So yesterday I was doin the Shootuh thing, which is spending my day off looking for good deals. (audio, video games, whatever) And came across a Pheonix Gold PG 25 amp. I have wanted one ever since Ttocs first brought them up a while back, so I have kept my eyes peeled for one.
The price was right at $40, and dude was willing to give me a $30 trade in on my Baja BA400, which is $10 more than I paid for it. The shop owner let me take it out to the hoopty to thrash on it for a minute, and I was very dissapointed with it's performance.
At low volume, it sounded way better than my current amp. But when cranked up to my usuall level, it sounded like hell. No amount of fiddling with the bass or gain could make it
sound right either. Plus, after about 5 minutes of play, this thing was too hot to touch.
Mind you, this thing was in "seen better days" condition, and had no built in LP crossover, and I am still all hurt that my dream amp pretty much flaked out on me.
Plus I was convincded I had the world's worst amp, and I obviously do not.....
So sad SADSADSADSAD
Replies (8)
30Hertz on 06/20/2007 14:36:26
Did you have the gains set correctly (voltage matched to the RMS output?) Did you have it wired at the correct impendance? Were u using this to drive a sub, or mids?
ShootuhMcBustaCap on 06/20/2007 14:59:51
I was driving a pair of subs with it, and considering what I heard about thae amp, having it at 2 ohms bridged was like child play for it.
As for the gain, i could only tune it by ear, as i do not have a voltmeter, and wouldn't know what to tune it too, as I'm not so much of a pro to know what it should be dialed in too.
I did mees with it as much as possible. Definitely glad I didn't buy it. TThats whay i love some pawnshops. Nothing like testing something out before you buy it.
Again, I am pretty sure that this thing was just a little old and abused. Some of the original terminal screwdowns were missing, and it had no external fuse holder, so this thing may have had an extermely abusive owner.
Ttocs said that this thing was a very stout cheater amp 24X2 at 4 0hms, and ending up being like almost 200X2 at half ohm, and almost 400x1 bridged into one ohm. He aslo said they could do it all day.
I have a thing for using low powered amps and ones that can take wild ohmage like that. How cool would it be to tell my homies I had a 50 watt 2 channel for subs, and none would be able to outbump me?
Oh, the sadness...........
MrBrownstone on 06/20/2007 15:10:11
I think you may not underdstand the application of that amplifier. It was designed to have multiple sets of speakers parallelled together.
24x2 @ 4 ohms
48x2 @ 2 ohms
96x2 @ 1 ohm
Basically, you got a 96Wx2 amp ..but in competitions, you were only 'charged' with having a 48Wamp...1/4 the actual output.
Try to remember, a 24Wx4 amp is a 24Wx4 amp when run at 4 ohms. The 'magic' of those old amps was the ability to run at disgustingly low impedances, yet not be destroyed.
The best 1990 amplifiers is run of the mill 2007 amplifiers. Think of the innovations in cars or TELEVISIONS in those 17 years?
Now, amps are:
More efficient
less expensive
more compact
higher output
more features...
get my drift.
This is why we talked about the 'Buck a Watt' rule when comparing the retail price of amplifiers vs the quality of the product.
30Hertz on 06/20/2007 15:40:19
To set gains on your amplifier you only really need a Digital Multi-Meter (DMM) that can be picked up at any Hardware Store [If they dont have one, they need to be shot]. When we tune by ear, to be perfectly honest its a crap shoot. Doing it properly is really actually quite simple, and accurate (since most of us don''t have an oscilloscope).
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Legend:
P = Power in watts
I = Current in Amperes
R = Resistance in ohms (nominal impendance)
V = Potential in volts (Voltage)
Knowns:
Resistance (load given by the speakers)
Power (desired wattage)
Unknowns:
Voltage (we''ll find this)
Current
Formulas:
P = I*V (formula for power)
V = I*R (ohms law)
After a little subsitution for voltage in terms of power and resistance we get:
V = square root(P*R)
Example: Say you have a 4ohm load presented to a 150 watt amplifier.
V = square root(150*4) = 24.5 volts
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Turn your head unit volume to 3/4 of maximum (Make sure to turn off all EQs, presets etc)
Connect your speakers to the amplifier (or find the same impendance by connecting resistors)
As a source, you should have a sine wave recorded at 0dB within the range you intend to amplify. For Subwoofer gain, I prefer to use a 60hz sine wave, for midrange I prefer to use a 1000hz sine wave. These can be downloaded from the web and burned onto a CD for use.
Turn your gains down all the way to 0 on your amplifier that needs to be tuned.
*Connect the positive lead of the DMM to the positive terminal on the amplifier (with load present)
*Connect the negative lead of the DMM to the negative terminal on the amplifier (with load present)
Turn on the DMM and set it to AC volts
Turn on your Head Unit and adjust it to 3/4 volume like stated above. [Your Amplifier should now turn on, if it doesn't you''ve got more problems than just tunine your amplifier GRIN ]
We now know by doing the math (shown above) we need to set the gains to 24.5 Volts AC.
Begin turning the gain nob on the amplifier till you read 25.5 volts AC (or close to it) on your DMM.
Congratulations, you have now correctly tuned your amplifier to supply the correct power at 3/4 volume (the highest volume we normally listen at) without clipping the signal.
WHEW,,,that was a long one. But its very simple and accurate. Use this for your future tuning application GRIN
-30
ShootuhMcBustaCap on 06/21/2007 01:08:08
Smooth. I need to get a DMM, but spending $20 on a tool pathetic as it sounds, means I may not make rent.
I think my broke hindquarters just got in the WRONG hobby. Audio is one expensive hobby. Maybe I should start knitting...........
gearhead on 06/21/2007 02:46:08
"Maybe I should start knitting........... "
I spend way less on audio gear than my wife spends on yarn. GRIN
swez on 06/21/2007 08:30:07
Having a decent DMM is a "solid investment" that can not only help us diagnose problems accurately before they damage our gear, but can also be used to help our homies with their install needs and diagnostics. (One can use this tool to make money too)
If a buddy or customer is having problems electrically, having a good meter and knowing when/how to use it, one can charge a modest fee and get things back on track fast for a modest fee. Mine makes/saves $$ almost every time I use it. SMILE
Swez
ShootuhMcBustaCap on 06/21/2007 11:11:42
Yeah, I have been borrowing my stepdad's when I need to use it. Unfortunately, it is a drive every time. I get paid today, I'll see what
I am working with after I do my budget.
I dunno, I still need to find a less expensive hobby. I'm like pretty low on ideas of how to improve my junk without replacing it all.
The price was right at $40, and dude was willing to give me a $30 trade in on my Baja BA400, which is $10 more than I paid for it. The shop owner let me take it out to the hoopty to thrash on it for a minute, and I was very dissapointed with it's performance.
At low volume, it sounded way better than my current amp. But when cranked up to my usuall level, it sounded like hell. No amount of fiddling with the bass or gain could make it
sound right either. Plus, after about 5 minutes of play, this thing was too hot to touch.
Mind you, this thing was in "seen better days" condition, and had no built in LP crossover, and I am still all hurt that my dream amp pretty much flaked out on me.
Plus I was convincded I had the world's worst amp, and I obviously do not.....
So sad SADSADSADSAD
Replies (8)
30Hertz on 06/20/2007 14:36:26
Did you have the gains set correctly (voltage matched to the RMS output?) Did you have it wired at the correct impendance? Were u using this to drive a sub, or mids?
ShootuhMcBustaCap on 06/20/2007 14:59:51
I was driving a pair of subs with it, and considering what I heard about thae amp, having it at 2 ohms bridged was like child play for it.
As for the gain, i could only tune it by ear, as i do not have a voltmeter, and wouldn't know what to tune it too, as I'm not so much of a pro to know what it should be dialed in too.
I did mees with it as much as possible. Definitely glad I didn't buy it. TThats whay i love some pawnshops. Nothing like testing something out before you buy it.
Again, I am pretty sure that this thing was just a little old and abused. Some of the original terminal screwdowns were missing, and it had no external fuse holder, so this thing may have had an extermely abusive owner.
Ttocs said that this thing was a very stout cheater amp 24X2 at 4 0hms, and ending up being like almost 200X2 at half ohm, and almost 400x1 bridged into one ohm. He aslo said they could do it all day.
I have a thing for using low powered amps and ones that can take wild ohmage like that. How cool would it be to tell my homies I had a 50 watt 2 channel for subs, and none would be able to outbump me?
Oh, the sadness...........
MrBrownstone on 06/20/2007 15:10:11
I think you may not underdstand the application of that amplifier. It was designed to have multiple sets of speakers parallelled together.
24x2 @ 4 ohms
48x2 @ 2 ohms
96x2 @ 1 ohm
Basically, you got a 96Wx2 amp ..but in competitions, you were only 'charged' with having a 48Wamp...1/4 the actual output.
Try to remember, a 24Wx4 amp is a 24Wx4 amp when run at 4 ohms. The 'magic' of those old amps was the ability to run at disgustingly low impedances, yet not be destroyed.
The best 1990 amplifiers is run of the mill 2007 amplifiers. Think of the innovations in cars or TELEVISIONS in those 17 years?
Now, amps are:
More efficient
less expensive
more compact
higher output
more features...
get my drift.
This is why we talked about the 'Buck a Watt' rule when comparing the retail price of amplifiers vs the quality of the product.
30Hertz on 06/20/2007 15:40:19
To set gains on your amplifier you only really need a Digital Multi-Meter (DMM) that can be picked up at any Hardware Store [If they dont have one, they need to be shot]. When we tune by ear, to be perfectly honest its a crap shoot. Doing it properly is really actually quite simple, and accurate (since most of us don''t have an oscilloscope).
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Legend:
P = Power in watts
I = Current in Amperes
R = Resistance in ohms (nominal impendance)
V = Potential in volts (Voltage)
Knowns:
Resistance (load given by the speakers)
Power (desired wattage)
Unknowns:
Voltage (we''ll find this)
Current
Formulas:
P = I*V (formula for power)
V = I*R (ohms law)
After a little subsitution for voltage in terms of power and resistance we get:
V = square root(P*R)
Example: Say you have a 4ohm load presented to a 150 watt amplifier.
V = square root(150*4) = 24.5 volts
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Turn your head unit volume to 3/4 of maximum (Make sure to turn off all EQs, presets etc)
Connect your speakers to the amplifier (or find the same impendance by connecting resistors)
As a source, you should have a sine wave recorded at 0dB within the range you intend to amplify. For Subwoofer gain, I prefer to use a 60hz sine wave, for midrange I prefer to use a 1000hz sine wave. These can be downloaded from the web and burned onto a CD for use.
Turn your gains down all the way to 0 on your amplifier that needs to be tuned.
*Connect the positive lead of the DMM to the positive terminal on the amplifier (with load present)
*Connect the negative lead of the DMM to the negative terminal on the amplifier (with load present)
Turn on the DMM and set it to AC volts
Turn on your Head Unit and adjust it to 3/4 volume like stated above. [Your Amplifier should now turn on, if it doesn't you''ve got more problems than just tunine your amplifier GRIN ]
We now know by doing the math (shown above) we need to set the gains to 24.5 Volts AC.
Begin turning the gain nob on the amplifier till you read 25.5 volts AC (or close to it) on your DMM.
Congratulations, you have now correctly tuned your amplifier to supply the correct power at 3/4 volume (the highest volume we normally listen at) without clipping the signal.
WHEW,,,that was a long one. But its very simple and accurate. Use this for your future tuning application GRIN
-30
ShootuhMcBustaCap on 06/21/2007 01:08:08
Smooth. I need to get a DMM, but spending $20 on a tool pathetic as it sounds, means I may not make rent.
I think my broke hindquarters just got in the WRONG hobby. Audio is one expensive hobby. Maybe I should start knitting...........
gearhead on 06/21/2007 02:46:08
"Maybe I should start knitting........... "
I spend way less on audio gear than my wife spends on yarn. GRIN
swez on 06/21/2007 08:30:07
Having a decent DMM is a "solid investment" that can not only help us diagnose problems accurately before they damage our gear, but can also be used to help our homies with their install needs and diagnostics. (One can use this tool to make money too)
If a buddy or customer is having problems electrically, having a good meter and knowing when/how to use it, one can charge a modest fee and get things back on track fast for a modest fee. Mine makes/saves $$ almost every time I use it. SMILE
Swez
ShootuhMcBustaCap on 06/21/2007 11:11:42
Yeah, I have been borrowing my stepdad's when I need to use it. Unfortunately, it is a drive every time. I get paid today, I'll see what
I am working with after I do my budget.
I dunno, I still need to find a less expensive hobby. I'm like pretty low on ideas of how to improve my junk without replacing it all.
Copyright ClubKnowledge 2009 * All Rights Reserved
