Hello,
the manual says 6L6 tubes are not useable with this R version.
Some review declare tu 8200 works well with 6L6 (without GC) or exotic tubes like 807 witk kt88 adapter.
I have got an 6L6 GAY pair (my ampnis under construction). Is it ale to use this 6L6 GAY with my 8200 R?
And 807 with adapter?
Thank you in advance!
the manual says 6L6 tubes are not useable with this R version.
Some review declare tu 8200 works well with 6L6 (without GC) or exotic tubes like 807 witk kt88 adapter.
I have got an 6L6 GAY pair (my ampnis under construction). Is it ale to use this 6L6 GAY with my 8200 R?
And 807 with adapter?
Thank you in advance!
My 2nd "plan" is to use my Tungsram and Philips SQ ECC40 pairs with ecc40 to 12au7 adapters instead of stock 12au7 tubes. It could be working flawless?
The thing is that many reviews you’re reading may be coming from those who aren’t really experienced with electronics, swapping in power tubes that aren’t rated for the plate dissipate may work initially but may lead to premature tube failure and worse yet, internally shorting which will kill the amp.
Also, be careful with the preamp tubes filament rating, I noticed a “flaw” in the use of the bridge rectifier (D7) in TU8200R where it’s running SUPER hot even with the stock 12AU7, which is as low as filament currents get for dual triode preamp tubes.
I mitigated this by putting a heatsink on D7… i would not mess around with alternate preamp tubes unless you take D7 off board and, using a larger bridge rectifier that’s bolted to the chassis
Also, be careful with the preamp tubes filament rating, I noticed a “flaw” in the use of the bridge rectifier (D7) in TU8200R where it’s running SUPER hot even with the stock 12AU7, which is as low as filament currents get for dual triode preamp tubes.
I mitigated this by putting a heatsink on D7… i would not mess around with alternate preamp tubes unless you take D7 off board and, using a larger bridge rectifier that’s bolted to the chassis
Thank you efm7!
As I saw the ecc82 and ecc40 has the same Vf value 6.3V. ( as I know ecc40 is the predecessor of ecc82).
In this case is neccessary or advised a bigger bridge rectifier?
Sorry, I think you noticed the If value, ecc40 0.6 vs ecc83 0.3A.
A thermal pad between br and tha chassis could be a solution against hotting?
Most indirectly heated tubes require 6.3V when their heaters are connected in parallel.
ECC40 is older than ECC82 but has different characteristics from many aspects. It is possible to use ECC40 with some redesign, but not with just a socket adaptor.
Yes but you cannot do that with the PDIP-4 package that’s currently on the board. You would have to do an off-board solution. with a bigger BR designed for chassis mount.
Not only that, that D7 also supplies the REF voltage so you have to make sure that the additional filament current doesn’t affect your TP 11,12 voltage of 1.0~1.2v
Please could you help me about this mod/redesign? I think the efm7 (thank you for your notification and help too) mentioned D7 will be not the one and only change that it is neccessary.
I believe paczelf is saying that the amp won’t operate as intended with a tube with different characteristic as the ecc82.
He’s a much smarter than me and by-the-book than I am. I’m a little bit more reckless and will come up with modifications to support more experimentation.
With that being said, I left my TU8200R alone, and made a clone for experimentation so I don’t ruin the original unit.
you can run 4 wires off the board to a off-board bridge rectifier.
He’s a much smarter than me and by-the-book than I am. I’m a little bit more reckless and will come up with modifications to support more experimentation.
With that being said, I left my TU8200R alone, and made a clone for experimentation so I don’t ruin the original unit.
you can run 4 wires off the board to a off-board bridge rectifier.
As I inderstand well the double of plate current of ecc40 could kill the d7 bridge rectifier or in a worst case more component if I only probe this tubes with an adapter but without any mod on the amp.
The heater bridge rectifier was upgraded to a 1.5A model from the original 1.0 A. It should drive ECC82 without problems. I don't remember anyone reporting rectifier failure in a TU-8200. How did you measure its surface temperature?
I used a FLIR C3X, while not the most accurate, usually measures in the side of cooler, was measuring 88 degrees C with the stock 12AU7, it was partially obscured by wires in the way of the lens too. While not deadly, I wouldn’t call it running comfortably cool… I certainly would not push it with preamp tubes with more than 300ma filament current. In fact, I got smoke using the same BR chip to power a set of 6CG7 filaments in a different unit, which was the impetus for checking the temp on this one
Again a noob question:
the measured value in the user manual: measured with probe between GND and the mentioned mesuring point? ( eg. probes Black to some GND point on pcb and Red to the sected mesauring point? )
the measured value in the user manual: measured with probe between GND and the mentioned mesuring point? ( eg. probes Black to some GND point on pcb and Red to the sected mesauring point? )
Thank you very much Victor for your help too!
I know I have very trivial questions for a lot of people here, but this will be my first "build" and thanks in advance for all yours help.
And I understand well it is enough to plug a headphone into the front panel jack under these probes/testing. ( I dont need to use my speakers for the "loading").
Do not use sensitive headphones as connecting the probe to some points can produce pops. Volume pot does not make a difference here.