It can be used with 6ohm speakers no problem. If using 4ohm speakers don’t play more than 25w and you should be fine. But to start with, I would stick to 6ohm or higher speakers to make sure things are working. Also, use cheap speakers to test first sound in case something goes wrong and you get full DC rail offset applied to your speakers. If you have the RTR SSR’s they will protect your speakers.
X, soldered up a new Vbe and voila the amp fired up with no problems so far. With the bias set at 26mV the offset is 3.0 mV. I will let it run a bit and bask in the glory. Then I will shut it down and remove the resistors used for testing, and tomorrow I will hook up the other channel and power up both using resistors on the outputs.
Thank you, Vunce, Zman01, Legis31, M. Johnson, bullitstang, wtnh, and any others I have missed for their help.
Myles
Thank you, Vunce, Zman01, Legis31, M. Johnson, bullitstang, wtnh, and any others I have missed for their help.
Myles
Thanks Vunce,
Must have got a bit to rough with the small legs. After getting things cleaned up a bit, I will hook up my laptop and play some amazon tunes through my iDecco. The iDecco has a pretty good dac and i can use the preamp section to connect to the FH9. Will report back when music starts.
MM
Must have got a bit to rough with the small legs. After getting things cleaned up a bit, I will hook up my laptop and play some amazon tunes through my iDecco. The iDecco has a pretty good dac and i can use the preamp section to connect to the FH9. Will report back when music starts.
MM
Hi X and others,
I powered up both channels and hooked up some speakers and received sound, but, the instruments were their and the vocals were recessed and faint in the back ground.
This is how I hooked it up:
PC > usb > iDecco. iDecco R & L preouts using rca with a/clips > FH9 input (one rca to in, one to AGND). Wired speakers with a/clips, Output GND to silver (-), Out to copper (+).
I then started thinking why have R & L preout to 1 channel, so I ran rca from Right preout to the IN on the input using a/clip, I then ran an a/clip from AGND on input to ground block. I just touched the a/clip to the speaker wire to complete the circuit, and received a bzzzt sound, so I knew this was wrong.
So I think I am close to jury rigging this to give proper sound, just need a few hints.
Would hate to blow something up at this stage.
Thanks,
Myles
I powered up both channels and hooked up some speakers and received sound, but, the instruments were their and the vocals were recessed and faint in the back ground.
This is how I hooked it up:
PC > usb > iDecco. iDecco R & L preouts using rca with a/clips > FH9 input (one rca to in, one to AGND). Wired speakers with a/clips, Output GND to silver (-), Out to copper (+).
I then started thinking why have R & L preout to 1 channel, so I ran rca from Right preout to the IN on the input using a/clip, I then ran an a/clip from AGND on input to ground block. I just touched the a/clip to the speaker wire to complete the circuit, and received a bzzzt sound, so I knew this was wrong.
So I think I am close to jury rigging this to give proper sound, just need a few hints.
Would hate to blow something up at this stage.
Thanks,
Myles
Hi Myles,
I don’t know what you mean by A/clip?
Have you adjusted the speaker for the correct bias current without the 10ohm current limit safety resistors in place?
The current should be around 80mA to 120mA. If it’s too low you will get weak distorted sound.
The voltage across the test points should be 18mV to 26mV.
The RCA center connection should go to IN +ve. The RCA shield should go to GND pin. Speaker should connect Speaker out and GND. Try one channel at a time.
Draw us a connection diagram. It’s really quite simple. Audio in +/- , PSU in +/- and GND, speaker out + and GND.
I don’t know what you mean by A/clip?
Have you adjusted the speaker for the correct bias current without the 10ohm current limit safety resistors in place?
The current should be around 80mA to 120mA. If it’s too low you will get weak distorted sound.
The voltage across the test points should be 18mV to 26mV.
The RCA center connection should go to IN +ve. The RCA shield should go to GND pin. Speaker should connect Speaker out and GND. Try one channel at a time.
Draw us a connection diagram. It’s really quite simple. Audio in +/- , PSU in +/- and GND, speaker out + and GND.
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MM,
Please find attached pics of the following connections to the PCB:
1. The V+, V-, Gnd Power connections
2. The + and Gnd speaker connections
3. The + (in) and Gnd connections for input (RCA)
Have you got then wired similarly?
Please find attached pics of the following connections to the PCB:
1. The V+, V-, Gnd Power connections
2. The + and Gnd speaker connections
3. The + (in) and Gnd connections for input (RCA)
Have you got then wired similarly?
Attachments
Last edited:
X, Zman01,Vunce legis31,all others,
Houston we have lift off, Wahooooooooo
My DefTech inwalls that I have put in an wooden frame have never sounded so good. The dynamics of this amp are really impressive, bass is great.
Thank you X for all the help you have given me on my first amp build. A few more things to do with power module, emi filter, soft start, ssr, and instant off module, but a great learning experience so far.
One question, is it normal for the bias to jump around a bit since everything is jury rigged for now. Wondering if bias will settle as the amp is played more and has the proper parts.
Pretty excited so far,
Myles
Houston we have lift off, Wahooooooooo
My DefTech inwalls that I have put in an wooden frame have never sounded so good. The dynamics of this amp are really impressive, bass is great.
Thank you X for all the help you have given me on my first amp build. A few more things to do with power module, emi filter, soft start, ssr, and instant off module, but a great learning experience so far.
One question, is it normal for the bias to jump around a bit since everything is jury rigged for now. Wondering if bias will settle as the amp is played more and has the proper parts.
Pretty excited so far,
Myles
I carried the amp up to my living room & hooked it up to my 6 ohm towers and let it rip.
Man, this thing has some serious horsepower!
Headroom galore too! Can you tell I'm a sucker for amps with balls?
I paired the amp with my Akitika PR-102. While the amp doesn't need a pre, I like to be able to switch sources from my recliner with a remote.
The amp didn't need any EQ either except at really low volume. I only had time to feed it from 2 sources; first I used a signal from the TV's headphone jack but that's not the greatest choice. Then I fed it some tunes from a hi-res Fiio music player capable of a line level output
and the amp & speakers really opened up.
Later today I'll try my cd player. I don't have a stand alone DAC yet to pull a better signal from the tv digital coax output. One thing at a time!
Man, this thing has some serious horsepower!
Headroom galore too! Can you tell I'm a sucker for amps with balls?
I paired the amp with my Akitika PR-102. While the amp doesn't need a pre, I like to be able to switch sources from my recliner with a remote.
The amp didn't need any EQ either except at really low volume. I only had time to feed it from 2 sources; first I used a signal from the TV's headphone jack but that's not the greatest choice. Then I fed it some tunes from a hi-res Fiio music player capable of a line level output
and the amp & speakers really opened up.
Later today I'll try my cd player. I don't have a stand alone DAC yet to pull a better signal from the tv digital coax output. One thing at a time!
Great news from your build there, Legis. It’s a muscular amp that’s for sure. There is a lateral FET version of this amp called the FX-8, and that amp is no where near as muscular. FH9HVX has solid bass and smooth sounding with a good top end.
What size (VA) and voltage transformers are you using?
Congrats on your nice sound with the big speakers!
What size (VA) and voltage transformers are you using?
Congrats on your nice sound with the big speakers!
X,
A 400va Antek with dual 38v secondaries which gave me just a hair under +/-52v.
A stereo configuration. I'm not sure I'd be able to hear the difference with a dual mono setup with my damaged hearing.
You were right when you claimed this amp could (and I'm paraphrasing here) knock any chipamp in the dirt!
A 400va Antek with dual 38v secondaries which gave me just a hair under +/-52v.
A stereo configuration. I'm not sure I'd be able to hear the difference with a dual mono setup with my damaged hearing.
You were right when you claimed this amp could (and I'm paraphrasing here) knock any chipamp in the dirt!
Hi Legis,
Glad you are rocking the house with it. What speakers are you using?
Dual mono will have better stereo separation for improved sound stage - it is a subtle effect. But 52v from 400VA trafo is about perfect. You will be at most running the amp at 50% capacity of the trafo.
If you want to hear something really cool, get one of my preamps like the PCA or DCA or Hakuin and feed the FH9HVX with it. Especially the Hakuin. It’s quite an amazing sound experience.
Glad you are rocking the house with it. What speakers are you using?
Dual mono will have better stereo separation for improved sound stage - it is a subtle effect. But 52v from 400VA trafo is about perfect. You will be at most running the amp at 50% capacity of the trafo.
If you want to hear something really cool, get one of my preamps like the PCA or DCA or Hakuin and feed the FH9HVX with it. Especially the Hakuin. It’s quite an amazing sound experience.
Are these preamps listed on your Etsy site?
My living setup is always in a state of flux and it's not my main system but currently the amp is powering the amazing yet entry level Andrew Jones designed Pioneer SP-52 towers. If money is tight, these are a phenominal
bang for the buck speaker! I think I paid around $150.00 for the pair. No sub required.
At some point I intend to build some large towers if I can find a design that won't ruin me financially or require my firstborn kid!
I've been listening to the amp since noon today and it's almost 11 pm. This amp is not fatiguing at all!
My living setup is always in a state of flux and it's not my main system but currently the amp is powering the amazing yet entry level Andrew Jones designed Pioneer SP-52 towers. If money is tight, these are a phenominal
bang for the buck speaker! I think I paid around $150.00 for the pair. No sub required.
At some point I intend to build some large towers if I can find a design that won't ruin me financially or require my firstborn kid!
I've been listening to the amp since noon today and it's almost 11 pm. This amp is not fatiguing at all!