$50 Three Tube Preamp

Poultrygeist · « **Reply #40 on:** 21 Jul 2014, 11:12 am »

I'd have to take mine apart to measure it but it fits nicely in my 10"X 7" case that's 3" tall. The tubes extend slightly through the open top but the whole board is elevated slightly on stand offs from Radio Shack. You could squeeze everything into a 7"x 7" case if you don't mind crowding things a bit.

I have no experience removing the pot and can only help with the transformer connections if it's 110v with all blue except for a single black wire. The two power leads being red.

The 6n3p-ev's are so cheap that a matched pair makes sense although I really don't think it matters. No need to replace the rectifier tube.

downunder55 · « **Reply #41 on:** 21 Jul 2014, 01:55 pm »

Quote from: Poultrygeist on 21 Jul 2014, 11:12 am

............ it fits nicely in my 10"X 7" case that's 3" tall. The tubes extend slightly through the open top

Thanks, hopefully someone hasn't enclosed theirs yet, I have found an aluminium case that is 48mm or 1 7/8" high was hoping that the caps would fit with this and I could then cut 3 neat holes in the top for the tubes to stick out the top and protect them with a little cage, I like that look !

Quote from: Poultrygeist on 21 Jul 2014, 11:12 am

The 6n3p-ev's are so cheap that a matched pair makes sense although I really don't think it matters. No need to replace the rectifier tube.

From what I could find you can get 8 Non matched tubes for around $20 delivered, or 2 matched for $23 ..... or if you are really keen a bulk pack of 100 !

Poultrygeist · « **Reply #42 on:** 21 Jul 2014, 11:06 pm »

The caps are slightly less than 1.5".

Poultrygeist · « **Reply #43 on:** 21 Jul 2014, 11:12 pm »

Going for this great look?

http://schiit.com/products/valhalla-2

downunder55 · « **Reply #44 on:** 22 Jul 2014, 04:33 am »

Quote from: Poultrygeist on 21 Jul 2014, 11:12 pm

Going for this great look?

http://schiit.com/products/valhalla-2

Thanks so much for the dimension ........ Ummie that Valhalla looks great, yes a more DIY look than that unfortunately, looking for a case something like this (a little cheaper hopefully) http://www.ebay.com/itm/S-2205-silver-panel-aluminum-box-enclosure-preamp-case-headphone-amp-chassis-sn-/191191824801?pt=US_Amplifier_Parts_Components&hash=item2c83ebb9a1

Plus some version of these - http://www.ebay.com/itm/Tube-Guard-Protector-PreAmp-Silver-12AX7-12AU7-6922-5687-ECC82-ECC81-6N11-/400500213654?pt=Vintage_Electronics_R2&hash=item5d3fac4796

Saw this board in my travels, could be interesting, checking with supplier to see if it also has pre-outs - http://www.ebay.com.au/itm/Assembled-Tube-6N3-6Z4-lehmann-circuit-Headphone-Amplifier-board-class-AMP-/120926988641?pt=UK_AudioTVElectronics_HomeAudioHiFi_Amplifiers&hash=item1c27cf6961

downunder55 · « **Reply #45 on:** 22 Jul 2014, 04:49 am »

Quote from: downunder55 on 22 Jul 2014, 04:33 am

Saw this board in my travels, could be interesting, checking with supplier to see if it also has pre-outs - http://www.ebay.com.au/itm/Assembled-Tube-6N3-6Z4-lehmann-circuit-Headphone-Amplifier-board-class-AMP-/120926988641?pt=UK_AudioTVElectronics_HomeAudioHiFi_Amplifiers&hash=item1c27cf6961

Unfortunately no pre-outs.

Poultrygeist · « **Reply #46 on:** 22 Jul 2014, 10:02 am »

Quote from: downunder55 on 22 Jul 2014, 04:49 am

Unfortunately no pre-outs.

For around $5 you can buy a cable with RCA's attached that plugs into that board. The plug in for that cable is in the right corner.

downunder55 · « **Reply #47 on:** 22 Jul 2014, 10:19 am »

Quote from: Poultrygeist on 22 Jul 2014, 10:02 am

For around $5 you can buy a cable with RCA's attached that plugs into that board. The plug in for that cable is in the right corner.

It seems to be marked input, so the RCA's you describe would be to provide input from the source I would think ?

I was hoping this board was going to be an alternative to the YJ6N3 pre-amp but also had a headphone amp attached, unfortunately not.

Poultrygeist · « **Reply #48 on:** 22 Jul 2014, 10:26 am »

wes_in_va · « **Reply #49 on:** 7 Aug 2014, 11:17 am »

I bought one of the 2 tube units from the seller doukmall on the bay of e.
I can't figure out the transformer wiring and can't find the answer after much googling.
Mine has 2 red and 2 black on 1 side, and 2 blue and 2 white on the other. On top it's labeled 0-110 on the 2 blue/2 white side and 6.3v/170v on the other side. Can anyone offer any help?

I'm dying to try this out with my TPA3110 Sure board but I don't want to risk frying the pre in the process!

mboxler · « **Reply #50 on:** 7 Aug 2014, 02:35 pm »

Quote from: wes_in_va on 7 Aug 2014, 11:17 am

I bought one of the 2 tube units from the seller doukmall on the bay of e.
I can't figure out the transformer wiring and can't find the answer after much googling.
Mine has 2 red and 2 black on 1 side, and 2 blue and 2 white on the other. On top it's labeled 0-110 on the 2 blue/2 white side and 6.3v/170v on the other side. Can anyone offer any help?

I'm dying to try this out with my TPA3110 Sure board but I don't want to risk frying the pre in the process!

Can you give us a picture of the label?

My guess would be that you would tie the two blues together and the two whites together.
Wire one of the tied pairs to house AC live, the other to house AC neutral.
I'd put a slow blow fuse on the live side.

The red wires are probably the 170V to the preamp for B+. The blacks are probably the 6.3v for the tube heaters.

Even with a picture, I'd test the tranny with a DMM, and PLEASE be careful.
The preamp can be replaced. You cannot.

Mike

ScheduleWon · « **Reply #51 on:** 16 May 2015, 12:29 pm »

Hey All,

I bought two and cannot get them to work. can anyone forward me directions please? Thanks.

lacro · « **Reply #52 on:** 16 May 2015, 05:12 pm »

Quote from: wes_in_va on 7 Aug 2014, 11:17 am

I bought one of the 2 tube units from the seller doukmall on the bay of e.
I can't figure out the transformer wiring and can't find the answer after much googling.
Mine has 2 red and 2 black on 1 side, and 2 blue and 2 white on the other. On top it's labeled 0-110 on the 2 blue/2 white side and 6.3v/170v on the other side. Can anyone offer any help?

I'm dying to try this out with my TPA3110 Sure board but I don't want to risk frying the pre in the process!

I looked at the suppliers site (doukmall). They do show transformer wiring instructions for some of their preamps. Which preamp do you have?

undertowogt1 · « **Reply #53 on:** 12 Jul 2017, 03:42 am »

Finally bought the Sain Smart Preamp, about 43 bucks Canadian shipped. Spent my free time the last few days making a box and making this thing look nice. I am happy for sure, sounds good and looks good. I am going to get some better tubes and see how it sounds. I just need to cut the holes in my top piece to accommodate the tubes sticking through.

Poultrygeist · « **Reply #54 on:** 12 Jul 2017, 10:24 am »

Great job with the Sain Smart. I did a second one with a premade case from a craft store. Cutting the holes for the tubes to protrude through the top was the most difficult part.

skrstc · « **Reply #55 on:** 19 Jul 2017, 05:06 pm »

http://www.sovtube.com/tubes/865-6cc42.html
Tesla 6cc42 sounds better then GE 5670.

undertowogt1 · « **Reply #56 on:** 27 Jul 2017, 05:15 pm »

look like they stepped up there game a little bit

https://www.sainsmart.com/tools-equipments/amplifier-1/sainsmart-assembled-6n3-hifi-buffer-audio-tube-headphone-amplifier-pre-amp-kit-with-transformer.html

Look pretty nice to me and still at an affordable price

Poultrygeist · « **Reply #57 on:** 27 Jul 2017, 11:58 pm »

A picture of my $35 Sain Smart with the lid down

Poultrygeist · « **Reply #58 on:** 28 Jul 2017, 12:06 am »

undertowogt1 · « **Reply #59 on:** 4 Aug 2017, 12:52 am »

Quote from: Poultrygeist on 27 Jul 2017, 11:58 pm

A picture of my $35 Sain Smart with the lid down

Very Nice. I think I will be adding an ON switch like your in the future.