PCB's waned lost finally arrived (they were sent to me at the end of april) I'd be willing to send you a blank pcb.
Phew...just plugged the amp into Castle Severn 2 in the attic. These amps are just A M A Z I N G!
Hi Bas,
I have had a quote from Toroidy for the power supply, OPTs 24% taps.
Have I got the specs right in the power supply
SUPREME TSTAS 100VA PRI: 240V SEC:
> 250V (250mA)
> 50V (20mA)
> 6,3V (5A)
Thanks again
Lee
I have had a quote from Toroidy for the power supply, OPTs 24% taps.
Have I got the specs right in the power supply
SUPREME TSTAS 100VA PRI: 240V SEC:
> 250V (250mA)
> 50V (20mA)
> 6,3V (5A)
Thanks again
Lee
Hi Francois.
I just started with 16.5k I was too lazy to try and see the difference. It sounds brilliant as is. Just too busy with work these days to even listen to anything unfortunately.
I just started with 16.5k I was too lazy to try and see the difference. It sounds brilliant as is. Just too busy with work these days to even listen to anything unfortunately.
Hi Bas,
while looking at other BH84 to compare with what I'm doing, I just noticed that you used higher wattage than suggested on R7 and R8. That is exactly what I noticed after having soldered them. Based on my experience on guitar amps, plate resistors do improve dynamics when they have higher wattage than standard 500 mW. Is it your experience too in Hi-Fi?
Thank you in advance.
Roberto
while looking at other BH84 to compare with what I'm doing, I just noticed that you used higher wattage than suggested on R7 and R8. That is exactly what I noticed after having soldered them. Based on my experience on guitar amps, plate resistors do improve dynamics when they have higher wattage than standard 500 mW. Is it your experience too in Hi-Fi?
Thank you in advance.
Roberto
Roberto,
I hope Bas will reply re. R7 & R8 on his views of these resistors. Interesting that you noticed better dynamics with higher watt resistors. Ian (gingetube) suggested that these be >1 watt resistors, if I remember correctly, to handle the high voltage across them comfortably.
I hope Bas will reply re. R7 & R8 on his views of these resistors. Interesting that you noticed better dynamics with higher watt resistors. Ian (gingetube) suggested that these be >1 watt resistors, if I remember correctly, to handle the high voltage across them comfortably.
I've found the posts you are referring to, where gingertube suggests 2 W:
EL34 Baby Huey Amplifier
EL34 Baby Huey Amplifier
I see also this article:
Technical Q&A
The increased dynamic could be an effect seen on overdriven stages, I've no experience in Hi-Fi.
EL34 Baby Huey Amplifier
EL34 Baby Huey Amplifier
I see also this article:
Technical Q&A
The increased dynamic could be an effect seen on overdriven stages, I've no experience in Hi-Fi.
I never did an a/b. Theoretically it should lower thermal noise? Not sure one can hear that. At the end of the day... It is just something I do when building amps.
Yes, Joule-Thomson noise is lower, but in mainly in EL34 amps is due max voltage (1/2 W resistors are rated for 350 V only across them). In EL84 would not be strictly needed (I squared x R is 100 mW, and dV is less than 250V), but I will report the differences if any.
99 bottles of beer on the wall, 99 bottle of beer; if one of those bottles should happen to fall, 98 bottles of beer on the wall. 98 bottles of beer on the wall, 98 bottles of beer, if one of those...
You can find your answer in the EL84 Mullard datasheet, pages 16-19: http://www.r-type.org/pdfs/el84.pdf
I bought 23% UL with 8 kOhm Raa.
Hi all
I am building this EL84 kit for a friend using Parsi's boards. I have started soldering according to BOM posted, but there are some difference on printed values on PCB and BOM.
R,20,R21 1M ,
PCB 470k
R18 : 680R
PCB : 1k
R39 : 33k
PCB : 15k
R16 : 15k
PCB 1.6k
R17 : 10k
PCB :1k
Can anyone confirm whether I should go ahead according to BOM and ignore printed values on PCB?
Regards
Sachin
I am building this EL84 kit for a friend using Parsi's boards. I have started soldering according to BOM posted, but there are some difference on printed values on PCB and BOM.
R,20,R21 1M ,
PCB 470k
R18 : 680R
PCB : 1k
R39 : 33k
PCB : 15k
R16 : 15k
PCB 1.6k
R17 : 10k
PCB :1k
Can anyone confirm whether I should go ahead according to BOM and ignore printed values on PCB?
Regards
Sachin
Here is what I did.
For the EL84 version use:
R16=15K
R17=10K
as per Schematic 1.6.
R18=1K
as on the Rev. 1.6 pcb.
For the EL84 version use:
R16=15K
R17=10K
as per Schematic 1.6.
R18=1K
as on the Rev. 1.6 pcb.
r39 is not that crucial as long as you can dial in the bias. So it depends on how high or low you bias supply is
R20/21 I don't remember.
R20/21 I don't remember.
Thanks Bas! I will go with your suggestion. I think 1K, 1/2 watt should be ok for R18?
Regards
Sachin
Regards
Sachin
As for R39 I stayed at 15k (but I have UL 23% and 8k Raa).
R20 and R21 at 1 MOhm improve the linearity of the PI.
R16 and R17 can be modded following this post for improved top end:
https://www.diyaudio.com/forums/tubes-valves/72536-el84-amp-baby-huey-243.html#post6401661
R20 and R21 at 1 MOhm improve the linearity of the PI.
R16 and R17 can be modded following this post for improved top end:
https://www.diyaudio.com/forums/tubes-valves/72536-el84-amp-baby-huey-243.html#post6401661
@ Bas :
Browsed very carefully (I thought 🙂 ) this thread and could not find a hint which manufacturer
you are using for your PCB's. Can you supply this info please
And......indeed as a lot of members already wrote: you did a great job. Respect!
Joe.
Browsed very carefully (I thought 🙂 ) this thread and could not find a hint which manufacturer
you are using for your PCB's. Can you supply this info please
And......indeed as a lot of members already wrote: you did a great job. Respect!
Joe.