Simple Killer Amp - Introductory Offer!

audiojerry · « **Reply #120 on:** 7 Mar 2006, 01:23 pm »

Nice investigative work JohnR and Lonewolf.
This revelation leaves me feeling a bit suspicious.
What's going on here?

gonefishin · « **Reply #121 on:** 7 Mar 2006, 02:33 pm »

Other than the fact that TNT bought an amp from amilfierguru...I don't see much else going on here. Neither hid the fact of who they are or seem to have any problems selling their amps to someone who (also) designs amps as well.

It just looks like a transaction to me. Anyway...

dan

audiojerry · « **Reply #122 on:** 7 Mar 2006, 03:45 pm »

Quote from: gonefishin

Other than the fact that TNT bought an amp from amilfierguru...I don't see much else going on here. Neither hid the fact of who they are or seem to have any problems selling their amps to someone who (also) designs amps as well.

It just looks like a transaction to me. Anyway...

dan

Perhaps, but the TNT post seems to contain a veiled message of some sort. The tone of the message was clearly negative. Whether it was warranted or not remains to be seen.
Stay tuned.

TNT · « **Reply #123 on:** 7 Mar 2006, 05:14 pm »

Yes I'm Tranh, designer of NuForce amps.

I never posted anything until the transaction with amplifierguru, which kind of forced me to post regarding that transaction, so that it can be completed. I'd rather stay out of any controversy and stick with R&D work. For that reason and also all the fun my work gives me, I won't be posting much in the future.

So you all can stay tuned but statics are usually there.

art · « **Reply #124 on:** 7 Mar 2006, 05:34 pm »

Is there, bubba?

Like here:

http://www.audiocircle.com/index.php?topic=25598.msg227674#227674

And now you expect us to believe that you had trouble building one of these amps, when Greg claims his amps are so simple that his grandmother could build one?

Give us a break. Better yet: give it a rest.

Pat

fly_fish_nz · « **Reply #125 on:** 7 Mar 2006, 05:57 pm »

I don't know much of anything about Nuforce, but it seems pretty straightforward that a manufacturer would keep track of the competetive market place in which they operate, including new offerings and designs. It also seems reasonable to use the designers instructions to build kits regardless of your level of expertise.

skrivis · « **Reply #126 on:** 7 Mar 2006, 06:02 pm »

Quote from: fly_fish_nz

I don't know much of anything about Nuforce, but it seems pretty straightforward that a manufacturer would keep track of the competetive market place in which they operate, including new offerings and designs. It also seems reasonable to use the designers instructions to build kits regardless of your level of expertise.

Do a search for TNT (put that in the author box) and you'll see he's been taking potshots at other designers anonymously. It wasn't until he was caught red-handed that he admitted who he was.

fly_fish_nz · « **Reply #127 on:** 7 Mar 2006, 06:16 pm »

hi skrivis,

you and art are certainly right that it would have been best had tnt disclosed his affiliation with nf, perhaps in his signature. on the other hand it doesn't seem like he took efforts to hide it either, using his company email address and giving highly technical responses regarding NF amp design.

i read the posts fairly quickly, so maybe i missed some things, but most seemed pretty inoffensive and informative. there were a few (e.g. regarding his preference regarding relative value vs. another amp and then in this affair with sanders) where it clearly would have been better to make things clear.

as i mentioned, i don't know much about nf, but nuforce vs. sanders and sanders vs. ati make for some interesting drama during coffee break.

best,

ffnz

randytsuch · « **Reply #128 on:** 7 Mar 2006, 06:25 pm »

Quote from: fly_fish_nz

hi skrivis,

you and art are certainly right that it would have been best had tnt disclosed his affiliation with nf, perhaps in his signature. on the other hand it doesn't seem like he took efforts to hide it either, using his company email address and giving highly technical responses regarding NF amp design.

i read the posts fairly quickly, so maybe i missed some things, but most seemed pretty inoffensive and informative. there were a few (e.g. regarding his preference regarding relative value vs another amp and then in this affair with sanders) where it clearly would have been better to make things clear.

as i mentioned, i don't know much about nf, but nuforce vs. sanders and sanders vs. ati make for some interesting drama during coffee break.

best,

ffnz

I beg to differ

If TNT's email address had not come out here

Quote from: amplifierguru

Hi Tranh,

Nice to hear you've received your kits. I will email your instructions just as I do with everyone else. Please check your nphysics email.

Thanks for your patience.

I know your an EE and design amps for a living but if you run into problems with the build feel free to contact me. I check my emails 3 times a day.

Cheers,
Greg

Then nobody would have figured out who he was. There is nothing in TNT's profile to link him to nphysics.
I think it was bad form for TNT to post here, and not reveal his true identity, especially when you look at his post history, as he posted in threads about digital amps and nuforce.

Randy

art · « **Reply #129 on:** 7 Mar 2006, 06:26 pm »

Inoffensive, probably. But it was obvious to me that he was hiding his identity and agenda from the beginning. Yeah, maybe I could have rooted out he is with some work, but why should we have to play Columbo?

Pat

fly_fish_nz · « **Reply #130 on:** 7 Mar 2006, 06:39 pm »

Randy and Art,

I certainly agree with you that it would have been better to have had disclosed the affiliation, just that it did not seem to me that he was trolling to specifcally to slam the competition or post glowing reviews of nf amps.

Regarding the email address, Randy, you are right that we would not have known. I was simply noting that he signed up here and purchased Greg's amp with his corporate email, so he was not hiding the info. from the site administrator or Greg. Still we all agree that it would have been better to make the connection obvious.

Best.

skrivis · « **Reply #131 on:** 7 Mar 2006, 09:14 pm »

Quote from: amplifierguru

Hi Agistos,

certainly, I will elucidate.

In a feedback amplifier there is a feedback loop, which is a chain of resistors and capacitors which define the gain of the amplifier and the feedback factor. It is common, in practice, to make the feedback factor 100% at DC to maximise stability of operating conditions and reduce the amplification of any DC at the input, to unity. This minimizes DC across the speaker voice coil.

The 100% DC feedback is commonly achieved by including a 10uF -470uF electroly ...

Hmmm... I'd think that DC blocking and coupling caps are more elegant a solution than trying to make the amp go down to DC. Will the power supply and output devices go down to DC? Then why let it in in the first place?

amplifierguru · « **Reply #132 on:** 8 Mar 2006, 03:44 am »

Hi skrivis,

Agreed that the PS, etc.. do not go down to DC - so why have an amp that does?

Because the best capacitor is no capacitor! In the case of DC blocking in a power amplifier, they, for convenience, are small electrolytics rather than huge polypropylenes. So if we can do the system DC blocking back in the preamp at higher impedance points, we may manage with a nice 1uF polypropylene so DC is blocked while using sonically superior capacitors. As the DC is now blocked from the signal path, the power amplifier, if it has reasonably good DC stability, can do without any DC blocking C's either on the input or in the feedback path.

The GB150D and GB300D were both designed as DIY experimenter amps with decent DC operating point stability of typ +/-25mV so that this can be explored simply by linking out the feedback C and adjusting the DC offset a couple of times. It may have no audible effect or it may?

Cheers,
greg

skrivis · « **Reply #133 on:** 8 Mar 2006, 08:59 pm »

Quote from: amplifierguru

Hi skrivis,

Agreed that the PS, etc.. do not go down to DC - so why have an amp that does?

Because the best capacitor is no capacitor! In the case of DC blocking in a power amplifier, they, for convenience, are small electrolytics rather than huge polypropylenes. So if we can do the system DC blocking back in the preamp at higher impedance points, we may manage with a nice 1uF polypropylene so DC is blocked while using sonically superior capacitors. As the DC is now blocked from the signal path, the ...

If DC does manage to get into the amp you'll have problems though.

I'm not sure I buy the "sonically superior" thing either. What's wrong with polyester for this usage?

For coupling caps, is this even an issue? It's my understanding that they don't actually charge and discharge in use, so much of the "superior" cap stuff doesn't apply.

What kind of distortion does a cap add? Can you measure it? Can you hear it?

There are certainly right places and wrong places to use certain types of parts, but I have a hard time buying into the whole "good sounding" parts thing. That goes for caps, for wire, jars full of pebbles...

I think it's great that you do give some choices. Your circuit also seems to be quite interesting. I've followed along with some of the explanations.

I might even buy the boards from you and try it out. That's high praise indeed.

amplifierguru · « **Reply #134 on:** 8 Mar 2006, 09:57 pm »

Hi skrivis,

There was a very detailed tech article published in the 80's in either WW or Audio on capacitor 'smearing', dielectric absorption and nonlinearity.

But a great way to evaluate this for yourself is to use an amp such as a DC coupled GB150D and experiment with a range of input coupling capacitors from polyester - polyprop - electro vs no coupling C, and see (or listen) for yourself for possible smearing or blurring.

Often, in the signal path, the best capacitor is no capacitor. It's nice to have the option.

Cheers,
Greg

RAW · « **Reply #135 on:** 8 Mar 2006, 11:22 pm »

Recieved my 150 kit today also the bassExtender.
Will be a little before I see them finished as I will have someone build them for me, just not enough time in the day.

Great job on the kit.

enzedone · « **Reply #136 on:** 9 Mar 2006, 01:52 am »

Please forgive me if this has been brought up before. I tried checking.

I have trans already at home but they are 25-0-25. If i decide to use these i will obviuosly get less power, but that doesn't worry me too much, but will using such low voltages hinder the setup of this amp?

amplifierguru · « **Reply #137 on:** 9 Mar 2006, 03:10 am »

Thanks Al, pleased you like it - see PM.

Hi endezone,

25-0-25 AC secondary will yield a power supply of +/-37V within about 2V depending on transformer regulation (~ size/type).

The GB150D amplifier can operate on this supply with a couple of minor resistor changes to optimise driver stage current and bias adjustment range. It should then deliver approx 65w into 8ohms and 120W into 4 ohms once again depending on PS holdup (traffo size and C bank).

Performance will not be compromised.

The difference between 120W and 150W is 1dB!

Cheers,
Greg

KLe · « **Reply #138 on:** 23 Mar 2006, 09:53 am »

Hi all

Thought that you might like this image

http://www.diyaudio.com/forums/showthread.php?s=&postid=875976#post875976
This amp was a Metaxas Solitare, but, now it's a Metaxas GB300D

KLe · « **Reply #139 on:** 24 Mar 2006, 07:06 am »

Quote from: KLe

Hi all
Thought that you might like this image http://www.diyaudio.com/forums/showthread.php?s=&postid=875976#post875976
This amp was a Metaxas Solitare, but, now it's a Metaxas GB300D

Hi all
I believe that it is easier to view the image at this url ...
http://www.diyhifi.org/forums/viewtopic.php?p=9000#9000