Amplifier Building vs old and used?

[donradick]

Re: Amplifier Building vs old and used?

I never thought speakers could have a different sound, i used to think its only the speakers and the quality of the medium being used. Boy was i wrong :P

How much did that irs2092 cost to make and how does it stack up musically against your other amps?

Get something like this:
http://www.ebay.com/itm/Assembled-LJ...item19f6af618c

The LJM designed boards are well-regarded.

And a power supply:
http://www.parts-express.com/abletec...6v-1a--129-147

So the base cost of the components is < $100. You of course need to add a case, power and signal connectors, etc.

I think the sound is very, very good. Massive power capabilities, ultra quiet and low distortion.
Plus, the amp is pretty small and light.

BTW, unless you are very experienced with soldering and electronics, buy finished boards.
there are plenty of challenges in the build, even with modular blocks.

Hope this helps.

[jason171717]

Re: Amplifier Building vs old and used?

Haven't read the other posts but the LM3886 is excellent. I have an audiolab 8000a which is a renowned integrated amp which cost around $1000 in the early 90s and the gainclones I used to use where probably better. That said the audiolab does something really awesome to electric guitars and has nice space. I love it. They go for $300 or less and they have a great phono stage if you're into that.

The cool thing about gainclones though is that if you need a 6 channel amp to go active or have surround or whatever, you just build more. Super useful thing to know how to do for an audio diy'er. Nelson Pass once posted a list of useful circuits with these included. Linkwitz used them in various designs.

I built my first one back when i thought you were supposed to drip the solder on to the joint and it worked regardless. No fires or anything, which is more surprising when you consider that I housed them in shoe boxes (dont do this). Its was really fun to demo a cardboard box with wires coming out of it and watch peoples faces when they heard them.

My point is that they are accessible for a first time builder. Maybe skip the shoe boxes though.

I so far have heard lots of great stuff about the lm chips i have a feeling that may be the chip for me to base my amp off.

That shoebox would be a real spectacle as long as it doesnt start to heat up! Cant believe you didnt have any problems making a shoe box amp ;)

That might be a pretty good thing to build multiples and run my 3 way mains as active speakers but then i have to get an electric XO right?

Your point is well noted, thanks! I am still deciding if i would be able to solder everything without issue or not :P

[jason171717]

Re: Amplifier Building vs old and used?

Well, a variety!

I've got a couple of DIY amps - LM3886 Gainclone (68W/ch) in my bedroom - a IRS2092 (250W/ch) I just finished, and a vintage Kenwood KM-208 (a real sleeper - great sound and specs).

They all sound a bit different, which was a big eye-opener for me.

I never thought speakers could have a different sound, i used to think its only the speakers and the quality of the medium being used. Boy was i wrong :P

How much did that irs2092 cost to make and how does it stack up musically against your other amps?

[upsideDownNBackwards]

Re: Amplifier Building vs old and used?

Haven't read the other posts but the LM3886 is excellent. I have an audiolab 8000a which is a renowned integrated amp which cost around $1000 in the early 90s and the gainclones I used to use where probably better. That said the audiolab does something really awesome to electric guitars and has nice space. I love it. They go for $300 or less and they have a great phono stage if you're into that.

The cool thing about gainclones though is that if you need a 6 channel amp to go active or have surround or whatever, you just build more. Super useful thing to know how to do for an audio diy'er. Nelson Pass once posted a list of useful circuits with these included. Linkwitz used them in various designs.

I built my first one back when i thought you were supposed to drip the solder on to the joint and it worked regardless. No fires or anything, which is more surprising when you consider that I housed them in shoe boxes (dont do this). Its was really fun to demo a cardboard box with wires coming out of it and watch peoples faces when they heard them.

My point is that they are accessible for a first time builder. Maybe skip the shoe boxes though.

[donradick]

Re: Amplifier Building vs old and used?

Thanks! I so far have been very impressed with the sound quality, though it seems to heat up fairly fast compared to all other amps i have, not sure if that is just its design or i have a problem, the speaker wire wasnt in all the way the first time, barely any contact (real rookie move ;) ). After that the heat subsided a bit but i was playing it quieter as well so by tomorrow when it has a fresh start we will see how it does it is too bad you gave away the hafler what amp do you use now?

Well, a variety!

I've got a couple of DIY amps - LM3886 Gainclone (68W/ch) in my bedroom - a IRS2092 (250W/ch) I just finished, and a vintage Kenwood KM-208 (a real sleeper - great sound and specs).

They all sound a bit different, which was a big eye-opener for me.

[weinstro]

Re: Amplifier Building vs old and used?

Thanks! I so far have been very impressed with the sound quality, though it seems to heat up fairly fast compared to all other amps i have, not sure if that is just its design or i have a problem, the speaker wire wasnt in all the way the first time, barely any contact (real rookie move ;) ). After that the heat subsided a bit but i was playing it quieter as well so by tomorrow when it has a fresh start we will see how it does it is too bad you gave away the hafler what amp do you use now?

When you feel up to the task, download the manual and check the bias voltage. One of the POOGE mods as described in Amateur Audio was to increase the bias, which causes the amp to dissipate more heat at idle.

As long as it's not so hot that you can't keep you hand on it for 30 sec, then there's minimal risk of damage.

[jason171717]

Re: Amplifier Building vs old and used?

My, that's a nice looking Hafler you have there. Was it in a time capsule?

I was wondering what type of trickery was going on myself :P

[jason171717]

Re: Amplifier Building vs old and used?

Very excellent choices! I scored the pieces from EBay a few years ago.
I gifted the DH220 to a very good friend, and still suffer remorse occasionally - but I still have and use the NAD preamp.

Thanks! I so far have been very impressed with the sound quality, though it seems to heat up fairly fast compared to all other amps i have, not sure if that is just its design or i have a problem, the speaker wire wasnt in all the way the first time, barely any contact (real rookie move ;) ). After that the heat subsided a bit but i was playing it quieter as well so by tomorrow when it has a fresh start we will see how it does it is too bad you gave away the hafler what amp do you use now?

[djg]

Re: Amplifier Building vs old and used?

My, that's a nice looking Hafler you have there. Was it in a time capsule?

[donradick]

Re: Amplifier Building vs old and used?

[ATTACH]59533[/ATTACH]

Thanks for all of your help i decided on a great combo! I havent had a chance to fully test but so far i am very impressed!

Very excellent choices! I scored the pieces from EBay a few years ago.
I gifted the DH220 to a very good friend, and still suffer remorse occasionally - but I still have and use the NAD preamp.

[jason171717]

Re: Amplifier Building vs old and used?



Thanks for all of your help i decided on a great combo! I havent had a chance to fully test but so far i am very impressed!

[Æ]

Re: Amplifier Building vs old and used?

Do you agree with he train of though that two smaller toroidal transformers are better than one larger one?

I do, however two large transformers are even better yet!

[weinstro]

Re: Amplifier Building vs old and used?

As for the lm chip, is that considered a pure 63 w? Or is that like the yamaha ratings?

I am not sure if i can use the rotel as a pre amp i still can not get rid of the electrical type of ticking noise it produces in anything connected to it when my theater/ game computer is running.

I was just putting that chinese website up here for mostly a shot in the dark ;) all web recommendations for canada will be taken much more seriously!

I will have to look into that leach amp some more it seems pretty popular.

I can second the vouch for the Haflers. They are audio appliances. At 4 ohms, they will exceed 200 W/ch - at least that was what the magazine test report said ~35 years ago. With careful shopping on e-Bay, $120 will get you one that should be OK, but may have some challenges. >$150 should get you a fine working unit. FWIW, I own 3. The DH-200 is pretty good, but the DH-220 added a number of circuit refinements and is a bit better. Next up might be an XL-280, but the main caveat with that amp is that it uses some hard to replace FETs on the input circuit. If you want gain controls and balanced inputs, consider the professional Haflers. With any used amp, be sure to check dc offset and heat generated at idle (bias).

The LM3886 will produce a true 68W into 4 ohms assuming that the power supply and heat sink are sufficient. Download the data sheet and take a look. Siegfried Linkwitz uses these on his Pluto speakers. Well, technically he uses an LM4702 and an LM3886 with active crossover. I've heard this system at numerous hi-fi audio meets and it has always sounded pretty stellar. I have a bunch of these chips and some "my ref" versions of the PCB sitting on my bench.

I'd do a little diagnostic work before re-capping that Rotel to eliminate ticking from one source. Could be something with the source, or input transistor that has gone noisy.

Regards,

Rob

[SpeakerScott]

Re: Amplifier Building vs old and used?

I've got a CE1000 and a DC300A Series II. Used some of the big-boys for work though. We used an AE-Techron (spin-off of Harman/Crown) 7200 watt model through a transformer to drive 500A RMS into a microohm load. Custom transformer. Secondary windings were sheets of copper. Amps would self-protect...but as far as I know none ever died. If I ever score a CE4000 for cheap it'll be a good day.

[DDF]

Re: Amplifier Building vs old and used?

Yeah...the BGW amp is great for cheap power...so is the Crown DC300A stock. Both can be drastically upgraded by improving the op-amp used in the differential stage and for the Crown...cleaning up the HORRENDOUS mess that is their grounding and wiring layout scheme. What the amps have in their favor is a nearly limitless power supply compared to their output rating that makes for a great foundation. You do need to know what your doing though...mis-application of grounding changes can yield crazy instability.

Used to use a Crown amp at work, awesome 300WPC brute that bridged to a massive number. Used it connected to a massive 5' sub to test sound leakage requirements for the US gov't: had to hit a phone with 125 dBSPL at 20 Hz.

THAT was fun. Had to test on a Saturday as you could hear it 2 buildings over. The Crown never gave us any grief in many years of use.