Bigbottle Phonostage Builders thread.

[Bigman80]

Probably I will do the same , there are some options there - 2SK170V or try to parallel BL’s but I need to get it soldered/working to do some simulations and atm I’m still working plus there is another little project I’m going through .

I will await your investigation Slav, as it appears there could be a voltage issue over the fet if we depart from the BF861C or 862.

IT ALSO seems that we may need to swap the 47R resistors to 68R if the 861c is to be used, to keep the valve in it's most linear state.

Alan and I were brainstorming this morning, over this very subject.

By brainstorming, I mean I asked loads of questions and Alan answered them lol

 

[Bigman80]

I'd settle for a raspberry Magnum



On the other hand I was listening to my build and enjoying what I was hearing when on the last track third album in the left channel started distorting and the full range driver was pumping in and out somewhat



Any pointers?

Erm.....innergroove distortion?

 

[Marra]

Unfortunately not with my Salas FSP back in play totally silent. Reconnected the Big Bottle everything turned on I turned up the left volume control and instant noise. Right channel is fine.

Feeling out of my depth with this So I will pm Alan and see if he would sort for me.

 

[slav]

What’s the cartridge and tonearm ? Possibly it could be combination of mismatch when it comes to compliance and effective mass and not perfect alignment,also what was the frequency of output oscillation , how quick sine mapping ? would help if you had an oscilloscope or use some oscilloscope software.

 

[slav]

Looks like we posted at the same time , please ignore mismatch comment

 

[Marra]

Thanks slav unfortunately my test gear has never expanded further than a few DMM.

 

[slav]

Thanks slav unfortunately my test gear has never expanded further than a few DMM.

Are both channels test same at DC condition?
I have no knowledge of the circuit so is just out of curiosity question , I'm certain Alan will sort it out

 

[ikir]

I will await your investigation Slav, as it appears there could be a voltage issue over the fet if we depart from the BF861C or 862.

IT ALSO seems that we may need to swap the 47R resistors to 68R if the 861c is to be used, to keep the valve in it's most linear state.

Alan and I were brainstorming this morning, over this very subject.

By brainstorming, I mean I asked loads of questions and Alan answered them lol

There seems to be BF861C available here: BF861C,215 NXP USA Inc. | Discrete Semiconductor Products | DigiKey

is it not what we need?

 

[Bigman80]

There seems to be BF861C available here: BF861C,215 NXP USA Inc. | Discrete Semiconductor Products | DigiKey



is it not what we need?

Yes

 

[Marra]

Are both channels test same at DC condition?
I have no knowledge of the circuit so is just out of curiosity question , I'm certain Alan will sort it out

I will recheck all the voltages again in the morning.

Hopefully Alan will be able to help me out as I was very much enjoying what I was hearing for most of the three LP's I listened to. Safe to say I think that Oliver is on a winner with this phono stage.

 

[slav]

Can you measure voltages on both channels for BF861C on all 3 legs as on one of attached earlier photos (photo on the left h/s) and check the outputs as well , thanks

 

[Bigman80]

I will recheck all the voltages again in the morning.

Hopefully Alan will be able to help me out as I was very much enjoying what I was hearing for most of the three LP's I listened to. Safe to say I think that Oliver is on a winner with this phono stage.

It is a good phonostage! I love mine.

Hopefully you can get this up and running soon

 

[Marra]

Can you measure voltages on both channels for BF861C on all 3 legs as on one of attached earlier photos (photo on the left h/s) and check the outputs as well , thanks

I measured voltages at the jfet pins and have at the gate 0v; source 0.284; drain 2v. This is on both channels. All other voltages at the valves are as before.

 

[Marra]

It is a good phonostage! I love mine.

Hopefully you can get this up and running soon

I am looking forward to that very much. I will be sending it to Alan next week for sorting. Hope he won't be to critical of my smd skills or rather lack of

 

[Bigman80]

I am looking forward to that very much. I will be sending it to Alan next week for sorting. Hope he won't be to critical of my smd skills or rather lack of

Lol, no he is far too much of a Gentleman to tell all.

 

[slav]

I measured voltages at the jfet pins and have at the gate 0v; source 0.284; drain 2v. This is on both channels. All other voltages at the valves are as before.

Thanks , anyone could share what's the load resistor , I take 47R is source/biasing value?

 

[Vivant]

Yes it is the source resistor. 0.284V is perfect giving a valve current of 6mA.

 

[Marra]

Bigman80 do you have a link to the the chassis you housed your build in please?

 

[Scotty38]

Think it's this one:


a.aliexpress.com/_d833bkK

 

[Sangram]

The correct link is this:

2018 New small rounded front / decode / BZ2409HFull Aluminum amplifier Chassis amplifier case|Amplifier|Consumer Electronics - AliExpress