In case anyone cares, I tried out a couple other high gain preamps this past week on the MoFo. HagTech Clarinet tube preamp and a Mark Levinson clone (ML) with boards from Ebay. They are borrowed units.
Both sound good in their own way. I was a little surprised by the ML.
It did a lot of nice things. It has a great presentation of musical performances. Good amount of detail. The Clarinet had a rich tone, but weak in the bass. The BA3-Pre can do what they do and more.
After a week and a half of listening to the other preamps, the BA3-Pre was a bit of a revelation. Wasn't expecting the level of performance it provided.
Last Thursday I heard a pair of Avalon Isis speakers, EMM Labs digital, Basis TT and BAT mono-blocks. It was soul crushingly good. A real DIY morale killer. So, it was nice to hear some of those qualities in a modest system with the MoFo and BA3-Pre. 🙂
Both sound good in their own way. I was a little surprised by the ML.
It did a lot of nice things. It has a great presentation of musical performances. Good amount of detail. The Clarinet had a rich tone, but weak in the bass. The BA3-Pre can do what they do and more.
After a week and a half of listening to the other preamps, the BA3-Pre was a bit of a revelation. Wasn't expecting the level of performance it provided.
Last Thursday I heard a pair of Avalon Isis speakers, EMM Labs digital, Basis TT and BAT mono-blocks. It was soul crushingly good. A real DIY morale killer. So, it was nice to hear some of those qualities in a modest system with the MoFo and BA3-Pre. 🙂
Yes, that is part of the fun of DIY. I will learn from things going wrong. It is always fun to make things a little bit difference than standard. Is it your impression that an output cap can be avoided if a few mV DC at the output is accepted? ....during AC operation I will see negative voltage relative to ground at the source of the mosfet caused by the "kick back" of the choke? ......if not I am a bit lost on how an output cap can be avoided.....
The benefits of removing the cap is not worth the risk to the speakers, in my opinion. Also, properly sized output coupling caps add essentially nothing to the signal. (As much as people will argue otherwise...)
I must admit that the E-caps I used for the ACA worked very well. I was sure I would be able to here some kind of "carpet" between me and the sound. But it seems very transparent. But I do not know how it would sound without output caps......if this was possible (I know it is not in the ACA construction).
Regarding speaker protection my thought was that as long I have the big choke installed at the output then DC will not be a problem as the PSU has to be very strong to be able to generate a DC which would harm the speakers. But I don't know if the choke could generate high voltage spikes is something goes wrong. Then I should add a kind of high voltage protection over the choke so it can deliver its energy to such a device. The output cap would not like high voltage either........
If the offset from 0V is low enough it is workable in theory, however I guess the scenario to beware of is an open choke, whereby your speaker terminal will be sitting at a few volts DC. Easy enough to try both ways with test speakers and you can see for yourself if you can really hear the cap or not. 🙂
It is a bit strange with this Cap discussion…..because in speaker crossovers many people swear (experienced audio people) that a bipolar E-cap in the signal for middle or tweeter would destroy the sound totally and the bipolar E-caps should only be used for some corrections of impedance. Also in tube amps people pay maybe $1000 for a V-Cap as coupling cap. Do you have the same relaxed relation to only using bipolar E-caps for speaker crossovers? …..the price difference may be 1:100 compared to using expensive film or foil capacitors. I know it is a bit "off topic" but an interesting "off topic" 🙂
The person who designed my speakers don't have same relaxed relation to E-caps in the signal path:
Alumen-Z-Cap
….so I followed his layout for the cross-over. It works…..but I don't know if I could hear the difference if I was more relaxed regarding which caps to use…..hope MoFo likes my speakers...…..and don't burn them…..
Alumen-Z-Cap
….so I followed his layout for the cross-over. It works…..but I don't know if I could hear the difference if I was more relaxed regarding which caps to use…..hope MoFo likes my speakers...…..and don't burn them…..
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If you build the project the way I wrote it up, you'll have no trouble. If you want an opinion about capacitors, I'm not the guy for that. 🙂
I will report when I have some progress and how the big choke works in a few weeks. In the moment I collect the other parts. Found the Bourns 20k pots at the "local" RS Components department.
Start? ….Get the PCBs from the DIY store (I did that) and then maybe read the MoFo article. There is a part list included.
Price......a rough guess…..400$ for two amps using SMPS......chokes and heatsinks are the most expensive parts. You can get a $100 heatsinks but also a lot cheaper. A preamp is needed that has some voltage swing.....
Price......a rough guess…..400$ for two amps using SMPS......chokes and heatsinks are the most expensive parts. You can get a $100 heatsinks but also a lot cheaper. A preamp is needed that has some voltage swing.....
The parts and PCBs were about $90 a channel in the USA, plus whatever you spend on heat sinks, connectors, and a piece of plywood. 🙂
You must, you must...
I didn't play around with P3, but that should be a piece of cake for you Mike.
I have it set straight up, but tweaking to taste is a plus.