mauropenasa said:
I was impressed with the concept, impressed with the kit from Russ and Brian, REALLY impressed with the sound, and am now impressed with the thorough description and the honesty shown by Mauro in where he got the original concept.
I can say that I am truly astonished with this amplifier in both price/performance ratio and more importantly SOUND.
Bravo to all involved and I hope this design sees wide spread acceptance and use. Of course with proper thanks to Mauro for further developing and renewing it.
Heatsinks
Hey guys, there was a question regarding copper/aluminum heatsinks.
IMO Alu is superior to copper in quite many respects:
a) is cheaper (nothing to say here)
b) can be extruded and is harder, a copper finned heatsink gets mechanically distorted pretty easy
c) is lighter (easier mounting)
d) can be easily black anodised (which increases surrface dissipation)
Hey guys, there was a question regarding copper/aluminum heatsinks.
IMO Alu is superior to copper in quite many respects:
a) is cheaper (nothing to say here)
b) can be extruded and is harder, a copper finned heatsink gets mechanically distorted pretty easy
c) is lighter (easier mounting)
d) can be easily black anodised (which increases surrface dissipation)
Your points are all correct. Copper is has better heat conductivity than aluminum, but it is not as "usable" for the reasons you mention. It's great to use as a heatspreader on the back of a heatsink with a thin base, or across multiple heatsinks. Also need to thik about dissimilar metal interaction (corrosion). You can usually use a copper alloy to avoid this.
I noticed that in the Rev. C schematic, the input capacitors, C13 and C29 are 1uF metallized polypropylene (MKP).
In the parts list they are given as Wima 1 uf 100V Polyester.
I think it was S.O.P.(Gerd) who replaced the polyester caps with MultiCaps at the RCA socket, keeping the cap.leads short.
Since I think Polyester caps at the input is not a good choice for such a quality design, I will use caps at the RCAs also (1uF 100V MultiCap Film and Foil Polystryrene).
Is there any reason that these caps should not be mounted off the board at the RCA sockets, and keeping the leads as short as possible?
Would appreciate your thoughts.
Audie
In the parts list they are given as Wima 1 uf 100V Polyester.
I think it was S.O.P.(Gerd) who replaced the polyester caps with MultiCaps at the RCA socket, keeping the cap.leads short.
Since I think Polyester caps at the input is not a good choice for such a quality design, I will use caps at the RCAs also (1uF 100V MultiCap Film and Foil Polystryrene).
Is there any reason that these caps should not be mounted off the board at the RCA sockets, and keeping the leads as short as possible?
Would appreciate your thoughts.
Audie
billabong said:
Hi Audie,
We anticipated people would want to use other caps, though I can say very emphatically the caps in the kits perform very well ineed. Certainly though there are other caps which may perform better.
I have actually used caps directly on the RCA jacks myself, so what you propose is very easy to do, and works quite well.
Have fun!
Cheers!
Russ
Russ,
Thanks. The caps are in the post, so I can now confidently go ahead and use them.
I accept your point that the supplied caps perform very well.
Being made by Wima, the quality is assured.
Who knows, it may be that used in Mauro's sophicated circuit, my chosen exotic caps may be too much of a good thing (if that is possible).
Audie.
Thanks. The caps are in the post, so I can now confidently go ahead and use them.
I accept your point that the supplied caps perform very well.
Being made by Wima, the quality is assured.
Who knows, it may be that used in Mauro's sophicated circuit, my chosen exotic caps may be too much of a good thing (if that is possible).
Audie.
Transformer problem
I've the Brian kit rec. C, I want to build a single chanel amplifier so I assembled only one monoblock.
The problem is how to connect to the transformer...
I've a normal transformer (not toroidal - unfortunetly!) that has as output 0V and 24V, how I make the connection to AC1, AC2 and PGND?
Do you think a trasformer with 100VA is suitable for the single monoblock? Or it's under-dimension?
Thank you and sorry for the question, but I'm really new to electronic...
Andrea
I've the Brian kit rec. C, I want to build a single chanel amplifier so I assembled only one monoblock.
The problem is how to connect to the transformer...
I've a normal transformer (not toroidal - unfortunetly!) that has as output 0V and 24V, how I make the connection to AC1, AC2 and PGND?
Do you think a trasformer with 100VA is suitable for the single monoblock? Or it's under-dimension?
Thank you and sorry for the question, but I'm really new to electronic...
Andrea
Congrats to Brian and Russ for a really excellent and professional looking kit.
Thanks to Mauro for sharing.
Will my 24 v rails have any effect on the performance of the circuit apart from max voltage swing?
I cannot see any problem but I have not studied the circuit carefully.
My speakers are 4ohm 90 db and should not need much more than that.
Thanks to Mauro for sharing.
Will my 24 v rails have any effect on the performance of the circuit apart from max voltage swing?
I cannot see any problem but I have not studied the circuit carefully.
My speakers are 4ohm 90 db and should not need much more than that.
Re: Transformer problem
Andrea,
If you only have one trafo with a single secondary that will not work.
Your trafo must either be dual ~24V secondaries or ~48V center tapped. One other possibility it to use two identical trafo in series, but only attempt that if you know what you are doing.
100VA is undersized, but it would probably work, just be careful not to stress it.
Cheers!
Russ
jeppix said:
Andrea,
If you only have one trafo with a single secondary that will not work.
Your trafo must either be dual ~24V secondaries or ~48V center tapped. One other possibility it to use two identical trafo in series, but only attempt that if you know what you are doing.
100VA is undersized, but it would probably work, just be careful not to stress it.
Cheers!
Russ
First impressions are of true class a sound and competitive compared to 300b and aleph x.Some small loss of air compared to tripath.Bass full and big but slightly lumpy in the midbass.
Distorts quickly at higher power levels and as heat increases distortion increases obviously.Probably small heatsinks.
Isn´t it (3886)supposed to shut down if temp is exceeded?
Does not sound like clean 40-50W are available.
Still breaking in though.
Distorts quickly at higher power levels and as heat increases distortion increases obviously.Probably small heatsinks.
Isn´t it (3886)supposed to shut down if temp is exceeded?
Does not sound like clean 40-50W are available.
Still breaking in though.
Transformer problem
Hello everybody,
I need some help from you...
This is my project: I'd like to build a guitar 2X12" cabinet using only one REV C PCB (monoblock) and connecting it to two 8 ohm speakers wired in parallel giving me 4 ohm impedance; the preamp will be Project 27 of Elliot (http://sound.westhost.com/project27.htm).
And now the questions:
- I've for nothing two transformer single secondary 0-24V 100VA, how can I wire the two transformer to AC1, AC2 and PGND?
- Are 2 transformer of 100VA suitable or are too small?
- The preamp need for input voltage +/- 15V could I pull a voltage of +/-12V from REV C, will it works also with this difference in voltage? If yes where exactly I pull the +/-12V on the PCB?
Sorry for the questions (and for english) I'm italian like Mauro Penasa but... I understand a little of electronic
Please help me!
Thank you!
Andrea
Hello everybody,
I need some help from you...
This is my project: I'd like to build a guitar 2X12" cabinet using only one REV C PCB (monoblock) and connecting it to two 8 ohm speakers wired in parallel giving me 4 ohm impedance; the preamp will be Project 27 of Elliot (http://sound.westhost.com/project27.htm).
And now the questions:
- I've for nothing two transformer single secondary 0-24V 100VA, how can I wire the two transformer to AC1, AC2 and PGND?
- Are 2 transformer of 100VA suitable or are too small?
- The preamp need for input voltage +/- 15V could I pull a voltage of +/-12V from REV C, will it works also with this difference in voltage? If yes where exactly I pull the +/-12V on the PCB?
Sorry for the questions (and for english) I'm italian like Mauro Penasa but... I understand a little of electronic
Please help me!
Thank you!
Andrea
Re: Transformer problem
It is but my opinion, but I feel a gain clone woulb be a better amp for you to use in this instance.
Try one of BrianGT's, or apex.jr has some boards with chips and everything mounted for 4 bucks.
jeppix said:Hello everybody,
I need some help from you...
This is my project: I'd like to build a guitar 2X12" cabinet using only one REV C PCB (monoblock) and connecting it to two 8 ohm speakers wired in parallel giving me 4 ohm impedance; the preamp will be Project 27 of Elliot (http://sound.westhost.com/project27.htm).
And now the questions:
- I've for nothing two transformer single secondary 0-24V 100VA, how can I wire the two transformer to AC1, AC2 and PGND?
- Are 2 transformer of 100VA suitable or are too small?
- The preamp need for input voltage +/- 15V could I pull a voltage of +/-12V from REV C, will it works also with this difference in voltage? If yes where exactly I pull the +/-12V on the PCB?
Sorry for the questions (and for english) I'm italian like Mauro Penasa but... I understand a little of electronic
Please help me!
Thank you!
Andrea
It is but my opinion, but I feel a gain clone woulb be a better amp for you to use in this instance.
Try one of BrianGT's, or apex.jr has some boards with chips and everything mounted for 4 bucks.
Ok, I upgraded the heatsinks and now they don´t heat up more than about 50degC even when playing loud.
I did further auditioning yesterday but I must say my initial impressions did not vary by a whole lot.
By the way I don´t believe in extended break -in in amplifiers.Ok maybe 4-5 hours but after that I have never seen any significant changes.
Anyway I will probably disappoint many fans here but here are my specific comments.
In the beginning everything sounds pretty good as I said with a warmish sound reminiscent of class a amps like the aleph etc.
More listening however reveals a lack of air around and between the instruments.The soundstage does not extend around as much as the other amps I have.The upper midrange has a darkish quality and traces of some underlying graininess.This is particularly apparent on strings and brass/trumpet.Very reminiscent of a class a/b amps in this freq range.
The bass is big and plentiful but could be a tad faster.
At louder volume levels I had the impression the amp would lose its composure and sound more congested compared to eg the tripath or the aleph x although I did not listen mainly at those levels.I think my average levels must have been around 10-20W.
The overall musical flow and timing was very good.
Overall though I would not prefer this amp to the 300b, the aleph x or even the tripath 2022 which are my favourites.I think in terms of similar simplicity and price the performance the tripath is clearly ahead of the MY-REF.
With a battery power supply (unfair advantage?)the tripath is threatening to dethrone my other two amps.With a AC pwer supply the race is closer.
Now I know Rudi and Dr.H claim that their power supply mods to the my-Ref elevate it to a higher category and it may well be.But would not a double trfo quadruple bridge also benefit the tripath?
I tested the tripath and the my-ref with a 120VA 18v trafo giving about 27 v rails so in this sense the fight was fair.However I did use a double hexfred bridge for the tripath although I do not think it could account for all the differences I heard.In any case the my-ref is supposed to be optimised with it´s own PS according to it´s designer.
I did further auditioning yesterday but I must say my initial impressions did not vary by a whole lot.
By the way I don´t believe in extended break -in in amplifiers.Ok maybe 4-5 hours but after that I have never seen any significant changes.
Anyway I will probably disappoint many fans here but here are my specific comments.
In the beginning everything sounds pretty good as I said with a warmish sound reminiscent of class a amps like the aleph etc.
More listening however reveals a lack of air around and between the instruments.The soundstage does not extend around as much as the other amps I have.The upper midrange has a darkish quality and traces of some underlying graininess.This is particularly apparent on strings and brass/trumpet.Very reminiscent of a class a/b amps in this freq range.
The bass is big and plentiful but could be a tad faster.
At louder volume levels I had the impression the amp would lose its composure and sound more congested compared to eg the tripath or the aleph x although I did not listen mainly at those levels.I think my average levels must have been around 10-20W.
The overall musical flow and timing was very good.
Overall though I would not prefer this amp to the 300b, the aleph x or even the tripath 2022 which are my favourites.I think in terms of similar simplicity and price the performance the tripath is clearly ahead of the MY-REF.
With a battery power supply (unfair advantage?)the tripath is threatening to dethrone my other two amps.With a AC pwer supply the race is closer.
Now I know Rudi and Dr.H claim that their power supply mods to the my-Ref elevate it to a higher category and it may well be.But would not a double trfo quadruple bridge also benefit the tripath?
I tested the tripath and the my-ref with a 120VA 18v trafo giving about 27 v rails so in this sense the fight was fair.However I did use a double hexfred bridge for the tripath although I do not think it could account for all the differences I heard.In any case the my-ref is supposed to be optimised with it´s own PS according to it´s designer.
Cool, protos, I am glad you like your Tripath. Enjoy! I too have one, but I must say some reviews would differ greatly from yours. Still this is not a thread about the Tripath so I will leave it at that.
Still this is a very subjective hobby, and there is no accounting for various listening situations/rooms/speakers/sources etc...
You might try again with 24V secondaries and the trafo you used is clearly undersized especially for 4ohm loads.
What sort of source are you using? Any preamp?
Cheers!
Russ
Enjoy! I too have one, but I must say some reviews would differ greatly from yours. Still this is not a thread about the Tripath so I will leave it at that.Still this is a very subjective hobby, and there is no accounting for various listening situations/rooms/speakers/sources etc...
You might try again with 24V secondaries and the trafo you used is clearly undersized especially for 4ohm loads.
What sort of source are you using? Any preamp?
Cheers!
Russ
Er, that's not fair at all. Try powering your AlephX with a 120VA trafo with too-low voltage and you won't be able to listen to it. The TriPath is digital, and much much more efficient than a class a or a/b amp. That trafo on the my_ref is way too out of spec.
Try a 250-300VA 24V secondary trafo per 4-ohm channel and I am absolutely positive your impressions will be different (better).