Glad to hear that - R17 had been a problem for one or two other customers so that got upgraded to an inductor on later revisions.
All volume pots are noisy (because they're resistors) so the lower the value, the better. I use 5k but worth checking your source doesn't mind such a low value.
All volume pots are noisy (because they're resistors) so the lower the value, the better. I use 5k but worth checking your source doesn't mind such a low value.
The volume pot has an obvious wiper problem creating audible scratchy noise in one channel in the low volume. I have a good quality 4.7k. That will be going in.
So amp was running well but now one channel still red light is on to long at power up . Goes out after 2-3 minutes and stays out..
I know where to focus to find issue. thanks!
So amp was running well but now one channel still red light is on to long at power up . Goes out after 2-3 minutes and stays out..
I know where to focus to find issue. thanks!
Been a while since I had mine in system but got them wrapped up in a chassis....finally. Not balanced input yet. That comes when I eventually get sorted with my active XO biamp set up.
Running a Meanwell LRS 100-24 per channel. No addition SMPS filtering as of yet.
Sounds very good as expected. Very good. Great bass, assume the DF is high. And a very 'holographic image'.
I will probably run a unity gain buffer (NP DIY FE) into a volume pot before the input transformers as means of balancing the eventual bi amp set up.
Does that sound like a good idea?
Liking having them back in action anyway.
Running a Meanwell LRS 100-24 per channel. No addition SMPS filtering as of yet.
Sounds very good as expected. Very good. Great bass, assume the DF is high. And a very 'holographic image'.
I will probably run a unity gain buffer (NP DIY FE) into a volume pot before the input transformers as means of balancing the eventual bi amp set up.
Does that sound like a good idea?
Liking having them back in action anyway.
Attachments
Its just an old bench SMPS chassis. Repainted the cover I'm VHT anthracite and a plexiglass front.
And forgetting to say after jogging my memory reading the 1st post again....this is with a DC coupled pre amp and no output caps in my dac output stage, but it's all trimmed down to probably less than 10mV so all seems to be working well.
The new to come input buffer will potentially have 3.3uf on the output of that
The new to come input buffer will potentially have 3.3uf on the output of that
I've changed out R17 twice on both boards. The amp will run for a week or so then it fails to start up. R17's measures high, 50 - 75 ohms..
Any suggestion for a permanent fix?
On later revisions we changed R17 to a 100uH inductor : https://www.mouser.com/ProductDetail/TDK/SLF6025T-101MR33-PF?qs=sZ9INdjBHvf46bc6WCrysg== I haven't learned of any failures of this inductor to date.
It would be very interesting to listen to this little amplifier. Could this be compared to traditional amplifiers ? I have an old Proton 520 and a Rotel AX 930. How do you think this MonoAmp would compare ?
My next experiment could be this MonoAmp to handle main speakers, Lii Song/Audio F6 Open Baffle to 100Hz. Then a TDA3255 (or similar) with XO and level control to handle Low frequencies.. (TangBand w1139 in Tapered Sub) Just need 20 watt to reach Xmax of 11.5mm and 115dB. So far just a theory but would be quite inexpensive and fun to test.
My next experiment could be this MonoAmp to handle main speakers, Lii Song/Audio F6 Open Baffle to 100Hz. Then a TDA3255 (or similar) with XO and level control to handle Low frequencies.. (TangBand w1139 in Tapered Sub) Just need 20 watt to reach Xmax of 11.5mm and 115dB. So far just a theory but would be quite inexpensive and fun to test.
Thomas, it's an unfair question. None of us have heard your amplifiers and speakers combination to compare with anything. This mono amp will certainly drive your speakers pretty well I guess.
What concerns me about your question is that both the amps you have currently are integrated amps (built-in preamp and volume controls). You cannot compare them to the mono amps directly. What is your music source and how are you going to feed the mono amps?
What concerns me about your question is that both the amps you have currently are integrated amps (built-in preamp and volume controls). You cannot compare them to the mono amps directly. What is your music source and how are you going to feed the mono amps?
@Thomas224466 - I concur with @twocents as regards the comparison with the amps you mentioned. They are integrated amps and monoAMP is a poweramp. The only way to know for sure if our amp suits your application is to have a try. If it doesn't work out, talk to us about how and why your aims haven't been fulfilled and we will work out a solution together through dialogue.
I hope your experimental idea comes to fruition.😉
I hope your experimental idea comes to fruition.😉
Thanks for feedback ! And yes I will buy this interesting MonoAmp later on to try it out. I was just trying to get some kind of perspective of what to expect. But realize it is hard to compare. The mentioned Proton 520 is from when I started my HiFi journey, soon 40 years ago... At the time I compared with many different (small) amps. Yamaha, Onkyo, Sony, NAD, H/K and so on. This with Heybrook HB1, HB2 and some Dali speakers. Sound signature of Proton, NAD and some H/K suited me best. Nice memories..
The Proton 520 has Pre Out/PowerAmp In and can be used separtely as PowerAmp if needed and the Rotel RB-930ax I have is a dedicated PowerAmp btw.
My intention is to buy the "Abbado III" Dac (ca 1.5V out) with the external Volume pot and connect directly into the "MonoAmp". Is that not a good idea ? Does it need more (pre)amplification to work/sound properly ?
The Proton 520 has Pre Out/PowerAmp In and can be used separtely as PowerAmp if needed and the Rotel RB-930ax I have is a dedicated PowerAmp btw.
My intention is to buy the "Abbado III" Dac (ca 1.5V out) with the external Volume pot and connect directly into the "MonoAmp". Is that not a good idea ? Does it need more (pre)amplification to work/sound properly ?
I think connecting the Abbado III into a pair of monoAMPs is a perfectly fine idea - with the 1V input sensitivity setting on the monoAMPs you'll have 3dB extra gain available at maximum to compensate for quieter tracks. We've built a couple of DAC-AMPs like this and haven't found the need for extra amplification but then we don't generally listen very loud. If you do love to listen loud (or even regularly clip your amps) then a little extra gain can be added to the monoAMPs through use of the permalloy input transformer. The drawback of including more gain is higher noise so I'd recommend don't add in more than you need.
Put my monoamps back in this week as have taken out the 'winter' class A M2X.
Had it cranked last night and I was getting dropouts.....holes in the music. But interestingly not on current hungry bass passages. Where I noticed it most was listening to some live recordings (YT) was during the applause from the audience. Seemed strange. Not sure what to look for really?!
Had it cranked last night and I was getting dropouts.....holes in the music. But interestingly not on current hungry bass passages. Where I noticed it most was listening to some live recordings (YT) was during the applause from the audience. Seemed strange. Not sure what to look for really?!
Jim - your amp setup is the one in post #386? And are the dropouts happening on both L/R channels at the same time or differently? I agree its strange to get dropouts on applause rather than on heavy bass as the bass would be what heats the TDA chip up. That would tend to indicate that the dropouts are not thermally induced. Did you notice whether the red LEDs came on at the same time?
Hi Richard. Hope you're well. Yes amp is as per post 386, exactly.
I was trying to rig up some fibre optical cables to add some indicators to the front panel but I lost patience! So I shall have a look out for the LEDs, will remove the lid so I can monitor.
And shall try to listen out for per channel drop outs!
Thanks and have a good Easter. If that's a thing in your neck of the woods!
I was trying to rig up some fibre optical cables to add some indicators to the front panel but I lost patience! So I shall have a look out for the LEDs, will remove the lid so I can monitor.
And shall try to listen out for per channel drop outs!
Thanks and have a good Easter. If that's a thing in your neck of the woods!