[Ferrari]

Quote:

Originally Posted by MASantos /img/forum/go_quote.gif Now where did you get those nice cases from?

I bought these 2 enclosures at the free market (Queen’s day in the Netherlands). They are both missing the aluminum top plate.
To complete it, I made 2 plates from 3mm aluminum. So, you could say... it’s partly DIY.

I have no clue where these enclosures are originally from, neither manufacturer nor model.
It has sufficient heatsinks and fits the 2 β22 boards nicely. I think it will work very well for the purpose.

@Bullseye, take a look here .

 

[guzzler]

Rather than just saying "it doesn't sound good" because of xyz, consider the real reason for using the "active ground" topology, ie, 3 channel: on the single supply amps, eg, M3, PPA, PIMETA, etc, the ground is virtual and has to be generated in some way. This is usually a voltage divider (as in the basic CMoy), or a TLE2426 (in the others mentioned). This is generally unbuffered, and so the virtual ground impedance is rather high; all a 3 channel topology does is buffer this higher impedance, to give a low impedance output. Rather nicely, they also divide the low current and high current sections.

Now, if you're using real ground, ie, either from a centre tapped transformer or from two bridge rectifiers then the ground impedance is low anyway and so you don't need to worry about adding a 3rd channel. All this does, as mentioned above, is to provide a buffer between high and low current sections and if your grounding scheme is good this is already irrelevant...

 

[Bullseye]

Quote:

Originally Posted by Ferrari /img/forum/go_quote.gif @Bullseye, take a look here .

Thnks Ferrari, However on the checkout I can't see any european country... Only USA states.

 

[Ferrari]

Send Jeff an email. I have got parts from him many times in the past.
He is quite busy with his daily work but you will get response.

A very nice guy to deal with.

 

[ting.mike]

Hahaha thanks for everyone's replies.

FallenAngel hits the bullseye though:

Quote:

Originally Posted by FallenAngel /img/forum/go_quote.gif Oh yes, 2 channel unbalanced is absolutely awful, unbearable and almost impossible to listen to, it's a must to go with active ground, and 2 of them so you can drive 2 pairs of headphones using active is absolutely necessary to keep your sanity. If there isn't enough sarcasm in there, let me know, I've got a few more zingers I can add.

Well, I am sure the 2 channel is great sounding and is much better than a lot of other desktop amps.

This is the question though: Is the 2 channel still good enough to be a "reference" amp? The thing is, most of the people building the Beta22 builds either 3 or 4 boards, and I don't hear much about 2 channel builds. (We really need a review of 2 channels vs 3 channels B22, btw)

I have listened to a lot of amps, and so my expectations for the B22 is very high. I want it to be "the end of the journey" kind of an amp.. if there is such a thing.

(Until I have money for O2 + BHSE)

Is a 2 channel build good enough for a "reference" amp?

 

[ting.mike]

Quote:

Originally Posted by guzzler /img/forum/go_quote.gif Rather than just saying "it doesn't sound good" because of xyz, consider the real reason for using the "active ground" topology, ie, 3 channel: on the single supply amps, eg, M3, PPA, PIMETA, etc, the ground is virtual and has to be generated in some way. This is usually a voltage divider (as in the basic CMoy), or a TLE2426 (in the others mentioned). This is generally unbuffered, and so the virtual ground impedance is rather high; all a 3 channel topology does is buffer this higher impedance, to give a low impedance output. Rather nicely, they also divide the low current and high current sections. Now, if you're using real ground, ie, either from a centre tapped transformer or from two bridge rectifiers then the ground impedance is low anyway and so you don't need to worry about adding a 3rd channel. All this does, as mentioned above, is to provide a buffer between high and low current sections and if your grounding scheme is good this is already irrelevant...

Thanks for a great explanation!

 

[rds]

Quote:

Originally Posted by linuxworks /img/forum/go_quote.gif ... 2ch is just fine. and mine powers speakers, too, fwiw.

2ch can also fit in a Hammond 1455 case (maybe requiring a perforated top?)

I need a speaker amp and I'm planning on the 2ch build too.

...also like Ferrari has shown, if you want to go crazy later you can build a second 2ch and use them as mono blocks.

 

[smeggy]

I could be wrong but while I'm sure there are measurable differences with active ground, I doubt I'd hear is as it doesn't seem to be a part of the 'sound' producing part, more a technically better way to operate. Still, I'm also going to be using the speaker outs which is a 2 board config anyway, it sounds amazing.

 

[MisterX]

Quote:

Is a 2 channel build good enough for a "reference" amp?

One of things you can always take for granted is any amp that requires a ton of effort to complete will be the best sounding amp you ever heard.

 

[rds]

If I want to use my 2ch B22 to power my 6 ohm PSB Image 2B bookshelf speakers in a small room is it possible that a single s22 with a 100VA transformer will be sufficient?

Using Io = sqr(Po/6) for the output current, I calculate 1.3A per board maximum for a 10W per channel amp (ideally what I would like).

If I set the s22 for +/-30V I will get 1.67A, and for +/-24V I will get 2.01A (to power both boards)

What kind of input current should I be looking for? I can't find the efficiency of the B22 on AMB's website, though no doubt it is there.

I did see that as a dedicated power amplifier 2 s22 are recommended for the 2ch configuration, but I'm hoping to get away with just one as a light weight power amplifier.

 

[ting.mike]

Quote:

Originally Posted by MisterX /img/forum/go_quote.gif One of things you can always take for granted is any amp that requires a ton of effort to complete will be the best sounding amp you ever heard.

Heheehe...

Seriously though.. is there a proper review of 2 vs 3 boards?

I'm sure the 2 boards are good, but how good? The 3 boards have been compared to the GS-X and Apache, which is pretty much the top of the line solid state amplifiers.

 

[JamesL]

Quote:

Originally Posted by ting.mike /img/forum/go_quote.gif Heheehe... Seriously though.. is there a proper review of 2 vs 3 boards? I'm sure the 2 boards are good, but how good? The 3 boards have been compared to the GS-X and Apache, which is pretty much the top of the line solid state amplifiers.

Whenever you ask someone to rate the "good-ness" of anything.. you're not going to get a very useful answer.

The only thing reviews are good for imo is for comparing the type of sound signature that it produces. I'm going to bet that the 2-channel and 3-channel beta22's sound fairly similar.
It's kind of like comparing laptops. It's one thing when you compare two different ones, but if you compare laptop X with a 2.66ghz processor, and the same laptop with a 2.8 or 3ghz processor, we know for certain the second configuration is better, but most people aren't really going to notice a difference when they're using it.

 

[ting.mike]

Quote:

Originally Posted by JamesL /img/forum/go_quote.gif Whenever you ask someone to rate the "good-ness" of anything.. you're not going to get a very useful answer. The only thing reviews are good for imo is for comparing the type of sound signature that it produces. I'm going to bet that the 2-channel and 3-channel beta22's sound fairly similar. It's kind of like comparing laptops. It's one thing when you compare two different ones, but if you compare laptop X with a 2.66ghz processor, and the same laptop with a 2.8 or 3ghz processor, we know for certain the second configuration is better, but most people aren't really going to notice a difference when they're using it.

Thanks, James. I get your point. But these are internet forums. How else would I be able to get a better idea of a 2 channel v. 3 channel, short of a direct audition?

 

[oneplustwo]

I'm in the process of building both a 4 and 2 channel so I'll give you my impressions when I'm done. Might be a while as I have a couple other projects in the works as well, but I will get it done as I've been looking for a definitive answer (at least to my own ears) to this question as well.

 

[fishski13]

does Ti have any measurements of passive ground vs. active ground?

my next HP build will be either a 2 channel B22 or a Dynalo.