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Bigbottle MC only Valve/JFET phonostage Group Buy

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Hi all,

This is a bit of a 'test the water' post.

Firebottle and I decided to do a joint project together a little while back. The goal was for me to have a valve phonostage that didn't cost the earth and could hang with the big boys. Alan (Firebottle) suggested I try a DIY project which would keep the cost down and could be built over time when funds were available.

I settled on a board I found online and spent the £9 it cost to buy and get here and I built it. The biggest issue I had was the lack of PSU. This needed building from scratch and pretty soon I was out of my depth and in need of some assistance.

However, this got me thinking. I wanted a DIY phonostage board that was so easy to build that anyone could do it from start to finish, practically unaided.
I searched the internet and there were a few SS ones which might have been a possibility but I wanted valves.

I couldn't find anything that was easy enough so I approached Alan about starting one from scratch. Luckily Alan agreed and we set about the BIGBOTTLE phonostage. I wanted to eliminate the need to build a PSU separately from the main PCB. I don't have the knowledge to build one so I decided that it must be included on the main PCB. Following the same 'paint by numbers' approach as the original DIY phonostage I built.

We took a decent lump of the design from Alan's Vivant phonostage but added a few tweaks. One being the EQ. I wanted a split Eq so that's what we did. The other major difference was MM/MC capability. I didn't want it, so it was made MC only.

We got as far as we could and then needed some help. We had a P2P prototype which I was very pleased with. It has been to a couple of bakeoffs and when compared against some stuff opposition, it was well received. Unfortunately, neither I nor Alan had the ability to convert the practical or theory into a PCB.

We reached out here, on DIYaudio to see if anyone could help. Enter JP.

Jean was willing to help us and took a hand drawn circuit diagram and converted it into a digital version. Next came the mock up PCB layout and on to the final build files.

I sent the files to a company in China and had 5 boards made. I kept one for myself, sent the others out to guinea pigs (lol) and 2 to JP to thank him for his work. I, got to work making mine. I built everything myself, a noob, with limited knowledge. And it worked!!! Alan has tested it and it's a success.

Now up and running and being thoroughly enjoyed daily, I have decided that as soon as JP has finished the final revisions to the design, I will offer a group buy for 10 people. This is going to be a controlled 'roll out' just to see how,

A) Easy it is to build.
B) Get some opinions on performance.

Included with the board will be a BOM. I will also do a Noobs build guide, which should be simple to follow as I have proved lol. The phonostage is MC only.

The first 10 boards will be sold at cost of the board plus postage.

If you are interested, just leave a note on the thread and I'll get in touch.

Pics of the board I built will be added asap.
 
Hello. count me in. What tubes it this thing using? Robert.

Hi Robert,

2x PCC88 & 1x ECC83

I've got Telefunken in mine but have tried a few others. I haven't managed to try any expensive or rare valves as of yet so that could be something worthwhile.

The choice of valves may seem odd but it gives very low Miller capacitance and low output Impedance. Also, being P valves, they are a bit cheaper whilst not sacrificing any performance IMO.
 
Hi Joachim,

I do, but i don't have permission to share it. I attained elements of the circuit on the basis of it not being published. Alan makes his Firebottle range and as this PCB has elements of the design, it would be unfair to share them against his wishes.

If there is something specific you wanted to know? Maybe i can either answer it or get an answer.
 
No idea how hot the 5W resistors get, but even if they only dissipate 1W they appear dangerously close to the film caps.

There's actually more space than the picture suggests, 5mm id estimate. There is also the option of mounting them a little more centrally if you manipulate the legs a little. Also, the 5W resistor is overkill. It was not necessary to use 5w, 3W was also over spec but i went a little OTT so there isnt a concern about heat from it.

The Capacitors are rated well for the location:

Climatic category: 55/105/56 IEC 60068-1 / Operating temperature range of -55°C to +105°C

Temperature checks have taken place and the range was well within spec with no cause for any concern.

I will just add that this was a prototype board and as with the other little bits i wanted to change, i did ask for a little more room on the board so there should be a bit more space between components on the final board design.

One of the things i really wanted to achieve was a board with as little distance as possible between components. That is what we have done. :yes:
 
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