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Thetiminator

Rolling power amp input valves - is it worth it?

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Hi everyone 

I’m new to valve amplifiers having just got myself a pair of Transcendent Sound Pinnacle OTL amps - which are truly superb by the way. A dealer friend of mine sent me a very expensive Kondo 300B amplifier to test but the Pinnacles spanked the Kondo’s bottom in every area. 

Anyhoo, there are 2 x JJ 803’s and one JJ802’s in each amp driving 4 x EH Gold Grid 300B’s. Question is how much do they input valves contribute to the sound and would it be worth trying a couple of different brands?

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Definitely worth a try. Arguably trying different signal valves is worth more than trying different output valves.

Slightly puzzled by your 'labelling' - as you will know, or shortly find out, there are equivalent valves with differing letters and numbers (usually depending on the intended market (USA or Europe).

ECC802 are 12Au7; and ECC83 (803?) are 12Ax7. These are the 2 most common in the smaller valve before the bigger bottled 6SN7 etc...

The main criterion to bear in mind is whether the valves are NOS (new old stock, ie., unused vintage valve) or a modern (or current) production (your JJs).

You missed some glorious Phillips mini watt and Bugle Boys in the classifieds by a whisker, but they were a bit special, and you really only need to pay £20-30 a throw. The 2 of the same number should be matched.

My advice is to have some fun exploring the internet for valve reviews, (but bear in mind different valves suit different amps more or less) draw up a short list and do a wanted ad in the classifieds.

I had some good results with RCA red tops but your amp might suit something different.

An OTL is a bold choice for a first venture into valves..

Apart from 'in the doghouse' where do you live? (County would be sufficient..)

Jack NSM

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To reiterate what Jack said, yes different valves do make a difference. Actually transformers make the most difference in valve amps, as a general rule of thumb, the heavier they are the more iron in them, the better they are - but of course there are different qualities of iron.. 

With a few exceptions, you really need to try what different valves do to the sound of your amplifier, and see what you prefer. System synergy is all.

Welcome to the wonderful world of valves.

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As the Transcendent Sound Pinnacle is a OTL amp (output transformer less)  the valves and quality of the coupling capacitors will have more impact on sonics.

Do try different 12au7's I always thought the Tungsol JTL were good value but their are loads out there with well documented characteristics. You should also be able to use 6sn7 (with a adapter) and probably even E80cc (but would need to check  with the manufacture first as to compatible tube alternatives).  

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I wouldn't bust a gut over the input valves though they will flavour the sound, but if it was my amp I'd be inclined to get more reliable output tubes than EH, especially since its an OTL. Personally I favour JJ 300b for real world money, they are rock solid valves that are easy to match and stable, but there are differing opinions about reliability and about sonics here. Emmissions Labs at more serious wonga are also a good shout. Both are on the neutral, extended end of performance in my Tron.
Welcome to valves, you've opted for an interesting (good) first choice

Sent from my BLA-L09 using Tapatalk

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Thanks guys I wasn’t sure how much the input valves contributed to the sound, so I wanted to double check before I threw any money at them. 

I took the plunge on the Pinnacles after hearing a few 300B amps at a dealers. Jools - It’s true what you say about the transformers, as we worked our way up the ladder cost wise you could hear the difference. But the first amp I could’ve lived with was a £15k power amp, my memory is vague but I think it was an SJS or something....

The Pinnacles are way better than anything I heard, a real bargain for the price. Although they don’t work out that cheap by the time you pay taxes, upgrades, build costs (i’m not technically capable), valves etc...probably the thick end £4K  by the time they’re done. Even still they’re a proper bargain. I had a £40k Kondo here for a play and all in all I’d say the Pinnacles were the better sound....

Thanks again guys 

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If you want to try 6sn7's in place of JJ 802/12au7 then I have two adaptors available which are on ebay at the moment.

https://www.ebay.co.uk/itm/292816850647

I'll do them to include postage

Edited by mr.me

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13 minutes ago, mr.me said:

If you want to try 6sn7's in place of JJ 802/12au7 then I have two adaptors available which are on ebay at the moment.

https://www.ebay.co.uk/itm/292816850647

I'll do them to include postage

I used to use 6SN7 instead of 12au7 in my Audio Innovations Second Audios and they do sound better to my ears.

Just make sure that the amplifier heater circuit can take the extra current draw of the 6SN7. I had to put in a new separate heater supply for the extra draw of the 6SN7. It was not difficult but it stopped the original power transformer burning out.

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Yeh I’ll let them bed in for a while. Any mods like that I’d have to send them back to David to do the work...

Rightly or wrongly I’m a little nervous about messing with them, I’ve no reason to believe that they might be unreliable but I guess it’s the kit thing...

Edited by Thetiminator

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Generally, always check on t'internet for any valve specifications and only use ones that are identical. As mentioned above, this can really matter for heater current, as many designs spec power supplies for heaters quite marginally. Look out for operating voltages too, as many supposed 'drop-in replacements' arte anything but.

As for signal tubes, there are hundreds of alternatives out there. Some make a surprising difference, but only some tubes and only in some circuits. I have had more than a few bits of valve stuff over the years, and some were almost immune to swaps.

When buying, unless you have extremely deep pockets, stay clear of the big-ticket NOS stuff lurking on the web. Things like gold-pin Telefunkens are 'worth' such insane prices, that fakes are all over the place, and more so tubes that are out of spec or hideously microphonic. For modern replacements for 12AU7 and 12AX7 I'll forever bang the drum for my favourites, respectively the JJ Gold Pin ECC802S and ECC803S. They also now do an E88CC (6922 equivalent). These are under £25 a go and I've found them close to some of the best NOS stuff. And bear in mind that my daft collection includes some 'holy grail' Telefunken ECC803S for comparison.

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Thanks very much Rab. Some excellent info, thanks for taking the time. I’ll update the thread once I’ve had a play....

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Incidentally, I had (and built and modified) a Transcendent pre-amp and the designs are very good. Amusingly under the circumstances, you'll see from the Transcendent forum that Bruce Rozenblit (the designer) is definitely NOT a fan of tube rolling, or any component swaps for that matter!

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Yeh I asked him about upgrading some bits and a got a very curt reply back along the lines of ‘don’t be a tw*t son’ lol. 

Tim from EAR is the same, swears blind that valves make no difference. Well when I changed the stock valves in my HP4 you’d have thought I’d changed amp and headphones! 

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Just as an update: 

On a rec from David Coe I ordered a set of the Toshiba NOS 803’s from Langrex for £15 a go. I ran them for c.10 hours before listening, then replaced the old JJ’s. They def make a decent difference...particularly in the bass and the ability to handle the complex stuff. They’re a tad smoother than the JJ’s but a lot more organised if you get my drift, way better bass and just more natural. 

Highly recommended for the outlay. Just one thing to note...David had said that he had a couple of duds and ended up with 4 to get 2 that were working properly. Mine were fine but just a heads up...

Edited by Thetiminator

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