Would that be more difficult to implement in the BA-3 preamp than the simple (...) volume pot? Another member who is helping me into populating the Sigma 22 PSU board pointed out that the Salas would need some power to work and that leads me to the question if this is not gonna make things too complicated for a first time DIY.
Would you be so kind to advise which road to hit and if, eventually, the Salas can be that road, how to get necessary power to drive it?
Grazie
^ Apologies for lack of clarity. I was saying that dual mono may add a bit more complexity. The overall input selector / volume should be okay re: complexity. Below may make it a bit more clear for you and others trying to help.
The dual mono ties to below + there is one additional confirmation/assurance needed as a caution. Perhaps others that have used it or have experience are willing to chime in. Also, I think there is a dedicated thread for the i-select, and Salas is a regular poster / very helpful.
Question 1 - If you're using dual mono power supplies, what is the best arrangement to power the i-select? If you run it off of only one PSU, then one PSU will see a slightly higher load than the other. I am not sure that's critical, but it deserves to be asked, IMO. Is there another wiring consideration that may work better / more ideally. With a single PSU, this question is irrelevant.
Question 2 - The PSU you're using has a fairly high voltage loss. As such, in order to achieve 30VDC output, you're using a transformer with higher than 22VAC secondaries (30VAC, I think). That takes powering the i-select directly off the secondaries out of contention. You're PSUs should deliver a regulated 30VDC, which is right at the maximum spec'ed margin for the i-select. While it is likely conservatively rated, I think it's wise to ask if there are any cautions that should be taken when running it with 30VDC. Are there better ways / options, or is this ok?
Both questions may be answered with... "Totally fine". However, it's nice to be sure and see if there are better ways we have not considered as novices.
Cheers!
The dual mono ties to below + there is one additional confirmation/assurance needed as a caution. Perhaps others that have used it or have experience are willing to chime in. Also, I think there is a dedicated thread for the i-select, and Salas is a regular poster / very helpful.
Question 1 - If you're using dual mono power supplies, what is the best arrangement to power the i-select? If you run it off of only one PSU, then one PSU will see a slightly higher load than the other. I am not sure that's critical, but it deserves to be asked, IMO. Is there another wiring consideration that may work better / more ideally. With a single PSU, this question is irrelevant.
Question 2 - The PSU you're using has a fairly high voltage loss. As such, in order to achieve 30VDC output, you're using a transformer with higher than 22VAC secondaries (30VAC, I think). That takes powering the i-select directly off the secondaries out of contention. You're PSUs should deliver a regulated 30VDC, which is right at the maximum spec'ed margin for the i-select. While it is likely conservatively rated, I think it's wise to ask if there are any cautions that should be taken when running it with 30VDC. Are there better ways / options, or is this ok?
Both questions may be answered with... "Totally fine". However, it's nice to be sure and see if there are better ways we have not considered as novices.
Cheers!
My first build (after the aca to be honest) was Salas‘ DCB1, which features the more less same signal-switch/volume-pot funcionality, and I got it working on first attempt 😉
On my next preamp (wayne‘s line stage) I used the i-select and powered it directly from a secondary of the toroid. Works hassle free. (If you go this route, make sure voltage is ok with your configuration…)
Salas is, BTW, a great guy, very precise and friendly!
On my next preamp (wayne‘s line stage) I used the i-select and powered it directly from a secondary of the toroid. Works hassle free. (If you go this route, make sure voltage is ok with your configuration…)
Salas is, BTW, a great guy, very precise and friendly!
Hello,
may I ask why to choose such a solution rather than to just use a pot?
I am putting together the BOM to populate the Sigma 22 boards, the MOSFETs for the BA-3 board made it home so it's about to complete the shopping list and understand which route to go, let's assume I make it dual mono with two transformers and two Sigma 22 boards, what is left is the volume control and input switches, would the Salas help or create further complications for a first time DIY?
I understand it requires some voltage to work and since there is quite a voltage drop with the Sigma PSU where would I take the necessary power to fire the Salas up?
Sorry for so many quesitons
Grazie
You are always nice with your help, I won't add further complication to your above points, since I am still at the very beginning phase where I only got the MOSFETs for the BA-3 board I am open to suggestions taking into account this being my first time build.
Dual mono bit is to match the line we choose to build the F4, price wise it adds a bit but not to a great extent but don't ask me the benefits of a dual mono build, on the power amp my friend suggested, as well as many others on the F4 thread, to go that route to avoid ground loops, dunno if that is an issue with a preamp and if it is worth the extra cost (dual PSU and dual transformer).
I can tell from above images that a stereo build with a big transformer can power the whole thing up but he's using a different PSU than the Sigma 22 I chose and with your calculations on the dedicated thread you found out that with Italian AC being 220V the Sigma would work well.
Grazie for your patience
Buonasera Giovanni,
only some thoughts from me:
I prefer building dual - mono - amps because of complete channel seperation between the left and right
audio channel. There can be no real interferences between them - or let's say minimized to the minimum.
If you build your amp the 'classical' stereo way (= two audio channels share one PSU in one case) this has
not to be worse.
If you build your BA-3- preamp, you can easily add the Sigma22 and test it with a regular potentiometer.
An Alps RK27 costs around 15 €. Some members in the forum discuss a lot about the quality of potentiometers. Then you could listen to this preamp without a case - to get an impression.
I have also added relayswitched attenuators to my preamps. I have built a MUSES 72320 digital volume
control and more. I gave the digital volume control as well as the relais switched its own little PSU. Why?
I was afraid of digital noise or switching noise getting to the audiosignal. But this is DIY. And we do a lot
of crazy things. Is it necessary? - Hmmm
Most often it is the wish to make it better or the search for the optimum.
My first BA-3-preamp, I have built, has an ELNA- rotary-input-switch and an ALPS-pot. And it still sounds
great.
I don't want to hold You back from using any input-selector or whatever. But if it is your first build, I would keep it simple. Upgrading is always possible. And I assume it will happen... 😉
Cheers
Dirk
only some thoughts from me:
I prefer building dual - mono - amps because of complete channel seperation between the left and right
audio channel. There can be no real interferences between them - or let's say minimized to the minimum.
If you build your amp the 'classical' stereo way (= two audio channels share one PSU in one case) this has
not to be worse.
If you build your BA-3- preamp, you can easily add the Sigma22 and test it with a regular potentiometer.
An Alps RK27 costs around 15 €. Some members in the forum discuss a lot about the quality of potentiometers. Then you could listen to this preamp without a case - to get an impression.
I have also added relayswitched attenuators to my preamps. I have built a MUSES 72320 digital volume
control and more. I gave the digital volume control as well as the relais switched its own little PSU. Why?
I was afraid of digital noise or switching noise getting to the audiosignal. But this is DIY. And we do a lot
of crazy things. Is it necessary? - Hmmm
Most often it is the wish to make it better or the search for the optimum.
My first BA-3-preamp, I have built, has an ELNA- rotary-input-switch and an ALPS-pot. And it still sounds
great.
I don't want to hold You back from using any input-selector or whatever. But if it is your first build, I would keep it simple. Upgrading is always possible. And I assume it will happen... 😉
Cheers
Dirk
Hi Giovanni,
Sorry for the late reply but it looks like you got some help already. I'm a newb to this DIY stuff and get by with all the help posted on these forums so I'm not too knowledgeable from a technical perspective. With that said, you may not want to take advise from me.... LOL!! But to answer your questions the I-select board can accept 15-30 VDC or 12-22 VAC so I pulled DC from one side of my Broskie Glassware PSU. But you can also choose to pull from the the transformer as well. Board gives relay input switching and ALPs pot mounting in single module which permits source signal isolation, for the most part, to the rear of the chassis. There is also a 12 VDC regulated out for LED or other needs as well. I went this route as it provides a versatile, elegant and simple solution for all my needs. I've used this board in 3 builds (2 x WBA2018 and the BA3 pre) without issue so IMHO does not add much complication to a build. Left a PDF with great info on the board that I pulled from Salas' GB post. Salas is always helpful and the guys in these forums are absolutely awesome so if you need help just ask and post pics. Solutions are a reply or 2 away. Hope that helps. Good luck with your build sir!
You can also try Muffsy Input Selector. You can view the description here
While I-select is okay, it is manually controlled only. The Muffsy can be controlled manually and remotely.
In my opinion, the advantage of the Muffsy over I-select:
1.) Remote or manually controlled
2.) Requires only 5Vdc that can be had with using just IRM-05-5
3.) Muted preamp to amp signal path
4.) Programmable
5.) Programmable 5V output for Solid State Relay (SSR) that can be used to turn the mains power On and Off
I have two (2) I-Select kits and chose to use the Muffsy instead in my BA-3 because I think it is an elegant source selector.
While I-select is okay, it is manually controlled only. The Muffsy can be controlled manually and remotely.
In my opinion, the advantage of the Muffsy over I-select:
1.) Remote or manually controlled
2.) Requires only 5Vdc that can be had with using just IRM-05-5
3.) Muted preamp to amp signal path
4.) Programmable
5.) Programmable 5V output for Solid State Relay (SSR) that can be used to turn the mains power On and Off
I have two (2) I-Select kits and chose to use the Muffsy instead in my BA-3 because I think it is an elegant source selector.
Looks like a great option with additional features. Appreciate the recommendation. Will look to try on my next build. Thank you!
Stumped. This is my second Ba-3 build. I've got 24DCV from the PSU to the amp board. But I can't get a pulse from my efforts to bias either channel.
I've double checked the resistors, capacitors, trimpots [500 ohm as I'm using2SJ313 & 2SKs013 Mosfets] sourced from a reputable source via references in this forum.
I'm hoping I've missed a simple step. Or maybe not.
Appreciate any thoughts.
I've double checked the resistors, capacitors, trimpots [500 ohm as I'm using2SJ313 & 2SKs013 Mosfets] sourced from a reputable source via references in this forum.
I'm hoping I've missed a simple step. Or maybe not.
Appreciate any thoughts.
Attachments
I suggest starting with the following:
1) Check all part values/locations again.
2) Measure voltage at V+ and V-, make sure you are getting +24V and -24V.
3) Measure voltages across R3, R4, R6, R7.
4) Measure voltages across R10 and R11. Do you get anything at all or is it zero even with P1 and P2 at max?
1) Check all part values/locations again.
2) Measure voltage at V+ and V-, make sure you are getting +24V and -24V.
3) Measure voltages across R3, R4, R6, R7.
4) Measure voltages across R10 and R11. Do you get anything at all or is it zero even with P1 and P2 at max?
I´d say there is no positive Voltage on the amp board (V- goes to to V- but Gnd goes to V+). Left channel seems to have no power at all.
See pics attached (shows how it should be).
Edit: are the Jumpers J1 and J2 on the PSU installed to tie the voltages together?
See pics attached (shows how it should be).
Edit: are the Jumpers J1 and J2 on the PSU installed to tie the voltages together?
Attachments
Last edited:
Right channel is not connected up. For left channel: V+ goes to V+ and ground V- goes to V- on the amp board.
I built his PSU a while ago and will have to research your question. my testing indicates I'm getting 24 VDC for both channels from the PSU.
To me it looks as if the black wire goes to V- and the red wire to V+ of one half of the power supply. So effectively you are feeding +/- 12 Volts.
Your power supply generates 2x24 Volts: V1- V1+ V2- V2+
V1+ and V2- make your shared ground and the board is fed with V1- and V2+.
J1 and J2 need to be installed which I think I see. Touch ground on the PS board with the black lead of your MM. Red to + you should get 24vdc. to - you should get -24vdc. Tie ground to ground on the linestage, - to - and + to +. If all of that is right, you're not getting anything then it may mean you need to keep turning the turn pot. It takes a lot of turns to get it going.
Measures [DCV]
R3 0.049
R4 0.00
R6 -0.587
R7 0.493
R10 -0.010 at Max
R11 -0.032 at Max
I suspect my P2 pot may not be good, as I can no longer dial all the way up and hear when I get to the end.