[dweekie]

External sounds good to me.  I would assume somebody could even hook up a linear supply externally if they wanted to should batteries become a pain or between chargings if one forgets.  It doesn't seem ideal, but it seems possible given the information thus far.  Any ideas on that?  The new lower pricerange is defintely very attractive to me. 

[rajacat]

I like the idea of an external auto type battery to keep the costs down, high capacity and easy replacement. A good looking battery box would be easy to build or the behind the wall solution seems good to me. A linear wall power supply could be an option but IMO defeats the main reason for battery power, add noise and would always be a source of upgrade nervosa.

-Roy

[gld]

I like the idea myself of selling it without batteries. The end users could use virtually any battery they wanted to use as long as it is 12 volts, Lithium Ion batteries are 12.8 volt packs which is fine as well.
More battery capacity means more play time. You would also have to have the proper charger for the batteries you are going to use. The biggest problem I see are the folks who want it but cannot or do not want to have to mess with getting batteries themselves, at that point I could offer a couple of packs that I know to work well.
I could also do a version that has an internal battery, 1 battery would service you for approx 2.5-3 hours and then require a 1.5 hour charge, it would be more expensive than a no battery version of course.
I think maybe offering both to start for those who want their own batteries and for those who just plain don't want to mess with batteries and charging. I would definately put a connector on every one of them just so even those who are using internal battery can also use external batteries any time they choose.
They would however have to disconnect or even remove the internal battery as it will not be capatible with other battery types and their associated chargers.
For those of you wondering it is a push-pull amplifier and it is operating in UL mode. Also someone asked if you could just use a normal linear power supply to power it, actually that would be a bad thing to do, it is deisgned to run on a battery, If a linear supply were used I think it would work but there would be noise generated and it would be audible. The 120 cy from the linear supply diodes and the grunge you just cant get rid of would conflict with the operating frequencies of the supply I designed and it would be audible totally defeating the purpose of a battery powered amplifier. The efficiency of the high voltage supply is approx 97-98% at full load of the amplifier. I really have done some special new things to achieve this high effiency along with very quiet high voltage.
With no internal batteries it could be made very small, something on the order of my phono stage, 7" wide x 12" deep x 3.5" tall. The tubes will have to be exposed due to the amount of heat those little tubes make. It's going to be a fun project any input is appreciated.
Gary

[JeffB]

Would there be any audible differences based upon the type of battery used.
I believe I read somewhere along time ago that Gel Cell type batteries were best because they discharge rapidly.

If we wanted a Gel Cell type battery could you give some idea how many Amp Hours the battery needs for a given amount of play.

I have a 5Ah Gel Cell for use with a Clari-T.  The thing will play all day on this and discharge very little.  Additionally, I can just play one album and it recharges in a few minutes. 

I also have a 12V 7Ah for use with a car audio cross-over.  To me these are quite compact, inexpensive, and easy to get chargers for.
Is this new amp going to need batteries a lot bigger than this?

[gld]

I don't know if 1 battery sounds different than another, sounds like snake oil to me. I mean whats the difference between pure dc and pure dc? Could be true though, never know until you try it yourself. Were not dealing with a tiny amp here that use milliamps. Were talking tubes, filimant current hungry little suckers. Then entire amplifier draws 4.8 amps continuously unless at full power and then it uses even more. Now consider in a perfect world with perfect batteries(yea right???) a 12 volt 5 amp hour battery will last 1 hour, not so it will actually last from 30 -45 minutes, depending on the condition of the battery.
So from this you can roughly calculate the amount of battery capacity needed to play the length of time you desire. The gel cell automotive batteries would be good for 20+ hours before needing charged, they would however require overnight to recharge.
Gary

[EDS_]

I just spoke with Gary about this new amp again. He is really happy with the sound.

The one thing that can really make the biggest difference in the price is the battery power supply options. He has been looking at Lithium Ion types, chargers, and the amount of space they take up. Multiple batteries make the chassis bigger and more expensive. Some may want enough power for 8 or 10 hours and some may only want enough for 3 or 4  hours.

Then there is the possibility of using gel cell type automotive batteries. They are a lot less expensive and would play a long time but would have to set on the floor or something because they are pretty heavy. One might even want to DIY a nice battery box for an automotive type battery and charger.

With all the possibilities out there, I then brought up the idea of building the amp with no internal batteries and making all the batteries external. So you can plug in any type of 12 volt battery that you want.

That would make the amp pretty small and much less expensive to build. Gary felt like he could make it look really nice in a small chassis and keep the price in the $900 range.

What do you guys think about offering the amp without batteries and then several external battery options?

A smaller chasis and an external battery would be far better IMO. 

[Jon L]

I just spoke with Gary about this new amp again. He is really happy with the sound.

The one thing that can really make the biggest difference in the price is the battery power supply options. He has been looking at Lithium Ion types, chargers, and the amount of space they take up. Multiple batteries make the chassis bigger and more expensive. Some may want enough power for 8 or 10 hours and some may only want enough for 3 or 4  hours.

Then there is the possibility of using gel cell type automotive batteries. They are a lot less expensive and would play a long time but would have to set on the floor or something because they are pretty heavy. One might even want to DIY a nice battery box for an automotive type battery and charger.

With all the possibilities out there, I then brought up the idea of building the amp with no internal batteries and making all the batteries external. So you can plug in any type of 12 volt battery that you want.

That would make the amp pretty small and much less expensive to build. Gary felt like he could make it look really nice in a small chassis and keep the price in the $900 range.

What do you guys think about offering the amp without batteries and then several external battery options?

A smaller chasis and an external battery would be far better IMO. 

Yup, smaller chassis with external battery would be my choice as well.
Just make sure to use male/female DC plugs everyone can find easily, e.g. at Radioshack

Not having the internal battery will make the amp cheaper, shipping costs less, much less chance of shipping damages, and make the amp more attractive to those of us who already have 12V battery supplies at home for T-amps, Empirical Audio stuff, etc. 

[HAL]

Sounds like a good application for an Absorbed Glass Mat (AGM) style deep discharge battery.  No venting needed like SLA's.

They are used for home power backup applications and others that need deep discharge.

Interstate batteries sells a 12VDC, 100AH AGM battery that work well for my AC backup system.  Have four of them in parallel.   Make sure you use a DC breaker on each battery for safety.

I use a 10amp 12VDC battery charger that has an automatic charge then trickle charge.  Make sure the charger is for an AGM battery and not a flooded battery.

[gld]

Use those batteries and a couple solar cells and let the sun charge em for you.
It would be pure dc so you would be able to listen and the batteires would be charged
continuously as long as the sun shines! aa
Gary

[EDS_]

Use those batteries and a couple solar cells and let the sun charge em for you.
It would be pure dc so you would be able to listen and the batteires would be charged
continuously as long as the sun shines! aa
Gary

I'd strongly prefer an integrated version.  Any idea/guess how far out that might be. My thinking is that a running batteries in a laptop/server, DAC and integrated might be the best way for a guy like the to go pure DC.

[stevenkelby]

I would just use a car battery and charger. Play all day then plug in to charge all night. Cheap.

[KS]

I would just use a car battery and charger. Play all day then plug in to charge all night. Cheap.

Uh-uh.  A standard car battery, a flooded lead acid battery, puts out hydrogen gas and some sulfuric acid vapor.  It must be isolated from the inside of the house and vented to the outside.  An absorbed glass mat lead acid battery...Concorde/Lifeline or Optima are well known brands...is sealed and OK for inside a house.  These have advantages over sealed gel cell lead acid batteries, also.

[stevenkelby]

Ah yes of course, I was thinking of an SLA or gel cell, like an Optima or something. Wouldn't want battery acid and fumes in the house! Even SLA batteries like RWA use are cheap enough.

[HAL]

Use those batteries and a couple solar cells and let the sun charge em for you.
It would be pure dc so you would be able to listen and the batteires would be charged
continuously as long as the sun shines! aa
Gary

Yep, something like I have to charge the AGM's for emergency purposes.

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=90599

[doug s.]

...Also someone asked if you could just use a normal linear power supply to power it, actually that would be a bad thing to do, it is deisgned to run on a battery, If a linear supply were used I think it would work but there would be noise generated and it would be audible. The 120 cy from the linear supply diodes and the grunge you just cant get rid of would conflict with the operating frequencies of the supply I designed and it would be audible totally defeating the purpose of a battery powered amplifier...

this amp seems like it would be something i wouldn't mind trying, but battery power is absolutely out of the question for me.  when you say normal linear power supply isn't a good idea, do you mean that this amp, powered by something like a lab-grade hewlett-packard 12v power supply wouldn't work well?  this is the only way i could consider using an amp like this.  my rig gets turned on when i come home from work in the evening, and doesn't get turned off until i leave the next morning.  and, on weekends, it's on from friday evening until monday morning.  music non-stop!   

thanks,

doug s.

[rajacat]

...Also someone asked if you could just use a normal linear power supply to power it, actually that would be a bad thing to do, it is deisgned to run on a battery, If a linear supply were used I think it would work but there would be noise generated and it would be audible. The 120 cy from the linear supply diodes and the grunge you just cant get rid of would conflict with the operating frequencies of the supply I designed and it would be audible totally defeating the purpose of a battery powered amplifier...

this amp seems like it would be something i wouldn't mind trying, but battery power is absolutely out of the question for me.  when you say normal linear power supply isn't a good idea, do you mean that this amp, powered by something like a lab-grade hewlett-packard 12v power supply wouldn't work well?  this is the only way i could consider using an amp like this.  my rig gets turned on when i come home from work in the evening, and doesn't get turned off until i leave the next morning.  and, on weekends, it's on from friday evening until monday morning.  music non-stop!   

thanks,

doug s.

I think that it would be easy to use a couple of sealed high capacity auto batteries, a high quality selector switch and a dual output charger to keep the amp in operation 24/7. Certainly it would be less hassle than feeding your turntable. A linear power supply certainly wouldn't be as quite as batteries.

-Roy

[Danny Richie]

Doug,

If background music is the goal then this might not be an amp to consider. This is a series amp that you'd want to turn on and sit in front of. You can use a Sonic-T amp for non-stop play of background music. .

[doug s.]

Doug,

If background music is the goal then this might not be an amp to consider. This is a series amp that you'd want to turn on and sit in front of. You can use a Sonic-T amp for non-stop play of background music. .

problem is, i live in a ~20x40 studio apartment, & my background music rig and my critical listening rig is one & the same; and this isn't gonna change any time soon...

doug s.

[Danny Richie]

Hey guys,

I went ahead and ordered one of these amps. I am having him make me one with a separate matching power supply with Lithium Ion batteries. I can't wait!