My experience with the RTP3D.
In January the RTP3 was ready for take off, i adjust everything that could be adjusted.
Some hours ago i checked all voltages and currents.
Same check the next two weeks, everything is stable and fine.
Nice preamp.
But last week the music was very quiet on one canal.
Short look inside, one tube doesen`t glow as bright as the other once.
Now i measured the voltage drop on the heater.It was to low.So the current of the heater ccs was to low.
Now checked all other heater voltage drop, most of the Tubes were in thair limits but not in the range i adjust them 3 months ago.
Readjust all heater ccs everything is fine an the RTP3 works.
I use a precision trimmer (25 times turnable) to adjust the current flow.
Doese anybody of you have an idea whats happened??
Is it some kind of tubeheater burn in that causes the variance??
I use the Electro Harmonix 6922(heater current is 365 mA and not as the historical 6922 with its 300mA).
Maybe some of you have made the same experience like me.
Have a look at your RTP3 maybe somthing is going wrong.
@Klaus (VTR)
Which caps in the superreg do you changed to Foilcaps??
Roland
In January the RTP3 was ready for take off, i adjust everything that could be adjusted.
Some hours ago i checked all voltages and currents.
Same check the next two weeks, everything is stable and fine.
Nice preamp.
But last week the music was very quiet on one canal.
Short look inside, one tube doesen`t glow as bright as the other once.
Now i measured the voltage drop on the heater.It was to low.So the current of the heater ccs was to low.
Now checked all other heater voltage drop, most of the Tubes were in thair limits but not in the range i adjust them 3 months ago.
Readjust all heater ccs everything is fine an the RTP3 works.
I use a precision trimmer (25 times turnable) to adjust the current flow.
Doese anybody of you have an idea whats happened??
Is it some kind of tubeheater burn in that causes the variance??
I use the Electro Harmonix 6922(heater current is 365 mA and not as the historical 6922 with its 300mA).
Maybe some of you have made the same experience like me.
Have a look at your RTP3 maybe somthing is going wrong.
@Klaus (VTR)
Which caps in the superreg do you changed to Foilcaps??
Roland
I don't think so. PCB is perfect in my opinion. Heaters conductors (+, ground, + for the second group of tubes) are made on the upper side of the board, straight and wide, when other connectors are located on the bottom side.
The problem was that regulated heater DC came from the independent totally isolated regulator, when other 6 regulators (4 for each tube HV, one for +15 and one for -24) had a common ground. Heater totally "floated" in the air. When I connected two grounds with 0.22 capacitor hum was dramatically reduced.
I hope it could be reduce even more by elevating heater voltage as VTR suggested by 40V, I'll try it later. It is pretty good right now.
I am massively surprised that you are seeing any benefit from DC heaters.
AC is absolutely silent on my non-balanced FVP5.
Shoog
AC is absolutely silent on my non-balanced FVP5.
Shoog
superreg and current heater
i changed thy main electrolyt to 10uf Foilcap, but be aware it can start oszillating.....
and yes heater burn in and some readjustment is usual when tubes are changed-allen recommended the pcc88 because this is designed for heater current.
i changed thy main electrolyt to 10uf Foilcap, but be aware it can start oszillating.....
and yes heater burn in and some readjustment is usual when tubes are changed-allen recommended the pcc88 because this is designed for heater current.
Group buy hint
Hello,
just to let you know. A group buy for ceramic parts has been started. Just let me know if you need something.
cheers, tom
Hello,
just to let you know. A group buy for ceramic parts has been started. Just let me know if you need something.
cheers, tom
Anybody know how much current Allen ran through the SSM2210s? (I.e. how much current for the current source in the phono section) Same as the JFETs?
9.5mA through each transistor - a total of 19mA through the CCS.
An externally hosted image should be here but it was not working when we last tested it.
Alex
Remote controlled RTP
Hello folks
I would like to share my RTP-clone with You. I had a lot of inspiration from the thread (and Alex Meganns homepage, Thanks Alex!) and now its payback-time.
I have been building for more than 1½-year and one of the things that made the build take so long was that I made the cabinets myself in my garage with hobby tools - that's a one time only experience. The cabinets started out as a 1m x 2m x 4 mm raw aluminium sheet and admitted I had a little help cutting the sheet to smaller pieces and bend the side-sheets. I even learned to anodize aluminium in the process.
For the PS I had custom made (by a local firm) trafos and chokes. The areas where my PS differ from the original is (my guess) that I use a choke filter for the bias supply and I have a 9V logic supply.
The main area where my Preamp differs from the original is that it is remote controlled – haven't bought the remote yet thou. Input selection (including ground) is done with relays close to the back. The volume control is a 64-stepped relay attenuator – and to get the fixed 50k that the phono stage demands I have chosen the expensive route and ordered special value tx2575 for line resistors and to save a bit tx2352 for the ground/shunt resistors.
Firing it up I had a little problem with noise from the super reg in the channel where the elevation of the heater supply was connected and so I chose to put the elevation in the PS before the super reg and put bigger caps across the supply-legs on the AD797 up-amp in the reg and the problem was gone.
Now I only have to order a pair front plates when I have the funds🙂
Hello folks
I would like to share my RTP-clone with You. I had a lot of inspiration from the thread (and Alex Meganns homepage, Thanks Alex!) and now its payback-time.
I have been building for more than 1½-year and one of the things that made the build take so long was that I made the cabinets myself in my garage with hobby tools - that's a one time only experience. The cabinets started out as a 1m x 2m x 4 mm raw aluminium sheet and admitted I had a little help cutting the sheet to smaller pieces and bend the side-sheets. I even learned to anodize aluminium in the process.
For the PS I had custom made (by a local firm) trafos and chokes. The areas where my PS differ from the original is (my guess) that I use a choke filter for the bias supply and I have a 9V logic supply.
The main area where my Preamp differs from the original is that it is remote controlled – haven't bought the remote yet thou. Input selection (including ground) is done with relays close to the back. The volume control is a 64-stepped relay attenuator – and to get the fixed 50k that the phono stage demands I have chosen the expensive route and ordered special value tx2575 for line resistors and to save a bit tx2352 for the ground/shunt resistors.
Firing it up I had a little problem with noise from the super reg in the channel where the elevation of the heater supply was connected and so I chose to put the elevation in the PS before the super reg and put bigger caps across the supply-legs on the AD797 up-amp in the reg and the problem was gone.
Now I only have to order a pair front plates when I have the funds🙂
Attachments
Hi sjoranum,
really nice, your interpretation of the RTP i like it a lot.
Mine is also remote controlled. I use kits from electronics.dantimax.dk.
They offer an relay input and relay volume kits.
Roland
really nice, your interpretation of the RTP i like it a lot.
Mine is also remote controlled. I use kits from electronics.dantimax.dk.
They offer an relay input and relay volume kits.
Roland
What's the gain of the phono section?
Where can I buy SSM2010, I searched the data sheet and didn't find it?
The original MAT02 is "MAGNATEC - BFY81 - TRANSISTOR, DUAL, NPN, TO-77?
TIA
Felipe
Where can I buy SSM2010, I searched the data sheet and didn't find it?
The original MAT02 is "MAGNATEC - BFY81 - TRANSISTOR, DUAL, NPN, TO-77?
TIA
Felipe
Sjoarnum
Thanx for sharing your complex build!
Nothing like a good challenge
Enjoy!
Regards
David
Thanx for sharing your complex build!
Nothing like a good challenge
Enjoy!
Regards
David
Hi Roland and Jushua_G thank s for the kind Words.
Actually al the logic circuits is from Dantimax, but since the rest of the pre is hard-wired I have tossed the PCB's carrying the signal and hard-wired those – all the controlling logic circuits is placed at the front of my Pre.
Only problem is that there only is 6 channels available hens 3 input lines where polarity switch is possible – Luckily I only listen to phono, digital and tuner but an extra line input would bee nice.
And I would have loved to have latching relays but couldn’t find a diy kit that could handle that – amb.org came close but didn't have the right front controls.
@Jushua_G
I couldn’t find a suitable cabinet and I therefore made it myself from 4 mm alu-sheet, 10x10mm alu-rods and stainless steel torx head screws. All holes and treads is hand made. A lot of work that I wouldn’t recommend unless you have access to professional tools
And maybe I should mention that the pre is very transparent and coherent – I'm not going to look for anything else.
Stig
Actually al the logic circuits is from Dantimax, but since the rest of the pre is hard-wired I have tossed the PCB's carrying the signal and hard-wired those – all the controlling logic circuits is placed at the front of my Pre.
Only problem is that there only is 6 channels available hens 3 input lines where polarity switch is possible – Luckily I only listen to phono, digital and tuner but an extra line input would bee nice.
And I would have loved to have latching relays but couldn’t find a diy kit that could handle that – amb.org came close but didn't have the right front controls.
@Jushua_G
I couldn’t find a suitable cabinet and I therefore made it myself from 4 mm alu-sheet, 10x10mm alu-rods and stainless steel torx head screws. All holes and treads is hand made. A lot of work that I wouldn’t recommend unless you have access to professional tools
And maybe I should mention that the pre is very transparent and coherent – I'm not going to look for anything else.
Stig
Fantastic job Stig. Super execution. Probably the most difficult preamp to build! I wonder if the OP (Binaural) built his? He is local to my area...
Best,
Anand.
Best,
Anand.