Bookshelf Speakers
Jul 26, 2009 at 1:26 AM Post #16 of 89
I have the parts for the ZBM4's, and it doesn't look like it will be too difficult of a build. Cyberspyder's build thread will be helpful for sure. For some reason I felt the need to start my diy bookshelf speaker building journey with the SR-71's, so I can't tell you from experience how they are to build...yet. I picked up an 41hz.com amp4 to power them, at 30watts I think it should be enough
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CodeToad: Where did you see that under 80db efficiency figure? Looking at the power handling section of zaph's project page, modeled response seems to show that they wouldn't take too much power to drive.
 
Jul 26, 2009 at 2:34 AM Post #17 of 89
Deciding on a transformer, the most suggested one seems to be the Avel 25+25, unfortunately it is $53 which ends up being more that the rest of the amp put together. I found another one that has been suggested costing $19, but their ordering process is well outdated (I have never actually had to send a check to buy something online, and I'm not too big on credit cards over the phone). Does anyone know of a similarly rated transformer (220VA 20-25V toroid) that is <$50?
 
Jul 26, 2009 at 2:38 AM Post #18 of 89
Jul 26, 2009 at 2:44 AM Post #19 of 89
Quote:

Originally Posted by ThePredator /img/forum/go_quote.gif
Does anyone know of a similarly rated transformer (220VA 20-25V toroid) that is <$50?


Look for the AN-2225 at antekinc.com. It's 25-0-25 rated 200VA, dual primaries. $29+shipping.
 
Jul 26, 2009 at 3:07 AM Post #20 of 89
Quote:

Originally Posted by JamesL /img/forum/go_quote.gif
Look for the AN-2225 at antekinc.com. It's 25-0-25 rated 200VA, dual primaries. $29+shipping.


Thank you very much, that brings it within my budget.




Adding everything together it would cost ~$100 to build the gainclone versus ~$60 for the AMP6-basic (assuming I can find a good enough power supply for $10). Will there be a big enough difference between the two to warrant the price difference?
 
Jul 26, 2009 at 3:15 AM Post #21 of 89
You know that AMP6 has a few surface mount parts on it right?
 
Jul 26, 2009 at 3:22 AM Post #22 of 89
Quote:

Originally Posted by CodeToad /img/forum/go_quote.gif
You know that AMP6 has a few surface mount parts on it right?


I am fine with SMD, I do a lot of digital/embedded (non-audio) electronics and it comes up a lot (though I am more inclined to just get a breakout board if one is available, especially now that more and more parts are MEMS) so it shouldn't be a problem.
 
Jul 26, 2009 at 6:02 AM Post #23 of 89
Quote:

Originally Posted by CodeToad /img/forum/go_quote.gif
http://www.zaphaudio.com/ZBM4-measured-response.gif


T amps are awesome. The one on my desk draws 4 watts. The speakers are 89db and they only get so loud but it's ok for nearfield. Plan on using a sub. Be careful using a sub though (http://www.head-fi.org/forums/f21/t-amp-sub-out-286583/ )


There doesn't seem to be a power rating provided with that chart to use it to decide the sensitivity of the speaker.

http://www.zaphaudio.com/ZBM4-powerh...-fullrange.gif
"Modeled low end response in vented box with excursion @ 1,2,4,8,16,32,64,128 watts"

At one watt, the woofer seems to be slightly above 90db in a vented enclosure. Yes, it's modeled and not measured, but it's a good estimate of what it should be.

In the end I think both the gainclone and the 41hz t-amp (with an AMP4) should do well with the ZBM4's. What sort of box are you thinking of making for the speakers, predator?
 
Jul 26, 2009 at 6:10 AM Post #24 of 89
After reading through the 41hz forums it seems that the consensus is that the AMP6 will be quite unsuitable for 8 ohm speakers near the efficiency of the ZMB4's. The AMP4 would work, but it would cost the same as the gainclone, and I am not sure it would be any better, so I am going to do the gainclone using the Audio Sector boards.

For volume control is this pot suitable (I know it is low quality, but it would be easy to replace later) for attenuating the input? (the build guide doesn't state a suggested resistance; my two most used inputs would be a PMP and Bantam DAC)

For the fuse, what is the most convenient/easy-to-use package? The build guide suggests that I would need a 2 amp slow blow, and I would rather avoid panel mount (rectangular holes are a PITA to make).

For the speakers, is there any advantage to using to using banana plugs/binding posts, or is that mainly a convention for larger systems? I would much rather use RCA or mono mini-TRS plugs so that I only have one cable running to each speaker.

Quote:

Originally Posted by Nebby /img/forum/go_quote.gif
In the end I think both the gainclone and the 41hz t-amp should do well with the ZBM4's. What sort of box are you thinking of making for the speakers, predator?


Just the standard one from the Zaph Audio page (probably from MDF depending on availability/price):
http://www.zaphaudio.com/ZBM4.pdf
 
Jul 26, 2009 at 3:03 PM Post #25 of 89
For the volume pot, anything Alps is golden...no need for any stepped pots or fancy schmancy stuff. RCA's and mono TRS are fine, as they do the same job as a pair of speaker wires, but do you only want the GC powering your ZBM4's? If you choose this route, you're limited to what you can power with the amp.
 
Jul 26, 2009 at 7:32 PM Post #26 of 89
Quote:

Originally Posted by cyberspyder /img/forum/go_quote.gif
For the volume pot, anything Alps is golden...no need for any stepped pots or fancy schmancy stuff. RCA's and mono TRS are fine, as they do the same job as a pair of speaker wires, but do you only want the GC powering your ZBM4's? If you choose this route, you're limited to what you can power with the amp.


I can put both binding posts and RCA jacks on the speakers, it would only add ~$4. I will also go ahead and grab an Alps RK27 (I always forget that mouser carries it).
 
Jul 26, 2009 at 9:57 PM Post #27 of 89
RCA and TRS are normally used for low level input/output, so it would not be a good idea to use them in place of a binding post, especially on the amp side. If you are interested in a single connect from amp to speaker, look into the speak-on connectors. They're pricey, but very heavy duty. If those are too expensive I'd say just stick with the standard binding posts.
 
Jul 26, 2009 at 10:59 PM Post #28 of 89
Quote:

Originally Posted by Nebby /img/forum/go_quote.gif
RCA and TRS are normally used for low level input/output, so it would not be a good idea to use them in place of a binding post, especially on the amp side. If you are interested in a single connect from amp to speaker, look into the speak-on connectors. They're pricey, but very heavy duty. If those are too expensive I'd say just stick with the standard binding posts.


Those do look a lot more convenient since they lock, and I don't usually mind paying for Neutrik gear (none of their stuff has let me down yet); but I will have to decide if adding around $20 is worth it (4 males at $2.30 and 4 females at $3.21). How easy are the Neutrik speakon plugs to solder?


I got the MDF today (only 4'x8' was available so I will have to find a few more speaker projects to use up the rest) and cut the panels, and either I or my table saw fence isn't very good (a mixture of both, I assume) so I ended up with about 1/16" extra on a few panels which hopefully I can get off using the router. Unfortunately it is probably going to take about two weeks for the drivers and cross-over components to get here though.
 
Jul 27, 2009 at 12:03 AM Post #29 of 89
Quote:

Originally Posted by ThePredator /img/forum/go_quote.gif
Those do look a lot more convenient since they lock, and I don't usually mind paying for Neutrik gear (none of their stuff has let me down yet); but I will have to decide if adding around $20 is worth it (4 males at $2.30 and 4 females at $3.21). How easy are the Neutrik speakon plugs to solder?


I got the MDF today (only 4'x8' was available so I will have to find a few more speaker projects to use up the rest) and cut the panels, and either I or my table saw fence isn't very good (a mixture of both, I assume) so I ended up with about 1/16" extra on a few panels which hopefully I can get off using the router. Unfortunately it is probably going to take about two weeks for the drivers and cross-over components to get here though.


Do you have a flush trim bit on your router? Better buy a spare, as it is going to get dull quick.
 
Jul 27, 2009 at 12:04 AM Post #30 of 89
The speakon plugs/jacks are typical neutrik...fairly easy and simple to solder.

If your side panels are properly cut, using a straight cut bit with the router leads to perfectly sized tops and bottoms
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cyberspyder: What bits have you been using? I've gone thru a good amount of MDF without much dulling on my bits.
 
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