Best Nelson Pass amp kit or project to go with Frugel-Horn Joan with MA200 drivers?

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Joined 2022
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#1
Starting the research well ahead of time and right here obviously the best possible place to do so🙂

I have been reading a lot here but there is so many posts it is hard to dig through it all so I hope those with the great experience in these things can help me out.

I will not likely get to the speaker build until mid fall, depending on weather so no big rush.

These will obviously be very efficient and am sure the Baby Sophia 10w P/P amp will drive them well, it has been fully upgraded and a great amp but I want to explore a low power class Amp build for them as well. I have no specs on the current draw on the BS amp so will have to measure it once I have it setup when speakers are done.

We are in a 434sq ft RV, seating is about 8-9 ft from front of speakers, 8 ft ceilings, two apposing slides just past where the speakers will sit, going to need some treatments of course.

Requirements:
Size, as small as reasonable.
Mono or Stereo, likely try both
Power, not likely to need more than 5 to 10 watts, could be less but not a big factor.
Lowest energy use as reasonable, on the grid but plan to go off grid eventually if I live long enough.
SMD? That would be a bit tough with my about to turn 73 eyes but I have steady hands and patience so a good LED magnifier might be all I need.
Needs to be in a case, PS internal or external, likely external as need small case(s) size as reasonable.
Cost, a few hundred to $800 or more if needed? That is for two mono amps could go up to around $1500 if bought over a few months or I save my pennies up.
Sound quality, the very best I can do for the requirements above.

Thanks,
Rick
 
#6
Thanks!
The SET on this particular amp does no stand for single ended, it means something like Sophia Electric. _______, it is indeed a Push Pull amp and drove my Edgarhorn Slimlines exceptionally well.

The Russian Military 6P1T tubes are quite good and last a very long time, I have a bunch of spares.

The NOS 5670 driver tubes are quite good and robust as well but there are others that are supposedly better, I will try a few if it will drive the speakers OK.

---------

I have been looking at the AMP Camp Amp, I like the size and there seems to be a number of upgrades for it that might be intesting to play around with and it is not to big, larger than I prefer but still not huge.

I will look at the F4, as long as not a big amp...., from what I can see so far it looks rather large.

Thanks again!
Rick
 
#9
Forum member kinku had some for sale a few years ago now F2 and F2J - try him with a PM , he might have a couple left.

This was his thread:
K

Thread 'F2 and F2J pcbs'

F2 / F2J Clone PCBs

Hi,
I have a pair of F2J pcb( separate left and right channels) and CRC power supply board for sale. Buyer has to pay for shipping and paypal fees.Please remember these boards are long 28cm.
These boards can handle boutique caps for output and inputs as there is provision for connecting capacitors with unusual dimensions( need to be outside the board). Standard caps on board are for polystyrene and poly-prop.
A mouser component list will be send with boards.
Both amp PCB have holes drilled for fitting 4U heatsink from DIYaudio store.
Power supply board has...
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#10
I know class A is not efficient, neither is my tube amp, just want to try one and a low powered one would not be that bad.

I plan to do a really good class D to try out as well and then I can use it for just having music playing most of the time and then play with the class A and or tube when I want to sit and really listen, which I do not do that much of, I prefer to work on projects.

Looked into the F2, big amp, I hope to hear from Nelson and see if he recommends anything.

Mark Audio MA200, again will be in the Fugel-Horn Joan with much attention paid to getting the stuffing just right.

RE6.8 Ohms
FS33.0003 Hx
SD0.0206 m2
VAS65.1957 L
CMS1.0990 mm/N
MMD19.4093 g
MMS21.1652 g
BL8.5460 T/M
QMS2.239
QES0.4086
QTS0.3455
RMS1.96 WM
SPL90.26 dB
POWER (NOMINAL)50 Watts
X MAX9 mm (one way)
COLOURMidnight Copper

Thanks, Rick
 
#16
Zenductor looks good except it creates a lot of heat🙁 Though that is not a worry in the winter and in the summer I run a ducted Evap cooler which is very effective and draws just 1.5 amps of current compared to the AC units I removed that used 24 amps. It would be on the far end of the RV where the cooling is the least effective though, even my custom built SFF computer would cause it to heat up a bit more than I like as all right at my desk.

So, I need to find just the right amp project that works with FR, draws the least current for the amount of heat it produces and sounds the best possible.

I very much appreciate everyone's input, thanks!!!

Rick
 
#17
The inductive loading significantly increases the maximum output voltage and efficiency of the Zenductor circuit compared to using a constant current source or a complementary output transistor. 10W of Class A output power on "only" a 16 volt supply is quite impressive, actually. If this is "too much heat", then a nice Class D or Chip Amp should be in your future. Compact, cool running, highly efficient, low energy consumption, etc. are not Class A trademarks.
 
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#18
Maybe I misunderstood what I was reading, dead tired all day, worked very hard the last two days and worn out a bit. I saw it saying the heat sink got very hot but I guess that is relative to the power draw, output and size of the heatsink.

Thanks for bringing this up, I will look into it more🙂

Rick
 
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