Solid State Guitar Amp Forum | DIY Guitar Amplifiers

Solid State Amplifiers => Amplifier Discussion => Topic started by: Farthing on September 21, 2011, 09:58:49 AM

Title: Modelling amps-genuine or not?
Post by: Farthing on September 21, 2011, 09:58:49 AM
There are many out there who describe modelling amp voicings as clinical or synthetic or even phoney.
It could be true in some cases. However the alternative, which is to buy the real deal-valve amps, is very expensive. A Marshall,Vox AC,Fender and Mesa alone can amount to several thousand pounds or dollars;you then need space to store the things. I own a small modelling unit and the sounds,while not capturing every nuance of what they imitate, come across as genuine enough for me.
Title: Re: Modelling amps-genuine or not?
Post by: teemuk on September 21, 2011, 01:26:54 PM
I think the answer greatly depends, and not in the least of personal preferences and opinions.

I've heard many modeling amps that - when set to a particular model - nail the tone of the tube amps that inspired them, at least in the amount of "reality" that I don't really bother to care if the tone isn't 100 percently "there". The very same modeling amps / preamps may also have a handful of models that, on the other hand, do not do as good job.

Add to that, it's greatly - GREATLY - a matter of how the thing is dialled in to sound in the first place. Most offer a great variety in how they can be dialled and there are good settings and bad settings. Add to that, reference amp may be dialled in certain way and the final user dials the modeling amp another way, so the two effectively end up sounding quite different. Personally, I don't even use my modeling multieffect/preamp pedal setup to try to sound like any specific amp in particular. I just exploit the overall possibilities of the different tones and dial the stuff the way I like it. My day isn't ruined if the "Blackface" patch doesn't sound exactly like some particular BF Fender model (which may sound different from rest of BF Fenders) or if the "Recto" patch doesn't nail the exaxt tone of some specific Mesa/boogie amp with some specific speaker cabinet, specific overall dial setup, at some particular stage or room.

I have also heard plenty of tube amps that soud clinical, synthetic and phoney. Heck, a great deal of the modern high-gain tube amps fill that clause. When you process the signal a considerable amount it will end up sounding processed no matter whether the processing is done by analog circuitry or by digital algorithms mimicing such. Tons of layered high gain, compression and drastic shaping of response will sound processed. That's just the nature of it.
Title: Re: Modelling amps-genuine or not?
Post by: Enzo on September 21, 2011, 10:33:13 PM
Teemu makes the point, it is about what sounds good to you, not whether the sound is an exact 100% accurate reproduction of the sound of some other amp.   Modellers are supposed to sound more or less like what they emulate.  Some are closer than others.   No one claims their modelling amp sounds identical to the originals, at least not honestly.  But if they sound good, and capture the spirit of the original, then they have done their job.

I'd agree, that rather than worrying if such and such a model is EXACTLY like the original, I just approach it like a versatile amp and dial in the tones I can get looking for ones I like.
Title: Re: Modelling amps-genuine or not?
Post by: darwindeathcat on September 23, 2011, 01:37:55 AM
Hi all....  I was just checking back in on this forum after a long absence and saw this thread. I thought i'd post because the reason I've been away so long is that I bought my first DSP amp simulator, and my quest for good quality sound at a low price was over! So I guess you'd call me a "believer" in amp modelers, but I do want to stress that I fully agree that they may not sound *exactly* like the amps they are trying to simulate. Not being an amp purist to begin with, this has never bothered me. To me, if it sounds good, then it is good, and my little RP unit sounds great to my ears! Personally, I think a lot of the bad rap these kinds of units get is from folks who bought them expecting a panacea, but never took the time to figure out how the things work, and never took the time to get all the levels set and their patches in good working order.

BTW, now that I'm a DSP guy (for tone), I'm now into SS amps even MORE than I was before. Only now my quest is simply for a nice clean amp to make my tone louder! I'm thinking about totally redoing my lm3885 amp with a nice clean buffer in place of the dirty little preamp I have in there, and then building a nice 2 way speaker cab to go along with it... It would be ideal to have this battery powered (at the cost of some output capacity) so I can take my show on the road (litterally).

Cheers,

DDC
Title: Re: Modelling amps-genuine or not?
Post by: Enzo on September 23, 2011, 03:15:29 AM
DDC, may I ask if you play on stage?  Or do you play at home?

It has been my experience that the people who give modellers a "bad rap," are people who tried them, liked the sounds, but found that while they sound good at home, once you get on stage and have to play at stage volume, and fit in with the test of the band, they often fall short.

Not saying that is always true, ther are people who use nothing but and are thrilled.  But that volume distinction is what sticks in my mind.
Title: Re: Modelling amps-genuine or not?
Post by: teemuk on September 23, 2011, 05:45:14 AM
I've heard the "doesn't cut through", "sounds like sh*t on higher volumes" arguments many times too. I've also seen many of the same amps those arguments were used against on stages cutting thorugh and sounding good.

In most cases it's practically just a user error: In their case the tone should have been tweaked at the band volumes with the band, not at whisper volumes, alone in the bedroom, and then turned up.

Many people just won't have the patience to go through the learning curve. Kinda like certain people's bias against Mesa/boogie's when the only real issue is the stubborness to keep every tone control at or close the noon and not having the patience to tweak a few minutes and try a bit more "unconventional" dial settings.
Title: Re: Modelling amps-genuine or not?
Post by: J M Fahey on September 24, 2011, 04:51:47 AM
Agree and add: this is a typical complaint from what can be called "bedroom rockers" .
Nothing bad about that, not everybody has a band with a fully setup studio (or at least a large garage) plus weekly gigs plus ample free hours to play whenever they wish, at loud volumes.
So it's usually you alone, playing along a mild, controllable backing track, at home, after work (meaning too late for everybody else), all of which mean a real low volume (compared to what playing 3 feet from a real drummer would be).
So with a versatile and powerful (I mean processing power, not the wall shaking kind) modeller you can easily dial a killer sound .... under those circunstances.
You can easily extract incredible bass from a relatively tiny cabinet ... at 85/90 dB SPL which is already too loud for family peace.
At the 100/105 dB required to match a drummer, that very same killer sound falls apart to pieces, *unless* you have a very powerful system to back it.
The *typical* complain I am asked to help with almost everyday is a guitar player with some fancy pedalboard or a Pod/Vamp/etc plugged into his trusty old Valvestate80/Bandit/Crate G80/etc. which typically is an SS combo, small, portable, 1x12" open back cabinet, etc.
You can easily dial a wall smashing Dual Rectifier_driving_a_4x12" sound there .... at home or light rehearsal levels ... but on Friday or Saturday night, on a real stage and trying to match a real drummer plus other real players, you simply don't have the required raw power, plus speaker efficiency and square inches ... it's simple physics laws which can't be beaten.
Funny thing is, that very same Bandit or whatever will work very well on that stage ... provided it's asked to supply its own sound, not somebody else's.
Does it mean sounding like a compact portable mid power combo? ..... well .... that's what it actually is !!  ;)
Title: Re: Modelling amps-genuine or not?
Post by: Farthing on September 24, 2011, 06:29:37 AM


On the subject of authenticity,in my experience Roland are pretty good. I own the microcube portable  4 speaker model. The AC30 setting is very authentic as is the Blackface . Not so good on high gain/ overdrive but then it is only 5 watts in total. The more recent 40 and 80 watt XL range have had good reviews.
As I said previously,the alternative is to buy 4 or 5 valve amps which add up to a lot of money. most guitarists are not proffesional.
Title: Re: Modelling amps-genuine or not?
Post by: Enzo on September 25, 2011, 04:38:42 AM
And the average bedroom warrior also does not have a PA system and a sound man to assist that great stage sound that some get.
Title: Re: Modelling amps-genuine or not?
Post by: darwindeathcat on September 26, 2011, 02:12:35 AM
I use my DSP pedal (a digitech RP unit) in small venues (like coffee houses), but I usually play out on the streets (I'm more of a busker than anything else). I use it with a small 20 watt PA (an old Realistic brand 2-channel with discreet transistors) at what I would call "reasonable" sound levels (i.e., no need for ear plugs, but loud enough to be heard in the back of the room). However, I'm a one-man band, so I don't have to compete with anyone else's (too) loud amplifiers. I use this set up to play both amplified harmonica and cigar box guitar. I love it because I have a range of tones at my fingertips (toes?) and I don't have to cart around a ton of equipment. I will say that my old PA doesn't stay clean enough at the volume that I need, and it starts to color the tone from my RP unit. This is one reason I'm considering to convert my more powerful lm-3885 amp to be basically a clean PA. I don't need extra volume, I just would like a bit more clean headroom.

fwiw, I totally agree that you have to program the unit at full volume. When I first got it, I made some patches that sounded great at home, but as soon as I plugged in an turned up, it was feedback city and bad tone. Instead of giving up, however, I tweaked. I soon realized that I just hadn't set up the damn unit correct. Also, I realized that I needed to re-tweak for EVERY different microphone I wanted to use with it. Settings that sound amazing with my stick mic sound like *s!!t* with my bullet, or with my bicuit mic, and vice versa.
Title: Re: Modelling amps-genuine or not?
Post by: joecool85 on September 26, 2011, 11:58:15 AM
Quote from: darwindeathcat on September 26, 2011, 02:12:35 AM...This is one reason I'm considering to convert my more powerful lm-3885 amp to be basically a clean PA. I don't need extra volume, I just would like a bit more clean headroom.

Did you mean LM3886?
Title: Re: Modelling amps-genuine or not?
Post by: darwindeathcat on October 03, 2011, 02:56:47 AM
Yeah, sorry. Mistyped. Actually, I'm considering to build a class D, as I kinda want a battery powered PA. The tripath chips can provide very decent output with single rail 12v power. I was looking at one kit for 2 x 15 watt stereo set up that claimed 2 amp peak current draw http://www.parts-express.com/pe/showdetl.cfm?Partnumber=320-308 (http://www.parts-express.com/pe/showdetl.cfm?Partnumber=320-308). If that's the case, you could even power a PA with rechargeable NiMh AA's and get at least an hour and a half of run time. Making that PA would be super easy, and the kit i was looking at is only $22. Couple it with a DSP pedal and you are good to go!

EDIT: This guy beat me to it! http://www.harmonycentral.com/docs/DOC-1833 (http://www.harmonycentral.com/docs/DOC-1833) This is EXACTLY the kind of rig I'm thinking about building. Super portable and GREAT sound!
Title: Re: Modelling amps-genuine or not?
Post by: joecool85 on October 03, 2011, 10:15:14 AM
Quote from: darwindeathcat on October 03, 2011, 02:56:47 AMEDIT: This guy beat me to it! http://www.harmonycentral.com/docs/DOC-1833 (http://www.harmonycentral.com/docs/DOC-1833) This is EXACTLY the kind of rig I'm thinking about building. Super portable and GREAT sound!

Neat!  I've thought about doing something like that for a while but never got around to it.  Plus at the time I was planning on using SLA batteries which are quite large and heavy compared to what he used.
Title: Re: Modelling amps-genuine or not?
Post by: gbono on October 03, 2011, 04:28:47 PM




wow over $100 just for batteries - portable but not cheap.









Title: Re: Modelling amps-genuine or not?
Post by: J M Fahey on October 03, 2011, 07:57:16 PM
For any reasonable power output (15/60W) the only cost effective battery I found was the ubiquitous 12V7A gel cell battery (the cheap ones used in alarms, emergency lights and such)
NiMH AA ones only provide usable life for 1 ior 2 W amps, barely louder than a steel string guitar, banjo, etc. ... unless you purchase U$100 worth of them.
Title: Re: Modelling amps-genuine or not?
Post by: darwindeathcat on October 03, 2011, 08:59:16 PM
@JMFahey: What class of chip amp were you trying to power? The reason I ask is that I've been lead to believe that class D (or T) chips are efficient enough to run off of low amp-hour batteries, but I have no direct experience with them. I don't need super high wattage, just enough to get heard on the street. I used to use NiMh's in my little pignose (which I've since sold on, since it was a one trick pony), and it was plenty loud at around 5W. It was one of the older discreet circuit ones too, but I still got several hours out it on a single set of NiMh's.

@gbono: Yeah, batteries ain't cheap! I looked up these new Lithium Ion batts he's using, and it looks like you can get a 12v pack for in the $30 range, which is similar to 12v SLA batts, but WAY less heavy (which is primo for a portable amp). The thing that always takes the price over the edge is the charger. You have to add on another $20 to $50 dollars for the damn charger! This is why I'm so keen to use NiMh. I've got tons of those already and a great charger. I use them in my cameras and other portable electronics.
Title: Re: Modelling amps-genuine or not?
Post by: J M Fahey on October 03, 2011, 11:54:19 PM
1) I've powered from a single LM383/TDA2002/3 (6W into 4`ohms, 10W into 2 ohms) to TDA2005 (16W into 4 ohms, what peavy Solo and Fender AmpCan use) to my Fet powered output transformer 40 and 60W amps to 60W conventional amps (discrete or chipamp) powered by SMPS type converters.
I've been making battery powered amps for a *long* time, as you see, and I've changed as technology does.
Haven't used class D amps yet.
2) please do not get confused by deliberately misleading sales talk.
Let's straighten this once and for all.
Class D amps (class T is just a marketing name) are "more efficient" as in they heat up less, but they don't magically create power they don't previously suck from a battery.
Let's put it in numbers:
just to simplify discussion, let's talk about "ideal" amplifiers:

Class AB (the regular kind)=70% efficient
Class D=100% efficient.

If we are talking about heat, a 30W RMS AB amp will lose 30Wx0.3= 9W in heat, a sizable amount which needs to be dissipated away or will quickly burn the chip.
So it "eats" 30+9=39W from the battery.
If we have a 12V one, it means 39W/12V=3.25A.
A 7AH battery will drain in 7/3.25=2.15 Hours

Now the class D one: it will eat plain 30W`from the battery, with no self heating at all (meaning it can have a small, non heatsinked chip)
Current conbsumptrion= 30W/12V=2.5A
Battery life= 7/2.5=2.8 hours.
Extra time=2.8/2.15=1.3 meaning 30% more.
Interesting but not mindblowing at all.

The Tripath guys let you think (although they are clever enough not to say so expressly) that you will get gobs of extra battery life from their product, which is simply not so.

Well, calling their amps class T is already a marketing gimmick too.

A of NiMH AA batteries, you will need 30 x 2700 MaH ones to match a single 12V7AH lead battery.
Don't know where you live , but in Buenos Aires, 3 or 4 AA batteries cost the same as a single Lead acid one.
Do the math.
As a side note, NiMH technology is new, so you need "good brand" batteries to fulfill their promise, I'm talking Sony, Panasonic, Sanyo ones, which means expensive.
Generic is much worse.
On the contrary, lead acid is 100 Years old technology, and the cheapest generic unbranded battery performs very well, there's no mystery for it.
Being a "feet on the ground" Industrial Engineer by training (not an Electronic Engineer as many assume), cost is a "technical parameter" as important for me as any other one, if not even more so.

As a side note, it's much easier to design a dumb Lead Acid charger than an intelligent NiMH one.
Let alone a Lithium cell charger; they are very complex because of the *certain* possibility of explosion and fire.
Remember Lithium cells are *forbidden* aboard planes, unless safely sitting inside your notebook, cellphone or whatever.
Just check fresh Airline Safety rules.
Title: Re: Modelling amps-genuine or not?
Post by: darwindeathcat on October 04, 2011, 01:40:49 AM
Thanks for the detailed response! That all makes perfect common sense. Thanks for clearing up the efficiency of class D versus others in terms of battery life. 30% extra battery life actually seems pretty good to me, though! That could be a few extra bills in the tip jar, ya know?!? :)

RE: NiMh's... The price ratio for NiMh batteries is quite a lot lower here in the states than for you down in Brazil. You can find name brand (energizer, duracell, sony, etc.) NiMh AA's for around $5 for a 4-pack if you shop at the right places, and decent chargers for around the $10 mark. So it's not SO outrageous. The cheapest decent 12 SLA batteries I can find locally have 5 AH ratings and cost about $15, plus still another $15 for the chargers... 7.5 AH rated SLA's go for about $25. So you are correct that SLA is still cheaper, but the margins are slimmer here in the states. Okay, so for fun (!), let's do some math to see what we could do with each battery for an equivalent perfmance:

So, if i can get good NiMh's for around $5 / 4, that's about $1.25 a cell. NiMh AA's run at 1.3v, so to get "12" volts you need 9 in series (9 x 1.3v = 11.7v). The ones I have (energizers) are rated for 2500MaH, so 9 batts should keep a 30watt tripath chip powered on full for at least an hour (which probably means closer to 1.5 hrs with real usage). This is 9 * 1.25 = $11.25, so we are getting real close to our SLA budget, and yes, this isn't really long enough to do much with. So, if we add a second array of 9 series NiMh AA's would up the MaH rating to 5, allowing for 2 hours straight playing at full volume (and perhaps even 3 hours of "normal" usage). While perhaps still a bit on the short side, I think we're finally getting into a decent range of use-time. SO, those 18 cells cost us 18 * 1.25 = $22.50. Let's add in the chargers: $10 for the NiMh, or $15 for the SLA charger. Okay, let's do the totals! $15 + $15 = $30 for the SLA, and $22.5 + $10 = $32.5 for the NiMh. This is interesting! For a couple of dollars more, you should get simialr performance at a fraction of the weight. What about that $25 7.5 AH SLA? Totals are: $25 + $15 = $40 for the SLA system. $33.75 + $10 = $43.75. Still about the same price margin.

Okay, let's look at other factors: It's definitely a pain that you can only charge 4 NiMh's at a time. For our 18 batts, that would mean you have to charge in 5 rounds!!! That sucks. For another $10, you can get a second charger and now do 8 at time. That's still at least 3 rounds... BUT, my NiMh charger takes only about 2-3 hours to charge up 4 cells. I think SLA chargers need like 6 or 7 hours usually, so although you have to be more proactive with the NiMh, if you have two chargers (or one that can take 8 batts), it's about the same charge time total. So now our price margin is not as slim. We've got about $15 more into the NiMh system at this point.

So, what to choose? My main reason for wanting to go with NiMh (or other standard small cell rechargeables) is for the weight reduction. SLA batteries are HEAVY man! And for a portable rig, I think it's probably worth the extra $15 or so to keep the weight down... Also, from what I understand, an advantage of NiMh is that they don't experience much voltage drop with use (ie, they stay pretty much at 1.3v throughout discharge), unlike alkalines that do drop voltage with use. The result is that performance doesn't decrease until the battery is basically drained (ie., no "low battery" syndrome). How does that compare with SLA? Do they drop voltage as they get discharged? If true, this could be another reason to use NiMh...

Anyway, it seems that either way, you are going to have to drop about $30-$40 just on the battery and charger system to build a battery powered amp that can hang for a few hours playing time at 30 watts. Now, if you decide to drop some power, and go down to, say, 15 watts (still pretty good for playing on the street), you can get double your playing time. In that case, you could potentially get at least 2 hours (potentially 3) out of your 9 2500 MaH NiMh's, and you'd only need to spend about $25. in any case, I've already got enough NiMh's to do the 9 battery configuration, and it's not TOO much of a pain to charge them using my one 4-batt charger. If I buy this amp module http://www.parts-express.com/pe/showdetl.cfm?Partnumber=300-385 (http://www.parts-express.com/pe/showdetl.cfm?Partnumber=300-385), I'll wire it up in dual mono as a PA, which means that if I only use one channel, I'm hoping I can get close to that 2-hours plus of battery life. The module costs only $15, and I've got an enclosure already built, which means that the most expensive piece of equipment will be the speaker. Just because I'm super cheap, and to keep this a super budget rig, I'm considering to use this low cost 10" driver (also from parts express so I can combine shipping with the amp module): http://www.parts-express.com/pe/showdetl.cfm?Partnumber=290-262 (http://www.parts-express.com/pe/showdetl.cfm?Partnumber=290-262). So, in terms of actual cost: I will be looking at about a $35 to $40 pay out after shipping costs. If I needed to buy everything, I could expect to spend probably about $70-$80, depending upon the enclosure. Comparable wattage commercial battery amps (like the taxi) are in the $160 range, so still a pretty good value! I have no idea about what it will sound like though!  ;D
Title: Re: Modelling amps-genuine or not?
Post by: joecool85 on October 04, 2011, 11:40:40 AM
Very interesting math.  Also of note, until the last year or so NiMH batteries were much more expensive than SLA.  Due to NiMH prices going down and SLAs actually going up (not a whole lot of people use them anymore), the margin is indeed quite slim.  I'm still a fan of SLAs for a lot of things though.
Title: Re: Modelling amps-genuine or not?
Post by: J M Fahey on October 04, 2011, 10:21:39 PM
The math is fine.
Only very slight correction is that you need 10 NiMH in series to approach an SLA battery, since they are actually 12.6V .
Most "car" type chips need that, and many rate themselves at 14.4V (just re-read`datasheets) because that's the car system voltage when the alternator is running and charging the batteries.
Othersa split the difference and spec at 13 something volts (13.5?)
Title: Re: Modelling amps-genuine or not?
Post by: darwindeathcat on October 05, 2011, 02:08:54 PM
Oh, cool! Thanks, I didn't realize that... Okay, so we will need 10 NiMh's for 13v to run our hypothetical battery amp. Good to know!

Actually, and somewhat ironically, just after I posted my last post, I went over to craigslist and noticed someone selling a Pyp PB-1 (http://pyp-bomb.com/home.html (http://pyp-bomb.com/home.html)) for $40 (they sell new for $150), so I snatched it up! The ironic part is that it's powered by a SLA battery!  :P

Of course, he was selling it so cheap because he had lost the wall wart adapter, and couldn't charge it. Now I need to find the specs for the missing wall wart so I can charge the sucker up (I'll start a new thread)! But the little bit of playing time that was left in it, was enough to convince me that this amp will really do the trick for me...
Title: Re: Modelling amps-genuine or not?
Post by: joecool85 on October 06, 2011, 10:56:14 AM
Quote from: darwindeathcat on October 05, 2011, 02:08:54 PM
Oh, cool! Thanks, I didn't realize that... Okay, so we will need 10 NiMh's for 13v to run our hypothetical battery amp. Good to know!

Actually, and somewhat ironically, just after I posted my last post, I went over to craigslist and noticed someone selling a Pyp PB-1 (http://pyp-bomb.com/home.html (http://pyp-bomb.com/home.html)) for $40 (they sell new for $150), so I snatched it up! The ironic part is that it's powered by a SLA battery!  :P

Of course, he was selling it so cheap because he had lost the wall wart adapter, and couldn't charge it. Now I need to find the specs for the missing wall wart so I can charge the sucker up (I'll start a new thread)! But the little bit of playing time that was left in it, was enough to convince me that this amp will really do the trick for me...

I didn't see any specs on their site, in the manual or in the pics of it on their site.  I'd contact them and see if they can tell you.  Because it uses a "smart" charging circuit in the amp itself, you will want to make sure you get the right adapter.  Or you could bypass that, hook the 2.5mm jack straight the battery and get an adapter that will "dumb" charge it (just remember to unplug it).  If you do this you will want a 12v adapter (unregulated, should put out 15v DC with no load) that is rated for 1/10 the battery.  IE - a 2AH battery would want a 200mah charger.
Title: Re: Modelling amps-genuine or not?
Post by: darwindeathcat on October 06, 2011, 04:32:38 PM
Thanks Joe Cool! I posted a schem I drew of the charging circuit in the other thread I started (http://www.ssguitar.com/index.php?topic=2318.0 (http://www.ssguitar.com/index.php?topic=2318.0)) plus a gutshot, so you can take a look at it over there. Yeah, I've sent a couple of e-mails to them with no response. I do have a "dumb" charger, so I think I might have to go that way in the mean time, because the battery is getting dangerously low... JMFahey is giving me some help over in that other thread, so i'll wait to hear back what he says after looking at the schem I drew before taking that measure... Thanks for all the help!

~DDC
Title: Re: Modelling amps-genuine or not?
Post by: gbono on October 06, 2011, 05:46:58 PM
My battery knowledge is weak but I do remember something about deep cycling lead acid batteries and lifetime/reliability. You can not deep cycle a car battery without significantly reducing its life. What about NiMh - I believe they are designed for deep cycle application - is the lead acid gel cel also a deep cycle technology?? You have to figure in the # of charges you will get from any battery technology - not cheap if it dies fast.......
Title: Re: Modelling amps-genuine or not?
Post by: joecool85 on October 07, 2011, 01:27:52 PM
SLA (sealed lead acid) doesn't like deep discharge.  It's safe to get down to about 1/2 charge on a regular though, 1/4 charge if you don't do it all the time.  NiMH is better at deep cycle but still not great.

**edit**
I guess NiMH is actually pretty good at deep cycle, I was thinking lithium-ion that doesn't love it.  Also, good ol' NiCads love a full discharge and they are dirty cheap.
Title: Re: Modelling amps-genuine or not?
Post by: J M Fahey on October 08, 2011, 08:33:21 AM
Yes, NiMH and NiCads *need* deep discharge and then full charge to "clean"them and avoid what we know as "memory effect" .
Smart chargers do just that.
Lead Acid batteries can be discharged down to 11V, but need to be re-charged, at least somewhat, at once, because when discharged the electrolyte turns into concentrated sulphuric acid which "eats" everything.
When charged said acid is combined with lead, and electrolyte becomes relatively mild.
Title: Re: Modelling amps-genuine or not?
Post by: Puguglybonehead on October 19, 2011, 02:10:29 AM
This looks like a cool idea. I'm getting interested in the idea of battery-powered amps myself. I'll be watching this thread to see what you finally end up with as a setup. If you're not totally set on having a 10" or smaller speaker, this 12" might be a better choice. 100 dB SPL, and the price is right.

http://www.ebay.ca/itm/160665836594?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649
Title: Re: Modelling amps-genuine or not?
Post by: J M Fahey on October 19, 2011, 06:11:46 AM
Slickly written ad.
The speaker is the cheap(est) Eminence.
The "censored " label hides the very tiny magnet.
100dB? No way !!!!!!
The real price is U$26, postage included, around $20 to 22 for the speaker itself.
That said, it may work, although I'd much prefer it in 4 ohms, what´s needed by the typical 12V 16/20W car chip amp.

Oh well, marketing !!!!
Title: Re: Modelling amps-genuine or not?
Post by: darwindeathcat on October 22, 2011, 07:47:56 PM
Well, since I was down at the local Fry's Electronics shopping for an unrelated item, I decided to price out batteries and charging systems so I could get an idea of what I'd pay retail here in Phoenix Arizona. First off, I looked at the SLA 12v batteries. The cheapest was $22 and was only 1.2AH. I'd say it weighed about 5 lbs. The other 12v SLA they had was 4AH, and went for $36, and probably weighed more than 10 lbs. Both batteries were "Tenergy" brand, which I've heard of. SLA "smart' chargers went for about $15, and an adjustable voltage universal wall wart that could be used as a "dumb" charger (12v, 500ma) went for $8. Best deal on NiMh AA's was again with the Tenergy brand-name, and was $11.99 for 4 AA's AND the charger. Remembering that we'd need TEN AA's to equal ONE 12v, that means we could buy two of those deals, and get a separate pack of 4 AA's for $7, or we could just splurge and get THREE of those deals so we could charge all in one go. These AA's were 2500ma. For a weight comparison I held a ten pack of regular alkalines. It was about half the weight of the small SLA, so I'd say about 2.5 lbs. If we go the AA route, we need some battery holders. The best arrangement sold in the store was to get one holder for 8 AA's ($2.49) and one holder for 2 AA's ($0.79), and wire them in series.

So, in a local retail setting the cheapest SLA set up would be about $30 for only 1.2 amp hours, and a dumb charging system, and the best SLA system would run you about $50 and you get 4 amp hours. You'd be adding 5-10 lbs of weight onto your amp. For a NiMh system, you'd spend between $40 and $45, and you get 2.5 amp hours.

Now, remember, this is buying retail. Better prices online could be found, but unless you can get free shipping (e.g., for an Amazon order above $25) or you can combine everything into one shipment for a reasonable rate, the price of shipping may be greater than the potential savings. For example, that 12" speaker listed on ebay sells for $12.99, but they want to charge you $28 in shipping!!!

Title: Re: Modelling amps-genuine or not?
Post by: J M Fahey on October 23, 2011, 09:57:06 AM
I must correct my mistake.
It isn´t even a cheap Eminence (I thought so because of the characteristic stamped frame) but an Eminence CHINESE COPY.
Oh well.
One buyer posted:
   "Nice speaker made in China by american famous Co.! Thanks!"

Reallly he should have written:
"made in China FOR american famous Co."
which is not the same.
Title: Re: Modelling amps-genuine or not?
Post by: Puguglybonehead on October 23, 2011, 06:31:51 PM
D'oh! Well, I ordered one of those speakers, so I'll have to see how well it actually works. Bargain-hunting is always a gamble. I'm actually ordering a 4-ohm 8" Jensen for my chip-amp project.
Title: Re: Modelling amps-genuine or not?
Post by: J M Fahey on October 27, 2011, 09:37:36 AM
It will work very well.
Please post your impressions.(or an MP3 or a YouTube) ;) ;)