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It’s that time audio enthusiasts! Registration for the 2019 Speaker Design Competition is now open! Visit midwestaudiofest.com for details and to list your speaker project. We are excited to see all returning participants, and look forward to meeting some new designers this year, as well! Be sure your plans include a visit to the Parts Express Tent Sale for the lowest prices of the year, and the Audio Swap Meet where you can buy and trade with other audio fans. We hope to see you this summer! Vivian and Jill
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Helium - a true micromonitor

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  • Re: Helium - a true micromonitor

    I can vouch for the Lepai 7498 insofar as it's ability to deliver a good amount of clean power. That little bugger packs some punch. However, if you go that route, don't be sold on the bluetooth functionality. That's a not-so-good quality of an otherwise very nice amp. Direct connections to that amp are very good. Bluetooth is a noticeable downgrade in quality.
    Bryan K.

    Midwest Audio Club

    Speedster | Sub Attach | The Wildeman | Sean's NLA Towers | COGAR, COUGAR II and COGAR JR | Triton | Lithium | J-Boom | Trym MLTL | Docere MLTL

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    • Re: Helium - a true micromonitor

      Originally posted by corradizo View Post
      Those look great!!! I am excited to say i'm ordering the parts for these today. This will be my first speaker build that isn't a subwoofer. I was trying to decide between these and a version of the Overnight Sensations to use as TV speakers in my bedroom. We are just using the TV's built in garbage speakers right now. Having never heard either speaker, i can only gather that the OS would be full range due to the larger cabinet size (i was thinking 14"Tall x 6"Wide x 5" Deep on the OS on-walls...may still build them for the basement as 26x6x5 mtm's) and the Heliums would need a sub as they reach down to 80hz. I'm going to try them without a sub for a while and see how they do. I was going to order a Lepai 2020 amp with them and plug it into the TV's headphone jack, will that little guy provide enough power to get the Helium's to reasonable listening levels if the bed will be about 12' away? Should i look instead to an entry level stereo receiver?

      thanks!

      Pete
      I definitely agree that an entry level receiver would be a better choice. If your budget extends to about $100, and you want to stay with the mini-amp format, the Lepai 7498 or Dayton DTA-120 would do the job. If you want to stay lower in cost, you can search that online auction site for tpa3116 and come up with some good inexpensive amps from offshore sources. You should do your homework on those to make sure you are buying from a reputable seller, of course. Or, you can build your own using the Yuan Jing amp boards PE carries...
      Keep an open mind, but don't let your brain fall out.

      Sehlin Sound Solutions

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      • Re: Helium - a true micromonitor

        Thanks, those are interesting options. I've never thought about assembling my own amp. Do any of those support a subwoofer pre-out? I'd like the flexibility to add a diy sub. Also, what is the sensitivity of the Helium's? I probably really only need a few watts as we only watch TV in the bedroom when the kids are sleeping so we wouldn't really play it loud.... although I'd try :-) I can't wait for my pe order to arrive!!!

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        • Re: Helium - a true micromonitor

          Originally posted by corradizo View Post
          Thanks, those are interesting options. I've never thought about assembling my own amp. Do any of those support a subwoofer pre-out? I'd like the flexibility to add a diy sub. Also, what is the sensitivity of the Helium's? I probably really only need a few watts as we only watch TV in the bedroom when the kids are sleeping so we wouldn't really play it loud.... although I'd try :-) I can't wait for my pe order to arrive!!!
          You'll be lucky if the Helium is 80db sensitive, which is extremely low. Here's an example of the SPL you'd get with a low power amp like the popular Lepai TA2020 which is 8w/channel. I think you said your bed was like 12' away. The SPL at a full 8 watt input will be around 71db, which is low. Conversely, if you use an amp like the DTA120, you will realize listening position SPL of around 80db, which is much better. Also consider that with "a few watts" you have zero headroom and therefore the dynamics will be flat if you ever watch a movie for example. Just some food for thought. Personally, I'd never run this particular speaker with a low power amp. Look for something in the 50w range and you'll be ok.

          If you build a DIY sub with a plate amp that accepts high-level inputs, you can pretty much hook it up to any main amp. I've built several 2.1 systems using the Lepai TA2020 and a Dayton SA25 or SA70. No problem there. If you end up buying a used HT receiver, you'll probably already have a dedicated LFE output, so you'd be set (you could use any amp for the sub). That's another reason to seek a "receiver" for your amplification. Good luck.
          Bryan K.

          Midwest Audio Club

          Speedster | Sub Attach | The Wildeman | Sean's NLA Towers | COGAR, COUGAR II and COGAR JR | Triton | Lithium | J-Boom | Trym MLTL | Docere MLTL

          Comment


          • Re: Helium - a true micromonitor

            Sensitivity is pretty low, as Bryan mentions. They are right around 79 dB. I was targeting about the same power Bryan recommends - around 50W. The good thing about the Heliums is that they can comfortably handle that power.
            Keep an open mind, but don't let your brain fall out.

            Sehlin Sound Solutions

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            • Re: Helium - a true micromonitor

              I'm looking at eBay for used receivers. In the meantime I have an old stereo/tape/CD all in one thingie I'll try. It looks like pe is out of this cap https://www.parts-express.com/dayton...citor--027-414 and the 39 ohm resistor. Should I ask them to send me a different cap?

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              • Re: Helium - a true micromonitor

                The other 2 uF caps would work, but would be more expensive. That particular value is pretty sensitive, so I would not advise substituting 1.8 uF or 2.2 uF. The happy zone is about 1.9 to 2.1
                Keep an open mind, but don't let your brain fall out.

                Sehlin Sound Solutions

                Comment


                • Re: Helium - a true micromonitor

                  Thanks Scott, everything showed up today so I'm excited to get started. Can I use this one? https://www.parts-express.com/solen-...citor--027-534

                  Sorry I'm a total newb and not sure if the 250v vs. The 400v matters.

                  Best,

                  Pete

                  Comment


                  • Re: Helium - a true micromonitor

                    Originally posted by corradizo View Post
                    Thanks Scott, everything showed up today so I'm excited to get started. Can I use this one? https://www.parts-express.com/solen-...citor--027-534

                    Sorry I'm a total newb and not sure if the 250v vs. The 400v matters.

                    Best,

                    Pete
                    Sure, you can use that one. The voltage rating is a maximum voltage tolerance. 400V gives you more safety factor than a lower rating, but 100V would be plenty for this application.
                    Keep an open mind, but don't let your brain fall out.

                    Sehlin Sound Solutions

                    Comment


                    • Re: Helium - a true micromonitor

                      Or you could put two of these in parallel:

                      https://www.parts-express.com/cat/no...%5D&PortalID=1

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                      • Re: Helium - a true micromonitor

                        Thanks Herman, I called on Saturday and they said they got a large shipment in so I'm hoping to get them this week. If my caps aren't in that shipment I'll likely do two of those or the solen. Thanks!

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                        • Re: Helium - a true micromonitor

                          I am interested in building a desktop monitor into Parts Express enclosure 300-7060. The outstanding candidates are the Helium, and Jeff Bagby's Quarks.

                          Jeff shows frequency measurements, phase curve and impedance curve in his thread. Are similar measurements available for the Helium? If possible, I would also like to see a system response curve with inverted tweeter polarity, to check the phase integration between drivers.

                          Many thanks in advance. jonathan

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                          • Re: Helium - a true micromonitor

                            Originally posted by jcarr View Post
                            I am interested in building a desktop monitor into Parts Express enclosure 300-7060. The outstanding candidates are the Helium, and Jeff Bagby's Quarks.

                            Jeff shows frequency measurements, phase curve and impedance curve in his thread. Are similar measurements available for the Helium? If possible, I would also like to see a system response curve with inverted tweeter polarity, to check the phase integration between drivers.

                            Many thanks in advance. jonathan
                            FWIW, I am a strong advocate of linear response and good phase integration but you can achieve that with horrible drivers and should only be considered one of the deciding factors.

                            That being said, I would be hard pressed to say Helium would not be a point-for-point match. Scott knows exactly what he is doing.
                            Don't listen to me - I have not sold any $150,000 speakers.

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                            • Re: Helium - a true micromonitor

                              In this case I believe the Heliums would have more bass.
                              -Dan
                              Mandolin Curved Cabinet Floorstanding; Dayton Reference 18" sealed Subwoofer; Sealed 12" Dayton Reference Subwoofer ; Overnight Sensation builds

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                              • Re: Helium - a true micromonitor

                                All of my parts are in! I have a silly question about the port. Can I get 3/4 ID PVC and cut it at a 45 deg angle and glue the pieces together? Alternatively could I use 3/4" copper pipe?

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