The Frugalamp by OS

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
ostripper said:
chased by indians in montana

OS what are those speakers? Sony?

What's up with those damned montana indians?! When I was 23 I rode a honda 450 motorcycle from maine to alaska and back. I went through canada on the way to Ak. and mainly through the USA on the way home.

Riding through browning montana, I was also chased by indians... a whole pick up truck full of em. They eventually ran me off the road into a ditch.


:mad:
 
OS what are those speakers? Sony? What's up with those damned montana indians?!

They are sharp's , Next , i'll unleash the genesis on them.

As far as indians go , some are very nice. One of them came along and told the first group to go away (I had my knife out and was ready to fight.) The good guy invited me to his house on the reservation and he was a real gentleman. The first group was drunk and just wanted to fight. :drink:

Sorry that you hit the ditch, don . After Montana , I avoided the SD reservations because I was told they are very bitter :(

OS
 
ostripper said:
. . . 3300u/ 50v's (need 2 more).

Done, and also sent 4 optoisolators for a LightSpeed Attenuator. . .
I'm wanting to play with a LightSpeed; however, the recommended amplifier input impedance is 100k with 50k listed as workable. Also within that range, there are some very inexpensive amplifier input filter caps that are nearly unbeatable on results (they're small, they're green, and you have them already). ;) Have fun man! ;)
 
ostripper said:
. . . ASKA amps use similar blackgates as an expensive upgrade option (hundreds of dollars $$). . . .

Its kind of funny that they would charge that much for $5 caps. ;)
One thing about esoteric caps is that they're quite good in the application which specifies them; yet, otherwise, they're more likely to do harm than good.

P.S.
Sorry, not building the amps yet. Trying to make some money again. Probably 0.4 bazillion scads of mismatched bicycle parts are going to hit ebay soon. ;) Wow, but I guess I should start that amp while its still fresh in everyone's memory.
 
Simple QC test?

ostripper said:
Welcome back , DWB!! I thought lightning hit you on your "journey".
Better be quick, I am moving to the great smokies in 2 weeks. (different address)

Are you building your amps yet? (your amp is the very first "supersym" ,visit the thread...)
OS

Hey OS. I've got a question.
Did you try those big Mallory as output caps? Maybe that's workable instead of an NFB cap? Even if only temporarily done that way, I think it can illustrate if your NFB cap selection is good or not.

For instance, if the NFB cap is really nice, bypassing it in favor of using a speaker output cap instead (for DC protect job) won't make an improvement in the sound.

Otherwise. . . maybe there could be an interesting illustration of what the amp could sound like if the NFB cap was good?
What do you think of that?
 
Did you try those big Mallory as output caps?

Those big mallories are going to be my surround amp's PS caps. (BTF50). I am all OCL in all my amps. Back 20 years ago , I had some single supply amps with OP caps , but this is 2009.

For instance, if the NFB cap is really nice, bypassing it in favor of using a speaker output cap instead (for DC protect job)

If you have a really stable amp , there should be no issue. I ran the pi$$ out of your amps for 7 months and had not one "hiccup". A offboard DC protect using various IC's might be a wise move.
OS
 
ostripper said:
. . . If you have a really stable amp, there should be no issue. I ran the pi$$ out of your amps for 7 months and had not one "hiccup". A offboard DC protect using various IC's might be a wise move.
OS

Sure, but DC protect wasn't the point.

More like this:
Is it okay to temporarily bypass the NFB cap and also temporarily use an speaker output cap as a substitute? This is helpful to me in testing the qualities *effect on sound* of the NFB cap. It is for the purpose of selecting which model NFB cap to use because any cap-induced variances at this small-signal point are subject to gain of the amplifier. After successful selection of a really good NFB cap, then the output cap would be removed. ;)
 
By DWB - Is it okay to temporarily bypass the NFB cap and also temporarily use an speaker output cap as a substitute?

something like that would be alright on a chip amp , their internal protection circuitry would be a safeguard against a mishap or DC event. On a discrete , I would not play around , a mishap (or DC event) would perhaps blow the output cap up or fry the OPS. you are dealing with an output stage that can pass a lot more current here.

The things you CAN play with are the values of the NFB DC cap (100u , 220u , 330u) , the NFB impedance's (the 22k/1k ratio)... it can be 15k/ 680R or 2.2k/47k.. etc.

you COULD use the 3300uf output cap (no worry about the 10mv offset or as just for a test to protect your speakers).

The NFB cap on this discrete sets the DC at the NFB side of the tail. Without it , offset would just "float" , stressing the whole circuit. On simulation , I got a full 7 volts offset by jumpering the nfb cap. While this would not blow anything up , clipping would be asymmetric and you would also lose input pair symmetry (much higher THD).
OS
 
ostripper said:
Something like that would be alright on a chip amp, their internal protection circuitry would be a safeguard against a mishap or DC event. On a discrete, I would not play around; a mishap (or DC event) would perhaps blow the output cap up or fry the OPS. You are dealing with an output stage that can pass a lot more current here.

The things you CAN play with are the values of the NFB DC cap (100u, 220u, 330u); the NFB impedance's (the 22k/1k ratio)... it can be 15k/ 680R or 2.2k/47k.. etc.

. . .

Oh, I'm so glad that I asked! Thank you.

47k? Can use Litespeed Attenuator?
 
I would leave the 22k/1K ratio. Using the LS attenuator would be best with an op-amp follower (no change to amp open/closed loop gain). When I do get all 4 of my amps going at once , I will use 4 of the LS's like this to safely attenuate/balance my F/R (maybe even remote controlled). I have a real clean +- 12v auxiliary supply .. why not use it ?
OS
 
Re: Simple QC test?

danielwritesbac said:


Hey OS. I've got a question.
Did you try those big Mallory as output caps? Maybe that's workable instead of an NFB cap? Even if only temporarily done that way, I think it can illustrate if your NFB cap selection is good or not.

For instance, if the NFB cap is really nice, bypassing it in favor of using a speaker output cap instead (for DC protect job) won't make an improvement in the sound.

Otherwise. . . maybe there could be an interesting illustration of what the amp could sound like if the NFB cap was good?
What do you think of that?


Polarized caps as output caps will need a DC bias voltage to prevent the cap being reversed biased for half of the output waveform. At the currents that are involved here the cap could be damaged or fail without the bias.
 
My old APT Holman amps ned a little help

thanks to everyone and specially Tom Holman for the commentary on this great Apt Holman amp. I am currently using them (pair) in Bridged mode, and just last week got a pair of Acoustat 3. one of my amp is about 50% less output than the other. so the balance on the pre amp at about 9:30 to get equal volume. the auto turn on feature on my Celestions and Baltic speaker required that you crank the volume up till you get the signal to go through and it sounded pretty rough for 20-30 seconds and sometime one amp would cut out requiring the cranking procedure again. Since driving the Acoustat 3 systems the auto turn on fires up almost every time but the one amp still has low output. Sound is pretty good on the Acoustats, okay it sounds amazing. Got any suggestions on the low output or where I could get these perked up for reasonable? I am not that savvy (yet) with electronics fixes and soldering irons
Thanks
Kim
San Luis Obispo, CA
 

Attachments

  • sn851450.jpg
    sn851450.jpg
    50 KB · Views: 823
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.