The ultimate integrated frugalphile gainclone

I've been thinking about a full purpose best bang for the buck integrated amp based on the gainclone for a long time and would like to present some guidelines and a feature set:

Inverted "T" configuration with SuperSymmetry on amplifier section

JFET buffered to achieve maximum current/minimum phase error

unregulated power supply

1 digital input to a five channel DAC

2 general purpose inputs

2 tape (analog) inputs and outputs

1 tuner (analog) input

1 phono input with MM/MC circuits

1 headphone jack and amplifier

Does anyone here see why this project couldn't be completed for less than $250? I think this can all fit in standard 430mm form factor with plenty of room. Please feel free to critique the idea and point out some of the difficulties we are likely to encounter.

Thanks to Dave (planet10) for the use of "frugalphile"
 
carlosfm
Actually, I am undecided. It would be a nice feature to implement with future DVD-A recorded material but it will add some complexity. I suspect, going from a two to five channel DAC will be less trouble than making five amps work well. I think I read that there are some high quality multichannel DAC chips available today but correct me if I'm wrong.
 
It depends of what you wanna do.
I don't know any "high-quality" integrated 6-channel (not five) dac.
High quality is single or two-channel dacs.

But this all depends what you want.
You'd better tweak a half-decent DVD-A player and forget about the multi-channel dac inside the amp.

Otherwise what you propose yourself to build is not possible for $250.
Don't forget (ideally) independent trafos and PSUs for everything.
 
Why complicate things? Get in tough with your frugalphile roots and just go mono.

altec.jpg


Transformers by the way make great stereo-to-mono converters. :)

se
 
carlosfm
Let's go for the two channel DAC. I'm assuming that you're thinking of three separate power supplies (phono, DAC and integrated amp) but perhaps we can get away with two alone.

Steve Eddy
From your "mono" perspective, the whole thing can be run with a battery supply and a single source supply for recharge.
 
yldouright said:
Steve Eddy
From your "mono" perspective, the whole thing can be run with a battery supply and a single source supply for recharge.

Absolutely. Not to mention your speaker budget is cut in half. Or to look at it another way, for the same money, you could make one really mondo speaker. :D

Here's a sneak peek at my latest "chip" endeavor.

I've dubbed it the IPSGTCBPBICA, for Integrated Passive Signal Gain Transformer Coupled Battery Powered Buffered Inverting Chip Amplifier. Also known as the MABTYASTA, for My Acronym's Bigger Than Your Acronym So There Amplifier. :D

Not sure it can rightly be called a "chip amp" though seeing as I'm using the chip as a unity gain buffer. All of the signal (i.e. voltage) gain is accomplished passively using transformers.

Feel free to take any ideas from it if you like.

[IMGDEAD]http://www.q-audio.com/images/ipsgtcbpbica.jpg[/IMGDEAD]

se
 
Steve Eddy
That's quite an interesting twist on transformer volume control but I think that your project definitely requires a new thread since it is an active speaker concept :)
The more I think about battery supplies for the amp, phono and DAC section, the more I like it. The whole thing can be arranged with 4 cells but the case requirements will probably increase. The 3875 likes the 12V supply on 4ohm loads but some people may not like the power numbers generated with only 12V on the amp rails. I've heard a battery gainclone with a 12V supply driving a bi-wire 4ohm two way speaker and it sounded pretty good to me and plenty loud too. I suppose it depends on the sensitivity of the speakers used.
 
Intergraded Amp

This is a wish list for a perfect intergraded amp for my use:

Inverted "T" configuration with SuperSymmetry on amplifier section

JFET buffered to achieve maximum current/minimum phase error

unregulated power supply

1 digital input to a two channel DAC (connected to my PC or a transport.)

2 general purpose inputs

2 tape (analog) inputs and outputs

1 tuner (analog) input

1 phono input with MM/MC circuits

1 headphone jack and amplifier

I could see using Peter's LM3875 amp, DAC, and new phono stage. I do not know were the buffer board would come from. I would also like to see not using battery but a normal power supply. The PS transformers could be housed in a different box to keep RF down and the size of the boxes small.

What is everyone thoughts on this?
 
Re: Re: Intergraded Amp

Steve Eddy said:


I would argue that batteries are the "normal" supply. :)

se

I aggree, battery supplies are the "purest" power you can get. The issue with batteries I see are the size of the battery(s), the extra charging supply for the battery, and the need to fill landfills with piles of dead batteries. We can all recycle but does 100% of the batteries get recycle or not?

I use a great power conditioner so the "need" to isolate the phono/DAC/pre-amp/amp power supplies from the AC power lines have been removed.

I would be insterested in seeing a test between battery/off line power supplies and transformer/on line power supplies. The test would include the overall size of the power supplies, amount of head room, flexability of the power supplies, sound quality the devices, and to finish this off, the total cost of each.

Bruce
 
Re: Re: Re: Intergraded Amp

BWentler said:
I aggree, battery supplies are the "purest" power you can get.

Yeah, that's rather the perspective I'm coming from here.

Batteries are DC from the start. Otherwise, you have to take a 120 or 240 volt sinewave, run it through a transformer to step down the voltage, rectify it into 100 or 120 Hz pulses (and their harmonics), then into some reservoir capacitors to make it look a little more like DC and if you want to reduce the ripple more, some form of voltage regulation.

And that's not counting upstream stuff like line filters, power conditioners, etc.

Just gets insane after a while. For me anyway. :)

The issue with batteries I see are the size of the battery(s),...

Yeah, that can be an issue if you need a lot of juice. But if you've got high sensitivity loudspeakers and are using something as relatively efficient as the power opamp chips, you don't need to use huge batteries. With the right speakers, you probably wouldn't need any more than 7Ah batteries for any typical listening session.

...the extra charging supply for the battery...

Yeah. But hey, the charging can also be done via solar, wind and/or human power. How 'bout an audio system that's completely off the grid? That's my goal anyway.

...and the need to fill landfills with piles of dead batteries.

We can all recycle but does 100% of the batteries get recycle or not?

So, just because some idiots will toss batteries into the landfill they should be disregarded?

Lead acids depending on how much you abuse them can last upwards of 5 years. And there's already a mature recyling system in place for lead acid batteries, thanks to the automobile industry. There's no excuse for any batteries to be dumped into the landfill in pursuit of audio.

I would be insterested in seeing a test between battery/off line power supplies and transformer/on line power supplies. The test would include the overall size of the power supplies, amount of head room, flexability of the power supplies, sound quality the devices, and to finish this off, the total cost of each.

Don't hold your breath on that one. :)

se
 
Let's get serious please. This isn't Gilligan's Island and noone here is going to fashion a bamboo bicycle to generate power for a gainclone. I will be generating a parts list and budget as we move along on the undisputed items. The inputs described are numerous and noone seems to object to the ten sets of RCA jacks that will be required (or nine if we decide to use another connector for the DAC input) so I submit:

$15-ten RCA Gold female input jacks
$20-ten position switch (or two switches making 12 positions)

Does anyone here have a problem with single ended inputs for this project? Given the fact that we will be running an "X" type amp, would we be better off with balanced inputs?
 
matjans
Your reply brings up an interesting point. Since the sources are more than likely to be single ended, do we need to bother implementing supersymmentry in the amp? Some of the folks here have modded their sources to run balanced but I will leave this to the readers of this thread if the benefits of noise cancellation outweigh the additional parts and the inconvenience of modding our sources. Is there anyone who has built the GCSS and the TGC who can tell us what to expect with single ended sources? Metalman? carlosfm? Nuke?