12V 5Ah SLAs give degraded sound from Bugle

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kreisler

  • Newbie
  • Posts: 3
12V 5Ah SLAs give degraded sound from Bugle
« on: 29 Jun 2007, 06:55 am »
Following suggestions here, I got two 12V 5Ah SLAs and hooked them up to power my recently built Bugle. I did it mainly because I was quickly going through regular 9V batteries, but I also gathered from posts here that there may be some enhancement of performance. So I was disappointed to hear a distinct degradation. On an hour or so listening and comparing, the sound strikes me as tinnier, the bass is weaker; instruments lose some of the distinctiveness of their sound. It is as if a grainy jangly veil has been thrown over everything.

I first built the Bugle for 60dB gain and used a 39 ohm load resistance, as suggested by the cartridge manufacturer. I was hearing more hiss than I would like, so I modified the Bugle according to a suggestion here (Topic: Do I need shielded ICs from TT to Bugle @ 60db??; Reply #2 on: December 30, 2004). I lowered the 13k and 390 gain setting resistors in the first stage to 3.3k and 100 ohms, respectively. And I lowered the series 1k resistor in the first stage to 100 ohms. This indeed reduced the hiss to acceptable levels. (I modified one channel and then tested. There was an obvious difference.) As a bonus, the overall sound was noticeably better. The midrange had seemed kind of too strong, or boomy, to me. The change cleared this up. The Bugle was sounding great.

So, what might be going on, and what could I do to still use the SLAs (and charger) that I bought and have the better sound that I got with the standard 9Vs?

kreisler

  • Newbie
  • Posts: 3
Re: 12V 5Ah SLAs give degraded sound from Bugle
« Reply #1 on: 5 Jul 2007, 10:31 pm »
I made two 9 volt packs of fresh alkaline D batteries taped together and hooked them up to the Bugle. The sound is BEAUTIFUL, clear throughout all registers. The speakers rose  up off the floor and dissolved into a clear full horizon of sound. The magic of the Bugle is evident.

I read that under low current draw, a 1.5v D cell might have 12-15 Ah capacity. That means I can expect a couple hundred hours of great listening.

I had even more D cells around, so I tried 12 volts worth for each side of the power. To my ears, 12 volts of D cells is like the 12v from the SLAs. Both produce a certain thinness, a constricting of the sonic range, a bit of harshness. Instruments seem off-color. Sometimes they sound as if they are playing in a tunnel. It is more tiring to listen to. Perhaps it’s not correct to say the bass is weaker, but it is less clear. When I go back to the 9v packs I usually notice something I didn’t notice with the 12v, and I could listen for hours. I tried 6v packs of D cells, and I get a thinness with that, too.

So, what to do with those 12v 5Ah SLAs giving me the subtly harsh, and comparatively thin, off-color sound?  I am not even an amateur at audio or electronic engineering. I was wondering if a simple 9v output voltage regulator based on the LM78L09 IC would introduce noise or other problems if I put one between each 12v SLA and the Bugle.

Thanks in advance to anyone who can tell me about this.

hagtech

Re: 12V 5Ah SLAs give degraded sound from Bugle
« Reply #2 on: 6 Jul 2007, 04:12 am »
Interesting.  I can't figure out why the 9V works best.  Certainly battery chemistry and state of charge will make a difference.

My guess is that a cheap regulator will end up doing more harm than good.  A super regulator designed for audio should be ok. 

jh

Kyle_C

  • Jr. Member
  • Posts: 17
Re: 12V 5Ah SLAs give degraded sound from Bugle
« Reply #3 on: 6 Jul 2007, 08:08 am »
Hmm, interesting. How would a newbie go about making a 9V D-cell battery pack? I'd love to give it a shot.

hagtech

Re: 12V 5Ah SLAs give degraded sound from Bugle
« Reply #4 on: 6 Jul 2007, 05:45 pm »
Well, that's 12 batteries.  Two packs of 6 each.  I wonder if DigiKey or Mouser has a 6-cell battery holder.  I know they do for AA size.

jh


kreisler

  • Newbie
  • Posts: 3
Re: 12V 5Ah SLAs give degraded sound from Bugle
« Reply #6 on: 8 Jul 2007, 05:38 am »
With materials around the house and about twenty minutes, I made three sets of two D cells taped end to end,  and lined them up together, with one in reversed direction. I used two short pieces of solid wire (perhaps a paper clip would do) to connect suitable positive to negative terminals on each end, just taping the solid wire pieces securely to the batteries. I taped wires onto the remaining free terminals. Taped down the wires so that the connections were secure if I moved the wires, then wrapped the whole business in duct tape for stability. The wires from the battery pack are connected (twisted together) with wires soldered into the Bugle board. (This is “research” configuration, allowing for quick changes of power source.) I guess I’ll get the battery holders (which are also sold with a 9v snap type connector) the next time around. Though my Bugle configuration is not the standard, it’s definitely worth a try.  The clarity and fullness of sound astounds me again and again.
Best,
K

Kyle_C

  • Jr. Member
  • Posts: 17
Re: 12V 5Ah SLAs give degraded sound from Bugle
« Reply #7 on: 2 Sep 2007, 03:52 am »
Thanks for the info. This is good stuff. Sorry for the long delay, I've been out of commission for a while.