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Posted (edited)

My Vincent SV-237 has developed a light hiss in the tweeters, and a crackle in one, both with the volume set to zero, and the hiss/crackle doesn't increase with the volume nob being turned up. 

The amp has a 12AX7, and  2 x 6N1P.  I swapped the 6N1P over last night and the crackle moved from one speaker to the other, so i'm confident it's a tube issue with the crackling (there were no inputs connected at the time).  I'm not sure about the hiss though in both tweeters.

At this point, i'll try replacing all 3 of the tubes, and hopefully it solves the issues.

 

I believe the Amp has V6N1P-EV Voshkod rockets, and a 12AX7 Telefunken.  

 

Wondering about options for sourcing, iv'e found:

https://www.audiozomba.com/product/vincent-sv-237-sv-237mk-integrated-amplifier-upgrade-vacuum-tube-replacement-kit/

https://www.tubedepot.com/products/telefunken-ecc83-12ax7-smooth-plate (NOS Telefunken 12AX7 is $500 arrggghh!)

https://www.tubedepot.com/products/telefunken-black-diamond-ecc83-12ax7 

https://www.telefunken-elektroakustik.com/product/ecc83-tk-12ax7 More reasonable at USD50, there must be some differences though compared to above.

https://www.amazon.com/TELEFUNKEN-Diamond-featuring-1-ECC83-Carbine/dp/B076VVBQD9/ref=sr_1_1?dchild=1&keywords=telefunken+12ax7&qid=1619998198&sr=8-1

Ebay has some too.

 

I think i'll just go ahead and replace with the same tubes as it has now, i'm pretty happy with the sound.  Not sure if i want to delve into the murky world of tube rolling ;)

 

Are there any local retailers I can look at?  I read a lot about fakes, so i just want to make sure i get what i pay for, total novice.

 

Thanks for the help :)

Edited by Janus77
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Posted (edited)

Another question, my speakers are quite efficient and so i barely get past 9 o'clock on the volume dial.  Would i be better off with a low gain tube in this case?  does gain in tubes impact volume?  Can you get different gain levels in the same brand/model tubes?

 

Is there a way to test the 12AX7 so i can work out if it's causing the hiss or not?

Edited by Janus77
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You can try directly subbing the 12AX7 with the lower mu 5751, which are usually a bit cheaper too.

Finding a good seller who can supply you with proper low noise 6N1P is key. 

@xlr8or might be able to point you in the right direction.

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@deanB is spot on with the 5751 recommendation for the 12AX7 position. Please aim to get a 1960's Raytheon windmill getter for this position. A new pair of 1970's 6N1P-EV's would be my choice for the existing 6N1P's. Don't go for the plain 6N1P option from the 1950's as they are noisy.

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Posted (edited)

is the hiss from the tweeter likely to be noise from the tubes?

 

the original owner of the amp (twice removed) has kindly offered for me to drop around and try a few of his spare tubes to determine if the hiss is coming from the tubes or not.  
 

I’ll keep an eye out for the ev version of the 6n1p’s.  

Edited by Janus77
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You can always run the one 6N1P tube in each channel to test this out. This will test if the hiss is coming from the tube or some other source. Try it and let us know how you go. Use the existing channel tube that has no hiss and swap it over and listen.

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Posted (edited)

So there are 2 x 6n1p-ev tubes and when I swap them the crackle moves from one speaker to the other.  Both speakers have a hiss at the same time regardless.  There’s only 1 x 12ax7 tube.  So might be this one causing the hiss?   Or else both of the 6n’s?

 

ive got some 95-96db efficient DIY 3 way speakers.  
 

thanks for the help!

649CB64F-7611-4BE0-ADC6-BEB32C7599EB.jpeg

Edited by Janus77
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My speakers are 97db, running a valve pre and power and I can hear hiss (tube rush) with my ear a few cm from the tweeter.

As you mentioned that you can't get the volume past 9.00, it may be that your amp has a bit much gain. The 5751 could help there. Vincent doesn't publish a gain spec for the 237 though so I'm just assuming.

Get your valves sorted and see where you're at. And let us know what you find.

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Posted (edited)

Some other things to try:

 

Firstly, I wouldn't use those spring clamps on the 6N1P-EV's as they most likely degrade the sound. Secondly, try cleaning the tube pins with metho and cotton buds and Caig's Deoxit. You can also try 0000 grade steel wool on the pins before the metho clean. Thirdly, try lifting the 6N1P-EV a few millimetres out above the tube socket to avoid it resting on the tube socket.

 

The tube rush is likely coming from the 12AX7. I personally luv tube rush. When music plays any tube rush disappears. It magnifies the sound nicely. Try the 5751 in place of the 12AX7 and let us know how you go.

Edited by xlr8or
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Thanks, yes the “rush” is only from a few cm off the tweeter.  I’ll try cleaning and lifting the 6n1p and see if that deals with the crackle.  

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Thanks Xlr8or and deanB for the advice, on Xlr8or's advice i'm now waiting on a set of NOS matched Voshkod rockets from Moscow, and a Raytheon 5751 from Nevada.  Looking forward to comparing the Telefunken and Raytheon.

 

I'll learn to enjoy the "rush"

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Tube 'rush' in a pimped-out tube system using efficient speakers is like the sound of a great concert hall before the performance, or a favourite singer's breathing, or even like an old favourite LP's background. Some sounds are full of promise...

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