Simple Killer Amp - Introductory Offer!

JoshK · « **Reply #100 on:** 1 Mar 2006, 03:56 pm »

Mike got his, I've got mine, I know a few others that have gotten their kits. It takes a little while because he got so many orders and has to put together all the little pieces. Rest assured that Greg is a good guy and you will get your kits.

amplifierguru · « **Reply #101 on:** 1 Mar 2006, 08:42 pm »

Thanks Josh.

Yes I really was inundated with orders 2-4 weeks back

, so much so I had to order another run of PCBs - and the mfg promptly sat on the order for a week so when I arrived to pick them up ( I needed to get out ) they hadn't started!

I couldn't despatch anything for 6 days and had kits minus PCBs everywhere!!

Almost caught up with the backlog. I'll take a day off this w'end.
Thanks all for your patience.

Now it's up to you to build them and see if they're any good?

Cheers,
Greg

James Romeyn · « **Reply #102 on:** 1 Mar 2006, 09:45 pm »

Josh
Get that sucker together & tell us how it sounds.

Man it's so depressing. I had THREE good chassis laying around for years & years & finally tossed them a few months ago.....

mgalusha · « **Reply #103 on:** 2 Mar 2006, 02:14 am »

I'm getting there. One board is done and I'm hoping to get the other knocked out in the next couple of days. Just haven't had much time to spend at my bench.

KLe · « **Reply #104 on:** 2 Mar 2006, 11:50 pm »

Hi All
Another friend listened to my GB300D based system, on Sunday (now about 30 hours of run in), and I asked him to write a summary of his listening experience. This was his experience ...

Quote

Dear KL

Firstly, let me thank you for introducing me to the GB300D. I had only read about it in the various audio forums and was very interested to hear it for myself. The following is taken from notes I made whilst auditioning the amplifier at your place, I was also able to compare this to the notes I had made at other listening sessions we had had with your previous (and highly regarded) amp.

My first impression was of an incredible smoothness to the music, certainly the best I have heard to date. The next impression was the total abscence of any sense of speaker location. When doing a critical listening session I always do so with my eyes closed in order to focus better on the music and these two features positively lept out at me immediately.

At first I thought the soundstaging was a little narrow, then another CD was played and the soundstage was well beyond the width of the speakers and had futher depth as well. This amp really shows up any flaws in the recording as you can clearly hear if the recording engineer has done his/her job properly. Dynamics were sensational as well, but yet again, the quality of the redording is paramount to getting the best dynamics. People who get this amp will certianly be searching for audiophile quality CD's as there is the quality there to show up whatever signal the amp is fed.

Now onto the various levels of the musical spectum. Bass was clean and clear, definitely not a one note bass amp, this one. It was very easy to discern the bass was played on either an electric or accoustic guitar. Mid range was exceptionally smooth and all the instruments played within this range were there right in front of you. Treble was also very good but perhaps not as prominent as your previous amp.

One feature I always look for is the quality of reproduction of the piano as this is the instrument I play. I can report that the GB300D has the honour of being the best I have heard to date. Prior to taking up playing the piano I had always found the reproduced piano music lacked a lot and it was only on hearing it played live that I found what rich harmonics this instrument has. As you would know the piano is a large instrument and this is because it has a large sound board in order to produce it's beautiful tones and harmonics, I am pleased to say that the GB300D is easily the best I have come across, well above all previous amps.

Lastly, I had an unusual experience during the latter part of the listening session, as mentioned before, I had my eyes closed whilst listening and at some stage I started visualising the group in front of me. I know critics have written of this before but it was my first experience of this and I found it quite startling to have this happen to me.

All in all an exceptional amplifier.

best regards
Ian

mine still to come

audiojerry · « **Reply #105 on:** 3 Mar 2006, 01:08 pm »

That's one helluva endoresment!
I look foward to hearing the views of our trusted AC members who have taken the plunge.

For the adept ones, do you think it would be possible to replace the amp section of a good, roomy, remote controlled receiver with these amp boards?

JoshK · « **Reply #106 on:** 3 Mar 2006, 02:41 pm »

Quote from: audiojerry

For the adept ones, do you think it would be possible to replace the amp section of a good, roomy, remote controlled receiver with these amp boards?

Possible? Yes. PITA? Don't know. It would be hard to say. If you do not wish to replace and rebuild the entire PSU, then the PSU specs would have to match, but there is a decent enough chance it would, especially since the design is very robust to different voltage levels.

Are we talking stereo receiver or Mch? Typically receivers pack things in very very tightly which makes it difficult to rebuild or work within. When things are this tight, layout is super critical to noise performance and much care and experimentation are usually required to get it right.

audiojerry · « **Reply #107 on:** 3 Mar 2006, 04:45 pm »

Hi Josh,
I was thinking more in the lines of a 80's / early 90's era 2 channel receiver w/o the bells and whistles. I was wondering if it's common for the preamp circuit board, and amp boards to be separate on these units.

amplifierguru · « **Reply #108 on:** 3 Mar 2006, 10:18 pm »

Hi KLE,

I gather your amp is sounding pretty good then? And you haven't even fitted blackgates yet?

I trust you'll be taking it along to your next Audio Club meet.

What is it - the R.A.C of Q?

Another 8 GB300D sets being despatched Monday for anyone feeling anxious.

Cheers,
Greg

KLe · « **Reply #109 on:** 4 Mar 2006, 12:06 am »

Quote from: amplifierguru

Hi KLE,
I gather your amp is sounding pretty good then? And you haven't even fitted blackgates yet?
Cheers,
Greg

Hi Greg
Yes, the GB300D is sounding very nice, indeed. Yes, no mods, yet, they are completely standard GB300D modules.

Greg, my friend, Ian, has since emailed me and reported the following criticism

Quote

I do have one criticism in that I felt it lacked some "sparkle" in the top end.

As good as the amp is, it would appear there is still more that can be done, to extract absolutely everything from this amp. What do you think?

amplifierguru · « **Reply #110 on:** 4 Mar 2006, 10:12 pm »

Hi KLe,

Yes your GB300D is in 'stock' AC couple configuration.

I've no doubt it is possible to extract even more from the design by exploring DC coupling and/or substitution of a few key components and their materials science

-

http://www.elna-america.com/tech_audio_series.php

Cheers,
Greg

Agisthos · « **Reply #111 on:** 5 Mar 2006, 01:27 am »

Now would be a good time to ask for the less technically inclined - what are the differences between ac and dc coupled and what are the strengths and weaknesses?

amplifierguru · « **Reply #112 on:** 5 Mar 2006, 01:53 am »

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 electrolytic capacitor on the input leg to ground of the feedback loop. This is believed, through the non-ideal nature of common electrolytic capacitors , to cause some low level smearing of the music. To reduce this a higher quality or film (large) capacitor may be used, but a more elegant solution is to eliminate this capacitor completely and go for DC coupling. Also similar DC blocking capacitors on the input if used.

However, to permit this elimination, the amplifier must be designed to minimise DC drift and allow for a trimming of DC offset which can be set to zero at normal operating conditions individually by the user. The alternative is to use a servo which adds complexity and it's own set of design problems which may reflect on the sound.

The GB150D and GB300D have been designed to allow AC or DC coupling so that owners, if they feel competent to set the adjustment, can explore the sonic advantages of NO CAPACITORS in the signal path - at least in the power amplifier.

Trust that helps.

Cheers,
greg

TNT · « **Reply #113 on:** 7 Mar 2006, 04:46 am »

I received the kit today, but found no schematic nor assembly nor drawing for the small PCBs, nor bias adjustment instruction normally needed. Too much bias will make the amp run hot, too little => crossover distortion.

How am I supposed to build the amps without them.

I saw some schematic of principle in related website, but how can one know it's applicable for the real amp too?

I'm an EE but have no desire nor time to reverse-engineer a kit.

amplifierguru · « **Reply #114 on:** 7 Mar 2006, 05:32 am »

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

JohnR · « **Reply #115 on:** 7 Mar 2006, 05:59 am »

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.

You are kidding me. TNT is someone called Tranh and he has an nphysics email address...

lonewolfny42 · « **Reply #116 on:** 7 Mar 2006, 06:06 am »

Quote from: JohnR

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.

You are kidding me. TNT is someone called Tranh and he has an nphysics email address...

This nphysics.... http://www.nphysics.com/ ??

theborg · « **Reply #117 on:** 7 Mar 2006, 06:25 am »

That one.

Agisthos · « **Reply #118 on:** 7 Mar 2006, 06:36 am »

Many amp manufacturers can be found on diyaudio.com . Incidently, that is where Greg got started with his kits.

ohenry · « **Reply #119 on:** 7 Mar 2006, 12:49 pm »

Quote from: lonewolfny42

Quote from: JohnR
You are kidding me. TNT is someone called Tranh and he has an nphysics email address...
This nphysics.... http://www.nphysics.com/ ??

I think I would have PM-ed him for those instructions...