Its an old post that I just saw by browsing back but its worth commenting I guess especially since my shunts are combined in some builds here.
I have not read that full article only seen the measurements part in the Linear Audio website which were really good and matched the SPICE predictions in difficult to cleanly & accurately measure areas without AP level gear, like the noise and Zo magnitude across a wide bandwidth.
As for the subjectives, due to much scattered information about the versions and practices with the SSLV its possible they did not know specifics and had small value undamped bypasses on that test preamp rails which can resonate with the sense wiring inductance. Especially if with longish wiring in Kelvin mode. In the face of so good measurements they either should have truly heard something lesser due to interference or oscillation, or simply some other regs were easily better. Given they have checked that the rails were untroubled before subjective tests for all designs, also that the current limit was well chosen for the test preamp dynamics in regs equipped with CCS.
Anyway after the SSLV1.1's objective performance got confirmed to spec by that big measurement effort from Jack going through so many designs (great lab work), the subjective evaluation thing is much simpler to be repeated by the reader for any featured reg from the article. Its just about trusting his ears after scoping for clean rails in a build. Specifically for the SSLV1.1 there is easy way to go conventional two wire output if there is trouble and other things to check. Its all in its builds thread.
Using the BA-3 gain stage (“Front-end”) as a line stage preamp. A mini build guide.
Any project needs to start with a good PSU - this is an Antek 20+20V shielded transformer, and 317/337 linear regulator PSU from Tubecad.com. (Model PS-12)
Jim, what is your rail voltage with that 20+20v Antek transformer? Would an 18+18v give 24v rails?
I couldn't order a PS-19 from tubecad as they're out of stock. I picked up an LCBPS from Twisted Pear--it's the same power supply circuit as the PS-19 from tubecad.
The rail voltage is whatever the regulators are set to...
Remember the regulators need a bit more input voltage than the nominal output - all regulators eat a volt or two when doing their job.
The Twisted Pear is a really nice board, it will work well.
So, theoretically, 18VAC * 1.414 yields 25.38VDC after rectification. Subtract a little for losses should give you a maximum of about 24volts DC?
Antek AS-0520 it is then.
That's what I used, this power supply on one BA-3 pre: GlassWare PS-19 Bipolar Power Supply Kit
And on the other was a PS built on Peter Daniels Power Supply boards that 6L6 helped GREATLY with! Thanks again 6L6!
Russellc
I have a couple of questions regarding my current BA3 fe build. The first relating to pot value on the input and the second regarding jfet/output cap placement.
Firstly, I plan to use an alps blue for volume control my question is should I use a 50k or 100k is there a technical/sound preference for one over the other.
Secondly, I have purchased some Mundorf evo oil 10uf caps as output coupling caps i.e. C3. My issue is that they are quite big i.e. 40mm diameter and 27mm long - so quite a squeeze. I have seen some use these have had to push the jfets over out of the way of the caps. My question is is it ok to do this and if so are there risks or issues i.e. does it matter if the jfets touch each other or the outside of the mundorf caps. An option I had thought about is to mount the jfets on the bottom of the board and use reasonably high offsets to give them some breathing space. Are there any particular pros and cons for doing this. Alternatively I had thought about mounting the mundrofs up high off the board to give the (top mounted) jfets some space, but should I put a spacer under the mundorfs, and if so what could I use - some balsa or something else. Again are there any issues for me to be aware of.
Any help would be appreciated, regards Nigel.
Firstly, I plan to use an alps blue for volume control my question is should I use a 50k or 100k is there a technical/sound preference for one over the other.
Secondly, I have purchased some Mundorf evo oil 10uf caps as output coupling caps i.e. C3. My issue is that they are quite big i.e. 40mm diameter and 27mm long - so quite a squeeze. I have seen some use these have had to push the jfets over out of the way of the caps. My question is is it ok to do this and if so are there risks or issues i.e. does it matter if the jfets touch each other or the outside of the mundorf caps. An option I had thought about is to mount the jfets on the bottom of the board and use reasonably high offsets to give them some breathing space. Are there any particular pros and cons for doing this. Alternatively I had thought about mounting the mundrofs up high off the board to give the (top mounted) jfets some space, but should I put a spacer under the mundorfs, and if so what could I use - some balsa or something else. Again are there any issues for me to be aware of.
Any help would be appreciated, regards Nigel.
Of those two, yes. I used 25K and many encouraged to drop to 10K. 6L6 used 50K, as he had a 50K goldpoint at hand. This looks like what I, and a few others used. Out of 3, I had one with a bad internal connection. Best 20 bucks I've ever spent on a volume pot. I used them on both BA-3 FE I built.
4POLE 24 Step Attenuator Volume Control Pot Log A 25K 25kA Stereo Potentiometer | eBay
Russellc
Hi to all pre amp bullders.
I am trying to find a proper power switch for my DCB1 and it looks like the tube cad ac switch would fit in nicely
Although it looks like it is out of stock at the moment.
Looking at the AC switch description it says, it could be used for 125 vac 600ma only.
Is this power enough to keep the ba-3 preamp amp running. Or does the switch used in this build allow more power to come through?
Do you know of any other rotary switch which could be used for the mains.
Could be two position - On-Off
Or three position like the one in this post
Thanks,
Oleg
Sent from my ONE A2003 using Tapatalk
I am trying to find a proper power switch for my DCB1 and it looks like the tube cad ac switch would fit in nicely
Although it looks like it is out of stock at the moment.
Looking at the AC switch description it says, it could be used for 125 vac 600ma only.
Is this power enough to keep the ba-3 preamp amp running. Or does the switch used in this build allow more power to come through?
Do you know of any other rotary switch which could be used for the mains.
Could be two position - On-Off
Or three position like the one in this post
Thanks,
Oleg
Sent from my ONE A2003 using Tapatalk
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If you look at 6L6's build steps, you will see that is the one he used. I used it in both of my BA3 preamps. It off - on -on. It was meant for a tube pre so that you could switch on the filaments only, then hit it again for the B+. I suppose maybe both on - on positions could be combined to give a higher rating, I find mine works fine as is.
Russellc
Which Peter Daniels boards are you referring to and where can they be purchased?
Thanks...