters - i bought these VU Meter set w/driver pcb
But even after reading a bunch of threads with little or no answers I still don't know what source to hook up to the pcb. On the pcb is a 3 part connection one for left in, right in, and ground, is this for a connection from the positive side of the line in jacks? Ground would go to the star or can I use the unused connector on the sse board? I know this is a real beginners question but honestly no one answered this in any of the threads I read and I just don't know.

2. Cathode bias meters and adjustments. On the Man cave thread he states he used some old heliopots in place of R17 & R27. And what does he mean "shunts for the meters" That seems easy enough to do but I don't have heliopots would a good wire wound potentiometer work? And if so what's the specs and a good value to use in this spot? And how is it wired? One side To each of the resister holes on the board with the wiper connected to one of the other pins? And how do I install "shunts" for the meters? (SEE I really do need help lol)

3. I'm also interested in the B+ adjustment and meter. Although I have no idea how this was made to work. Anyone have any ideas how it was implemented ? I tried asking on the thread but the member has not answered in over a year so i thought I'd throw it out there and see if perhaps someone with more experience would answer. Any schematics or how to would be greatly appreciated. I don't think adding a wire wound pot to the circuit here would be a good idea but really have no idea how this was done.

If anyone knows the original builder of the Man Cave SSE and can get in touch with him to ask how it was done I would absolutely be thankful.

Anyway I am looking forward to putting my amp into a chassis and putting it in a place of honor in the living room. I have an aluminum topplate and have some really nice colorful wood dyes, now I am looking into getting some exotic woods for the skirt. I'll post some pics as I go. Thanks in ADVANCE!

Attached pic of VU meters and pic from Man Cave amp for those who don't want to follow the link. I take no credit for that amp it is totally someone else's creation that I admire.
Attached Images
File Type: jpg s-l1600.jpg (109.2 KB, 200 views)
File Type: jpg _MG_9127.JPG (211.2 KB, 200 views)
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Old 28th April 2018, 03:09 AM   #8
w5jag is offline w5jag  United States
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The eBay ad said the sensitivity was -15 dB, which doesn't really tell much. I suppose you would attach those board inputs to the speaker output of the amp, and use the 10 turn potentiometer to set the meter to read 0 dB at the amplifier clipping point, or some other arbitrary point, such as 1 watt. Were there no instructions?

If you want to use a variable resistor for the bias resistor s, 1K would be about right I would think. Clarostat use to make these, I have some 25 watt ones I picked up at hamfests and use on the bench. I wouldn't use less than 25 watt parts, probably. It looks like that fellow has some old style 10 turn counters with a lock to run the bias pots. These are not real common these days. Philmore used to import a cheap plastic line with a vernier. Real ones are sometimes found at hamfests. Fair Radio or Surplus Sales of Nebraska probably also have them. These are $1 or $2 parts at hamfests, but will not likely be inexpensive from a surplus house.

I didn't see anything on that amp to adjust the B+ - it just looked like there was a chinesium meter on the AC line and on the B+ line for eye candy. Different rectifier tubes have different voltage drops and can be used to somewhat adjust the loaded B+ voltage. You do not want to use a potentiometer ( ohms law ).

Hope this helps. Others may have different thoughts.

Win W5JAG
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Old 28th April 2018, 01:05 PM   #9
riven67 is offline riven67  United States
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Quote:
Originally Posted by w5jag View Post
The eBay ad said the sensitivity was -15 dB, which doesn't really tell much. I suppose you would attach those board inputs to the speaker output of the amp, and use the 10 turn potentiometer to set the meter to read 0 dB at the amplifier clipping point, or some other arbitrary point, such as 1 watt. Were there no instructions?
No instructions were included, I had to search for that photo in other auctions for the same set of meters.
Quote:
If you want to use a variable resistor for the bias resistor s, 1K would be about right I would think. Clarostat use to make these, I have some 25 watt ones I picked up at hamfests and use on the bench. I wouldn't use less than 25 watt parts, probably. It looks like that fellow has some old style 10 turn counters with a lock to run the bias pots. These are not real common these days. Philmore used to import a cheap plastic line with a vernier. Real ones are sometimes found at hamfests. Fair Radio or Surplus Sales of Nebraska probably also have them. These are $1 or $2 parts at hamfests, but will not likely be inexpensive from a surplus house.
Thanks, Yes the original "Heliopot" is not that common these days, and they are not cheap when you do find them. But knowing what specs to look for i'm sure i can find a suitable pot.
Quote:
I didn't see anything on that amp to adjust the B+ - it just looked like there was a chinesium meter on the AC line and on the B+ line for eye candy. Different rectifier tubes have different voltage drops and can be used to somewhat adjust the loaded B+ voltage. You do not want to use a potentiometer ( ohms law ).
Oh my mistake, I thought the dial under the B+ Meter was for that although I didn't understand why he'd call it an attenuator. Doh!! Thats the volume control!! Lol ok so I'm an idiot, in this case.
Quote:
Hope this helps. Others may have different thoughts.
Yes it did indeed, thank you!

Win W5JAG[/QUOTE]
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Old 28th April 2018, 03:37 PM   #10
w5jag is offline w5jag  United States
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Not to nit pick, but they are "helipot".

I've attached a better pic of what the turns counter look like, and a pic of the ceramic Clarostat that I use. This is a 25 watt, 1K, single turn part.

SSON has multiturn helipot style parts, but I only saw five and ten watt parts in 1 and 2K values. That may be adequate for a ceramic wirewound device, but I'm not sure how robust those multi turn parts are. DC current through a regular carbon type pot will eventually make it noisy, and I'm not sure how good those multi turn pots are at dissipating heat. So to my mind, bigger equals better at holding off these potential problems.

Personally, I would use a single turn wirewound ceramic with a big knob if you want easier resolution. It's not like high precision is needed .....

The better way to wire one is to short the wiper to one end of the pot, so that it is simply shorting out a part of the resistance. This way if the wiper opens, the full value of the pot is in circuit, rather than creating an open circuit.

Anyone who reads my posts and threads know that I make a lot of mistakes. Whatever I know is from practical experience, some of it learned the hard way, from simply stupid, to spectacular. If George sees this, he is the expert on these matters. Others may also have thoughts on the matter.

Win W5JAG
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File Type: jpg IMG_20180428_091149.jpg (90.9 KB, 147 views)
File Type: jpg IMG_20180428_091916.jpg (16.5 KB, 145 views)
File Type: jpg IMG_20180428_091920.jpg (19.0 KB, 146 views)
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