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Messages - Vitrolin

Pages: [1] 2 3 ... 5
1
Amplifier Discussion / Re: Peavey basic 50 weird sound
« on: February 05, 2017, 11:51:22 AM »
your preamp will not drive a speeaker, that is the power amps job.
the jack you used is like a fx loop

2
Amplifier Discussion / Re: power amp signal meter question
« on: February 02, 2017, 03:19:15 PM »
manual states 130W in 8ohm 1%THD
at clipping

https://assets.peavey.com/literature/manuals/80300574.pdf

3
Amplifier Discussion / Re: power amp signal meter question
« on: February 01, 2017, 04:43:12 PM »
The meter is driven by a LM3915, and its a voltage dB meter, so indicates how far the output voltage is from railvoltage.
or as manual states headroom left.


4
Amplifier Discussion / Re: Fender Mustang 1 Transformer Identification Help
« on: September 29, 2016, 04:36:11 PM »
Fahey is right in his correction of my last post anything directly connected to mains supply is lethal.

please take voltage meas on alle U301 pins, not pin 5...
pin 6 doesn't seem right check diodes and caps around it.

...you could make yourself an isolation transformer.
if you mains voltage is 230 or 220V you could take a pair of identical transformers with 110 or 115v sec.
make a series connection with the secondaries and you hav an isolated 230V.
use identical transformers with sufficient powerrating, or you could have some "interresting" results when loading, i have done this myself before i got my hands on a real mains isolation trafo.

5
Amplifier Discussion / Re: Fender Mustang 1 Transformer Identification Help
« on: September 22, 2016, 04:49:31 PM »
Hi could you take those measurements again with reference to GND at U301 pin4,

pin 6 should be around 15VDC (form D315)
pin 5 needs a scope to be measured see enzos and faheys posts
pin eight should be quite high +300VDC, be carefull it can kill you.!!
the optocoupler on pin 2 is a galvanically isolated feedbak from secondary side, this should be low to operate correctly.


6
Amplifier Discussion / Re: Fender Mustang 1 Transformer Identification Help
« on: September 20, 2016, 05:14:57 PM »
its a switch mode power supply, you could start by checking if the primary switcher is running, ive seen that more than once...

7
The Newcomer's Forum / Re: MPSU07 & MPSU57 alternatives?
« on: September 04, 2016, 01:57:06 PM »
where are you going to use them?
without that information it will be hard to find a substitute..

8
Tubes and Hybrids / Re: 6v6 power amp circuits
« on: July 16, 2016, 12:00:34 PM »
that gonna be hard to obtain, a KT120 might get you there.

but there i a reason most mid to high power amps are with a push pull output or when single ended with paralleled output tubes

but why must it be with only one output tube, it going to need a massive power transformer to get around 40W output.

remember that the output power claimed is depending on the THD level accepted, 24W maybe be with how much distortion?

24 watts at 10% THD or higher would be my guess.
yes hardly comparable to someone who accepts 5%


9
Tubes and Hybrids / Re: 6v6 power amp circuits
« on: July 14, 2016, 03:36:49 PM »
according to datasheet, 280V plate voltage you should give you around 14W per pair with a 8k output transformer.
with 4 output tubes you want a 4k OT.
look for an OT for el34 that will get you pretty close..

3k6 a little low
http://www.tubeampdoctor.com/en/shop_Output_transformers_Output_Transf_for_Marshall/Output_transf_for_Marshall_50W_2x_EL34_4_8_16_Ohm_165

4k5 probably better
http://www.tubeampdoctor.com/en/shop_Output_transformers_Output_Transf_for_Marshall/Output_transf_Marshall_for_40W_DSL401_1368

remember that the output power claimed is depending on the THD level accepted, 24W maybe be with how much distortion?

10
Hard to read but 4 Ohms is written on the back of the bottom 2 drivers.
Phil.

when i zoom, alot i see that all 6 says 4ohms,

so new speakers or fun with paralleling.



in theory you could also take 2 paralleled speakers in series with a speaker and a 4ohm paralleled
remember heatsink and a adequate power rating for that resistor.
not shure how i would work tonewise.



11
you could use 4 4ohm speakers in series/parallel getting 4ohm load for one output, and the two remaining speakers in parallel making a 2ohm load, guessing that 2ohm is close enough to 2,66ohm.

or decide that 6 i almost the same as 4, having a parallel pair in series with one speaker.

you could also wire the OTs in parallel, then it should be loaded with 2ohm or 1,33ohm deending on OT tap.

OTs wired in series would demand a load of 8ohm or 5,32ohm depending on tap

dont try to mix and match OT taps

this might help:
http://www.silvertoneworld.net/schematics/silvertone_1485.pdf

12
The Newcomer's Forum / Re: ESD precautions
« on: June 03, 2016, 04:35:55 PM »
IC damaged by static doesn't necesarely fail the moment they are exposed to static.

static can make the very thin connections in side ic even thinner, and the will then fry later...

13
Amplifier Discussion / Re: Bi-amping/ Tri-amping
« on: May 13, 2016, 01:49:50 PM »
Well, get over that, because transformers are inductors too.

And so are speakers...

14
Tubes and Hybrids / Re: Ibanez TSA30 Mains transformer
« on: May 06, 2016, 01:47:03 PM »
hey gustaf
i was informed by the swedish supplier that they didnt have any could but the factory had some they could order for me.
the amps owner didn't have interrest in buying the transformer at the moment so i dont know what what the final price is. also i think theyre very strict about not selling directly to consumers.

15
Amplifier Discussion / Re: Bi-amping/ Tri-amping
« on: May 03, 2016, 03:35:31 PM »
reurning to the original question about the punch from a speaker...

are we talking about a speaker in a cabinet or is it a "homeless" unit on the table?

speaker cabinets have a great influence on speakers low end response, simplified no cabinet no lows since the are cancelled out.
soundwave is long enough to go around the speaker and cancel the pressure difference

 

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