Wayne's BA 2018 linestage

[william2001]

Wayne's LS has a really nice low output impedance and low DC offset, so I have found that I like an autoformer on the output for more gain (+6). I use the 80% nickel Cinemags (CMOQ-4H). The Jensens's from the F6 work well too. Slightly different character.

 

[soldersmoker]

Wayne's LS has a really nice low output impedance and low DC offset, so I have found that I like an autoformer on the output for more gain (+6). I use the 80% nickel Cinemags (CMOQ-4H). The Jensens's from the F6 work well too. Slightly different character.

Yes, that looks like a perfect solution for what I want. I saw your builds while going through the thread earlier today and realized 6 dB gain using transformers were exactly what I was looking for--and hadn't realized it until I saw it. Thanks for the inspiration!

 

[william2001]

I've got the diagram for the Jensen somewhere too if someone needs it.

 

[soldersmoker]

That will prove useful to me, thanks, William. Do you have a photo of the Cinemags in situ, just so I can be 100% confident that I install them correctly?

 

[El Reino]

Hello all, i was listening Wayne's LS and MoFo. Super combination. Thank you Wayne, 6L6, and all you.

 

[soldersmoker]

Dumb question about the Cinemag line out transformers: Can I use them as input transformers inside the F4?

 

[william2001]

That will prove useful to me, thanks, William. Do you have a photo of the Cinemags in situ, just so I can be 100% confident that I install them correctly?

Not my best work with the coax. I was just trying to bypass an intermittent RCA connector that was causing some frustration.

 

[elwood625]

Will a 10K log pot work for a volume control, I remember reading somewhere on this thread about 20K, just not sure. I have a 10K in stock, if 20K is best, then I'll go find one.

 

[soldersmoker]

Not my best work with the coax. I was just trying to bypass an intermittent RCA connector that was causing some frustration.

That is what I needed. Thanks.

 

[Russellc]

I've got the diagram for the Jensen somewhere too if someone needs it.

Unless you already posted it, I asked about this back when you first added the transformers, I believe they were jensens at first? You may have posted it then. Otherwise I would like to see this with jensen, with my rebuild (got a new board from store) I would like an alternate out with this. One out regular, one out hooked to transformers.

Thanks,

Russellc

 

[william2001]

Credit to Zen Mod for this one:

 

[Russellc]

Thanks!

Russellc

 

[Mark Johnson]

I think if you study the schematic attached to post #1 of this thread, you will discover that the gain of the entire PCB is (R16 + R17)/R17.

Thus you can CHANGE the gain, either upwards or downwards, by changing the resistance value of R16 or R17 or both.

Naturally you must consider the circuit's stability (propensity not to oscillate) too. In this case with single dominant pole compensation, the circuit happens to become more stable when you increase the gain. Good news perhaps, for people who want an extra +6dB.

 

[soldersmoker]

I think if you study the schematic attached to post #1 of this thread, you will discover that the gain of the entire PCB is (R16 + R17)/R17.

Thus you can CHANGE the gain, either upwards or downwards, by changing the resistance value of R16 or R17 or both.

Naturally you must consider the circuit's stability (propensity not to oscillate) too. In this case with single dominant pole compensation, the circuit happens to become more stable when you increase the gain. Good news perhaps, for people who want an extra +6dB.

Fantastic explanation, Mark! I will experiment, within reason.

 

[stablgr]

Hi all. After successfully completing the Whammy headphone amp and building an external power supply for a pre and power amp I've almost got all the parts sourced for building the BA2018 line stage. I'm looking for some advice regarding the selection of potentiometer for the volume control. I've got two Alps pots to hand, 10k and 50k. Would one of these be better suited than the other, or is there a different value I should be looking at using?

Thanks in advance,
Gary

 

[avdesignguru]

I prefer the 50K with this circuit

 

[6L6]

The BA2018 doesn’t care about pot value, your sources do. If you have something that has a tube output, you’ll likely have the best luck with the 50K. If your sources are all solid state output, the 10K will work well.

Try both, see if there’s much of a difference.

 

[stablgr]

Thanks guys. I don’t have any tube gear, at least not yet (never say never), so will try the 10k version first.

 

[6L6]

Get building!

Tube/Valve stuff is a lot of fun. Try a power amp.

 

[stablgr]

I think I’ve got enough on the cards to keep me busy for a while. Building the Whammy really got me hooked and I now should have most, if not all, of the boards and parts to build an F5, M2x, Korg B1 and a Pearl II. But no harm in adding more to the list.