I have tried several caps too like the old Obligato (copper body), PIO motor run, Bennic, Russian (brown). Basically caps I have on hand. I am surprised about the Bennic, but currently have the Clarity cap installed.
I will try the Auricaps.
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Hi guys,
As I reported before, I have Muses volume control to my preamp but I am getting a slight hum when connected to a tube amp.
The Muses is powered by a VRDN. No hum if I connect the combo to my M2X and of course, F4. No hum if I use regular vol pot to the BA-3 for both SS and tube amps. So, if I may, looking at the diagram, the correct way to manage the ground is:
R+ and L+ of the input RCAs to 1 (in+ X5) and 1 (in+ X4), R negative to 2 (X5) independent of L negative to 2 (X4). For the output to BA-3, X5 #3 to Lin BA-3, X5 #3 to Rin BA-3 and then wire from X4 #2 to L -in >BA-3 and X5 #2 to R-in > BA-3.
Or should I use R+ and L+ from Muses volume to BA-3 inputs, then connect PSU for Muses GND to PSU for BA-3 GND?
Thank for your help!
As I reported before, I have Muses volume control to my preamp but I am getting a slight hum when connected to a tube amp.
The Muses is powered by a VRDN. No hum if I connect the combo to my M2X and of course, F4. No hum if I use regular vol pot to the BA-3 for both SS and tube amps. So, if I may, looking at the diagram, the correct way to manage the ground is:
R+ and L+ of the input RCAs to 1 (in+ X5) and 1 (in+ X4), R negative to 2 (X5) independent of L negative to 2 (X4). For the output to BA-3, X5 #3 to Lin BA-3, X5 #3 to Rin BA-3 and then wire from X4 #2 to L -in >BA-3 and X5 #2 to R-in > BA-3.
Or should I use R+ and L+ from Muses volume to BA-3 inputs, then connect PSU for Muses GND to PSU for BA-3 GND?
Thank for your help!
Attachments
I was able to adjust H2 and H3 relationship (magnitude wise) in my BA-3. It is a tedious process and took me many hours to do the adjustments. I use Focusrite Solo for soundcard, a DIY 10k load, and a DIY attenuator and the investment is worth it.
Right now, H2 is ~9 to 10 dB higher than H3 for both channels and I ended up with the ff measurements.
L Channel: R11=0 .98V, R12= 0.987V, offset at 9.1mV
R Channel: R11= 0.992 V, R12= 0.992V, offset is at -6.3mV
The sound is dynamic and detailed than dominant H2 (I measured and adjust equal resistance leg of the pot at P3 before installation) and the soundstage is just right for me.
Thank you ra7 and chede for the tips and guidance! Amazing preamp and I do think that adjusting P3 is a must.
Right now, H2 is ~9 to 10 dB higher than H3 for both channels and I ended up with the ff measurements.
L Channel: R11=0 .98V, R12= 0.987V, offset at 9.1mV
R Channel: R11= 0.992 V, R12= 0.992V, offset is at -6.3mV
The sound is dynamic and detailed than dominant H2 (I measured and adjust equal resistance leg of the pot at P3 before installation) and the soundstage is just right for me.
Thank you ra7 and chede for the tips and guidance! Amazing preamp and I do think that adjusting P3 is a must.
Attachments
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I'm considering inserting a BA-3 between my Linear Tube Audio MICROZOTL MZ2 preamp and my F4. The MZ2 voltage gain into a 4-ohm load is 10.3dB. Input impedance is 50k, output impedance is 2 ohms. I don't anticipate any problems, but just in case, should I be aware of any gotchas?
I have used a couple of tube amps as gain stages--with resistors across the outputs--with no problems already.
I have used a couple of tube amps as gain stages--with resistors across the outputs--with no problems already.
soldersmoker,
If your MZ2 preamp is ahead of your F4, then it is facing a much higher impedance than 4 ohms. I don't think the voltage gain will be the lower 10.3dB specification. It will be at least 12.4dB or more. The input impedance of an F4 is 47K ohms.
If you don't have the ability to measure the overall gain of amps/preamps, I suggest contacting Linear Audio and asking them what the overall gain is of your MZ2 unit when faced with a much higher impedance. This is for your own education and going back to what Zen Mod is saying. You need to adjust the overall gain of your amp/preamp/speaker/listening setup to your needs.
This also depends on your sources, whether digital or vinyl or both, the sensitivity of your main speakers, size of your room and where your listening position is. Many times with digital only systems, the output voltage is considerably greater than 2V RMS, as such the overall gains needed to achieve good playback levels are much lower. Paying attention to this can provide you significant gains in the overall listening experience as you are optimizing the signal/noise ratio of your overall system. For example, I have found with 90dB sensitivity speakers, a listening position of 8-10 feet, and a voltage source of 2-3V RMS that one doesn't need more than 26dB of overall of gain after the source. That can come all from the amp, or all from the preamp or distributed in between.
In my system for example, I need about 14-20dB maximum for all my recordings and playback SPL needs.
I anticipate that you can be satisfied with a BA-3 only preamp coupled with the F4 and use the MZ2 for another setup or as a headphone amp. The BA-3 does have significantly better specifications overall than the MZ2 on my cursory glance but I am all about experimenting. That being said, remember that adding a BA-3 means another set of interconnects, another power cord, etc...in other words, I am wondering if you can simplify your system.
ZenMod's suggestion of using an autoformer is an excellent one, as it is passive without the encumbrances of designing yet another power supply, purchasing/designing yet another power cord, etc...i.e. simplification of your system is something I suggest with or without the use of a BA-3.
Best,
Anand.
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I think I smoked the FQP3P20 and FQP3N30 on me BA-3. I did not read the instructions on setting the bias, like I should have and the heat sinks became very hot and now I get no readings from my voltmeters and the Mosfets stay cool. There was no smoke, and the Mosfets look okay.
The power supply is a +/-24 from Glass-ware. All the voltages test good.
Any suggestions on other things to check?
The power supply is a +/-24 from Glass-ware. All the voltages test good.
Any suggestions on other things to check?
Hi,
I am using +- 30 Vdc on mine and have adjusted the bias to about 1.7 Vdc across R10 and R11 without problems using FQP3P20 and FQP3N30. That is 102 mWatts across R10 and R11 (resistor rating is 250mW). Yes, I have small heatsinks on the mosfets (rated 52 watts max power dissipation!!).
You can try this:
For one channel, set P1 and P2 to minimum (all the way CCW). Make sure you can measure voltage at the top of R10 (24V in your case), and R6 (less than a volt) to GND. Then voltage at top of R11 (-24V) and R7(less than - 1 volt) to GND. Also, across R3 and R4 (less than 80 mV). Connect voltmeter to R10 and R11. Move, say P1, CW while looking at the reading at R11. It will take you about 4 to 5 full turn CW (on a 30 turn pot) before you can see a reading on the meter across R11 in millivolts. Once you see a reading, stop and do the same for P2/R10 combo. Then continue for each to get as close to 1V for R11 and R10 with minimum offset.
Hope this helps!
I am using +- 30 Vdc on mine and have adjusted the bias to about 1.7 Vdc across R10 and R11 without problems using FQP3P20 and FQP3N30. That is 102 mWatts across R10 and R11 (resistor rating is 250mW). Yes, I have small heatsinks on the mosfets (rated 52 watts max power dissipation!!).
You can try this:
For one channel, set P1 and P2 to minimum (all the way CCW). Make sure you can measure voltage at the top of R10 (24V in your case), and R6 (less than a volt) to GND. Then voltage at top of R11 (-24V) and R7(less than - 1 volt) to GND. Also, across R3 and R4 (less than 80 mV). Connect voltmeter to R10 and R11. Move, say P1, CW while looking at the reading at R11. It will take you about 4 to 5 full turn CW (on a 30 turn pot) before you can see a reading on the meter across R11 in millivolts. Once you see a reading, stop and do the same for P2/R10 combo. Then continue for each to get as close to 1V for R11 and R10 with minimum offset.
Hope this helps!
Post #2 of this thread.
Pots 1 and 2 need to be measured in circuit with a DMM. Pot #3 must be measured using a spectrum analyzer or equivalent, if not, just leave it at the middle setting. In other words, for a 25 turn pot, set it to 12.5 turns or just measure it with a DMM and leave it at 50 ohms or thereabouts.
Best,
Anand.
Sorry, I should've been clearer.
I'm gathering parts and wondering what builders prefer. Is it better to select pots with fewer or more turns?
Thanks.
I'm gathering parts and wondering what builders prefer. Is it better to select pots with fewer or more turns?
Thanks.
