TEA2SE conversion from High Gain to Low Gain

[Bhope58122]

Hi, all

I've tried contacting CJ via email to no avail to check on what is needed to be carried out in order to convert my TEA2SE from HG to LG. From my understanding its a few resistors and a change of valve that's all that is needed, can anyone confirm this? Of course my next question is, does anybody know the resistors which need changing, or even better have the schematics?

Regards,

Ben

[admin]

Try giving them a telephone call as well. I know sometimes they can get very busy with emails and makes communication difficult.

Also, they don't sell any DIY home kits or parts, so you would need to send your unit in for any modification.

I'm not aware of any schematics available for the unit.

[AnotherJohnson]

As admin points out, they’re not going to sell you parts.

As you surmise, it is relatively simple.

You might just try the tube swap. 12AX7 most 12AT7 middle 12AU7 least.

[AnotherJohnson]

From the current owners manual:

The TEA2 is available in High Gain and Low Gain versions. Both versions share a common circuit approach featuring a zero loop feedback circuit with passive RIAA equalization. Gain is provided by two single ended triode stages in both versions. Both use a pair of 12AX7s for the input stage (with the two triode sections con- nected in parallel to minimize noise). The high gain version uses a third 12AX7 for the second gain stage, while the low gain version uses a 12AU7. Because these tubes are quite different, the two versions also have different resistors associated with these tubes.
Choosing the Correct TEA2 for Your Application
With 55 dB of gain, the TEA2HG high gain version is well suited to cartridges with rated output of 1.0 mV (1000 micro Volts) or below. It is not recommended for use with higher output cartridges, as they may overload the circuits resulting in excessive distortion. For cartridges with rated output above 1.0 mV, choose the low gain TEA2LG (gain of 40 dB).
A TEA2 can be changed from HG to LG configuration and vice versa at the factory. The change will entail replacing resistors and the phono stage tubes. There will be a charge for parts, labor, and return shipping.

In my opinion 40 dB of gain is usually not enough for a 1 mV at 5 cm/s cartridge. I’d want to go with something around 2.5 mV at 5 cm/s or higher if all my phono preamp could do was 40 dB of gain.

[AnotherJohnson]

FWIW, I think that the HG version is going to match with excellent LOMCs. I’m not sure what cartridge HOMC or MM would be worthy to be paired with a TEA2SE.

JF may be shaking his head.

I realize that these things are subjective and that my opinion doesn’t really have any weight in someone else’s choices.

What cartridge are you trying to match it to? It may make perfect sense …

If you’re using one of Peter Lederman’s or Grado’s MI cartridges, it might be cheaper to just buy one of Peter’s phono stages and keep from modding the TEA2.

[Bhope58122]

Thanks for the replies, I'm in the UK so don't really want to give them a call. I'm not enthusiastic about going through the UK dealer either for various reasons.

The reason I want to convert it is because I wish to use it with my Kiseki Purpleheart and EAR MC4 SUT combination, rather than selling the TEA2 and buying another MM Stage.

As much as I love the TEA2, it really isn't the quietest stage I've owned, hence me going down the SUT route. I was hoping converting it would lower the noise floor due to the reduced gain

[AnotherJohnson]

There is something else wrong. The TEA2 is seriously quiet if it’s right. I owned an HG model for years.

If it’s hiss, you’ve got a noisy 12AX7.

[AnotherJohnson]

FWIW, replacing all three 12AX7s with specimens that measure well for low noise, low microphony, and tight balance would be cheaper than buying an EAR MC4.

There is no reason to put up with noisy tubes … at least not yet.

[Truth71]

Another reason for everyone to go to Western Electrics site and tell them what tubes you'd like them to produce.

https://www.westernelectric.com/expand

[Big Dog RJ]

Can certainly confirm that!

I've used the TEA2, SE and now upgraded to the MAX version, all three units were anything and everything about absolute quietness, dead silence! And I'm using full range stats, so if at all there's any noise, these stats will certainly pick it up.

One of the quietest phono-preamps I've ever had the pleasure of owning, even far quieter than some top tier SS phonostages that I've used in the past. CJ's TEA series phono-preamps are superb! Well worth the investment.

Just a note; because these are the latest phono-preamps of CJ's TEA series, any mods that are wanted done by owners, CJ will want to undertake the job. Simply because, still in current production and service is still supported. If it were vintage or obsolete then CJ wouldn't be too interested, they don't have the time.

OTOH if the owner did have any past vintage or obsolete gear and chose CJ to do the job, CJ will oblige but with a fee of course! After all, it's a business and they need to stay afloat.

So, trying to do this mod yourself however easy it may seem... is not in favour of JF's policy. CJ's dealers should be willing to support the product but seems like you've got your reasons not to approach them... in which case you may have to resort to third parties for some sort of schematics or parts knowledge... someone who knows CJ gear. In any case, by going this route the warranty will be void... I'm guessing that the warranty is already past...

All the best! RJ

[admin]

I also agree that if there is noise, then something is up. I like AJ's advice about first trying a new set of tubes. This is low hanging fruit and may be the issue. I would also double check that there is no very minimal ground loop issues or interference.

I once had noise with my phono-pre and was solved by moving the interconnects away from a power cord. The cables must have shifted and were now touching, a small separation and no noise.

As a side, I also had a similar issue once with my sub-woofer in the home theater setup. So, it can affect speakers as well. Moved the RCA interconnect away from the power cord, and back to normal.

[AnotherJohnson]

I also agree that if there is noise, then something is up. I like AJ's advice about first trying a new set of tubes. This is low hanging fruit and may be the issue. I would also double check that there is no very minimal ground loop issues or interference.

I once had noise with my phono-pre and was solved by moving the interconnects away from a power cord. The cables must have shifted and were now touching, a small separation and no noise.

As a side, I also had a similar issue once with my sub-woofer in the home theater setup. So, it can affect speakers as well. Moved the RCA interconnect away from the power cord, and back to normal.

Yes, the cable routing issue is definitely a good place to look too. If it’s hiss, it’s probably a 12AX7. If it’s hum, it’s probably an interference or ground loop problem.

In any event, it appears that the consensus is that the TEA2 HG is dead quiet.

[Bhope58122]

Thanks all, I'll try and source some 12AX7s from a reliable source and take it from there.

I'll keep you posted.

[AnotherJohnson]

FWIW, I owned a TEA2 HG MAX for several years. I only recently sold it, and the new owner is thrilled with it.

After I’d owned it for a couple of years, I noticed that the noise floor had become noticeable from totally unnoticeable.

I replaced the tubes with Upscale’s platinum grade, and it was immediately back to an inaudible noise floor. I’ll bet you have the same experience.