I might just be having a complete brain-meltdown.
Is the 47R in the right part of the schematic the I/V-resistor or is it part of a filter together with the 47nF cap?
Is the 47R in the right part of the schematic the I/V-resistor or is it part of a filter together with the 47nF cap?
An externally hosted image should be here but it was not working when we last tested it.
I THINK I got it right this time, just not sure wich pin in the opamp-sockets I should connect the I/V-resistor to?
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Hi Jonas, The I/V resistor is R7 or R2 depending on which schematic you built. The one on the left appears to be for NOS. As you noted there are filter components around the I/V and I believe that is to compensate for high end roll off. Sin X compensation. You shouldn't get any mV reading across the RCA jack if your connected across R1 or R5. The output coupling capacitor should block that. Unless the tube circuit is oscillating. Fairly unlikely. 
Hi Jonas, The 47n capacitor could be looked at as one pole of filtering. It's actual job is to limit high frequencies above the audio band of 20 Khz. When the frequency rsponse of the tube and cap are considered it makes for a decent filter. Not unlike the cap across my transformer filter that I am experimenting with. Dave
Well, it's playing now
The entire system has been powered on less than 10minutes, but I can allready tell it sounds good
About the DC on the outputs, I've read about others experiencing this, and at the low levels: about 0,00 to 1,5mA when warm, there should be no issue.
The dac is deadquiet with the volume turned down too.
The entire system has been powered on less than 10minutes, but I can allready tell it sounds good
About the DC on the outputs, I've read about others experiencing this, and at the low levels: about 0,00 to 1,5mA when warm, there should be no issue.
The dac is deadquiet with the volume turned down too.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Tbh, I can allready say that soundstage and tone of instruments are improved, not by just a bit either, it's a huge difference.
No, correction, I can't tell a difference...the difference is HUGE.
Pantera - Cemetary Gates OMG!
Drive, dynamics, soundstage, tonal balance and as I wrote...how natural the instruments sound!! Guess I've got a few opamps to sell now
No, correction, I can't tell a difference...the difference is HUGE.
Pantera - Cemetary Gates OMG!
Drive, dynamics, soundstage, tonal balance and as I wrote...how natural the instruments sound!! Guess I've got a few opamps to sell now
Hi Jonas, Yes, I thought you'd like the tube setup! That's what my second build is about to try different things. So I will let you in on a secret. I have plans to try a Nuvistor tube output stage. Actually a nuvistor and a output tube. Gain stage + buffer. Just one of several ideas. So far I find the AD844 Pedja I/V and transformer to be a winner.
Hi Jonas, Yes, I thought you'd like the tube setup! That's what my second build is about to try different things. So I will let you in on a secret. I have plans to try a Nuvistor tube output stage. Actually a nuvistor and a output tube. Gain stage + buffer. Just one of several ideas. So far I find the AD844 Pedja I/V and transformer to be a winner.
You were right, the sound from this DAC with tube output is better than any DAC I've heard before.
I expected a severe drop in volume, but there's still plenty of headroom in the system.
In fact I'll take most, if not all, of tomorrow just to listen to and enjoy my new DAC
Hi Jonas, You have discovered what most TDA1541A enthusiast know. It's a super DAC and there is a lot one can do to squeeze every bit of quality from it. The reason I didn't build the Analogmetric "analog" side was that I know Sallen-key filters don't sound good. Way to much phase shift. Now with my Pedja I/V experience I realize I can improve my GIC setup by switching over to an AD844 I/V. Enjoy your listening! Always a good idea. You may rediscover your music collection. The bass on the second build is awesome on good recordings! I won't get to mod it today. Supposed to visit my Cousin tonight. Dave
The bass on the second build is awesome on good recordings! I won't get to mod it today. Supposed to visit my Cousin tonight. Dave
Hi Jonas, You have discovered what most TDA1541A enthusiast know. It's a super DAC and there is a lot one can do to squeeze every bit of quality from it. The reason I didn't build the Analogmetric "analog" side was that I know Sallen-key filters don't sound good. Way to much phase shift. Now with my Pedja I/V experience I realize I can improve my GIC setup by switching over to an AD844 I/V. Enjoy your listening! Always a good idea. You may rediscover your music collection.
I've fallen head over heals so to speak over the TDA1541A
The Analog metric PCB is indeed a very nice platform to build the digitalsection, not that it sounds bad with opamps, it's just that much better with passive I/V and tube output.
Today will be a day of resting and enjoying the fruits of my(and those who have helped) labour
I'll have to find other projects for the OPA627's and AD797's I've got/have ordered.
I wonder how long I can expect the NOS ECC86 to last? I listen on average about 2-3 hours a day I'd say. I've got another NOS tube to replace this one when it's worn out.
Jonas
Sound quality is so good now that I honestly don't dare to change a thing in case I somehow should lose the sound I have now.
Apart from making the box look nicer I consider this DAC done.
It performs on a whole different level than I had even hoped for in my most optimistic dreams during the build.
The sound is downright addictive
Apart from making the box look nicer I consider this DAC done.
It performs on a whole different level than I had even hoped for in my most optimistic dreams during the build.
The sound is downright addictive
I like the Amtrans AMRG, are the ones you suggest that much better?
Most of the internal wiring is done with 0,6mm pure silverwire in PTFE-tubing.
The rest is done with multistrand silver plated OFC copper with ETFE insulation.
It's all a matter of taste I hasten to add, but the NeOhms are in a league of their own in my own NOS version of this same dac - I have been making resistors from Manganin wire and the sound is much more "mellow" than the Isotan [which is same sound as the Vishay Zfoil (TC2575) IMO] but the NeOhms are that much better again for the I/V position, unless you do actually want the rather bright, extremely detailed sound that is available from the Vishays.
One of the most surprising things about both the Manganin and the NeOhms is the amazing clarity in the bass - the extra detail and better imaging I did expect, but not the bass improvement.
Again, there is Silver wire, and there's other silver wire - probably the best I've used is that Ohno crystal stuff from Neotech - UPOCC, I think (they do some rather good copper, too)
The Mundorf Silver/gold is again somewhat more "mellow" or, as they say, a "darker" sound but no loss of detail, etc and I've found it relatively easy to brighten up the sound if necessary but a real PIA to get rid of the 'too bright artifacts' - this also may be useful with the valve o/p stage.
But, again, these results have been noted in the NOS versions, oversampling chip removed - might be different.
One of the most surprising things about both the Manganin and the NeOhms is the amazing clarity in the bass - the extra detail and better imaging I did expect, but not the bass improvement.
Again, there is Silver wire, and there's other silver wire - probably the best I've used is that Ohno crystal stuff from Neotech - UPOCC, I think (they do some rather good copper, too)
The Mundorf Silver/gold is again somewhat more "mellow" or, as they say, a "darker" sound but no loss of detail, etc and I've found it relatively easy to brighten up the sound if necessary but a real PIA to get rid of the 'too bright artifacts' - this also may be useful with the valve o/p stage.
But, again, these results have been noted in the NOS versions, oversampling chip removed - might be different.
I don't know as I haven't heard any of the AMGRs but I would imagine that there would be quite a significant difference between the Carbon AMRGs and the wirewound NeOhms - I think the only way would be to try them out.
If so, Rhopoint will charge a substantial P&P fee for small numbers - resistors are about 3.6 GBPounds each, so you might compare the cost of getting some from Farnell's, etc.
If so, Rhopoint will charge a substantial P&P fee for small numbers - resistors are about 3.6 GBPounds each, so you might compare the cost of getting some from Farnell's, etc.
I wouldn't mind trying them, however farnell and many others will only sell to companys here in sweden sadly.
Any suggestion as to where I might buy just a couple and not have to pay a fortune? The AMRG's weren't cheap either...
The fiance is playing Paramore - Riot!
Damn, it sounds great
Still haven't gotten used to how fast this dac is!!
For example how dynamic and fast the snaredrum starts and stops.
Don't know if it's the correct term, but there's plenty of dynamics without lingering tones.
It starts and stops lightning fast
Damn, it sounds great
Still haven't gotten used to how fast this dac is!!
For example how dynamic and fast the snaredrum starts and stops.
Don't know if it's the correct term, but there's plenty of dynamics without lingering tones.
It starts and stops lightning fast
Decided to build a dac for my Lehmann BCL clone headphone amp next.
I've ordered a small one with PCM2706 and CS4398.
The NE5532 will be swapped to LM4562 or opa627/ad797 on browndog adapter.
Got everything I need at home except the dac I just ordered.
I have no illusions that it'll be as good as the tda1541a dac, but it'll be alot better than running the BCL straight from the asus p8z68-v motherboard in my PC.
I've ordered a small one with PCM2706 and CS4398.
The NE5532 will be swapped to LM4562 or opa627/ad797 on browndog adapter.
Got everything I need at home except the dac I just ordered.
I have no illusions that it'll be as good as the tda1541a dac, but it'll be alot better than running the BCL straight from the asus p8z68-v motherboard in my PC.
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