EAR 834P - Tube Rolling
- Thread starter rough edges
- Start date
The 5751 is not an equivalent for a 12AX7 (ECC83). The 5751 has more in common with a 12AT7 (ECC81) and has about 30% less gain than 12AX7. This should be born in mind especially when in used in a phono stage where gain and signal to noise is very critical.
If the OP is still around: the 834P was designed for three 12AX7/ECC83 tubes (these are identical tubes). Stay with these. I have been rolling tubes in and out of my 834P for ten years and have seen no improvement using any other type, in particular the most frequently recommended alternatives, a 5751 in V1, and a 12AU7/ECC82 in V3. My current configuration is EI ECC83 in V3 and V2, and a Rogers 12AX7 in V1. It sounds wonderful.
The problem there is that Rogers do not and never have, made valves.
No doubt, like all the other brands/labels, the actual manufacturer varied over the years.
Anyone will REALLY struggle to source Ei valves too - they are out there but very seldom identified as such. I believe CVC used to list them, but they were bought by another company a year or two back and no longer sell hifi valves.
Although Ei was originally set up by Telefunken, almost all their production was on Philips tooling and most (all????) of their production was sold via Philips, including being branded Mullard. Philips factory code for Ei is an inverted capital U with a dot between the legs.
No doubt, like all the other brands/labels, the actual manufacturer varied over the years.
Anyone will REALLY struggle to source Ei valves too - they are out there but very seldom identified as such. I believe CVC used to list them, but they were bought by another company a year or two back and no longer sell hifi valves.
Although Ei was originally set up by Telefunken, almost all their production was on Philips tooling and most (all????) of their production was sold via Philips, including being branded Mullard. Philips factory code for Ei is an inverted capital U with a dot between the legs.
rough edges
Sapere Aude
Thanks for sharing your experiences with tubes other than 12ax7/ECC83. I have no intention of using anything other than the intended tubes, but will definitely try some vintage 12ax7/ECC83's in the future.
Right now, I'm just enjoying the stock 834P as is; it seems to be getting sweeter with each passing day. Very happy here...
Arkless Electronics
Trade: Amp design and repairs.
Re mods to cathode followers outlined up thread here https://pinkfishmedia.net/forum/threads/ear-834p-tube-rolling.232341/ and also in similar recent threads on Croft etc, ie active loads, changing resistors to optimise bias for other valves etc etc...
If anyone wants to go ahead with it then here's a cross-link https://pinkfishmedia.net/forum/threads/arkless-electronics-services-offered.222567/#post-3777278
If anyone wants to go ahead with it then here's a cross-link https://pinkfishmedia.net/forum/threads/arkless-electronics-services-offered.222567/#post-3777278
Arkless Electronics
Trade: Amp design and repairs.
This thread has just prompted me to swap the bias resistors at V3 to better suit the ECC82 I'm running in that position.
Thanks to GT and Jez for the nudge.
What current are you running it at?
Mike P
Trade: Pickwell Audio
The standard value was 68K which I measued as giving 1.3mA.
I had 22K and 10K to play with.
22K gave about 3.9mA and 10K gave about 7.8mA
I fitted the 22K (3.9mA) on the reasoning that I already liked the sound with the 68K/1.3mA combination.
Very happy to change the values if you recommend different?
I had 22K and 10K to play with.
22K gave about 3.9mA and 10K gave about 7.8mA
I fitted the 22K (3.9mA) on the reasoning that I already liked the sound with the 68K/1.3mA combination.
Very happy to change the values if you recommend different?
Arkless Electronics
Trade: Amp design and repairs.
10K should be best out of those but use at least a 1W resistor. The original 1.3mA is about what the ECC83 tops out at but absolute max rating for 82 is a whopping 20mA!
Check that the voltages to other stages isn't effected too much by the much higher current draw.
Mike P
Trade: Pickwell Audio
OK, thanks for the info Jez.
rough edges
Sapere Aude
I've had the 834P for about 10 days, and I continue to be amazed at just how big a difference it has made to the enjoyment of vinyl. It replaced a nice solid state phono stage from Graham Slee that I had been happy with, until I heard the EAR. The presentation is so different, in a very good way; it just sounds more interesting, real, and above all, musical. Mine is standard, and truth be told, I'm in no hurry to roll tubes through it at this point.
It sounds better and better as time passes...more dynamic, richer, and more engaging, and it seems that this could/should continue for a while yet. Fun times...
Tarzan
pfm Member
I’ve had mine for close to 10 years now.
Adding an external SUT (a DIY Cinemag affair in my case) did bring significant gains over the internal transformers.
I’ve been tempted to tube roll it too, but to be honest, I can’t really be bothered at the moment! It sounds great stock.
Adding an external SUT (a DIY Cinemag affair in my case) did bring significant gains over the internal transformers.
I’ve been tempted to tube roll it too, but to be honest, I can’t really be bothered at the moment! It sounds great stock.
Gaius
pfm Member
I have a EAR 834P with Silvercore SUT. The valves make a huge difference but it can be an expensive game. I ended up with Mullards, check Hot Rocks who supplied me a NOS set, I have also acquired a couple of second hand sets, one military grade. Also allow warm up time for optimum performance. Best of luck, it's a great phono stage.
purplepyramid
pfm Member
I've been using the EAR 88PB phono amp for several years and replaced the stock valves with NOS Mullards. A good all round improvement.
I originally auditioned it against the Linn Urika (as I have a LP12) and preferred the EAR.
I originally auditioned it against the Linn Urika (as I have a LP12) and preferred the EAR.