Simple SE build in 2012

[oldngray]

Starting a new build thread... 3 questions for the moment...

Digikey and Mouser seem to be out of the panasonic capacitors (C1 47uF & C2 120uF) and the possible substitutes are from Cornell Dubilier and they have snap in leads.

1) Will the snap in units work or should I keep searching?

Regarding the switches for the Cathode Feedback and Triode/UL modes of operation

2) what are the power requirements for the Cathode Feedback and Triode/UL mode switches? Is 6 amps at 125V AC good enough or should I use something with higher capacity?

3) Can you switch between these various modes while the unit is up and running or are they something you change before turning the unit on?

thanks!

Oh and I received my PC board yesterday... it's a beautiful thing to hold... which I had ordered a 2nd!

[cddeluca]

The Panasonic C1 and C2 are snap-ins

It may not be for me to say but George describes UL and CFB as wiring configuration options, not switch-on-the-fly. Personally, I wouldn't even consider it for fear of the 'transient make big boom' phenomenon.

47uF equivalent from Mouser: 598-80LX470M500H012
120uF equivalent: 598-80LX121M500K022

[neomat]

I'm interested in building this amp too and I'm looking for a unique supplier who has all soldered parts. Do you know an equivalent at Mouser for IXCP10M45S (U10 & U20) and a reference for FRED diodes (D1 & D2) ?

Thanks in advance.

[rknize]

1) The panasonic caps are snap ins. The CDE caps will work just fine. If you can find the 500V version, spring for those.

2/3) A standard 250VAC-rated switch will work just fine. The CFB operates at a few 10s of volts and has a huge cap across it, so it's no big deal to throw the switch while the amp is on. The triode/UL switch also only operates at a few 10s of volts across the contacts, but the entire switch is elevated to B+. Throwing this switch while the amp is on will create a pop on your speakers, and it generally frowned upon. It is important that the switch case be grounded to the chassis (which should be earth-grounded per George's instructions). The same holds true for any switch, including the power switch for the amp.

[RuiR]

Originally Posted by neomat

I'm interested in building this amp too and I'm looking for a unique supplier who has all soldered parts. Do you know an equivalent at Mouser for IXCP10M45S (U10 & U20) and a reference for FRED diodes (D1 & D2) ?

Thanks in advance.

Hi Neomat.

I already started building it. George told we can direct replace IXCP10M45S with the DN2540N5 which is available from Mouser. You only have to change the R13/23 resistors to a value around 200 Ohm. I order several of them and will try until find the right one to run the 12AT7 at 9mA. I'm still waiting the OPT but when i figure it i will gladly post.


The only soldered parts i didn't order from Mouser was the sockets and the 0.22uf coupling capacitors. From them i got also the potentiometer, 100k though. Orders above 75€ have free shipping

[neomat]

Thanks for this answer ! What did you order for D1 & D2?
I saw 10M45s at onlinecomponents but they do not have all other components.
I will follow this post to know which value you choose for these resistors.

[RuiR]

Originally Posted by neomat

Thanks for this answer ! What did you order for D1 & D2?
I saw 10M45s at onlinecomponents but they do not have all other components.
I will follow this post to know which value you choose for these resistors.

I didn't ordered them, i will use only the 5ar4 as rectifier.

This is oldngray building thread. I have a thread asking about it, i will write there and send you a message. If you don't want to wait you can always order some around 200 Ohm as they wont break the bank

I'm a newbie, don't take granted what i write although in this one George from Tubelab said it work

[oldngray]

Making progress on my board... here are some pictures of my 'inverted build'

also had to make substitution on the heat sink. this is part # HS104-1-ND if you're interested. the item on the parts list was only available in bulk.

also this is the 1/2" standoff, 3/8 with 8-32 threads, also from digikey, 1926BK-ND.

photo 1-6.JPG photo 2-8.JPG photo 3-4.JPG photo 4-1.JPG

Time to build the case and get some aluminum plate... waiting on the the delivery from Edcore.

[nate]

Hi Oldngray,

I'm just beginning my build as well, and seeing you get started really makes me excited! I have all the parts assembled, I'm just waiting on my transformers.

My build is as follows:
O'Netics OPTs Level 1 (it turns out they are local and Bud is really a cool guy) supposedly they are in a vat of enamel being vacuum impregnated.
Edcor power transformer and choke
Switched cathode reistors (per rknize's build) I'm using the 5w silicone coated Dale resistors from Mouser- I've used them in some speaker designs and they sound pretty good- not as good as Mills, but for the cost and purpose i'm sure they will do fine.
Supplemental motor run cap
tube rectified power supply
Cardas film caps (ouch)
JJ electrolytics
cardas wire and connectors etc...

I have a nice pair of JJ EL34s, enough EH 6550s to last me a decade and two pair of Tungsol 6550s. I might try some kt88s later, but I have a feeling that I will prefer the el34s and I'm praying that they will give me enough power for my 90db diy speakers.

Keep the build photos coming! Mine will start soon,

nate

[oldngray]

Regarding the tubes, I suggest that you test fit them as soon as the sockets are installed in the board. My sockets were so tight I couldn't insert the tubes so I pulled out a round spudger and gently opened up each hole on each socket. Expanding the sockets after the components were installed on the reverse side of the board would have made the process much more difficult.

What did you end up choosing for your motor run cap and where did you get it?

Carl