My betsy build

[fameless]

The betsy's are complete! Thanks to Paul for the build tips and great customer service! I really like the sound, need to swap the Klipsch Heresy's back in to see who gets crowned king of my living room. Here's my equipment breakdown: main source is my computer using J. River Media Center playing .flac files, Chaintek AV-710 soundcard optical out, Firestone audio Spitfire DAC with the Supplier power supply, NAD 165BEE preamp, DIY Class D amp TK2050 from Helder-HiFi, NHT X1 crossover and A1 amp for the subs, and the subs are two Klipsch SW-10II's turned passive after their amps went bad. NHT says not to use the X1 with subs other than their evolution subs, but I haven't seen an NHT evo sub for sale anywhere, besides it sounds good to me. I did have the betsy's running into the X1 crossed at 80hz, but I've been running them full range and like the results. So, what are your thought's? Suggestions to improve the betsy's or my equipment set up? Paul suggests running a cap from the preamp to the amp. I'll need to look up the imput impeadence of the amp boards to find the correct cap value.

 

[pjanda1]

The high pass filter would be to lower distortion and improve dynamic range, but it is only a really good idea because he has subs below it! And my thinking is that when possible, a line level filter is better than speaker level in terms of sound and cost, and passive tends to beat active for the same reasons. Fameless, I didn't mention this in the email. But many sub amps have 24db/octave or 18db/octave lp slopes, so forcing the OB's to have a steeper roll off may also get a better blend with the sub(s).

Great pics, thanks for posting them! How quiet are those amps through the Betsy? I've done Sure boards with Meanwell SMSP's and found the noise to be borderline. Amazingly, my tube amps are pretty quiet.

Paul
Wild Burro Audio Labs - DIY Full Range Speakers

 

[fameless]

There's a little bit of hiss, but it isn't noticable one meter away from the drivers. They get plenty loud as well. With the heresy's I had to turn the volume up half way to get uncomfortably loud, the betsy's reach the same level with only a quarter turn.

 

[nicoch58]

put a pot and try without a preamp ...how know ?

I build a lot of tripath sound very good but man the tubes....

Marry Christmas to all

 

[pjanda1]

Given that his pre drives both main and sub amps, I don't know if "passive" is a possibility. And it certainly wouldn't help my recommendation of a HP cap at line level!

Paul
Wild Burro Audio Labs - DIY Full Range Speakers

 

[nicoch58]

work very good with a tripath ,all the gain need , plus as at the input there is a cap for the bias of tripath input stage can be lower this for HP cap , better than have two in series

 

[pjanda1]

Its not just an issue of gain though. Keep in mind that the loads of the tripath and the crossover are in parallel. Either on its own may be fine, but together they may create a pretty tough load. I'm a big fan of passive pre amps and keeping the gain down, but when you start driving multiple amps, they make less sense. Which isn't to say that I haven't done it, but I'm thankful for my pre stage and occasional chip buffer to alleviate such concerns.

Paul
Wild Burro Audio Labs - DIY Full Range Speakers

 

[nicoch58]

you are right, but one eye to the source output , 47k on tripath and one eye on sub input impedence

 

[norman bates]

You could try a bigger ob.

I'm planning on a 5' tall ob using 3 sheets. Center baffle 12", left baffle 15", right baffle 19". The driver is 37" off the ground. 25" is too low for me, I've had fullrangers that low and didn't like it. But I see that in your setup, it is almost lined up with the center of the tv.

You could try some 20g magnet wire untwisted as speaker wire soldered directly onto the terminals.

You can make a foam box to go around the back of the driver.

Norman

 

[pjanda1]

Norman,

I agree that many folks, myself included, might like the drivers a little higher. I'd suggest that anyone make them as tall as they (and their partners) can tolerate. Tilting back (like the JE labs baffle) doesn't do much for me. You do make a good point about the TV though.

Are you thinking untwisted as a way to raise inductance in the speaker wire? That works well for speakers that are a little hot in the treble, but the Betsys shouldn't need it. Depending on the source of the hiss, it may help there. I tried clamp on ferrites with a chip amp I used to run. Didn't help much. A LP filter on the amp input did. But, I also suspect much of this noise is either in the chip itself or due to the power supply.

Any more specific suggestions on the foam box?

Paul
Wild Burro Audio Labs - DIY Full Range Speakers

 

[pjanda1]

Two more thoughts:

I always try and keep an eye towards economy. The 48" height is so you can get a stereo pair out of one 4x8 sheet.

Next, I was just looking again at the speaker cable in the pic. IME, class-t amps don't like much capacitance in the speaker cable. I don't know if those have a zobel, or how similar they are to what I've used. I had not only a very bare bones class-t (the original SI), but very high capacitance cable (braided cat 5). Still, you might find the amp sounds a little happier with something else.

Paul
Wild Burro Audio Labs - DIY Full Range Speakers