I think that a couple of people that got cases with bipolar transistors have spoken up to trade with Fast Eddy. Since the MOSFET sidepanels would bolt right into their case it makes the most sense for them to do this. Fast Eddy was just offering the sides of the case- two slabs with heatsinks that will bolt onto their Pass case, in exchange for their slabs with bipolars which he will strip off and then bolt on his Aussie Amps boards..
Eric,
It seems that you only need 4 channels per amp, because, as you mentioned, the front and rear facing tweeters could share a channel, and since they use very little power, they probably should. I suppose it depends on what you build , but almost all Pass designs can handle very low impedence.
Of course if they are in series it would be high impedence not low
If they are in parallel they would be low impedence which the amps should be able to handle also as I mentioned.
Nelson once told me that he could find no correlation between damping factor and bass, so don't worry about that. I'm sure he will correct me if I misunderstood.
Mark
It seems that you only need 4 channels per amp, because, as you mentioned, the front and rear facing tweeters could share a channel, and since they use very little power, they probably should. I suppose it depends on what you build , but almost all Pass designs can handle very low impedence.
Of course if they are in series it would be high impedence not low
If they are in parallel they would be low impedence which the amps should be able to handle also as I mentioned.
Nelson once told me that he could find no correlation between damping factor and bass, so don't worry about that. I'm sure he will correct me if I misunderstood.
Mark
" ... Semi-complete chasis would sure make it much more likely that I will get to build amps ..." ... " ... Fast Eddy was just offering the sides of the case- two slabs with heatsinks that will bolt onto their Pass case, in exchange for their slabs with bipolars which he will strip off and then bolt on his Aussie Amps boards.. ..."
That's part of my trouble as well: My tired old eyes used to point a mean iron, but lately I have to have my soldering subbed out, I can still work the correct end of the screwdrivers, however = thus the reliance on amp modules rather than board level work =
BTW: I believe Nelson and I have a plan for the board / side hardware that will suit my purposes just fine and dandy = so I don't think I will need to swap any parts ... except maybe the xformer.
That's part of my trouble as well: My tired old eyes used to point a mean iron, but lately I have to have my soldering subbed out, I can still work the correct end of the screwdrivers, however = thus the reliance on amp modules rather than board level work =
BTW: I believe Nelson and I have a plan for the board / side hardware that will suit my purposes just fine and dandy = so I don't think I will need to swap any parts ... except maybe the xformer.
" ... My brother's chassis has a 2x 50 volt transformer. Are you saying you would trade a 2x 25V for this? ..."
The one I have does not match Nelson's list at all: I have a 2x 18 VAC transformer with the dual primaries (~160 VA = http://www.avellindberg.com/transformers/d4000_range.htm / http://www.avellindberg.com/transformers/d4000_range_specs.htm = +18 +18 = Model D4030). I would really like to swap this one for your 2x 50 (any watt rating that will fit in the chassis), and I would gladly pay all shipping costs both ways.
... I already have a +45 / +45 by 6.6 amp (total ~ 600 VA) but it has several other secondaries as well, so it will wind up being mis-used for my purpose. I could sweeten the deal with that ...
Can't help much with the caps, mine are both 100 VDC rated as well (15K uF).
The one I have does not match Nelson's list at all: I have a 2x 18 VAC transformer with the dual primaries (~160 VA = http://www.avellindberg.com/transformers/d4000_range.htm / http://www.avellindberg.com/transformers/d4000_range_specs.htm = +18 +18 = Model D4030). I would really like to swap this one for your 2x 50 (any watt rating that will fit in the chassis), and I would gladly pay all shipping costs both ways.
... I already have a +45 / +45 by 6.6 amp (total ~ 600 VA) but it has several other secondaries as well, so it will wind up being mis-used for my purpose. I could sweeten the deal with that ... Can't help much with the caps, mine are both 100 VDC rated as well (15K uF).
This is complicated.. I haven't checked as to what he actually has and probably won't be able to for a while. I was just going off the list. Of course the caps aren't a problem, just higher V than required but will work fine..
If anyone else wishes to deal with Mr. Fast E. I have no objection as I really need to check my brother's amp and discuss his options with him before any further action..
If anyone else wishes to deal with Mr. Fast E. I have no objection as I really need to check my brother's amp and discuss his options with him before any further action..
OMG OMG OMG OMG OH MY GOD OH MY GOD OH MY GAAAAWD!!
Oh WHY why why didn't i go to this! I dropped a brick when i saw that photo of all those amps, chassis, transformers goodies! I'm sick now. Oh Heaven.
I have often had dreams of rummaging though the pass labs back room and finding some pass treasure that i somehow managed to talk Nelson out of and bring home...From the looks of that pile....That dream may have not been far off!
Those of you that brought home one of those projects. I seriously hope you realize just how lucky you really are!
I will be there next year Even if i have to ride a bike, walk, hitchhike, row in a canoe, crawl, hop a train, ride in the back of a pig farmers truck, or grow wings and fly!
Holy Nightmare Batman!
Oh WHY why why didn't i go to this! I dropped a brick when i saw that photo of all those amps, chassis, transformers goodies! I'm sick now. Oh Heaven.
I have often had dreams of rummaging though the pass labs back room and finding some pass treasure that i somehow managed to talk Nelson out of and bring home...From the looks of that pile....That dream may have not been far off!
Those of you that brought home one of those projects. I seriously hope you realize just how lucky you really are!
I will be there next year Even if i have to ride a bike, walk, hitchhike, row in a canoe, crawl, hop a train, ride in the back of a pig farmers truck, or grow wings and fly!
Holy Nightmare Batman!
" ... Still no pictures on the site from this year`s show? ..."
Take a look at the Burning Amp Festival pages: http://www.diyaudio.com/forums/showthread.php?s=&threadid=106844&perpage=25&pagenumber=51 ... from about page 50 on ...
Take a look at the Burning Amp Festival pages: http://www.diyaudio.com/forums/showthread.php?s=&threadid=106844&perpage=25&pagenumber=51 ... from about page 50 on ...
Still More Questions (w/ Some Repeats)
From the two Pass amps I was so fortunate to have land in my lap, my current plan is to create a pair of mono blocks a la the F4. I anticipate running them in balanced mono mode (per the F4 manual) but may find myself running them in straight stereo as well – the flexibility of the F4 is pretty amazing. I’d like to maximize the power of the system without corrupting the F4 topology. To this end, I have number of questions that I hope may be useful to others with similar goals.
From the two Pass amps I was so fortunate to have land in my lap, my current plan is to create a pair of mono blocks a la the F4. I anticipate running them in balanced mono mode (per the F4 manual) but may find myself running them in straight stereo as well – the flexibility of the F4 is pretty amazing. I’d like to maximize the power of the system without corrupting the F4 topology. To this end, I have number of questions that I hope may be useful to others with similar goals.
- MOSFET Outputs
One of the amps I have has BJTs and the other has IRF240/9240 pairs. I’d like to stick on the MOSFET path so am looking to convert the BJT amp to a MOSFET model. As I described to Nelson earlier today, here’s what I think my options are…
a. Find someone who wants to swap my BJTs for their IRF240/9240 combos or something close.
b. Source some IRF240s and IRF9240s and modify my current BJT boards. This may require doing some matching on my own — I don’t know exactly what I would be getting myself into just yet with this.
c. Create two N-channel amps based on the 250s that Nelson has on hand. I don’t know if I can get all the flexibility of the F4 if I do this. I’d like to understand this better.
- Power Rating
Since the output stages in the amps use 4 matched pairs, would the output power rating be 25% greater than the F4 due to the extra matched pair?
- Driver Board
I’ve been wondering what driver circuit/board Nelson used for his experiments. Are they the same as the F4 or different? Any suggestions on what we should use?
- Transformer
My BJT amp is the one that has a transformer. The MOSFET one does not. I don’t think the Cotswold Electronics Ltd., Model D1054 at 45+45V is for me if I want ±22V rails as with the F4. And unless any of you guys knows how to get one, I’m probably out of luck for the second one anyway -- can't find any info on this guy.
- Filter Caps
I have two pairs of 31,000µF/50V filter caps so I think I’m good here.
- Power Supply
Since the F4 is the reference, I’ve been thinking that an F4 PS would be the way to go. What is everybody else doing? Options?
[/list=1]
I hope these questions aren't too basic (or stupid
) for this thread. I’m hoping that I’m not headed off if the wrong direction. Also, please let me know if I should be asking these questions elsewhere. Any constructive guidance would be appreciated.
k
Re: Still More Questions (w/ Some Repeats)
As these are stereo amps, I recommend all N channel to replace
the BJT's, and as I said, I have the IRF250's. They will make a
scary single-ended version of the F4.
We can easily use the 45 volt secondaries by running the primaries
in series, giving 22V secondaries, and you'll end up with more
power than a stock F4. Poor baby...
I recommend building followers out of these, and then if you need
more drive, we'll come up with some outboard gain.
This is pretty much the default plan for all these amps, as it will
get us the most performance from all of them and is flexible
enough to cover all the chassis / OS configurations.
kurtbauer said:
As these are stereo amps, I recommend all N channel to replace
the BJT's, and as I said, I have the IRF250's. They will make a
scary single-ended version of the F4.
We can easily use the 45 volt secondaries by running the primaries
in series, giving 22V secondaries, and you'll end up with more
power than a stock F4. Poor baby...
I recommend building followers out of these, and then if you need
more drive, we'll come up with some outboard gain.
This is pretty much the default plan for all these amps, as it will
get us the most performance from all of them and is flexible
enough to cover all the chassis / OS configurations.
F4 Threads
FWIW, I found some threads on the F4 last night after a lot of searching that I wanted to pass along. For those of you that have been around these parts for a while, this will be old news. But for me it's all new.
This is the main one, F4 power amplifier, that chronicles Nelson's introduction of the F4 to this group. It's extremely long but loaded with F4 information.
I found another link, WTB: F4 PCB boards, that is shorter but has some good information on boards, parts lists and such.
This slope is slippery.
FWIW, I found some threads on the F4 last night after a lot of searching that I wanted to pass along. For those of you that have been around these parts for a while, this will be old news. But for me it's all new.
This is the main one, F4 power amplifier, that chronicles Nelson's introduction of the F4 to this group. It's extremely long but loaded with F4 information.
I found another link, WTB: F4 PCB boards, that is shorter but has some good information on boards, parts lists and such.
This slope is slippery.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.