Best place to buy Mullard ECC82?

[gazcarts]

Hi all,

I recently received a Croft Micro 25 line preamp and Series 7 power amp. They sound glorious, although still running in. I need to reduce the gain, so Adrian (Audioflair) and Glenn Croft have recommended I fit an ECC82 valve into the power amp. They've recommended a Mullard, and so far I've found some for sale at Watford Valves for £55 plus VAT, as well as some slightly cheaper ones on eBay. Is the Watford Valves price realistic, or can NOS ones be bought for much less elsewhere?

Many thanks

[guy]

I have found German sellers on ebay better on price than UK.

These look promising (and Siemens made good valves):

http://www.ebay.co.uk/itm/3x-ECC82-12AU7-SIEMENS-HALSKE-17mm-SMOOTH-PLATES-NEW-OLD-STOCK-IN-BOXES-/191216706698?pt=Vintage_Electronics_R2&hash=item2c8567648a

Need to be quick though.

Guy.

[gazcarts]

I have found German sellers on ebay better on price than UK.

These look promising (and Siemens made good valves):

http://www.ebay.co.uk/itm/3x-ECC82-12AU7-SIEMENS-HALSKE-17mm-SMOOTH-PLATES-NEW-OLD-STOCK-IN-BOXES-/191216706698?pt=Vintage_Electronics_R2&hash=item2c8567648a

Need to be quick though.

Guy.

How do the Siemens compare to Mullards?

[Jimbo]

Hi Gary,

just be careful buying NOS Mullards, there are plenty of fakes out there. The Watford valve price looks about right to me.

[guy]

That I wouldn't know, I think it would depend a lot on year of manufacture, production batch, state of "conservation" - not sure if that makes sense, but how well they have been kept over the years.
I also don't know about Mullards, but I think that lots of Philips group companies (Siemens, Valvo, Telefunken?) shared production facilities and "rebadged" depending on where they were sold.

Watford valves seem to rate Siemens generally, have a look at prices for different manufacturers on Watford valves, that may give an indication of the regard people hold for particular types.

Guy.

[Jimbo]

You could try a JAN GE 5751 in the power amp to reduce the gain a little. I have one in my series 7 and it sounds excellent but reduces the gain a tad over the stock JJ,s.

[fiddlemaker]

I'd strongly recommend getting hold of a cheap old ecc82 to see if you like it before you shell out for an expensive one.
To my ears, any valve other than an ecc83 or 5751 doesn't sound right in this application (and I've tried several: ECC99, 12bh7a, e80cc as well as ecc82).
I know Glenn says its fine, but I couldn't get on with it at all.

The 5751 will only reduce the gain by a small amount, as James says. About 1 o'clock's worth on the volume control.

[PaulStewart]

Hi Gary,

just be careful buying NOS Mullards, there are plenty of fakes out there. The Watford valve price looks about right to me.

Plus one to this

[gazcarts]

Thanks guys. I may buy one of the Watford Valves ones. It's mainly to reduce the volume, which Glenn tells me should be 10db. Don't want to degrade the sound quality, so any improvement would be great. What does Glenn fit as standard to the amps? Maybe I could get the ECC82 version of that?

[Dunluce978]

Have not used this company personally but a hi fi acquaintance has bought many valves from them and recommends them…

This page has a few NOS ECC82 and they also stock 5751

http://www.tubeampdoctor.com/catalog.php?product_search=ecc82

They also offer matching and balancing.

[Jimbo]

Glenn used JJ ECC83 as standard. Don't think they do a lower gain version.
I had a GE 12 BH7A with a nominal gain of 20 (mu)
ECC83 is (mu -100)
ECC81 (my-60-70)
The GE 12 Bh7a certainly lowered the gain in my Croft power amp.
Check with Glenn to make sure this is ok to use.

[gazcarts]

Is JJ the same as JJ Electronics? If so, there are some JJ ECC82 on the tubeampdoctor website.

[Jimbo]

Not sure of they are JJ Electronics. They are JJ Tesla. Watford valves sell them. Actually if you speak or email Watford valves they are very helpful and will give you a recommendation themselves as they know Glenn's amp well.

[julesd68]

Is the Watford Valves price realistic, or can NOS ones be bought for much less elsewhere?

Hi Gary, try Robert at Alto Fidelity - he specialises in Mullards and should be able to help ...

http://www.altofidelity.com/link1.asp

[gazcarts]

Not sure of they are JJ Electronics. They are JJ Tesla. Watford valves sell them. Actually if you speak or email Watford valves they are very helpful and will give you a recommendation themselves as they know Glenn's amp well.
Ok. Thanks. Just reading an older post I see something about lowering the gain by changing the value of the feedback resistors. How easy is that to do?

[gazcarts]

Hi Gary, try Robert at Alto Fidelity - he specialises in Mullards and should be able to help ...

http://www.altofidelity.com/link1.asp
Thanks

[Jimbo]

Ok. Thanks. Just reading an older post I see something about lowering the gain by changing the value of the feedback resistors. How easy is that to do?

Very easy if you are good with a soldering Iron. Or find a techy who can do it for you:)

[gazcarts]

Very easy if you are good with a soldering Iron. Or find a techy who can do it for you:)
I'll stick with changing the valve then :D

[fiddlemaker]

I'll stick with changing the valve then :D

Honestly, if I were you I'd live with the higher gain of an ECC83 or 5751.

I have enormous respect for GC and his products, but don't think this idea of controlling the gain by substitution of a lower mu valve in the 7 input stage works at all well. I found that the sound became rather thin, dry and "shouty" with an ECC82 or 12bh7a in this position. I initially liked it (expectation bias, I'm sure) but couldn't live with it long term.
I know Glenn uses a low mu 12bh7a in the input stage of the 7R monoblocks, but this is a different circuit optimised for this valve, AFAIK.

Having said all that, maybe it's just me.:)

[Jimbo]

Honestly, if I were you I'd live with the higher gain of an ECC83 or 5751.

I have enormous respect for GC and his products, but don't think this idea of controlling the gain by substitution of a lower mu valve in the 7 input stage works at all well. I found that the sound became rather thin, dry and "shouty" with an ECC82 or 12bh7a in this position. I initially liked it (expectation bias, I'm sure) but couldn't live with it long term.
I know Glenn uses a low mu 12bh7a in the input stage of the 7R monoblocks, but this is a different circuit optimised for this valve, AFAIK.

Having said all that, maybe it's just me.:)

I have to agree with you there John. I had a 12 bh7a in the series 7 for sometime but much prefer the GE 5751, it works so well in the power amp. I could not return now to a 12Bh7a as so much is lost in dynamics, detail and soundstage.

[gazcarts]

Thanks for the responses so far. Just out of curiosity, is the following worth a try:

http://pages.ebay.com/link/?nav=item.view&id=291171809265&alt=web

[Firebottle]

The only way to bias the 7 for correct operation with an ECC82 is to reduce the anode load resistors.
They are usually 100K, for an ECC82 I would suggest replace with 22K or wire a 27K across each 100K. This is a bit guesswork as I don't know the exact supply voltage but it won't be far off.

Cheers,
Alan

[gazcarts]

The only way to bias the 7 for correct operation with an ECC82 is to reduce the anode load resistors.
They are usually 100K, for an ECC82 I would suggest replace with 22K or wire a 27K across each 100K. This is a bit guesswork as I don't know the exact supply voltage but it won't be far off.

Cheers,
Alan
Sorry, I'm completely lost? Is that for any ECC82 or just the ones in EBay?

Thanks

[fiddlemaker]

The only way to bias the 7 for correct operation with an ECC82 is to reduce the anode load resistors.
They are usually 100K, for an ECC82 I would suggest replace with 22K or wire a 27K across each 100K. This is a bit guesswork as I don't know the exact supply voltage but it won't be far off.

Cheers,
Alan

Alan, could you possibly do a quick sketch of the circuit diagram for the 7 input stage?

[Firebottle]

Give me untill tomorrow as i've had a couple of pints................

[gazcarts]

;)
The only way to bias the 7 for correct operation with an ECC82 is to reduce the anode load resistors.
They are usually 100K, for an ECC82 I would suggest replace with 22K or wire a 27K across each 100K. This is a bit guesswork as I don't know the exact supply voltage but it won't be far off.

Cheers,
Alan
Pretty simple to do then?! ;)

[The Barbarian]

My vote goes to Telefunkenz

[fiddlemaker]

My vote goes to Telefunkenz

that is a perfectly valid opinion.

[Firebottle]

Here is the input circuit for the Croft 7 with the suggested mods for ECC82.

Usual disclaimer: DO NOT ATTEMPT ANY MODIFICATIONS IF YOU ARE NOT COMPETENT TO DO SO. ALWAYS DISCONNECT THE MAINS AND WAIT FOR THE POWER SUPPLY TO DISCHARGE. ONLY EVER HAVE ONE HAND INSIDE THE CASE WHEN DOING MEASUREMENTS.

http://i601.photobucket.com/albums/tt97/Paramotorpilot/P1040024.jpg

Either replace the 100K with 27K or connect a 39K across the 100K leaving it in place. Must be a 1W resistor minimum rating. The 100Ks are connected to pins 1 and 6 on the valve base.

This modification is probably not suitable for the 7R as more current will be drawn from the high tension supply. The 7R HT may be limited, I don't know.

:cool: Alan

[fiddlemaker]

Thanks, Alan.
If someone wanted a useful "plug-in" reduction in gain without changing resistors, but with minimum distortion, perhaps a 12AY7 in place of the ECC83 would be a sensible choice?

[Firebottle]

Hi John,
Certainly worth trying although the operating characteristics will be a little squashed, but not as badly as using an ECC82.

Good suggestion,
Alan

[gazcarts]

So am I correct in thinking I shouldn't contemplate fitting an ECC82 unless this mod is carried out? Just wondering why Glenn or Adrian didn't mention this?

[fiddlemaker]

So am I correct in thinking I shouldn't contemplate fitting an ECC82 unless this mod is carried out? Just wondering why Glenn or Adrian didn't mention this?

You won't do any damage by fitting an ECC82, and it might well sound fine to you. I was only recommending that you try a cheapie first to see if you are generally OK with how an ECC82 sounds in this circuit, rather than getting spendy with an NOS Mullard, then deciding that the sound is not your cup of tea..

[Jimbo]

So am I correct in thinking I shouldn't contemplate fitting an ECC82 unless this mod is carried out? Just wondering why Glenn or Adrian didn't mention this?
Or try a NOS RCA 12 BH7A - this will certainly reduce the gain!

[gazcarts]

You won't do any damage by fitting an ECC82, and it might well sound fine to you. I was only recommending that you try a cheapie first to see if you are generally OK with how an ECC82 sounds in this circuit, rather than getting spendy with an NOS Mullard, then deciding that the sound is not your cup of tea..
Sorry, I was referring to Alan's instructions. Does this need to be done to benefit fitting an ECC82? I'm still waiting on a reply from Watford Valves by the way.

Oddly, playing vinyl tonight for the first time in a few days and I notice the volume isn't as high as it is when playing music through the SB Touch. I didn't notice a difference before receiving the Crofts so I'm a bit confused by this. The volume pots are about 30 degrees higher to get the same volume?? I've checked the -20db switch on the rear of the PPA20 and it's definitely off.

Volume still only a 3 o clock though :)

[fiddlemaker]

Sorry, I was referring to Alan's instructions. Does this need to be done to benefit fitting an ECC82? I'm still waiting on a reply from Watford Valves by the way.


Hi Gareth, if you fit an ECC82 into the existing circuit you will certainly achieve the reduced gain that you seek. But the valve will be operating a long way from the regime in which it provides lowest distortion. Glenn will obviously be well aware of this, but I guess he is approaching the problem from a strongly subjectivist standpoint:i.e. if it sounds OK, then it is OK. I personally have no problem with this approach in general, sometimes it can work surprisingly well IMO. But with my equipment, music and ears the use of ECC82 and other valves with similar characteristics in this circuit doesn't come into this category. It didn't work for me. It might well work for you.
Perhaps the most sensible approach is to get an ECC82 and try it. If you find that you preferred the sound with the ECC83 you could always go back to it, or have the circuit modified as Alan suggests.
My system also operates with volume controls at around 3 o clock for normal listening levels. I don't find it a problem. Maybe you could get used to it and learn to love the amp with its original ECC83 (or NOS replacement)?

[Jimbo]

I think ultimately Gareth you would be best reducing the gain by changing the circuit as recommended by Alan, even it does been a bit of soldering as any other solution will compromise the sound.

Like John said although other valves will lower the gain they do not allow Glenns superb amps to sound there best. I found this out myself after trying a fair number of valves in the input section of the series 7.:)

[gazcarts]

I think ultimately Gareth you would be best reducing the gain by changing the circuit as recommended by Alan, even it does been a bit of soldering as any other solution will compromise the sound.

Like John said although other valves will lower the gain they do not allow Glenns superb amps to sound there best. I found this out myself after trying a fair number of valves in the input section of the series 7.:)
Thanks. I don't fancy doing any soldering so I'll probably leave them as they are. I'll hopefully get the pre upgraded to R spec at some point in the future so may ask Glenn to reduce the gain then.