Croft valve rolling question

[Jimbo]

I was not aware the 7R power amps used the 12BH7a valve in the input stage. I would use some nice NOS Brimars in this position if I were to valve roll in this position.

Interestingly I use standard JJ Tesla ECC83 valves I the regulation stage of my 25R as they seem to work very well in this position. The beat my NOS Tesla valves in the regulation stage. However the Phono stage has to be Teslas for me. I put them up against everything I could get my hands on including Telefunkens and they came out top. Very clear powerful sound with great top end detail and nice full midrange.

Of all the 12BH7a valves I have used the NOS RCA have been the best all round sound. I am using Brimar at the moment which have a powerful darker sound but balance the Teslas nicely.

[fiddlemaker]

I was not aware the 7R power amps used the 12BH7a valve in the input stage. I would use some nice NOS Brimars in this position if I were to valve roll in this position.

Interestingly I use standard JJ Tesla ECC83 valves I the regulation stage of my 25R as they seem to work very well in this position. The beat my NOS Tesla valves in the regulation stage. However the Phono stage has to be Teslas for me. I put them up against everything I could get my hands on including Telefunkens and they came out top. Very clear powerful sound with great top end detail and nice full midrange.

Of all the 12BH7a valves I have used the NOS RCA have been the best all round sound. I am using Brimar at the moment which have a powerful darker sound but balance the Teslas nicely.

Hi Jim, only the 7R monos use the 12bh7 (or ecc99) as standard.

[Jimbo]

Hi Jim, only the 7R monos use the 12bh7 (or ecc99) as standard.

Thanks John, I never knew that. I am sure the first 7r had ECC83s.

[Jazid]

Hi Jim, only the 7R monos use the 12bh7 (or ecc99) as standard.

My 7r stereo amp did as well, but it was 'Tannoy spec' so an upgraded rather than standard model.

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[Bigbird]

I got my 7R's from Glenn via Adrian at Audioflair in late 2016. They came with;

RCA 12BH7A stamped "USA"
Mullard 85A2
JJ ECC83S

The distilled discussion as to valve rolling with Adrian and his recommended valve supplier, Matt Francesco, was;

For the 12BH7A, alternatives might be Tungsol grey or black plates having more "grip" but the RCA's with more "presence". Another comment; "The 7R's being very grippy anyway I can see why some go for the RCA". Otherwise GE with a "dryer, cleaner" sound. I didn't audition the alternatives and stuck with the RCA's.

For the 85A2, Mullard was deemed "best" so I stuck with that.

For the ECC83S, NOS Mullard ECC83 were recommended for a "more noticeable uplift". I auditioned these and they stayed put.

I have been very much enjoying the 7R's, now with a more recently acquired Micro 25R (2 x Electro-Harmonix 12AX7, 3 X JJECC83S, Mullard 85A2), all revealing music with great presence, life, detail and transparency whilst not dry or clinical. I have an RIAA-R, which seems to offer great opportunity for valve rolling. Can't quite remember the original valve compliment but it is now;

Tungsol 12BH7A grey plate
2 x Tesla E83CC
2 X Mullard ECC83
Mullard 85A2

Since I have the RIAA-R my next step is to get Glenn to remove the phono stage from the 25R and upgrade to the 25RSLS linestage (perhaps with some other mod's). I will probably start with Glenn's USA RCA12BH7A's and see how it goes from there. Should hopefully be done in August.

Have fun.

That will be some system when youre done matey. Do you know what other mods can be done after its been turned into full blown 25RLS??
I think when the time comes to send mine back to glenn to go full blown RS id like to max it out completely with any extra mods so that im not sending it back and forth from Oz everytime an upgrade is imminent

I think i too will use the RCAs ive ordered in the monos in place of the GE that are currently in there.


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[Bigbird]

I was not aware the 7R power amps used the 12BH7a valve in the input stage. I would use some nice NOS Brimars in this position if I were to valve roll in this position.

Interestingly I use standard JJ Tesla ECC83 valves I the regulation stage of my 25R as they seem to work very well in this position. The beat my NOS Tesla valves in the regulation stage. However the Phono stage has to be Teslas for me. I put them up against everything I could get my hands on including Telefunkens and they came out top. Very clear powerful sound with great top end detail and nice full midrange.

Of all the 12BH7a valves I have used the NOS RCA have been the best all round sound. I am using Brimar at the moment which have a powerful darker sound but balance the Teslas nicely.

I wasnt either Jim, bloody good job i checked before i spent 100 quid on some nice 5751’s.

I may try a NOS tungsol in the pre.. any experience with them yourself mate?

Failing that i will just track down another 56 RCA if i like the sound of the others. Might get some nice synergy with 3 of them in there?


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[Antinchip]

Karl,

What I will be going for is removal of the phono stage and replacement with the 25RSLS line stage to have one 12BH7A per channel giving four line inputs. Perhaps not "full blown" since it will not have the separate PSU, I have too many boxes already.

As I understand it from my e-mail exchanges with Glenn, other options include;
Paper in oil output caps.
Better phono sockets.
Better pots.
But he did go on to write "Etc. The sky's the limit....". Maybe that's another conversation.

Cost is clearly a factor so I am keeping my options open whilst saving up until Glenn is ready to do the work in August.

Have fun.

[Bigbird]

Karl,

What I will be going for is removal of the phono stage and replacement with the 25RSLS line stage to have one 12BH7A per channel giving four line inputs. Perhaps not "full blown" since it will not have the separate PSU, I have too many boxes already.

As I understand it from my e-mail exchanges with Glenn, other options include;
Paper in oil output caps.
Better phono sockets.
Better pots.
But he did go on to write "Etc. The sky's the limit....". Maybe that's another conversation.

Cost is clearly a factor so I am keeping my options open whilst saving up until Glenn is ready to do the work in August.

Have fun.

Ah ok I understand what your saying. Mine is already at that point so the next step is seperate PSU and beyond. Maybe i will try get hold of glenn and ask him myself.

You dont have his email do you please? Ive tried emailing him recently with no reply so maybe im using the wrong address?

Thanks

Karl


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[worrasf]

Here you go

glenn@croftacoustics.co.uk

glen.croft@btinternet.com

I think he may be on leave as I am waiting for him to get back to me on parts availability for the very 25RS upgrade under discussion

Steve

[Bigbird]

Here you go

glenn@croftacoustics.co.uk

glen.croft@btinternet.com

I think he may be on leave as I am waiting for him to get back to me on parts availability for the very 25RS upgrade under discussion

Steve

Ah ok that may explain it then. Thankyou buddy appreciate that.

Bet you cant wait for that upgrade??


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