DIY Simple Active Preamp
- Thread starter HypnoToad
- Start date
It's alive!
I had more on my plate this weekend than I realized so I only got to assemble the B1 Buffer to testing stage. I graded the 12 x 2sk170BL's and got two pairs that were very close to the 10ma that Nelson recommends. So far I have run it connected to the PSU I built and it works fine. No hum or noise at all.
I did make one change, there is a 10uf cap at output of the 2sk170, Nelson Pass recommended using a polyester. I hate polyesters so I put in a 10uf Nichicon Muse ES and a 0.1uf polypropylene bypass cap. Using just an Electrolytic with the bypass cap is better than a polyester IMO YMMV.
Now to the sound, I have plenty of volume, 11.30 is about right for my bedroom system with plenty in reserve. I know my phono stage had a high output so with lower output stages there will still be enough.
Things have to burn in of course, but out of the box the sound is very clean, open and detailed. It seems more forward than the DIY simple preamp I was using, but could mean that the other was laid back.
Also I am going to try it on batteries after some burn in, but it is very good and not needing any more gain I am not sure if I need the Jfet BOZ but since having a PCB and parts for it I will build it and see what it's like.
I had more on my plate this weekend than I realized so I only got to assemble the B1 Buffer to testing stage. I graded the 12 x 2sk170BL's and got two pairs that were very close to the 10ma that Nelson recommends. So far I have run it connected to the PSU I built and it works fine. No hum or noise at all.
I did make one change, there is a 10uf cap at output of the 2sk170, Nelson Pass recommended using a polyester. I hate polyesters so I put in a 10uf Nichicon Muse ES and a 0.1uf polypropylene bypass cap. Using just an Electrolytic with the bypass cap is better than a polyester IMO YMMV.
Now to the sound, I have plenty of volume, 11.30 is about right for my bedroom system with plenty in reserve. I know my phono stage had a high output so with lower output stages there will still be enough.
Things have to burn in of course, but out of the box the sound is very clean, open and detailed. It seems more forward than the DIY simple preamp I was using, but could mean that the other was laid back.
Also I am going to try it on batteries after some burn in, but it is very good and not needing any more gain I am not sure if I need the Jfet BOZ but since having a PCB and parts for it I will build it and see what it's like.
skywave-rider
Slumming in Akihabara
Awesome.
I assume you'll run the JFET BOZ following the B1?
I assume you'll run the JFET BOZ following the B1?
No need to as I have more than enough volume now. The Phonoclone 3 phono stage has the output of a typical CD player.
I really like the smooth increase in volume, with the internal preamp of my Yamaha CR-1020 I can only have it at 9.00am. With the B1 that level is reached at 12.00pm and at lower levels I still have very detailed sound, the Yamaha seems to lose that at lower volumes for some reason.
It is more open than the op amp Simple PreAmp I made, but hey this is a Nelson Pass design so it's what you would expect from the Guru.:thmbsp:
skywave-rider
Slumming in Akihabara
I'm impressed you popped out those boards so quickly. Congrats.
When you put it in a case, will you keep the (-) of the in/out floating from the chassis?
When you put it in a case, will you keep the (-) of the in/out floating from the chassis?
I can but it's really not necessary IMO.
Russellc
Addicted Member
It's alive!
I had more on my plate this weekend than I realized so I only got to assemble the B1 Buffer to testing stage. I graded the 12 x 2sk170BL's and got two pairs that were very close to the 10ma that Nelson recommends. So far I have run it connected to the PSU I built and it works fine. No hum or noise at all.
I did make one change, there is a 10uf cap at output of the 2sk170, Nelson Pass recommended using a polyester. I hate polyesters so I put in a 10uf Nichicon Muse ES and a 0.1uf polypropylene bypass cap. Using just an Electrolytic with the bypass cap is better than a polyester IMO YMMV.
Now to the sound, I have plenty of volume, 11.30 is about right for my bedroom system with plenty in reserve. I know my phono stage had a high output so with lower output stages there will still be enough.
Things have to burn in of course, but out of the box the sound is very clean, open and detailed. It seems more forward than the DIY simple preamp I was using, but could mean that the other was laid back.
Also I am going to try it on batteries after some burn in, but it is very good and not needing any more gain I am not sure if I need the Jfet BOZ but since having a PCB and parts for it I will build it and see what it's like.
There's a board for the J-fet BOZ? Ordid you make it? If so lets see a mini tutorial! (on the BOZ board particularly) Nice little power supply!
Russellc
Hmm mini tutorial. :scratch2:
First off I make the PCB design in ExpressPCB and printout the bottom copper layer onto Glossy Inkjet paper using my laser printer at work. The bottom copper layer prints out the right size automatically and doesn't need to be reversed.:
I copy the silkscreen to the clipboard from the Edit menu and paste it into Paint so I can reverse the image, if not it's back to front. You have to scale it to the correct size before printing though, you can print it onto regular paper to get the size right first before using the Glossy paper.
Get the right size copper clad or cut a piece to size using a hacksaw. Always cut or drill while using a mask. Use a green scouring pad with some Ajax/Comet on it to get it shiny clean. Using a steam iron, turn off the steam and set to the hottest setting. Iron on the printout for the bottom copper layer first pressing down fairly hard, I take 2 - 3 minutes and let it cool. Put it in some warm soapy water for 15 minutes which will allow the paper to peel off easily. Run the copper clad under warm water and rub it gently with your fingers until all the slimy glue stuff from the paper comes off.
Check your design and touch up any missing bits with a BIC permanent marker there better than Sharpies for this.
I use Sodium Persulphate etchant, you can buy it online, I get mine from Frys. Mix 2 or 3 heaped plastic teaspoonfuls in a plastic dish with enough hot water to cover your copper clad, be careful, wear rubber gloves and eye protection.
Put the copper clad in face up and let it sit for ten minutes then start to slowly agitate it so there are little ripples on the surface, do this every few minutes until all the bare copper is gone. Dispose of the solution carefully, don't throw it down the drain or let it come into contact with metal. Only use plastic containers for it.
Wash the copper clad thoroughly wearing rubber gloves and let it dry. Drill the holes. I use Carbide bits in a rotary tool press, 0.75mm for resistors, 0.85mm for larger capacitors, 0.95mm for diodes and 1.1mm for leads.
Once done you can clean off the black toner with the scouring pad and Ajax/Comet. Once dry you iron on the silkscreen to the other side, line it up using a bright light, it's easy. Put it in the soapy water again for 15 minutes and wash and clean the sticky glue stuff off under warm running water.
Now your ready to go.
First off I make the PCB design in ExpressPCB and printout the bottom copper layer onto Glossy Inkjet paper using my laser printer at work. The bottom copper layer prints out the right size automatically and doesn't need to be reversed.:
I copy the silkscreen to the clipboard from the Edit menu and paste it into Paint so I can reverse the image, if not it's back to front. You have to scale it to the correct size before printing though, you can print it onto regular paper to get the size right first before using the Glossy paper.
Get the right size copper clad or cut a piece to size using a hacksaw. Always cut or drill while using a mask. Use a green scouring pad with some Ajax/Comet on it to get it shiny clean. Using a steam iron, turn off the steam and set to the hottest setting. Iron on the printout for the bottom copper layer first pressing down fairly hard, I take 2 - 3 minutes and let it cool. Put it in some warm soapy water for 15 minutes which will allow the paper to peel off easily. Run the copper clad under warm water and rub it gently with your fingers until all the slimy glue stuff from the paper comes off.
Check your design and touch up any missing bits with a BIC permanent marker there better than Sharpies for this.
I use Sodium Persulphate etchant, you can buy it online, I get mine from Frys. Mix 2 or 3 heaped plastic teaspoonfuls in a plastic dish with enough hot water to cover your copper clad, be careful, wear rubber gloves and eye protection.
Put the copper clad in face up and let it sit for ten minutes then start to slowly agitate it so there are little ripples on the surface, do this every few minutes until all the bare copper is gone. Dispose of the solution carefully, don't throw it down the drain or let it come into contact with metal. Only use plastic containers for it.
Wash the copper clad thoroughly wearing rubber gloves and let it dry. Drill the holes. I use Carbide bits in a rotary tool press, 0.75mm for resistors, 0.85mm for larger capacitors, 0.95mm for diodes and 1.1mm for leads.
Once done you can clean off the black toner with the scouring pad and Ajax/Comet. Once dry you iron on the silkscreen to the other side, line it up using a bright light, it's easy. Put it in the soapy water again for 15 minutes and wash and clean the sticky glue stuff off under warm running water.
Now your ready to go.
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HT,
I finished a tub of turkey breast sandwich meat last week, now I have an enclosure for a board.
I enjoy shocking my friends. The same as Fasterdamnit shocked me with a phono stage in a cardboard box that I couldn't even tell when it was on. No noise, no hiss no hum. Impressive!
I finished a tub of turkey breast sandwich meat last week, now I have an enclosure for a board.
I enjoy shocking my friends. The same as Fasterdamnit shocked me with a phono stage in a cardboard box that I couldn't even tell when it was on. No noise, no hiss no hum. Impressive!
westend
Audiopile
Hypno, your tutorial on etching makes this seem too easy, I've got to try this!
Yeah, the B1 is basically a disappearing act, no coloration and good detail. If you haven't built one, the F5 amp should be on your list for projects. The B1 and F5 are like peanut butter and jelly.
Yeah, the B1 is basically a disappearing act, no coloration and good detail. If you haven't built one, the F5 amp should be on your list for projects. The B1 and F5 are like peanut butter and jelly.
Woody1911a1
Active Member
wonder how it would sound with a turbo F5 ?
"The F5 continues to be more popular than I expected. As a reward to the
faithful, I have completed the F5 Turbo.
The pc boards are on order, and when they arrive I will present it complete.
ps - you can modify existing F5's to make one. " Nelson Pass
"The F5 continues to be more popular than I expected. As a reward to the
faithful, I have completed the F5 Turbo.
The pc boards are on order, and when they arrive I will present it complete.
ps - you can modify existing F5's to make one. " Nelson Pass
Smoked or Mesquite?
It makes a difference to the sound you know.
Jim is a shocker alright, he put one in a gold trimmed box as well.
Russellc
Addicted Member
wonder how it would sound with a turbo F5 ?
"The F5 continues to be more popular than I expected. As a reward to the
faithful, I have completed the F5 Turbo.
The pc boards are on order, and when they arrive I will present it complete.
ps - you can modify existing F5's to make one. " Nelson Pass
Great....another project....where is the F-5 turbo? I'll go search around DIYaudio site....whoops, just found it!
Russellc
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The secret is using Glossy Inkjet paper and it must be printed with a laser printer, you should also set the printer properties to Glossy paper as well. I cut it into 3 pieces and use the envelope slot on the laser printer. Then select bottom copper layer and envelope as the paper size. That way you get 3 printouts per sheet of paper.
Also you must make sure you clean off all the gooey stuff on the PCB after ironing and soaking under warm running water. If you don't your board will not etch properly.
I learned the hard way.
Woody1911a1
Active Member
please reread my quote of NP "The pc boards are on order, and when they arrive I will present it complete."
and he posted that in the F5 thread just a few mins ago
nashvillebill
Super Member
The secret is using Glossy Inkjet paper and it must be printed with a laser printer, you should also set the printer properties to Glossy paper as well. I cut it into 3 pieces and use the envelope slot on the laser printer. Then select bottom copper layer and envelope as the paper size. That way you get 3 printouts per sheet of paper.
Also you must make sure you clean off all the gooey stuff on the PCB after ironing and soaking under warm running water. If you don't your board will not etch properly.
I learned the hard way.
I've been meaning to try this (PCB etching) for years. Too many projects on my list though!
Thanks for the tips!!!
skywave-rider
Slumming in Akihabara
HypnoToad,
Have you looked at any of the other variations to the schematic seen in the JFET BOZ DIY thread? Looks like you've used the original Pass schematic. I've been bouncing around in that thread looking, but getting bleary eyed.
Original
R5 and R6 controversy.
Have you looked at any of the other variations to the schematic seen in the JFET BOZ DIY thread? Looks like you've used the original Pass schematic. I've been bouncing around in that thread looking, but getting bleary eyed.
Original
R5 and R6 controversy.
No I just went on what Nelson Pass did, but resistor values can be changed at any time.
I have been listening to the B1 a lot and I find it just too clean and sterile, the sound stage and "musicality" of the simple preamp is better IMO. But that may just be mental illness on my part.
Maybe the difference is the op amps give it a bit of coloration that I like and the 2sk170's don't. It's a really revealing and good sounding stage but maybe not my cup of tea. It's kinda like putting in LM4562's in my phono stages, of course they have low distortion and other great specs but the sound is too cold for me especially on there own.
I am going to finally remove the two 15k resistors from the simple preamp and fit all 10k resistors in the feedback loops. I will also put the 25k pots I got for the B1 into that to see if that's an improvement.
But as it stands I don't think even getting a high end output cap is going to bring the B1 into what I like. YMMV
Russellc
Addicted Member
No I just went on what Nelson Pass did, but resistor values can be changed at any time.
I have been listening to the B1 a lot and I find it just too clean and sterile, the sound stage and "musicality" of the simple preamp is better IMO. But that may just be mental illness on my part.
Maybe the difference is the op amps give it a bit of coloration that I like and the 2sk170's don't. It's a really revealing and good sounding stage but maybe not my cup of tea. It's kinda like putting in LM4562's in my phono stages, of course they have low distortion and other great specs but the sound is too cold for me especially on there own.
I am going to finally remove the two 15k resistors from the simple preamp and fit all 10k resistors in the feedback loops. I will also put the 25k pots I got for the B1 into that to see if that's an improvement.
But as it stands I don't think even getting a high end output cap is going to bring the B1 into what I like. YMMV
May be system dependant, I find mine clean, but hardly sterile. Mine is warm with lots of bass. What amp and speaks are you using? I do tend to favor my pre with gain in some instances. I need to throw together the J-fet BOZ!
Russellc