After seeing how the simple capacitor I use for the crossover of a FOSTEX T500 affects the response of my JBL2441/Truextent I am thinking I need a dedicated amplifier for these. Maybe I could figure out how values to keep it from creating a rising response but I would rather just power the T500s separately and not touch my crossover for the 2441s.
Cannot afford an SIT1 for just the tweeters - I could not afford the SIT1 to begin with but I had to have it.
I would like a single stage design since I am lazy. I do not have a problem with caps on the inputs and outputs - would not have a problem with transformers, either.
Crossing over at 9 to 10KHz so very little power is required. Of course, a first order slope will be used so it needs to be GOOD sounding since it will influence frequencies below for an octave or so.
I was thinking about a spud amp using that Russian tube that Romy uses but I thought I should stick with the PASS signature since the range above 100 hz is driven by First Watt amplifiers and a tube could lend discontinuity to the sound.
Suggestions will be greatly appreciated.
Cannot afford an SIT1 for just the tweeters - I could not afford the SIT1 to begin with but I had to have it.
I would like a single stage design since I am lazy. I do not have a problem with caps on the inputs and outputs - would not have a problem with transformers, either.
Crossing over at 9 to 10KHz so very little power is required. Of course, a first order slope will be used so it needs to be GOOD sounding since it will influence frequencies below for an octave or so.
I was thinking about a spud amp using that Russian tube that Romy uses but I thought I should stick with the PASS signature since the range above 100 hz is driven by First Watt amplifiers and a tube could lend discontinuity to the sound.
Suggestions will be greatly appreciated.
AMP CAMP AMP - aha! If only I would search before asking ...
Thanks, again.
a minute of two later:
I have most of those parts on hand. Ordered the PCBs from THE STORE.
Not too sure about using switchers but then I have phobias.
What would you think about lowering the amount of feedback to get some more gain?
I have this unbearable desire to do SOMETHING different with it. Likely I will leave it alone - If I need gain I will put an autoformer in front of it.
Will it be happy with just a 1uF output cap? Sure hope so ...
Thanks, again.
a minute of two later:
I have most of those parts on hand. Ordered the PCBs from THE STORE.
Not too sure about using switchers but then I have phobias.
What would you think about lowering the amount of feedback to get some more gain?
I have this unbearable desire to do SOMETHING different with it. Likely I will leave it alone - If I need gain I will put an autoformer in front of it.
Will it be happy with just a 1uF output cap? Sure hope so ...
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Rick,
The ACA manages to sound more powerful than the 6w suggests. Not sure how it does it.
I built it with a linear supply and it sounds fine to me. Never heard it with laptop supplies, so I can't comment on the sound with bricks.
Vince
Same for me exactly. I was shocked at the sound from these little amps. Mine is stereo in the same case, linear supply much as all the FW stereo amps.
ya can call it Poor Man's SIT amp
Well, if we replace the current source with resistors could we come closer to a poor man's SIT1?
Or is this the place to try choke loading the MOSFET?
Any thoughts?
Just found ZM's SHADE version. ZM, should I try this?
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I seem to recall a well known amplifier designer/theoretician who likes them.
Efficiency means nothing in this application. This amp is wildly powerful for driving a tweeter above 8kHz (I would think).
Would Ing. Pass be willing to tell this soldering tinkerer how to proceed? If you get me started I think I can figure it out ...
That last sentence is probably wildly optimistic ...
Take care,
Efficiency means nothing in this application. This amp is wildly powerful for driving a tweeter above 8kHz (I would think).
Would Ing. Pass be willing to tell this soldering tinkerer how to proceed? If you get me started I think I can figure it out ...
That last sentence is probably wildly optimistic ...
Take care,
after that you can replace upper half with few power resistors
............ then listen .......... leave whichever iteration you like most
again - output cap goes in size and flavor of your liking
Attachments
naah ........
5R625 - not exactly value carved in stone
however - you can find them easily at ,say, mouser
chassis mounted (usually goldish) , 25W resistors
two of 1R8 and one of 2R (or 2R2) , all series connected , will result in nice 75W resistor group
you can get them for under 20 bucks (for all 6) ....... shipping excluded
http://eu.mouser.com/Passive-Compon...s/_/N-7h7zf?P=1z0wncuZ1z0x737Z1z0x703Z1z0wn9m
5R625 - not exactly value carved in stone
however - you can find them easily at ,say, mouser
chassis mounted (usually goldish) , 25W resistors
two of 1R8 and one of 2R (or 2R2) , all series connected , will result in nice 75W resistor group
you can get them for under 20 bucks (for all 6) ....... shipping excluded
http://eu.mouser.com/Passive-Compon...s/_/N-7h7zf?P=1z0wncuZ1z0x737Z1z0x703Z1z0wn9m
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I'm not overly bothered with "non-inductive" resistors , finding usual Dale-ish goldies enough non-inductive for my liking
feedback - same as I wrote for trying active vs. resistive loading - try original ACA , then change one thing at a time
why should you want changing stage gain , in first place , without any defined starting point ?
feedback - same as I wrote for trying active vs. resistive loading - try original ACA , then change one thing at a time
why should you want changing stage gain , in first place , without any defined starting point ?
To satisfy my curiosity - I read that some have recommended using high voltage B+ - is this simply for more power or is there a sonic benefit to doing this?
The reason I keep going on about the feedback is to adjust level if that is needed; there is the 4 dB difference between ACA and SIT1.
I will be using a crossover arrangement similar to what I am using for the JBL/Truextent on the SIT1 - both input and output caps sized for the crossover point but with the addition of an inductor for a .5 Q slope.
I have found with the JBL that an Lpad/damper really makes an audible and measurable difference and for that i will likely need the extra gain. If you think the distortion from low feedback would spoil the whole thing I will dismiss it now.
Do you think a 2200pF input cap could cause problems?
THANKS!
The reason I keep going on about the feedback is to adjust level if that is needed; there is the 4 dB difference between ACA and SIT1.
I will be using a crossover arrangement similar to what I am using for the JBL/Truextent on the SIT1 - both input and output caps sized for the crossover point but with the addition of an inductor for a .5 Q slope.
I have found with the JBL that an Lpad/damper really makes an audible and measurable difference and for that i will likely need the extra gain. If you think the distortion from low feedback would spoil the whole thing I will dismiss it now.
Do you think a 2200pF input cap could cause problems?
THANKS!
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