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Messages - bry melvin

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Amplifier Discussion / Re: Heatsinks for your poweramp
« on: May 05, 2012, 01:28:39 PM »
On using computer heat sinks: I've been adding these (P4 or socket7 heatsinks  to Fender15G/R amps that I fix (TDA2050) on a regular basis.  I've been using a pair of these on 4ohm cabs in my studio. I've been buying returned  Fender squier/amp/guitar combos( repair and resell) for a while most of these have a burned out TDA 2050. For larger amps I've found the massive P3 passive (no fan) heatsinks Compaq used to use in P3 Servers and business desktops work quite well.

Also STAY AWAY from some of those Silver Computer heat sink goops some of them are CONDUCTIVE electrically.

Amplifier Discussion / Re: headphone jack feeds back?
« on: February 04, 2012, 12:13:36 PM »
I have run into similar problems with using adapters

Check the length of the adapter with other stereo 1/4 inch jacks

I have run into adapters that are just a little short keeping the tip from activating the switch that cuts the speaker off

Amplifier Discussion / Re: Randall RH100 issue
« on: February 04, 2012, 12:07:52 PM »
Even though the amp is new I would replace ALL the jacks:

I've been buying returns from musicians friend fixing them and reselling them:

About half of the returns are bad jacks  corroded contacts.

A lot of these "new amps" have spent a long trip in a container from China!

Only do this if your soldering skills are good.  It's very easy to damage the traces on these amps  So if you doubt your desoldering techniques don't try to fix waht aint broke :D

Amplifier Discussion / Re: Using Combo As Extension Speaker
« on: April 23, 2011, 02:56:51 AM »
I am considering taking an old guitar cable and removing the metal housing from one end
never EVER use a guitar cable for speaker wire  wrong gage and the second wire is the shield

doesn't work well and CAN kill an amp although a low power amp might not get killed by it

fwiw I always paint the cable ends of a 1/4 speaker cable red so roadies don't screw up my rig

I learned by cooking a a JTM one night years ago

Amplifier Discussion / Re: Watts vs Volume (db)
« on: April 12, 2011, 04:00:41 AM »
one factor everyone forgets about is frequency!  I often use a Fender 25 R for my steel... you can definitely hear it in the mix.

My bassist however cannot use her 60 Watt Acoustic practice amp with it (the Acoustic Brand not FOR acoustic)
25 wats is then > 60. seemingly.

She does use that amp when we're doing unplugged stuff...doesn't own an acoustic bass. And to agree with what's said before...get a different drummer. Two dreadnoughts electric bass and a drummer works for our acoustic blues gigs. And actually when I switch to the 000 for a few songs it pierces through to the top as it is less bassy...have to back away from the mikes.

Because we simply don't hear bass as well.

On the same token, scooping the midrange out makes an amp apparently softer then the same levels clean because we hear midrange best...That's why my steel and mandolin can get through the mix with much less power.

Actually for a too loud drummer buy him electronic drums...turn his earbuds up and turn him down in the mix  :lmao:

p 8 p9 p10 are AC from transformer with p9 the center tap. not DC till the diodes following in the schematic.

P2 and 3 are also AC from the second set of secodaries from the transformer.

The p 8 9 10 secondary set provide 2 voltages After the rectifier diodes  and filter capacitors you then have the +-27 and after dropping resistors and zeners you have +-12

P2 P3 windings go to a single sided power supply  rectifier dioes filters an provide 11.5 VDC to a 5 volt regulator for the DSP etc.

If you are using a stomp box low current preamp design you probably can get away with using the 11.5 VDC for the stomp box design preamp, You don't need the 5 volt portion of the circuit

and then use the other set seconaries circuit only as far as the +-27 Volt for your chip amp lm3886 power amp.

you won't need the 12 volt part of the circuit.

take a look at the power supply rectification guide on hammond transformers site.

with diode rectification  your 27 Volts comes from X (ac voltage) times 1.414 - approxiamtely a volt for the diode

Hammond explains it better than I do

so that transformer is approxiamtely 18 0 18 or 36VCT on one winding and approximately 9 volts on the other

my best suggestion for this project if you are not experienced would be to hunt junk amp that has useable voltages. And even some parts or circuits you can borrow or copy. Example the schematic I attached is a Fender Frontman 25 DSP

I just saw a lot of 5 of them on ebay for about 25 bucks yesterday

Note this amp was designed for 3876  some of them (later ones) and the frontman 25Rs actually had 3886s in them

Tubes and Hybrids / Re: hi gain tube preamp to solid state power amp
« on: March 31, 2011, 02:46:20 AM »
Here's a preamp that actually WORKs well. It's Peavey used in BOTH bass and guitar rack preamps.

Would be a good starting point/

I'd take a serious look at Carvin SX series.

Your 350 will buy one + They have blems on ebay for less too

I use Carvin SX 200s for jazz/blues etc. They have chorus. Albeit not stereo Alternatively you could look at used JC120s BUT there are several different JC120s all are not the same. Some really s---.

You can alos look for used AMPEG vh140C or crate Gx130cs used. However the crates  tend to need to be overhauled as they were made quite cheeply. The cement resistors burn up and fall apart. The large bus connecters cause a lot of problems and need to be hardwired at the power amp end.(near 2 resistors that heat everything up) These both are similiar and date from when LOUD ended up with both brands.

Amplifier Discussion / Re: Any Thoughts on a Carvin SX-200 for $100
« on: March 19, 2011, 11:41:08 AM »
What type of music do you play/record with this amp?

The Carvins were bought to do this album:

clarification  the album was recorded using a vintage (64) Guild amp ART digital processors and Peavey rack preamps DI.

I asked Carvin for something to use to do the album live.  Ended up with SX200s.

Note you need the footswitch for the effects on this amp to work properly. With the footswitch the channels remeber the settings as you switch back and forth.

Also you get a sharper cleaner tone by removing the footswitch and plugging directly into input 2

I have never used this AMP without the bues switch on (channel 1)  That gives me the best tube emulation/blues sound I have ever gotten from an SS amp.

Amplifier Discussion / Re: Any Thoughts on a Carvin SX-200 for $100
« on: March 19, 2011, 11:36:26 AM »
I looked up c24  shows polarized so those would be tantalum.

Amplifier Discussion / Re: Any Thoughts on a Carvin SX-200 for $100
« on: March 18, 2011, 03:30:47 PM »
 I use Carvin SS amps for performing and recording.

They are great amps:

However IF you can't figure it out yourself almost no one fixes Carvin amps. Carvin has an exchange program. Currently the SX200 exchange is 200.

The Carvin SX200 blem on sale at Ebay from Carvin themselves for 269 might be a better deal as it comes with a Warranty.

If you are confident of your skills I'd go for it though.

Another thing is Carvin has been through several speaker suppliers. If it is an older 200SX with the speakers that were made by eminince it's worth the 100 bucks for the two speakers.

I use NEWER sx200s to perform....but I have sets of those old emminence made speakers that I use in them. They simply sound much nicer. I find the newer GT12 Carvin speakers have a woody hollow sound to them.

Tubes and Hybrids / Re: Run my amp head through P.A. Speaker???
« on: March 18, 2011, 03:17:27 PM »
you probably can:

this assumes the impedence matches:

however guitar speakers and PA speakers do NOT sound the same IT probably will sound pretty bland. Guitar speakers tend to distort in ways that favor guitar sound. PA speakers are essentially hi fi.

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