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BA312 replacement

I am sure @Hipocrates version will perform very well also. However it will most likely perform similar to mine and the original as this is( if i am not mistaken) same transistor version. Yes I am attempting to approach sparcos by using modern OA.
 
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TupolevFan said:
Dan, if you rewind this thread couple of pages back you will see that one of the AK member @aldena007 did test my versions of the boards (transistor version). And conclusion is that they perform as originals not worse not better. Schematics was given by @Hipocrates I think. By the way smd version is only 10mm tall. My current idea is to use OA in attempt to improve it. It might or might not work. Will see
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Out of curiosity, not to rush you, but do you have an idea of when you might know if your new version is superior? I would love to get these made up ASAP. What I might do is just order number of boards that use the three transistors so I can finish up this Marantz, but then make sure I have the stuff as back up for, the superior design.

Dan
 
saabracer23 said:
Out of curiosity, not to rush you, but do you have an idea of when you might know if your new version is superior? I would love to get these made up ASAP. What I might do is just order number of boards that use the three transistors so I can finish up this Marantz, but then make sure I have the stuff as back up for, the superior design.

Dan
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Me and another AK member will test them in the following weeks(depending on his availability). Problem for me is that I do not have test unit to work with. However someone else does and I sent assembled boards as well as couple of empty adapters to him. First will test phono corrector and if all is well then will do control Amp section which should be even easier as it will have less components.
 
TupolevFan said:
Me and another AK member will test them in the following weeks(depending on his availability). Problem for me is that I do not have test unit to work with. However someone else does and I sent assembled boards as well as couple of empty adapters to him. First will test phono corrector and if all is well then will do control Amp section which should be even easier as it will have less components.
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Oh, I had no idea you were doing multiple units. I should go through this thread and read everything, my ADHD makes it hard to absorb the information though lol. If you don’t mind, what is the difference between the phono corrector and the control amp section? Are they different versions of the BA312?

Dan
 
saabracer23 said:
Oh, I had no idea you were doing multiple units. I should go through this thread and read everything, my ADHD makes it hard to absorb the information though lol. If you don’t mind, what is the difference between the phono corrector and the control amp section? Are they different versions of the BA312?

Dan
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No it is same BA312 just the circuitry around it is different. I call it phono corrector, people call it equalizer board.
 
TupolevFan said:
No it is same BA312 just the circuitry around it is different. I call it phono corrector, people call it equalizer board.
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I’m going to go ahead and order a batch of the boards that has the three transistors and the few resistors and then once you get this other board measured and figured out will definitely be ordering a batch of those as well.

I saw that you recommended the 2SC3324 which I’m told is the equivalent to the 2SC2240. Unfortunately. The 2SC3324 is no longer available unless you want to roll the dice on eBay, which I don’t do. Another recommendation I saw was the 2SC2713. I also have been told that is a direct 1:1 replacement for the 2SC2240. So are the 2SC3324 and 2SC2713 essentially the same thing? Would you say one performs better than the other? I guess it doesn’t really matter, as you can’t get the other one, but I do have a couple hundred 2SC2713-BL. Speaking of, is there a gain range you would suggest? BL good? I really need to build up my SMT stash. My through hole is doing pretty well, but SMT could use some help.

Are there any other SMT transistors you wouldn’t suggest in this project? I’ll probably grab another couple hundred of the 2713 just in case. It seems more and more devices are being given the axe. Also just in case I will pick up the devices for your second board. Any recommendations or help you might want to add I would be very grateful.

I really appreciate you guys taking on this project.

Dan
 
saabracer23 said:
I’m going to go ahead and order a batch of the boards that has the three transistors and the few resistors and then once you get this other board measured and figured out will definitely be ordering a batch of those as well.

I saw that you recommended the 2SC3324 which I’m told is the equivalent to the 2SC2240. Unfortunately. The 2SC3324 is no longer available unless you want to roll the dice on eBay, which I don’t do. Another recommendation I saw was the 2SC2713. I also have been told that is a direct 1:1 replacement for the 2SC2240. So are the 2SC3324 and 2SC2713 essentially the same thing? Would you say one performs better than the other? I guess it doesn’t really matter, as you can’t get the other one, but I do have a couple hundred 2SC2713-BL. Speaking of, is there a gain range you would suggest? BL good? I really need to build up my SMT stash. My through hole is doing pretty well, but SMT could use some help.

Are there any other SMT transistors you wouldn’t suggest in this project? I’ll probably grab another couple hundred of the 2713 just in case. It seems more and more devices are being given the axe. Also just in case I will pick up the devices for your second board. Any recommendations or help you might want to add I would be very grateful.

I really appreciate you guys taking on this project.

Dan
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If you look at the specs of 2SC3324 then it looks like it has has a bit better specs in terms of noise then 2SC2713. But i think in our case both should be OK i would say that FJV1845 will also do the trick very well.
 
I have had excellent results with the three transistor through hole version. In fact quite a few AK members have built them with great results. The smd version with the above mentioned transistor should be marginally better yet. Will be interesting to see how the latest design from Mr T works out :)
 
TupolevFan said:
Me and another AK member will test them in the following weeks(depending on his availability). Problem for me is that I do not have test unit to work with. However someone else does and I sent assembled boards as well as couple of empty adapters to him. First will test phono corrector and if all is well then will do control Amp section which should be even easier as it will have less components.
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I just got a 990DB to fix and would be happy to pay for a few boards to test if that's still needed.
I normally buy the ones from magnepanman on eBay but boy those are expensive.
 
ivandezande said:
I just got a 990DB to fix and would be happy to pay for a few boards to test if that's still needed.
I normally buy the ones from magnepanman on eBay but boy those are expensive.
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Just got my box of boards delivered. I heard I paid a little more than normal and I’m guessing that’s because of expedited shipping or something. I placed my order on Friday and I have them Tuesday. Crazy.

Anyways, still waiting on some resistors from mouser.
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I have the boards populated with 3 2SC2713BL which from what I understand is a 1:1 2SC2240 in SMT form. Low noise, high gain. One of the lower noise BJTs still available. Wish more was available. Anyways, I also have the 10 kohm resistors in there, I have a bunch of 0.1% tolerance resistors. The rest of the resistors should be here on Thursday.

Used my microscope to align the pins and get them on as well.
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I’d be curious to know what transistors magnepanman is using specifically. I made a trade with member here (don’t want to say their name without their okay), hard to get transistors for hard to get transistors. So I have a few hundred 2SC3324 on the way, from what I hear a little bit lower noise than the 2SC2713, both being better than the 1845. Who knows if you’ll hear a difference though.

His are kinda spendy, but for those that don’t do SMT might be worth it. If you’re in need of some ivandezande I could whip up 6 or 8 boards for you and send them your way. Save you $21 bucks a pop! Sheesh.

Dan
 
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I’m curious how this board compares fully populated with 2SC3324, or 2SC2713, or fjv1845 to the original using a 2N5089 and a pair of 2N3904. I have both in SMT form and they’re widely available. Just for those looking, I wonder if there would be an audible difference.

Dan
 
Hipocrates said:
I think that you are in the best position to let us know. Grab your analyzer, test them and post some frequency response and THD graphs.

I would say that it won't matter THAT much, but is just me guessing.
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I will have to familiarize myself with the analyzer a bit more. I’d say it’s highly more likely for the analyzer to notice a difference than the human ear. Even if the distortion comes down by a factor of 10, don’t think that would be audible.

TupolevFan said:
Dan i suspect that they all will sound very similar.
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I agree.

Hyperion said:
It's pretty safe to say that transistors in, and of themselves don't have 'a sound' :)
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I’m speaking more on the noise of the transistor, ultra low noise vs standard.

Dan
 
Hyperion said:
The 'new' BA-312 (using whatever transistors you choose), will be so much quieter than the original, that any noise from it will be lost in the noise from the rest of the unit.
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I’m sure that is true, but some of these are good enough to wear. The end user can hear a fairly dramatic cleanup. Like with the Sparkos devices, people saying the noise floor drops dramatically.

Dan
 
saabracer23 said:
I’m sure that is true, but some of these are good enough to wear. The end user can hear a fairly dramatic cleanup. Like with the Sparkos devices, people saying the noise floor drops dramatically.

Dan
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I did test these and the noise went down but, from memory, no more than 10dB. As @Hyperion says, only to be sucked up by the noise floor of the rest of the unit. All that voltage gain to get the big watts out causes a lot of that.
 
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