Many thanks oc11, -but man, there sure are a lot of posts in this thread
Well, I will give it a go. Any others who wants to chime in? Thanks again
tiimyjones, when I decided to do this I read the whole thread from page 300 and something and on to the end. I like to plan thoroughly before doing anything. I like to find out the issues that people have experienced building this thing to try not to make their mistakes. I kept notes of a lot of things, not all. You are going to be building a Nelson Pass design! Do it as best as you can, take your time, you do not have to do it tomorrow.
Two things to be aware of, the IRF610s are very sensitive to static, and the unit will be hot. The most common problem people have had building ACA is poorly soldered components, many people have had to resolder them. This is by and large what you see discussed in the blog. There is also a lot of discussions about modifications, preferred types of components, and issues with driving hard to drive speakers.
I'll echo the advice that was given to me when I first decided to build the ACA:
Firstly, it depends on your line source voltage level. For anything under 2V, you'll need a preamp with gain. I'm using a laptop and a Sabre DAC and I need a preamp with some gain. This I discovered only after building a Pass B1 buffer preamp (no gain).
Secondly, it depends on the sensitivity of your speakers. For anything under 90dB, you WILL need preamp gain - unless the room is tiny and you listen at low levels.
Disclaimer: This is based on my own experience. Others' opinions may differ.
I recently built the AKSA Lender preamp and chose components to give 15dB gain. Oh boy, what a difference it made to my system. Not only does the ACA (6W version) now drive my 94dB dual driver mini-Karlsonator speakers with authority, the soundstage and imaging went from really good (with the B1) to unbelievably good!
So, I want to stress; the preamp you choose now is going to make or break your ACA system.
oc11, great advice. I will surely go thorougly through this thread before I start building.
I guess I am getting ahead of myself here talking about the preamp for ACA's that haven't been built yet. Also thanks for the tip about the IRF610's and poor soldering.
The LS3/5A's are 83db but still seems to work well with low powered class a amplifiers.
Semmyroundel, thanks for the advice for the Objective 2 preamp. Although many describe it as flatsounding, its the most promising lead I have for the preamp so far.
I guess I am getting ahead of myself here talking about the preamp for ACA's that haven't been built yet. Also thanks for the tip about the IRF610's and poor soldering.
The LS3/5A's are 83db but still seems to work well with low powered class a amplifiers.
Semmyroundel, thanks for the advice for the Objective 2 preamp. Although many describe it as flatsounding, its the most promising lead I have for the preamp so far.
Not at all. Now is the best time to plan and decide on a preamp.
I think he meant IRFP240, not IRF610.
Not with the ACA. My advice is that you need to start thinking about more sensitive speakers for use with the ACA.
The AKSA Lender preamp (and the B1) is anything BUT flat-sounding!
Skylar88, are you sure? I ran these speakers with wonderful results with a Sugden A21A(series 1) without pushing the amplifier. I think this was 20 watts, but only class A up to a certain level. In fact, this former setup is the reason I am looking for a class a amplifier again. In hindsight I should have kept the Sugden of course. My thought was bridging the ACA's to get 15 watts, and using an active preamp to get ok results with my speakers. I will not part with my LS3/5A's. It's become a relationship you see. We are a teamThe LS3/5A's are 83db but still seems to work well with low powered class a amplifiers. Not with the ACA. My advice is that you need to start thinking about more sensitive speakers for use with the ACA.
Please note that the LS3/5A has a handling capacity of max 25watt.
I looked over the AKSA thread timmyjones, and unless you are capable of doing surface mounting with no problems (or you can get the boards with pre installed surface mount components), this one is not for you. If you feel comfortable with through the hole soldering but not with SMT you should look elsewhere.
By the was the standard level gain of the BoSoZ is 12dB, and this is not adequate for the needs of an F4, as per the blog information, but should be fine for an ACA. The circuit is a bit finnicky though.
Yes, sorry IRFP240s, sorry. They are still sensitive to static.
By the was the standard level gain of the BoSoZ is 12dB, and this is not adequate for the needs of an F4, as per the blog information, but should be fine for an ACA. The circuit is a bit finnicky though.
Yes, sorry IRFP240s, sorry. They are still sensitive to static.
Last edited:
I definitely agree. Choosing the right preamp will release the full potential of the ACA. A high quality preamp is a must and is going to make a huge difference.
That is simply not true. The standard PCB pack comes with through hole boards AND a set of extra SMT daughter cards, but that's optional. You don't have to use it. It's very handy if you want to build an extra pair of input daughter cards with more gain. I think 30dB+ is possible.
What do you mean by "the circuit is a bit finicky"? When I built mine, it worked first time. Admittedly, the circuit is not as simple as the ACA's and there is no component kit, just PCB's, but it's not finicky for someone who's built an electronic device or two. Also, all components are easily available - unlike some other designs. It does have a lot going for it sonically. It's a superb preamp!
Last edited:
So, Skylar88 what is the gain of the AKASA preamp without the daughter cards?, pray tell. I will agree the AKASA is capable of good gain, but how much gain with it have if you limit your build to the through the whole board only?
The BoSoZ has had a myriad modifications (like changing some of the IRF 610s for 2SK270BLs) and boards, all of which fit certain amps but not others (read the blogs). The modified ones can be pushed a fair degree in terms of gain but there is increased distortion and possible clipping. What flavor of BoSoZ did you build, what gain, balanced or not?
Pray give the whole story here.
The BoSoZ has had a myriad modifications (like changing some of the IRF 610s for 2SK270BLs) and boards, all of which fit certain amps but not others (read the blogs). The modified ones can be pushed a fair degree in terms of gain but there is increased distortion and possible clipping. What flavor of BoSoZ did you build, what gain, balanced or not?
Pray give the whole story here.
Last edited:
If you take some time to actually read a bit in the AKSA Lender preamp thread, you'll see that all the boards are through hole. There is also an extra set of SMT daughter cards, which are optional.
A fully operational preamp can be built using only the main board and two daughter cards - all through hole, if SMT is too daunting for you.
A fully operational preamp can be built using only the main board and two daughter cards - all through hole, if SMT is too daunting for you.
Zero gain and zero sound without the daughter cards. They are needed for the preamp to operate. A nice feature of the design is that the daughter cards can be built with a specific gain. Build two or more sets and just plug in different daughter cards to change the gain.
Regarding preamps and the aca ...
I'm running a single 8 watt per channel aca amp in stereo into 95 db sensitive speakers. All of the 3 preamps in the house will all drive the amp and speakers nicely in regards to volume even though their gain ranges from 8 to 22 db.
The sonic signature of the preamps seems far more important than the gain. One is a bit too lush, one is too laid back and the 3rd is a pretty good match up. The one that matches up reasonably well has 12 db of gain but the sonic signature seems far more relevant than the gain.
I was planning on building a B1 preamp buffer until several folks said unity gain wasn't the right match for the aca amp. So like several other folks I'm curious as to what bubbles up on this board.
A pre drilled chassis and not having to source parts from many locations makes it a whole lot easier (and a lot quicker) for some of us weekend warriors to build a project. It turns months of work into hours (or days). It moves a project from a "perhaps" and "if I get time" to an actual finished project.
B3 kits?
I'm running a single 8 watt per channel aca amp in stereo into 95 db sensitive speakers. All of the 3 preamps in the house will all drive the amp and speakers nicely in regards to volume even though their gain ranges from 8 to 22 db.
The sonic signature of the preamps seems far more important than the gain. One is a bit too lush, one is too laid back and the 3rd is a pretty good match up. The one that matches up reasonably well has 12 db of gain but the sonic signature seems far more relevant than the gain.
I was planning on building a B1 preamp buffer until several folks said unity gain wasn't the right match for the aca amp. So like several other folks I'm curious as to what bubbles up on this board.
A pre drilled chassis and not having to source parts from many locations makes it a whole lot easier (and a lot quicker) for some of us weekend warriors to build a project. It turns months of work into hours (or days). It moves a project from a "perhaps" and "if I get time" to an actual finished project.
B3 kits?
Sure thing Skylar, the through the whole board cannot work by itself. If you cannot do surface mounts you will have to either breadboard your own daughter cards or do your own through the hole PCBs in order to get the thing to work, correct? Does this sound simple to you? I mean for someone that wants to keep it simple?
The changeability of the daughter cards is indeed a great feature, thank you.
The changeability of the daughter cards is indeed a great feature, thank you.
Not correct, oc11. There are two sets of daughter cards, one set is through hole and the other(optional) set is SMT.
Have a look at the pictures below. Through hole daughter cards are supplied in the PCB set. No need to make your own boards...
The first picture is the two sets of daughter cards. Use the set on the left. It's through hole.
The second picture shows the complete set of boards. The daughter cards are the four little ones at the bottom - two for through hole and two for SMT. I hope it makes sense now.
Attachments
Last edited: