BRN: I think preamp choice is totally dependent on your power amp/speakers and what you are looking to achieve. Your amps are 2nd harmonic dominant amps (Sissy SIT and M2) so I would look at something clean and fast...since the power amp is giving you your sweetness.
I've built the BA-3 front end, Juma's iteration of the LSK preamp, the Salas DCG3, The regular b1 and the Korg b1. I am using an f5 turbo as a power amp and I think the Korg b1 is the winner. But that's a different kind of power amp than yours. I do like Juma's LSK preamp a lot and it's probably the best all around-er. But I am a soundstage depth and width guy and the Korg B1 seems to do that trick better than anything I have tried.
I've built the BA-3 front end, Juma's iteration of the LSK preamp, the Salas DCG3, The regular b1 and the Korg b1. I am using an f5 turbo as a power amp and I think the Korg b1 is the winner. But that's a different kind of power amp than yours. I do like Juma's LSK preamp a lot and it's probably the best all around-er. But I am a soundstage depth and width guy and the Korg B1 seems to do that trick better than anything I have tried.
Couple of other folks have asked for some details as well. So, I'll post here.
The PS is quite simple. Borrowed from NP's BOSOZ article. Figure 2 is attached.
https://www.firstwatt.com/pdf/art_bosoz.pdf
I built up a 30 V zener reference into the gate of the MOSFET. The trafo is putting out about 37 V. Ideally, it would be good to get a bit more out of the trafo. Under load, there is about 28V into the preamp on both rails. I used the same Fairchild MOSFETs as the main preamp in the PS. You can see the PS on a perf board to the top of the first image.
My build is quite the ghetto build. Please build yours with safety in mind. I literally built this in an afternoon and I am in capacitor swap mode right now, so I haven't put it in a case as yet. I used on hand parts from my parts bin, so you might see, for example, that the resistors and even the heat sinks do not match. At least I got a pair of the same sinks for each channel. The PS caps are Panasonic Nichion types, but nothing special. I installed the MOSFETs in reverse and had to fix that.
In the past, if I read a post about the sound of capacitors, I would just skip over the post because I thought capacitors couldn't possibly have a 'sound' as long they are well made and of the same value. This preamp has changed that belief. Bought some boutique caps and have been playing around with them.
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The M2 has third harmonic as the dominant one--at least on mine. What level were you looking at? I believe F5 is also third harmonic dominant, but don't have one to measure right now. EDIT: F5T is adjustable, just like BA-3, to make 2nd and 3rd harmonic content of your choice.
I am a soundstage junkie as well (thank Pano for that 🙂 ) and found the BA-3 to be above and beyond anything I've heard in that department. I have not built the Korg B1, but have the regular B1. How would you compare the Korg B1 with the BA-3?
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hikari1,
Thank you for that input it is very helpful. I bet the Korg B1 sounds nice. I’ve run DHT amps and a directly heated pentode preamp in the past and know what you mean. It adds the nice fullness to the sound, and when done right does not bloat sound.
ra7,
I wish I could just throw something together and not feel rushed to put a lid on it, but I have a young son who is very inquisitive. I know that I would be playing with fire and he would get a bad shock.
I’m a believer that caps make a difference, and have gone down the rabbit hole of buying expensive boutique caps for my amps. Today I try a pick caps that I like that don’t break the bank. That are a lot of value propositions.
What amp are you using with your BA-3?
Thank you for that input it is very helpful. I bet the Korg B1 sounds nice. I’ve run DHT amps and a directly heated pentode preamp in the past and know what you mean. It adds the nice fullness to the sound, and when done right does not bloat sound.
ra7,
I wish I could just throw something together and not feel rushed to put a lid on it, but I have a young son who is very inquisitive. I know that I would be playing with fire and he would get a bad shock.
I’m a believer that caps make a difference, and have gone down the rabbit hole of buying expensive boutique caps for my amps. Today I try a pick caps that I like that don’t break the bank. That are a lot of value propositions.
What amp are you using with your BA-3?
I have not heard an m2. But there was a 6moons article comparing the f5 and m2 and I believe j2 a while back. F5 was definately considered more uptight.
Honestly, the korg B1 and Ba-3 are not alike at all. Even if you adjust the 2nd harmonic with an analyzer on the ba-3 it does not have the same effect. The korg B1 is much more dimensional than Ba-3. In all honesty, ba-3 was not my favorite. I built the same circuit as ba-3 with feedback and I preferred it.
Juma’s current mirror version of the lsk preamp is probably the best “soundstage” solid state preamp I have.
Juma's LSK
Need to get mine together, at the very least something quick and dirty to give it a listen. These boards have been tested and should be ready to go. Used a DCA75 to get closely matched transistors on the Cubie 2's (set up as a preamp only). The blue boards are Super Regulators from the Store.
Need to get mine together, at the very least something quick and dirty to give it a listen. These boards have been tested and should be ready to go. Used a DCA75 to get closely matched transistors on the Cubie 2's (set up as a preamp only). The blue boards are Super Regulators from the Store.
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Interesting. I am using an F4 power amp, which pretty much lets the preamp do the talking. The harmonic structure of the power amp will definitely play a role. The F5 also has gain. My experience so far is with the DAC itself, the 01a DHT pre, and the BA-3. Will be building an 801a and the Luminaria in the future.
I adjusted the BA-3 for higher 2nd than 3rd at 2.8V out, or about 1W. See attached pic. Note that you get a different effect with P3 going one way or the other.
We have many choices and I've come to realize that all of them must be really good, otherwise NP wouldn't have published them. He has been weeding out bad circuits all his life and we get to hear the cream of the crop.
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Yes, dual secondaries wired into one bridge rectifier each. Can't remember the the spec. But I can look it up tonight.
Well, with an f4 I can see the ba-3 working well. Lots of gain and swing. The ba-3 power amp follower is the F4. Same design. So they are literally made for each other.
I’d put the korg b1 in front of the ba-3/f4 and give it a try though. Might be a flavor you like and you will have much more gain and ability to get loud or drive insensitive speakers.
Korg b1 is cheap. Mine has no boutique (and I have spent a lot on boutique parts in my life) parts except Iam using a linear lm317 psu. Iam not even using my stepped attenuators, just carbon pots and it sounds great. So far, I prefer it to all my super reg, Takman, clarity cap, rhodium rca Jack preamps I have at my disposal.
I’d put the korg b1 in front of the ba-3/f4 and give it a try though. Might be a flavor you like and you will have much more gain and ability to get loud or drive insensitive speakers.
Korg b1 is cheap. Mine has no boutique (and I have spent a lot on boutique parts in my life) parts except Iam using a linear lm317 psu. Iam not even using my stepped attenuators, just carbon pots and it sounds great. So far, I prefer it to all my super reg, Takman, clarity cap, rhodium rca Jack preamps I have at my disposal.
The marking on the trafo is unreadable but I am getting 27 V AC before the rectifier. I would shoot for at least 7 V above the rail voltage you want to supply the preamp. In the BA-3 article Nelson mentions anything from 24 to 32 V should work just fine. If you start dropping more than a few volts across the PS FET then it should carry a heatsink. I put a small clip-on heatsink on it and it does not get warm. Current draw should be about 60 mA per channel if you build it to spec.
F4: Aikido or Wayne's BA 2018 🙂
In my case, both preamps are very clean, low distortion designs that are absolutely quiet.
In my case, both preamps are very clean, low distortion designs that are absolutely quiet.
I have an Aleph P Boards and caps for sale... kinda happy with what I have and not interested in building the Aleph P anymore...
LSK pre - BAF 2013
Post 485. This one really surprised me. Not enough swing for use with just an f4 though.
Post 485. This one really surprised me. Not enough swing for use with just an f4 though.
I decided to build the BA-3 first. I have most, if not all of the most expensive parts so it seems like the most logical choice.
I’m looking forward to how is sounds.
I’m looking forward to how is sounds.
I've been looking for a pre and came across this thread. I'm searching for clean and fast as I will probably use it to front end my Baby Huey tube amp. I'm not interested in passive either, been there done that and prefer some gain. I definitely want a phono input, but that can be added to most anything. I am also looking at vintage/commercial as chassis and input selection is a bit of a pain to DIY. So anything from the past might work if it's easily modified and upgraded. Of course for new DIY, all the Pass designs are also high on the list as "Pappa" obviously knows what he's doing! And newer designs have the advantage of learning from the past.
So, since it's been almost a year, I was wondering if you had any updates or input? The ba-3 and the ACP+ are both fairly high on the list right now, at least for custom build DIY. The ACP+ is currently out of stock, but I'm sure they'll eventually be available.
Thanks, gabo
So, since it's been almost a year, I was wondering if you had any updates or input? The ba-3 and the ACP+ are both fairly high on the list right now, at least for custom build DIY. The ACP+ is currently out of stock, but I'm sure they'll eventually be available.
Thanks, gabo