CCS resistor values
Hi,
I've finally commenced building my TramII kit. In the building of the PCB for the CCS'es I'm a bit puzzled about one of the resistor values. According to the schematics there shall be a 10 Ohm resistor on the reverse side of the potmeter. On the PCB itself a 1R value is printed at this location. However, in the package containing the CSS bits the only risistor value in the ballpark is 33 Ohm. Do anyone know if evolution has shown this to be a better value? I plan to run 45 DHTs first (for testing) and then swap to 2A3's after re-adjustments.
Geir
Hi,
I've finally commenced building my TramII kit. In the building of the PCB for the CCS'es I'm a bit puzzled about one of the resistor values. According to the schematics there shall be a 10 Ohm resistor on the reverse side of the potmeter. On the PCB itself a 1R value is printed at this location. However, in the package containing the CSS bits the only risistor value in the ballpark is 33 Ohm. Do anyone know if evolution has shown this to be a better value? I plan to run 45 DHTs first (for testing) and then swap to 2A3's after re-adjustments.
Geir
CCS resistor values
Geir, I used the 10 ohm resistors supplied in the kit. See the Tram2 picture on the right hand side of the picture for the CCS 10 ohm value. You can just see the resistor value. I am using the Full Music 45 ST plated tubes. I have purchased the Rod Coleman Regulators. Desmo is the guru/master of mods for the Tram2. Have a look at his threads.
Geir, I used the 10 ohm resistors supplied in the kit. See the Tram2 picture on the right hand side of the picture for the CCS 10 ohm value. You can just see the resistor value. I am using the Full Music 45 ST plated tubes. I have purchased the Rod Coleman Regulators. Desmo is the guru/master of mods for the Tram2. Have a look at his threads.
Attachments
Thank you for replying Ptashton.
I will then buy some power resistant 10 Ohms resistors then or temporarily run soem regular resistirs in parallell to give the correct value and take some heat.
Thank you also for the very detailed photo where I can study a feasible layout of the resistor arrangement at the DHTs.
I've also bought the Rod Colemans DHT heaters and will insert these later after ensuring that the rest of the pre-amp runs OK with the initial set-up. Just for info; the supplied DHT heaters from DIYHifisupply are the new ones with increased cooling area. Looks very neat but I guess they might not be as noise-free as Rods. I'll probably know when I tested and replaced in the future.
Geir
I will then buy some power resistant 10 Ohms resistors then or temporarily run soem regular resistirs in parallell to give the correct value and take some heat.
Thank you also for the very detailed photo where I can study a feasible layout of the resistor arrangement at the DHTs.
I've also bought the Rod Colemans DHT heaters and will insert these later after ensuring that the rest of the pre-amp runs OK with the initial set-up. Just for info; the supplied DHT heaters from DIYHifisupply are the new ones with increased cooling area. Looks very neat but I guess they might not be as noise-free as Rods. I'll probably know when I tested and replaced in the future.
Geir
With 45 tubes there are no heat or noise issues with the original DHT regulators, it's with 2A3 tubes there can be problems. My experience with the original DHT regulators was, that when I increased the cooling area, the noise dropped a bit (agin this is with 2A3 tubes). So I guess that the new regulators with larger cooling area will actually be more suited for 2A3 tubes than the older ones.
The big difference between the original DHT regulators and the Rod Colman is not the noise performance, the big difference is, that the sound is so much better with the Rod Coleman regulators. The lower noise is just a nice bonus...
The big difference between the original DHT regulators and the Rod Colman is not the noise performance, the big difference is, that the sound is so much better with the Rod Coleman regulators. The lower noise is just a nice bonus...
Hi again folks,
I've started testing the kit after assembling. My next challenge is that the B+ voltage out from the FCUPS module to the 6NP13 super-Mu follower tube is reading 400V and raising. The manual says the value should be 250V. The bias value of from the same power supply to the DHTs reads -110V while the manual says -74V. I've checked that the feeding voltages to the FCUPS is correct so the suplly from the main transformer seems OK.
Similarly is the heater of the 6NP13 also functioning.
Any ideas?
Best regards from Geir
I've started testing the kit after assembling. My next challenge is that the B+ voltage out from the FCUPS module to the 6NP13 super-Mu follower tube is reading 400V and raising. The manual says the value should be 250V. The bias value of from the same power supply to the DHTs reads -110V while the manual says -74V. I've checked that the feeding voltages to the FCUPS is correct so the suplly from the main transformer seems OK.
Similarly is the heater of the 6NP13 also functioning.
Any ideas?
Best regards from Geir
Question on channel imbalance on Tram. I just replaced my Rev 2 filament supplies (one which burned out) with the Rev 3. All voltages are adjusted per spec, but it only produces about 1/3 to 1/2 the volume from the right channel, compared with the left.
A question:
I swapped tubes left to right, and used another pair of 2A3 with no change in channel imbalance.
I would like to receive some feedback on what to check on the unit to get it back in tip-top shape. This imbalance happened after I replaced the filament supplies (and it looks like both Rev 3 filament units are both operating properly. Thank you, Forch
A question:
I swapped tubes left to right, and used another pair of 2A3 with no change in channel imbalance.
I would like to receive some feedback on what to check on the unit to get it back in tip-top shape. This imbalance happened after I replaced the filament supplies (and it looks like both Rev 3 filament units are both operating properly. Thank you, Forch
OK, things are resolving slowly here if I only read the testing procedure carefully ;-P.
My only nit now is to get the bias down to -74V (now its still -117v).
And the source selector /volume system is only switching occasionally (but remote works
Geir
My only nit now is to get the bias down to -74V (now its still -117v).
And the source selector /volume system is only switching occasionally (but remote works
Geir
Bias Voltage e-mail from Simon DIYHIFI Supply
GeirT, I have the same voltage measurement in my Tram2, so I e-mailed Simon and this is his response. He asked his Technician to measure the Bias voltage from the FCPSU.
On 7/30/2012 4:12 PM, tpashton@bigpond.com wrote:
Simon, the Tram2 Manual will have to get re-written because there are people questioning the ‘Bias –73 volts’ when they are getting –110 volts from the FCPSU. It will clear up this mistake in the Tram2 Manual. Thanks again
Peter
From: Simon
Sent: Monday, July 30, 2012 6:06 PM
To: tpashton@bigpond.com
Subject: Re: Testing ABS FCUP Tram2 Boards
sorry i misunderstood. they measured -110v of FCPSU. It's correct.
regards,
Simon
GeirT, I have the same voltage measurement in my Tram2, so I e-mailed Simon and this is his response. He asked his Technician to measure the Bias voltage from the FCPSU.
On 7/30/2012 4:12 PM, tpashton@bigpond.com wrote:
Simon, the Tram2 Manual will have to get re-written because there are people questioning the ‘Bias –73 volts’ when they are getting –110 volts from the FCPSU. It will clear up this mistake in the Tram2 Manual. Thanks again
Peter
From: Simon
Sent: Monday, July 30, 2012 6:06 PM
To: tpashton@bigpond.com
Subject: Re: Testing ABS FCUP Tram2 Boards
sorry i misunderstood. they measured -110v of FCPSU. It's correct.
regards,
Simon
Ptashton, I'm so thankful for your reply!
Then I don't have to bother Simon concerning the bias.
This also means that the preamp functions as intended! As I finished it 2 AM last night I only listened to it connected to my headphone amp. It sounded nice and had real dynamics and punchy bass.
Then I don't have to bother Simon concerning the bias.
This also means that the preamp functions as intended! As I finished it 2 AM last night I only listened to it connected to my headphone amp. It sounded nice and had real dynamics and punchy bass.
To forch, if you think one of your Rev 3 filament supplies is not working properly, e-mail Simon and mail it back to him for testing. Swap over the Rev 3 modules and see if the fault follows. I had a suspect ABS module and it was replaced under warranty. If you are getting the correct voltage out of your filament supply, you could replace the Rev3 modules one at a time with your remaining Rev2 module to see if your imbalance goes away. Check all voltages per the Tram2 manual.
I'm running Emission Labs 2A3 tubes in the pre now and even though the current draw is in the order of 2.5A, the new filament heater supplies (with the new increased cooling area) is doing fine without any noise issues. The cooling fins are hot and cannot really be touched more than a second though.
The CCS should be adjusted to 125V for the 2A3 tubes as well, should'nt they?
Geir
The CCS should be adjusted to 125V for the 2A3 tubes as well, should'nt they?
Geir
ptashton, thanks for the recommendation. I was thinking that would be the next step, but wanted to check with the experts before swapping them. Forch
I live in the US so shipping one back would be a bit expensive, but if I can isolate the problem to possibly a unit, replacement would be the best way to go.
I live in the US so shipping one back would be a bit expensive, but if I can isolate the problem to possibly a unit, replacement would be the best way to go.
My original heaters also ran fine without noise issues - sometimes. At other times there was noise... But once again: The big difference between the original regulators and the Rod Colman is not the noise floor. The big difference is the much improved sound.
If one does not care about the improvement in sound, then I'm sure that the increased cooling area of the new version of the original regulators does the trick. My original regulators was unstable with 2A3's with the original small heatsinks, but with a bigger heatsink they were both stable and had lower noise.
Yes: 120V (according to my manual) no matter if you use 45 or 2A3.
Hi Rod,
As you can tell I have given the Tram II crowd the heads-up on your regulators
Both Bjarne and I are still surprised at the improvement in sound in our Tram II preamps... One thing you could do was to make more room for a better cap instead of that small piece of plastic - you know the on. Upgrading that cap and the current sensing resistor lifts the performance a bit more. There is even better dynamics and a bit more natural sound.
Thanks again for these regulators..!
Cheers,
Morten
ptashton, I found out that while I was adjusting the bias, the CCS tube was dying and threw off my bias, making one channel louder than the other.
I replaced the CCS tube with anothe and that took care of the bias stability between the channels and I now have loudness balance between the channels. With the Rev 3 filament supplies, my noise radically dropped compared with the Rev 2's as well. Thanks for the tips.
Forch
I replaced the CCS tube with anothe and that took care of the bias stability between the channels and I now have loudness balance between the channels. With the Rev 3 filament supplies, my noise radically dropped compared with the Rev 2's as well. Thanks for the tips.
Forch
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