Hi Everyone,
I wanted to share my ACP+ build with the community. My plan from the beginning was to house the preamp in an enclosure, so many of the pcb mounted I/O's and controls were left off during assembly. Chassis mounted switches and RCA jacks are from Parts Express. The anodized aluminum enclosure is from Par Metal Products in New Jersey.
I started with the full kit from the DIYAudio store so sourcing parts was not an issue. Assembly was very straight forward. However, I really miscalculated how much room I would have to work with inside my enclosure. The chassis itself is 12 x 8 x 2. This made clearance between the controls and the boards a challenge. Also, my first experience soldering signal wires to the pcb and controls was a real learning experience. I had hoped to use Mogami cable but room was just too tight. After I was finished I resolved to go back in and shorten many of the signal carrying wires fearing noise issues. However, when I powered up the unit it was so quiet between tracks I decided to leave them as is.
The unit powered up without a hitch. I am really impressed with the sound quality. This unit will mainly serve as the preamp to the FH9HVX power amplifier I completed in March.
I really want to thank Mr. Nelson Pass, 6L6 and all of the DIYAudio staff that bring these quality audio projects to novices such as myself. Also, I have enjoyed being part of this community. Everyone has been so helpful when I have questions, making the learning process very enjoyable.
Respectfully,
Dave M.
I wanted to share my ACP+ build with the community. My plan from the beginning was to house the preamp in an enclosure, so many of the pcb mounted I/O's and controls were left off during assembly. Chassis mounted switches and RCA jacks are from Parts Express. The anodized aluminum enclosure is from Par Metal Products in New Jersey.
I started with the full kit from the DIYAudio store so sourcing parts was not an issue. Assembly was very straight forward. However, I really miscalculated how much room I would have to work with inside my enclosure. The chassis itself is 12 x 8 x 2. This made clearance between the controls and the boards a challenge. Also, my first experience soldering signal wires to the pcb and controls was a real learning experience. I had hoped to use Mogami cable but room was just too tight. After I was finished I resolved to go back in and shorten many of the signal carrying wires fearing noise issues. However, when I powered up the unit it was so quiet between tracks I decided to leave them as is.
The unit powered up without a hitch. I am really impressed with the sound quality. This unit will mainly serve as the preamp to the FH9HVX power amplifier I completed in March.
I really want to thank Mr. Nelson Pass, 6L6 and all of the DIYAudio staff that bring these quality audio projects to novices such as myself. Also, I have enjoyed being part of this community. Everyone has been so helpful when I have questions, making the learning process very enjoyable.
Respectfully,
Dave M.
Attachments
Very nicely done!!
🙂 🙂 🙂
ACP+ is absolutely worth making an enclosure and using as a primary preamp... as you've found out, it's wonderful.
🙂 🙂 🙂
ACP+ is absolutely worth making an enclosure and using as a primary preamp... as you've found out, it's wonderful.
I have a few FQP30N06L.
Is it possible to use them?
Are changes to component values required?
Do you think it could be worth testing them, or is that nonsense?
Is it possible to use them?
Are changes to component values required?
Do you think it could be worth testing them, or is that nonsense?
They are pin compatible. FQP30N06L and IRF610, but there is a large difference in Input capacitance 800pF vs 104pF, transconductance 24S vs 0.8S and Vgs is lower.
I think it will give a different outcome than what Papa designed it for.
FQP3N30 will be a better replacement.
I think it will give a different outcome than what Papa designed it for.
FQP3N30 will be a better replacement.
Busy with my 'De Luxe' version: ACP+X preamp plus relais volume v10
Kicad7.0 rules.... went from version 4.07 to 7.0, but is way more user friendly.....
Kicad7.0 rules.... went from version 4.07 to 7.0, but is way more user friendly.....
^ Awesome! I have been taking KiCad classes online along with trying to learn a bit of SPICE. Seeing things like this keeps me moving. Right now... My brain hurts.
Hi!, hopefully, this is the correct place for help getting the AMP+ working? I am getting nothing out of it at all, and no signal even passing through Q2 to the output stage... Also, I'm pretty competent normally, and my solder skills are good, so I'm thinking there's a funky component thing going on or a complete brain fail. Here's some details:
Thank you! Dan
- Firstly, I bought a naked PCB and sourced my own components, getting forum-recommended replacements (or build guide typo resolution) where needed.
- I got a quad of the Toshiba 2SJ74 Quad Idss 6-8mA from the diyAudio Store. I discovered after first failed power up (no output) that these had a reversed pinout compared to the LSJ74 (Drain source swapped) so have removed and put in correctly. (Rookie error 🙁 )
- Testing config: 1khz 1v sine wave at the input (#1) and an oscilloscope to probe.
- On powerup with reversed 2SJ74 I get no output at all, with the following observed on Q1,2 or 3:
- Q1 Gate, Q1 Source (pin 1): 1khz sine wave biased up to ~14v
- Q1 Drain (pin 3) 5.6v
- Q2 Gate: 17.2v mean, no sine wave
- Q2 Source (pin 1) 1khz sine wave biased up to ~14v (as expected as its attached to Q1 source)
- Q2 Drain (pin 3): 0v (as its connected to gnd)
- Q3 (J113): Drain (pin 1): 26v mean
- Q3 Gate (pin 3) 1khz sine wave biased up to ~14v (as expected as its attached to Q1+Q2 source)
- Q3 Source (Pin 2) 1khz sine wave biased up to ~14v
- And on the output IRF610s: (IRF610, not IRFP610 as somewhere on the forum it stated a typo)
- Q6 Gate: 5.6v, Drain: ~20v, Source 0v
- Q5 Gate 26v, Drain 26.4v, Source:~20v
- Output: Nada.
Thank you! Dan
This should not be the case. The Toshiba and LS JFETs should have the same pinout. There was a bad LS data sheet roaming the world at one point, and the Toshiba datasheet that I use has a proper engineering drawing, but it is often misinterpreted.
Either way... this is the correct orientation for both parts...
LS Data sheet
Toshiba data sheet. The view is pins / bottom up.
Hmm... I may have found the bad one.. I have that LS data sheet... and this toshiba one (same as you) . Although I had taken the drawing as being a top-down orthographic of the side view... Anyhoo.. have corrected and STILL get no output! 🙁 (also thanks for the quick response)
New Readings when inputting a 1v 1khz sine wave:
Q1 S+G: 11.6v +signal. D: 3.2v
Q2 s: 11.6v+sig. G: 14.4v no sig. D: 0v
Q3 D: 23.3v, s: 12v+sig g:11.6+sig
output: nada.
New Readings when inputting a 1v 1khz sine wave:
Q1 S+G: 11.6v +signal. D: 3.2v
Q2 s: 11.6v+sig. G: 14.4v no sig. D: 0v
Q3 D: 23.3v, s: 12v+sig g:11.6+sig
output: nada.
Please post pictures of the top and bottom of the board, including all wiring.
1. What is the value of R4 and the voltage drop across it?
2. What is the voltage drop across R15?
3. What is the voltage at test point DC1 relative to ground?
There is no need to input a signal, so disconnect the oscillator.
1. What is the value of R4 and the voltage drop across it?
2. What is the voltage drop across R15?
3. What is the voltage at test point DC1 relative to ground?
There is no need to input a signal, so disconnect the oscillator.
Hi Ben,
R4 is 125R,
R15 V drop is 3v on right channel, 3.2v on left.
DC1 test point is 20.1 on right, 20.3 on left.
Photos below:
Thank you!
R4 is 125R,
R15 V drop is 3v on right channel, 3.2v on left.
DC1 test point is 20.1 on right, 20.3 on left.
Photos below:
Thank you!
The current through Q3 is too low. The current is set by R4. You need to reduce the value of R4 until the current through it and Q3 is 10mA. Calculate using Ohm's Law. Ask if you need help with the calculation.
Thanks, Silly question: When I drop the R down, the voltage drop decreases as well, so how do you calculate for 10mA.
i.e. if V=0.4v across 125R = 0.0032A, so to get 0.01A, 0.4v/0.01 = ~40R .. but then the voltage drops to 0.21v with a 40R... so 0.005A..
do I take the voltage at the between R4/Q3 junction and ground with no R4 in?
how do you work out this value?
Also... I have output and DC1 is 11.4v, so technically working! 🙂 Thank you SO much. This forum is such an amazing resource...
i.e. if V=0.4v across 125R = 0.0032A, so to get 0.01A, 0.4v/0.01 = ~40R .. but then the voltage drops to 0.21v with a 40R... so 0.005A..
do I take the voltage at the between R4/Q3 junction and ground with no R4 in?
how do you work out this value?
Also... I have output and DC1 is 11.4v, so technically working! 🙂 Thank you SO much. This forum is such an amazing resource...
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Since R4 is a trial and error thing that tends to give people trouble trying to figure out what value needs to live there, I tend to do something like this picture in those situations.... I rob some pins out of an old IC socket and install those. Now swap resistors to your hearts content. You can then solder your magic resistor (now with the perfect value) in place (to the sockets) as a permanent solution.
