[BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD

[zayance]

Some good infos here concerning fuse rating:

https://groupdiy.com/threads/calculating-fuse-for-power-transformer.58300/

 

[TLRT]

what fuse do you use ? can't find any info about it ?

1.2A for 230v mains is ok, the unit consuming approx 80watts max

 

[wrentema]

Hey Herbert. Do you have a link of this meter? Can find it on Aliexpress. Thanks

I have finished my Sta Level after nearly a year. A very good sounding Compressor, phat, especially on Vocals...! Mine one is with Sowter InTX and Hammond OutTX, NOS Philips 6BA6 tubes, I ve used a cheap TR-76 from AliEx and printed the Meterscale from the thread on the Inlet. Looks really good! Frank from frontpanels.de has done the frontpanel on anodisised Alu.
I had Issues with the PSU, DjFatum helped me to get this PSU working - thanks man!!!

Some experiences I want to share:

- if you want to use a TR-76 (Simpson looking) Meter - the Standard R7S Resistor with 68 Ohm is correct, if using a TR-57 (looks like the Sifam Vintage Al20SQ) you need to increase this Resistor to 100 Ohm to get in the Range for Calibration of the Meterzero

- R3 only with 3W like mentioned in the BOM - it is to less! - it should tweak the Voltage from ~400VDC after the Rectifiering Diodes/first Cap to about ~300VDV -> I ve used a 1K Resistor for this 100V Voltagedrop. So this HT Rail pulls about 0,1A

- 10W Power > I really recommend for R3 a 50W Resistor!!! Then this Resistor gets only warm, not hot - mount it on the case ... The Resistance of R3, as said, depends from Voltage after the Rectifier - before R3. And if your Power AC Plug gives you 220VAC, 240VAC or 250VAC the seconday AC also can be higher or lower.....As further Example if you have about 420 Volts before R3 you need to tweak about 120V down to about 300V - that means -> use for the pulled 0,1A - HT Voltage Rail a 1K2 Resistor with over 25W for R3. If the HT Voltage is then correct after the HT Regulator with about 300V the Bias Voltage should also fit with about 100V.... Correct me, if I am wrong. But its logical..

- my first Terroid PSU was from DONs - audible hum and vibrations like hell, the 5V AC rail Voltage also was way tooooo low for usage, only 3,7V after the Regulation. .... So I ordered a stronger new custom Terroid with 120VA (Pri 230V, Sec1 300V 0,2A, Sec2 8,5V 8A, and Sec3 7V 1A, electrostatical screen) from Audiophonics France, 3Months waiting time - about 90 Bucks incl. delivery in Europe. Perfectly...

-and I really recommend a good TO220 Insulator made of Cermic!!! for the LM338 Heater/Filament 6,3VDC Regulation mounted on the case. It emits the most heat of all components in my case. And I had a tricky shortage with the 338 Regulator to the case there...
All 6 Tubes (using the 6BA6 Tubes) are pulling about 2,1 A at 6,3V Filamentvoltage!

Thank you Zayance and Bernbrue for this great work!!

 

[HerbertR]

Hey Herbert. Do you have a link of this meter? Can find it on Aliexpress. Thanks

Hi,
https://a.aliexpress.com/_mrwOtfS

 

[1wildthing]

Hi HerbertR, may I ask you about the Sec2 specs of your custom terroid? They seems to be a bit different from the suggested ones (8,5v at 8A Vs 9v at 4A)? I’m going to order a custom trafo as well and I don’t want to make mistakes

I have finished my Sta Level after nearly a year. A very good sounding Compressor, phat, especially on Vocals...! Mine one is with Sowter InTX and Hammond OutTX, NOS Philips 6BA6 tubes, I ve used a cheap TR-76 from AliEx and printed the Meterscale from the thread on the Inlet. Looks really good! Frank from frontpanels.de has done the frontpanel on anodisised Alu.
I had Issues with the PSU, DjFatum helped me to get this PSU working - thanks man!!!

Some experiences I want to share:

- if you want to use a TR-76 (Simpson looking) Meter - the Standard R7S Resistor with 68 Ohm is correct, if using a TR-57 (looks like the Sifam Vintage Al20SQ) you need to increase this Resistor to 100 Ohm to get in the Range for Calibration of the Meterzero

- R3 only with 3W like mentioned in the BOM - it is to less! - it should tweak the Voltage from ~400VDC after the Rectifiering Diodes/first Cap to about ~300VDV -> I ve used a 1K Resistor for this 100V Voltagedrop. So this HT Rail pulls about 0,1A

- 10W Power > I really recommend for R3 a 50W Resistor!!! Then this Resistor gets only warm, not hot - mount it on the case ... The Resistance of R3, as said, depends from Voltage after the Rectifier - before R3. And if your Power AC Plug gives you 220VAC, 240VAC or 250VAC the seconday AC also can be higher or lower.....As further Example if you have about 420 Volts before R3 you need to tweak about 120V down to about 300V - that means -> use for the pulled 0,1A - HT Voltage Rail a 1K2 Resistor with over 25W for R3. If the HT Voltage is then correct after the HT Regulator with about 300V the Bias Voltage should also fit with about 100V.... Correct me, if I am wrong. But its logical..

- my first Terroid PSU was from DONs - audible hum and vibrations like hell, the 5V AC rail Voltage also was way tooooo low for usage, only 3,7V after the Regulation. .... So I ordered a stronger new custom Terroid with 120VA (Pri 230V, Sec1 300V 0,2A, Sec2 8,5V 8A, and Sec3 7V 1A, electrostatical screen) from Audiophonics France, 3Months waiting time - about 90 Bucks incl. delivery in Europe. Perfectly...

-and I really recommend a good TO220 Insulator made of Cermic!!! for the LM338 Heater/Filament 6,3VDC Regulation mounted on the case. It emits the most heat of all components in my case. And I had a tricky shortage with the 338 Regulator to the case there...
All 6 Tubes (using the 6BA6 Tubes) are pulling about 2,1 A at 6,3V Filamentvoltage!

Thank you Zayance and Bernbrue for this great work!!

 

[HerbertR]

Hi HerbertR, may I ask you about the Sec2 specs of your custom terroid? They seems to be a bit different from the suggested ones (8,5v at 8A Vs 9v at 4A)? I’m going to order a custom trafo as well and I don’t want to make mistakes

Hi, a high quality 9V 4A should work fine. My filament secondary is with 8A oversized for sure. My custom build transformer was originally planed for a dual build when it was ordered (but the project got a little bit too expensive...), 8.5V because of less heat dissipation of the LM317 - it gets verrrry hot - take care for a good ceramic insulation plate and mount this regulator directly on the case..... Its my opinion, greeez

 

[1wildthing]

Hi, a high quality 9V 4A should work fine. My filament secondary is with 8A oversized for sure. My custom build transformer was originally planed for a dual build when it was ordered (but the project got a little bit too expensive...), 8.5V because of less heat dissipation of the LM317 - it gets verrrry hot - take care for a good ceramic insulation plate and mount this regulator directly on the case..... Its my opinion, greeez

Thanks!

 

[TLRT]

Hi, a high quality 9V 4A should work fine. My filament secondary is with 8A oversized for sure. My custom build transformer was originally planed for a dual build when it was ordered (but the project got a little bit too expensive...), 8.5V because of less heat dissipation of the LM317 - it gets verrrry hot - take care for a good ceramic insulation plate and mount this regulator directly on the case..... Its my opinion, greeez

The relays needs only around 70mA at 5v in series connection(in paralell it is 250mA pretty useless connection I think) put a dropping resistor to your 8.5v to reduce around 7v and save your lm317 for long term usage.

 

[1wildthing]

Hi, still working on orders here. I have a quick question: what are the correct values for C10S and C11S?
On PCB they are marked as c10s =470nf/200v and c11s 1uf/200v but on the BOM c10s is 0.1uf/400v and c11s is 470nf/200v. I'm a bit confused.

 

[zayance]

Make them both 400V

If you check the specs of the "proposed" components on the BOM link, you'll see they are both rated for a 400VDC

 

[Jim50hertz]

I'm pulling together parts for this build. I currently have the KidSquid power transformer, which I gather may not be optimal for the build.

Can any one who has recently built this point me in the right direction for either an off the shelf transformer or specs for a custom build?

 

[wrentema]

I'm pulling together parts for this build. I currently have the KidSquid power transformer, which I gather may not be optimal for the build.

Can any one who has recently built this point me in the right direction for either an off the shelf transformer or specs for a custom build?

This one should work. I just emailed because I’m ordering one too. They told they should be back in stock 2 weeks (ish)

https://www.don-audio.com/TB3009S-Audio-Power-Toroidal-Transformer-Sec-300V-9V-5V-Shield

 

[f.aiseur]

Hi folks!

I have a question regarding the 7pin tubes sockets :

Is it ok to solder them like i did on the picture? (they were kind of standing on the holes)
Or would it be better to file/twist them a little bit so they can get thru the holes?
I ordered the ones from the BOM, they dont quite fit in the board.
It just seems a bit odd to me that the sockets would stand like that above the pcb, but maybe there is a reason for that!
Thanks for your help, happy summer to all of you!

 

[TLRT]

Hi folks!

I have a question regarding the 7pin tubes sockets :

Is it ok to solder them like i did on the picture? (they were kind of standing on the holes)
Or would it be better to file/twist them a little bit so they can get thru the holes?
I ordered the ones from the BOM, they dont quite fit in the board.
It just seems a bit odd to me that the sockets would stand like that above the pcb, but maybe there is a reason for that!
Thanks for your help, happy summer to all of you!


View attachment 97108

Cut the legs in 45degrees but better using this socket:
https://www.banzaimusic.com/tube-socket-7-pin-pc-mount-sku58617.html

 

[1wildthing]

Hi guys, I didn’t find the info in the thread, which tubes need to be matched in this build?
I’m about to order them and the price is higher for matched pair. Thanks in advance.

 

[TLRT]

Hi guys, I didn’t find the info in the thread, which tubes need to be matched in this build?
I’m about to order them and the price is higher for matched pair. Thanks in advance.

Ecc81 for sure as phase inverter. If you use ef93 then they should be matched also for full gm/transconductance as the tubes will continiusly vary the anode/grid voltages during compression,it is better if the curves working together.(same true for 6386) El90's should be close too but you can trim out the cathodes.

 

[1wildthing]

Ecc81 for sure as phase inverter. If you use ef93 then they should be matched also for full gm/transconductance as the tubes will continiusly vary the anode/grid voltages during compression,it is better if the curves working together.(same true for 6386) El90's should be close too but you can trim out the cathodes.

Thanks a lot!!!

 

[TLRT]

Thanks a lot!!!

I have many selected tubes if you need any.

 

[f.aiseur]

Hi there,
Made the first measurements this morning, i'd like to share them with you and maybe get some hints from anyone.
I used Edcor In and Out Tx, custom power transformer as follow :
230v PRI, SEC1 300v, SEC2 10,5v, SEC3 7v
Meter and tubes were not plugged yet.
There is definitely wrong things happening, but i could spot only one mistake (i soldered R12s on H test point as you can see on the picture, although i guess its ok like this too)

So here we go , all DC voltages, reference to ground :

B+ = 321
V+ = 2,8
F+ = 3,3
Bias = 97,9

A - 310
B- 0
C - 0
D - 0
E - 0
F - 0
G - 311
H - 316
I - 296
J - 0
K - 0
L - 0
M - 0
N - 296
O - 321
P - 0
Q - 0
R - 321
S - 243
T - 23,8

What do you think? should i already try to put the tubes in?
I'm a bit scared!!

Thanks everyone

 

[lilpaula87]

Hi guys, for this build I bought the Hammond 1650G transformer and I'm now trying to wire it. The wiring of the primary stage is pretty simple (colour coded) but I'm not sure about the secondary. I'm not expert so your help would be appreciated. Could you please advise me on the right solution? I attach the product sheet.