• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Need 3-5W tube amp

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R

rpi

Member
Joined 2015
Lingwendil, do they usually mention the material from which the socket was made of? Or do you define that just by looking at the picture? I see there are brown and white ones.

kodabmx, thank you for proposal! Do they have pads for screws? I believe that's what I will need to mount sockets.
 
G

Guerilla

Member
Joined 2018
rpi said:
I'm trying to collect in one place the info scattered across multiple pages. Here is the final schematic for PS and the parts list.
[/code]
Click to expand...

I believe you can edit your opening post when its final and finished, but not sure. Or you and the proposers could decide names for the builds and make new threads. Awesome work and collaboration. Its been a joy to follow so far
 
V

VictoriaGuy

Member
Joined 2008
kodabmx said:
Personally, I find Chinese sockets work well enough if you don't do a lot of "tube rolling", but I prefer NOS Soviet parts.
...........

I find GDparts to be reputable. Never had any issues, but of course you might want to buy them from the USA instead of China.
Click to expand...

I like Soviet tube amp parts, but there don't seem to be so many available on eBay as in past years.

One caution about the ceramic Chinese sockets - some of them have smaller round pin holes and on a couple I ran into 'undersize' holes in the ceramic. So be sure to test before you bolt them into a chassis!
 

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R

rpi

Member
Joined 2015
Unfortunately I cannot edit my previous post. Here is the new list which includes all proposals except the one about teflon foil capacitor for C2 as what I found is a little bit bulky. Is it possible to find any alternative for C1? I'm afraid that I'll wait too long just for this one capacitor. Thank you!

m-4.png

Code: 
T1 - GXSE15-5K
[URL="https://www.edcorusa.com/gxse15-8-5k"]EDCOR - GXSE15-8-5K[/URL]

V1 - 12AX7
[URL="https://www.ebay.com/itm/Sino-12AX7B-Preamp-Vacuum-Tube/152759915406"]Sino 12AX7B Preamp Vacuum Tube  | eBay[/URL]

V2 - 6P15P-EV
[URL="https://www.ebay.com/itm/6P15P-EV-4Pcs-Russian-Military-Long-LIFE-Vacuum-Pentode-tube-OTK-same-year-EL83/292276425741"]6P15P-EV 4Pcs Russian Military Long LIFE Vacuum Pentode tube OTK same year EL83  | eBay[/URL]

C1 - 0.082uF 400V
[URL="https://www.ebay.com/itm/Polystyrene-Capacitors-K71-5B-0-082uF-82nF-160V-Diamond-tolerance-5-2pcs/223031743363"]Polystyrene Capacitors K71-5B 0.082uF 82nF 160V ◊(Diamond) tolerance+/-5% 2pcs.+  | eBay[/URL]

C2 - 0.1uF 400V
[URL="https://www.mouser.com/ProductDetail/Cornell-Dubilier-CDE/716P10454LA3?qs=sGAEpiMZZMv1cc3ydrPrF%252bj%252bsGhgO1VgJsu1Cvqz28U%3d"]716P10454LA3 Cornell Dubilier - CDE | Mouser[/URL]

C3 - 680uF 16V
[URL]https://www.mouser.com/ProductDetail/Nichicon/LKG1E681MESYCK?qs=sGAEpiMZZMtZ1n0r9vR22d%252blFeYd%252bH4EB5OPpYC2i4g%3d[/URL]

C4 - 180pF 1kV
[URL]https://www.mouser.com/ProductDetail/Vishay-Cera-Mite/561R10TCCT18?qs=sGAEpiMZZMt1mVBmZSXTPFXppOBlV6Pk7PmGGS9GNQY%3d[/URL]

R1 - 100 kOhm 0.5W
[URL]https://www.mouser.com/ProductDetail/Xicon/273-100K-RC?qs=sGAEpiMZZMukHu%252bjC5l7YSH9ftMmKdBZT00PQY2CJlc%3d[/URL]

R2 - 100 Ohm 0.5W
[URL]https://www.mouser.com/ProductDetail/TE-Connectivity-Neohm/CBT50J100R?qs=sGAEpiMZZMuDPtTs5Gda2%2fwGMz2hofsMQd4Ntiy7tL8%3d[/URL]

R3 - 820 Ohm 0.5W 1%
[URL]https://www.mouser.com/ProductDetail/Welwyn-Components-TT-Electronics/MFR4-820RFI?qs=sGAEpiMZZMukHu%252bjC5l7YRDwiouGrKBmwSsVuz94HuQ%3d[/URL]

R4 -150 kOhm 2W
[URL]https://www.mouser.com/ProductDetail/Vishay-Dale/CPF2150K00FKE14?qs=sGAEpiMZZMu61qfTUdNhGz34irntT%2fJFIKWZR%2fBAcb0%3d[/URL]

R5 - 100k 5W wirewound 
[URL]https://www.mouser.com/ProductDetail/Xicon/280-PRM5-100K-RC?qs=sGAEpiMZZMtbXrIkmrvidHiKlRtT248Uj8xqXsZy2zA%3d[/URL]

R6 - 150 Kohm carbon film 1W
[URL]https://www.mouser.com/ProductDetail/Xicon/294-150K-RC?qs=sGAEpiMZZMu61qfTUdNhG3GWZmU6PwDPWeAE%2fkNyxUU%3d[/URL]

R7 - 220 Kohm carbon film 1W
[URL]https://www.mouser.com/ProductDetail/Xicon/294-220K-RC?qs=%2fha2pyFaduiRHRkVJgnDOB3vlddufLrLIToe7QaFR9Q%3d[/URL]

R8 - 10 kOhm 0.5W
[URL]https://www.mouser.com/ProductDetail/KOA-Speer/MFS1-2DCT52R1002F?qs=sGAEpiMZZMu61qfTUdNhG%2fDQawzJ6c7PUByy9d4vcCE%3d[/URL]

R9 - 470 kOhm 0.5W
[URL]https://www.mouser.com/ProductDetail/Xicon/293-470K-RC?qs=sGAEpiMZZMukHu%252bjC5l7YTF6je7BkLxK9noGLdhjO%252bM%3d[/URL]

R10 - 10 kOhm 0.5W
[URL]https://www.mouser.com/ProductDetail/Kamaya/RC1-2103KTD?qs=sGAEpiMZZMuDPtTs5Gda2zVPfE%252bWF6fk0b2CdrHg4Pk%3d[/URL]

R11 - 150 Ohm 0.5W
[URL]https://www.mouser.com/ProductDetail/Bourns/91A1A-B16-A28L?qs=sGAEpiMZZMtC25l1F4XBU0EalYS803k25mXQbjueSAw%3d[/URL]

R12 - 100 Ohm 0.5W
[URL]https://www.parts-express.com/100-ohm-1-2w-flameproof-resistor-10-pcs--002-100[/URL]

Recommended speakers 3" 8 Ohm 91 dB:
[URL]https://www.parts-express.com/faitalpro-3fe25-3-professional-full-range-woofer-8-ohm--294-1104?AID=1457483&PID=7598510[/URL]
 
R

rpi

Member
Joined 2015
Here is the BoM based on the components in the parts lists.

Power Supply:
$63.83 without resistors, shipping and tax (if any)

Amplifier:
$72.47 - one channel
$72.47 * 2 + $11.95(12AX7) = $156.89 without shipping and tax (if any)

----------------------------------------------------------------------------------------

Total: $63.83 + $156.89 = $220.72 without shipping and tax (if any)

The price also doesn't include sockets.
 
Last edited:
R

rpi

Member
Joined 2015
The components arrived, software release done, so I'm switching back to this project. I've tried to address the comments for the power supply in the following schematic - changed 110V to 120V, renamed T1 to L1, added bleeder resistors R1, R2:

ps-5.png


Now I'm trying to get the values for R5, R6. It looks like the current required for the tube heaters is 0.15 (12AX7) + 0.76(6BQ5) = 0.91. Using Ohm's Law we get 12.6/0.91 = 13.8/2 = 6.9 Ohm (12W) for R5, R6 which is a way different from 100 Ohm in this schematic:

https://www.diyaudio.com/forums/att...7189d1546834037-3-5w-tube-amp-dgse-ver2-0-jpg

Another mismatch with the same schematic is B++ voltage. In that schematic it's +255V, in our case it's +150V (same as in 6BQ5 datasheet). Which one is correct?

I've tried to use PSU Designer II to get R3-R4 values but couldn't figure out how can I do that in that program. Here is what I got so far:

psu-1.png


I would appreciate any help.
Thank you!
 
Last edited:
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