• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

EL84 SE design recommendations?

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#161
SUCCES !!! 🙂

Behold;

My very first "poweramp"


Thank you, Mr. Kitic, for the RH84SE design

and thank you all for the willingness to explain what and why.


Cheers,

Empee
 

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#163
hi there,


I guess you're not refering to my amp 'cause I usee a solid state rectifier bridge for this one.

With a transformer of sec. 250V with no centre tap this was the
easiest way to get to the 300V B+ asked for in the schematics.

I now get it to run at 297V


However,
I'm currently working on a new amp, my "model two",
which is going to have a double sec. tranny, both channels
each their own EZ81 rectifier and choke / cap.

How's that for channel seperation ?

🙂



Cheers,

Empee
 
#165
Hi !

I run my little amp on various speakers,
actually I like to try every speaker I can get my hands on.
You'll be amazed how far these 5 Watts will get you !

Used it on Philips AD1065M's in open baffles (a 10" fullrange w. whizzer cone,
great on jazz), Yamaha NS10's, JBL 4208's, Eltac's and even a pair of
Fane Expanders (horn-loaded 3-way PA-monitors :smash: )

Currently I use it in my studio on a pair of Jean Marie Reynaud Menuet 1's.
Small, bookshelf-type speakers, 91dB sentitive. Great sound.

Last weekend I took my little amp to a friend and tested his Canton Ergo 1002DC's.
However only 89dB sensitive, I really got the windows shaking :devilr:

For all you bass-lovers;

Get Trentemöller's album "The Last Resort".
Track 2, "vamp".

deeeeeeeep bass
😀 😀 😀 😀 😀 😀
 
#167
UL and RH

I know it was asked if UL was tried in the RH 84 and was said no because didn't have outputs.

But if someone has SE-UL outputs, any issues implementing them on an RH 84 amp?

And what types of tweaks would one suggest to the schem to accommodate them if they will in fact workout here?

Thanks!
 
#168
What are people using for the power supply choke in these RH84 amps? The schematic doesn't mention the DC resistance. The Hammond P-T158L, 15H, 75mA, 411 ohms, about $17 looks attractively priced.

Do you think I could substitute a 6CA4 for the rectifier? My power transformer has no 5 volt winding. Would I be likely to need any other component substitutions if went with a 6CA4?
 
#169
A 6CA4 would be just fine, but that choke is a bit small in it's MA rating.

I wouldn't go any lower then one rated for 100ma, that resistance will knock your B+ down as well.
(For a stereo amp that is, for a mono amp 50ma should be fine)

Don't know what your power trannie is so it's hard to guess what B+ you'd get with a choke like that.

Download PSUDII power supply simulator (free, google search) plug in your values to get a good idea
of what you need to build the voltage output you desire.

But Yes a 6CA4 has more then the capabilities needed here.
 
#171
The only thing I do not understand is why people choose
to use a direct heated rectifier tube on a indirect heated
tube amplifier ?

B+ will rise until the output tubes start conducting,
wich takes more time indirect heated,
putting stress on the PS caps

so you better use 450V-or-more DC rated caps,
or you might get into trouble.


Cheers,

Empee
 
#178
looking good !!


Here's my latest version of the RH84.

The case used is from an army surplus,
in it was a 24V relais (a BIG one)

sound is brilliant, but it's the last time I use such a small housing
(I was cursing all the way through assembly!)

🙂
 

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