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  • #46
    Re: Amplifier Building vs old and used?

    I should also point out that a lot of vintage gear collectors point to the use of those modules as the start of the "BPC" or Black Plastic ...ahem....Carp period of audio equipment.
    DIYRM-A Thread, a 60 page speaker design guide
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    • #47
      Re: Amplifier Building vs old and used?

      Originally posted by jason171717 View Post
      Do you agree with he train of though that two smaller toroidal transformers are better than one larger one?
      Assuming the single tranny is properly rated for the load impedances presented by the speakers, don't agree. If the idea is to get better separation and headroom between channels, and assuming teh single xformer is properly rated, just use sufficient capacitance on the power rails. Way cheaper and more effective than 2 xformers. Multi xformers only make sense if you have them and don't want to buy a higher rated single. One of the 2Bs had been modded with 2 tranny's, I pulled one out and went back to single.

      Originally posted by jason171717 View Post
      "and no one was too thrilled with i" could that be because of the lack of headroom?
      Maybe that's some of it, but mine was failry powerful and well heat sinked. I listened with it for weeks and it just sounds like an old cheap amp to me. It's hard to describe, but its "grey", not clear sounding. The chip-amp guys swear you need boutique parts to make them sound good, but this had standard r's and c's (name brand, but not fancy). The other thing I really don't like about some of the chip amps is the overload protection circuit (National called it "Spike") which starts to cut maximum output voltage with operation below 4 ohms. I made sure to only use it into speakers that didn't trigger Spike protection

      Originally posted by jason171717 View Post
      "but more expensive" i stopped reading temporarily ;) on a more serious note, have you ever actually heard the amps in question or just heard from your sources?
      I was only comparing amps that I mentioned directly in my post. I've listened to all those amps in my post for many months or many years (1 NAD and 1 Bryston for 3 decades) except the LJM amp which I only heard for a couple hours. The ClassDAudio I haven't heard yet but trust positive opinions I hear of it, and given its similar to the LJM, trust that feedback. I almost bought one but bought ncores instead. I offered no opinions on amps mentioned by the other posters, so can't really help you with those

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      • #48
        Re: Amplifier Building vs old and used?

        Originally posted by SpeakerScott View Post
        Yeah..I've re-capped quite a few. If you're willing to put in a little hobby time that is fun for you it's not that bad of a job...at this point I've re-capped: McIntosh, Krell, Classe, Crown, BGW, SAE. Some are easier than others...the McIntosh PCBs were very high quality and easy to resolder...the BGW amp....less so.

        Scott
        Bryston was awesome, and mailed me all new caps for the 2Bs for free despite the amps being 20+ years old.

        I "pooged" one of the NADs when I bought it early/mid 80s and used good (for the time) panasonic electrolytics; its caps have been rock solid and outlasted the other amps. It might be because it was in near constant use though.

        At one of the local audio DIY get togethers we hear everything from brute force 70's sand amps to big tubes, Class D, Nelson pass first watt jobs, and novel DIY designs. They all sound pretty good to me except the big old 70s transistor amps which clearly sound very bad and very different from everything else.

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        • #49
          Re: Amplifier Building vs old and used?

          Originally posted by DDF View Post
          Bryston was awesome, and mailed me all new caps for the 2Bs for free despite the amps being 20+ years old.

          I "pooged" one of the NADs when I bought it early/mid 80s and used good (for the time) panasonic electrolytics; its caps have been rock solid and outlasted the other amps. It might be because it was in near constant use though.

          At one of the local audio DIY get togethers we hear everything from brute force 70's sand amps to big tubes, Class D, Nelson pass first watt jobs, and novel DIY designs. They all sound pretty good to me except the big old 70s transistor amps which clearly sound very bad and very different from everything else.
          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.
          DIYRM-A Thread, a 60 page speaker design guide
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          Direct link to DIYRM-A/B Updated PDF

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          • #50
            Re: Amplifier Building vs old and used?

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            Ended up grabbing this set of three, thanks for all of your help i wont be able to reply for a little while i still need to test it out ;)

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            • #51
              Re: Amplifier Building vs old and used?

              Originally posted by SpeakerScott View Post
              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.

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              • #52
                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.
                DIYRM-A Thread, a 60 page speaker design guide
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                Direct link to DIYRM-A/B Updated PDF

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                • #53
                  Re: Amplifier Building vs old and used?

                  Originally posted by jason171717 View Post
                  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

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                  • #54
                    Re: Amplifier Building vs old and used?

                    Originally posted by jason171717 View Post
                    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!

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                    • #55
                      Re: Amplifier Building vs old and used?

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                      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!

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                      • #56
                        Re: Amplifier Building vs old and used?

                        Originally posted by jason171717 View Post
                        [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.

                        I think I hear a difference - wow, it's amazing!" Ethan Winer: audio myths
                        "As God is my witness I'll never be without a good pair of speakers!" Scarlett O'Hara

                        High value, high quality RS150/TB28-537SH bookshelf - TARGAS NLA!
                        SB13/Vifa BC25SC06 MTM DCR Galeons-SB13-MTM
                        My Voxel min sub Yet-another-Voxel-build

                        Tangband W6-sub

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                        • #57
                          Re: Amplifier Building vs old and used?

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

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                          • #58
                            Re: Amplifier Building vs old and used?

                            Originally posted by donradick View Post
                            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?

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                            • #59
                              Re: Amplifier Building vs old and used?

                              Originally posted by djg View Post
                              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

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                              • #60
                                Re: Amplifier Building vs old and used?

                                Originally posted by jason171717 View Post
                                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.

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