DIY EAR834

[per-Sony-fied]

Has anyone purchased/own a DIY version Tim's 834 phono stage that seem to be available from various places on the web?
Just interested whether it's worth a punt as it seems very cheap for the main components.

 

[djftw]

I have an MM only version, the MM/MC versions seem to use a very different battery head-amp. With modern JJs ecc83s at each end and an ecc82 in the middle it sounds pretty incredible. It sounds very murky to me with vintage valves, I have a high output DV20 into it at the minute. I bought it as a stop gap, got it cheap part built, but I may well keep it!

 

[Chops54]

I've built two but I think the circuit board is a bit big tbh. Point to point makes it more compact. I also don't understand the infatuation with ever larger capacitors

 

[Tarzan]

Where are you chaps purchasing this bad boy from?

 

[Chops54]

eBay. I have a spare phono board and a spare psu board if you're interested. I can post some pics of the finished article if you wish.

 

[Mike P]

I have an MM only version, the MM/MC versions seem to use a very different battery head-amp. With modern JJs ecc83s at each end and an ecc82 in the middle it sounds pretty incredible. It sounds very murky to me with vintage valves, I have a high output DV20 into it at the minute. I bought it as a stop gap, got it cheap part built, but I may well keep it!

I don't know about the version you have but in most EAR834P clones the middle tube (V2) is part of the RIAA circuit and absolutely must be an ECC83. It's usually V3 (the front tube in a genuine EAR834P) that can be swapped to an ECC82.

If you want to use an ECC82 at V3 then really you ought to change the bias resistors.

I've tried an ECC82 at V3 but ended up going back to a trio of ECC83.

 

[Mike P]

I've got one of these clones:

https://www.ebay.co.uk/itm/MM-RIAA-Vacuum-Tube-Phono-Stage-Preamp-Stereo-Audio-Preamplifier-for-Turntables/263721314879?_trkparms=aid=1110006&algo=HOMESPLICE.SIM&ao=1&asc=225076&meid=8d9611481c8d4e519af56d80253ce570&pid=100010&rk=4&rkt=12&mehot=lo&sd=274288132321&itm=263721314879&pmt=0&noa=1&pg=2047675&algv=DefaultOrganic&brand=Douk+Audio&_trksid=p2047675.c100010.m2109

I've done a fair bit of tinkering with it and have swapped out many of the parts for highly quality ones including close tolerance polystyrene caps in the RIAA and a stepped attenuator in place of the fake Alps Blue.

Warning! If you buy one of the above phono stages you must securely earth the chassis to the IEC inlet before using it. It isn't safe otherwise.

 

[Chops54]

I went with the Thorsten mods and an ECC82 in the output stage. I modified two of the phono stages to take 6n2p in the first two slots. If you get good ones they sound cleaner than ECC83s but that’s only my opinion. The other reason for the change was cost. Good 83s are not cheap any more.

 

[djftw]

I don't know about the version you have but in most EAR834P clones the middle tube (V2) is part of the RIAA circuit and absolutely must be an ECC83. It's usually V3 (the front tube in a genuine EAR834P) that can be swapped to an ECC82.

If you want to use an ECC82 at V3 then really you ought to change the bias resistors.

I've tried an ECC82 at V3 but ended up going back to a trio of ECC83.

It’s not that one, maybe different board layout? but I’ll double check, I’d like to think I’d notice if I’d screwed up the RIAA equalisation but I have been tinkering a lot lately so I could be misattributing some effect to something else...

 

[Stunsworth]

I've got one of these clones:

https://www.ebay.co.uk/itm/MM-RIAA-Vacuum-Tube-Phono-Stage-Preamp-Stereo-Audio-Preamplifier-for-Turntables/263721314879?_trkparms=aid=1110006&algo=HOMESPLICE.SIM&ao=1&asc=225076&meid=8d9611481c8d4e519af56d80253ce570&pid=100010&rk=4&rkt=12&mehot=lo&sd=274288132321&itm=263721314879&pmt=0&noa=1&pg=2047675&algv=DefaultOrganic&brand=Douk+Audio&_trksid=p2047675.c100010.m2109

I've done a fair bit of tinkering with it and have swapped out many of the parts for highly quality ones including close tolerance polystyrene caps in the RIAA and a stepped attenuator in place of the fake Alps Blue.

Warning! If you buy one of the above phono stages you must securely earth the chassis to the IEC inlet before using it. It isn't safe otherwise.

I have the MM/MC version of that and it sounds excellent. However that was after I’d sent it to Jez (@Arkless Electronics ). When it arrived there was a lot of hum which Jez fixed by moving the power supply to a separate box. He also replaced some components and corrected the dangerous earthing set up. Now I’m pleased as Punch.

 

[djftw]

I went with the Thorsten mods and an ECC82 in the output stage. I modified two of the phono stages to take 6n2p in the first two slots. If you get good ones they sound cleaner than ECC83s but that’s only my opinion. The other reason for the change was cost. Good 83s are not cheap any more.

Any links to anything that explains the Thorsten mods? Also are 6n2p just a different pin layout or does that mod require new sockets? I’m pretty new to valves, I’m young enough they didn’t exist so far as my formal education in electronics was concerned

 

[Chops54]

Just google ear834p thorsten mods and it'll be at the top of the page.

The 6n2p is not pin compatible with the ECC83. The heater wiring needs altering. It's not difficult to do but I will say that if good 83s weren't so bloody expensive i wouldn't bother. I have some pics in my archives which I'll dig out later.

 

[djftw]

I don't know about the version you have but in most EAR834P clones the middle tube (V2) is part of the RIAA circuit and absolutely must be an ECC83. It's usually V3 (the front tube in a genuine EAR834P) that can be swapped to an ECC82.

If you want to use an ECC82 at V3 then really you ought to change the bias resistors.

I've tried an ECC82 at V3 but ended up going back to a trio of ECC83.

I’ll go back to three ECC83s for a bit first and see if you found that best! But if I do decide to give the ECC82 another go what value should I be going for? I think these 68k3w at either side must be the bias resistors...

...still trying to get my head round valves! There is loads of room in this box, I could probably even fit parallel resistors with switches so I could switch 83/82s at will!

 

[Mike P]

I’ll go back to three ECC83s for a bit first and see if you found that best! But if I do decide to give the ECC82 another go what value should I be going for? I think these 68k3w at either side must be the bias resistors...

...still trying to get my head round valves! There is loads of room in this box, I could probably even fit parallel resistors with switches so I could switch 83/82s at will!

I used 22K when I tried it but Jez Arkless suggested to me at the time that 10K may be more optimal.

 

[Chops54]

A lot of Thorsten's stuff has disappeared from the web. Fortunately I printed off the 834p mods and filed them away. There's also a lot about the 834p and various mods on the LH forum if you're patient enough to sift through the many pages and extract the relevant info.

 

[djftw]

A lot of Thorsten's stuff has disappeared from the web. Fortunately I printed off the 834p mods and filed them away. There's also a lot about the 834p and various mods on the LH forum if you're patient enough to sift through the many pages and extract the relevant info.

Yes, I’m finding it all rather fun to decipher. I did discover some of Thorsten’s instructions, but the embedded link to the circuit diagram was broken... LH has some very useful photographs. However, long rambling threads discussing several different mods all at once seem to be the default!

Interestingly Thorsten originally seems to have recommended leaving the bias resistor as is if using ecc82 in v3, but increasing it to 120k if using ecc83 (which makes sense, the original value is running it close to max) He later seems to have revised this to 22k for ecc82. I have ordered some resistors to try Jez’s (@Arkless Electronics) recommended 10k, but think I could also try 24k with what I have.

 

[Chops54]

Sifting through all those threads and posts is quite stimulating!

As per Thorsten mods I left the cathode bias resistors at 68k when using the ECC82 because of the changes between the second and third stage. When I look at the circuit diagram it seems to me that making the changes to the output stage will affect the RIAA so it's a balancing act.

 

[Arkless Electronics]

'friad I have no idea what this mod is that I apparently recommended.... I'm guessing cathode resistor for cathode follower? It's not critical if so.

 

[djftw]

'friad I have no idea what this mod is that I apparently recommended.... I'm guessing cathode resistor for cathode follower? It's not critical if so.

That's the one, I'll give it a go now I ordered the resistors, but at the end of the first LP with your GTI and an effectively new MC (might be coming up to 5h) - I suspect the 834 clone's days are numbered only by the scarcity of donor stages your waiting list and possibly me needing to sell a few more bits of surplus kit as I'm supposed to be keeping my lockdown tinkering and box swapping cost neutral with my severely curtailed pandemic income!

 

[Mike P]

Here you go:

https://pinkfishmedia.net/forum/threads/ear-834p-tube-rolling.232341/page-2