tubes

Zinky Superfly Blog - Part 37: Great News?

From: david@dave.st
Subject: Re: Superfly- Basically done. Just have to put it back in the shipping box
Date: 19 August 2008 10:04:42 BST
To: info@zinky.com

That's great news. Can I just recap on what I needed / wanted to be done?

- Fix the intermittent reverb;
- Replace the power tubes at $60 cost to me;
- Fit the $100 upgrades which will obviate the need for the retrofit reverb level box as well as other improvements;
- Supply a head-only cabinet with black grille cloth at $290 cost to me (as per your email of 16 April you were not sure if you'd have to recover in black one you had already covered in silver);
- Ship back to me at my cost.

I hope I haven't forgotten anything there. I'm sure looking forward to having the amp back.

Regards,

David

So here's a short but complete list of what I'm expecting - again.

Bruce has had the amp for three and a half months, so none of this should be a surprise, right?

We should really be on the homeward straight, yes? Sadly not - Bruce did not reply to this email at all so a month later I was in a less optimistic mood - see part 38.

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Zinky Superfly Blog - Part 24: Any More Information

From: zinky@zinky.com
Subject: Re: Shipping Superfly chassis
Date: 16 April 2008 19:56:12 BST
To: david@dave.st

David, Yes, it's the same pan. That'll save you $20, and it will verify performance before the amp is re-assembled.

Tubes- We used to buy tubes in bulk, then sort them ourselves. The problem we found was a lot of tubes that biased really hot, which wouldn't last. (those are the ones that often hum, too). There were also the very cold tubes which didn't make power, as if they were pre-aged.

Only the 5881WGC tubes work properly. The others are merely 6L6 copies, and not nearly as good. The WGC is a military tube with SIMILAR specs, but they are not optimized for performance in 6L6 circuits. The Superfly wants to se the WGC tube.

I'll find the shipping cost for you, your cost = my cost. We typically use Fed X economy delivery, which takes about a week.

BZ

Bruce confirmed that I should send one of the reverb pans and some gave useful information about likely shipping time.

I still wasn't sure about the power tube explanation, but if Zinky could supply some tested tubes (especially having my amp to test them with), that should be fine?

I never did get the shipping cost, so after a few days I made my own enquiries and let Bruce know - see part 25.

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Zinky Superfly Blog - Part 23: More Confirmations

From: david@dave.st
Subject: Re: Shipping Superfly chassis
Date: 16 April 2008 19:23:48 BST
To: zinky@zinky.com

I was going to send one of my reverb pans with the amp (you may recall I bought a replacement to see if it helped my problem - it didn't) so I wouldn't need a third one from you unless the actual spec of the pan has to be different after the upgrade? The original one in my combo is a type 4FB3B1B.

Tube-wise, I'm curious why the new Sovtek tubes that I bought caused a loud hum on the output after an hour of use, but I'll go for a new set from you anyway. Strangely the tubes that were in the amp when I bought it look to be a mismatched set of different makes. I'd welcome a suggested procedure for checking the bias as my knowledge is sketchy.

That's the first quote I've had for the head-only cabinet, AKA shell. It's got to be black really (and black grille cloth please), so I'm hoping you do still have a black one in stock. Overall I believe I'm looking at $100 (upgrade) + $290 (shell) + $60 (four power tubes). Plus cost of return shipping I guess.

Regards,

David

We finally seemed to be getting somewhere after 7 days of exchanging emails.

I pointed out I shouldn't need a new reverb pan and tried to summarise the known costs.

Bruce's reply was still on track, fortunately - see part 24.

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Zinky Superfly Blog - Part 22: Full Costs At Last?

From: zinky@zinky.com
Subject: Re: Shipping Superfly chassis
Date: 16 April 2008 18:53:21 BST
To: david@dave.st

Hello David;

It's going to be $100 for the reverb fix, plus power supply and other updates. No tubes necessary there, but
if in doubt, you should have a spare set of output tubes. That way, if there's ever a question, you just replace the
tubes, give it a listen, and if the sound improves, buy a new set of spares.

What I was wondering was the price quoted on the cabinet. I may still have one new one in black, but what I might have to do would be to uncover a silver cabinet and re-cover it in black...That's a whole lot of work to clean off the old glue. You have to rid yourself of the old glue if you want the vinyl to sit flat on the cabinet, without lumps. That would run $250 for the raw cabinet, and $290 assembled (with new reverb pan, logo, your choice of Black or Cream grille cloth), as the transformers get braced against the pan and the cabinet to reduce chassis damage in shipping.

Tubes- We sell burned in, tested, graded and matched sets for $60. No biasing necessary, just plug them in and go. We found that carefully selecting the tubes yields much better reliability and consistency. Another benefit is that you can just plug in the new tubes without worrying about bias.

Truthfully, bias refers to the idle current of a tube, no signal. You can do it yourself with a voltmeter and your EARS more accurately than anyone using a 'scope (Testing the response of a sine wave on a guitar amplifier is meaningless) or other paraphernalia.

BZ

Finally some costs for the amp shell...

However there's a little doubt there as to whether there is one available quite as easily as I'd expected, considering that the Superfly was/is still advertised as being in production.

Also, I shouldn't need another reverb pan - I've already got two which work as well as each other!

Finally some thoughts on biasing that rather went over my head. $60 for a new set of power tubes should sort things out though. I hastened to respond - see part 23.

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Zinky Superfly Blog - Part 12: A Year Later

From: david@dave.st
Subject: Superfly problems revisited
Date: 9 April 2008 17:28:31 BST
To: zinky@zinky.com

Hi, you may remember me emailing early last year. To keep it brief, my problem was that the reverb on my Superfly Combo kept cutting out. No crackling, just one minute it was there and the next gone. An exchange of emails ensued discussing possible reasons and other issues with the Superfly but after 15 March 2007 I sent three more emails, none of which was replied to.

Jumping foward to where I am now:

1 I bought a new set of pre-amp tubes and figured out where the 12AT7 should be (not the socket where it was when I bought the amp!) This has not fixed the reverb problem.

2 I bought a replacement reverb pan direct from Accutronics. It sounds just like the original but has not fixed the reverb problem.

3 I bought replacement power tubes, taking care to get proper Sovtek 5881s. I guess I should have scheduled in a bias adjustment because when I fitted them and used the amp for band practice the amp developed a loud hum and smell of excessive heat after about an hour. The tubes are marked 42mV on the boxes. I have re-instated the previous set of tubes for now but would like to know what is required to get the amp running happily on the new set. It was also unclear from previous communications which amp tecs in the UK would be qualified to work on it?

I understood that, for a charge, there are some upgrades that can be done to the Superfly, but that the chassis would have to be sent back to you.

I have now bought a backup amp so I can get along without the Superfly for a period of time. I would like to send it back to you so I can get the upgrade done and the reverb problem checked out.

Additionally, I have found that the overall weight of the combo format is just too much for transporting it around. Can you supply me a case for the head alone - I have already transplanted the speakers into a separate speaker cab to use with my backup amp?

By the way, despite taking the chassis out of the cabinet and having another damn good look, I still cannot find a serial number anywhere.

I'll pay the cost of shipping, I'll pay for the upgrade, I'll pay for the head-only case, I'll pay for shipping it back to me. I would just like to get the issues resolved finally so that I can use the amp to its full potential. To recap: reverb, upgrade, bias, head-only case.

Please let me know how I should proceed.

Kind regards,

Dave Jackson

In the preceding year I had lived with the intermittent reverb but understandably was not happy at having to do so. As I outlined in my next email (opposite), I'd bought new pre-amp valves and even gone to the trouble of buying a new reverb pan (not particularly expensive considering it was sent from the USA), but that did not help the original problem.

By April 2008 the situation had changed partly due to the effect of having put in new (and supposedly good-quality) power valves.

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Zinky Superfly Blog - Part 11: Mis-placed Valve?

From: dave@dave.st
Subject: Valve positioning affecting Superfly Combo reverb problem?
Date: 18 March 2007 20:03:46 GMT
To: zinky@zinky.com

I have spent several hours today trying to work out more clearly where the problem is, but for some reason this time the reverb did not cut out for any length of time so I was not able to establish whether there was still a signal into the reverb tank when it is inaudible.

However, having taken off the rear grill and reading your previous email again I am suspicious that the 12AT7 is in the wrong place.

Looking at the amp from behind and starting at the left end there is a large transformer which logically is the power supply as it's very near the mains power socket.

To the immediate right of that is an RCA jack which I believe is the reverb send (it has the red RCA plug in it which connects to the left RCA jack on the reverb tank, currently via the extra reverb control box to reduce the send level as much as possible and minimise audible distortion on clean settings).

To the immediate right of that RCA jack is a small valve. This is currently a 12AX7 (make uncertain). To the immediate right of that is another 12AX7 (SOVTEK). They are both partially obscured by the two leftmost output valves (both SOVTEK 5881/6L6) which are nearer the back edge of the chassis.

Further along to the right of those two valves is a bit of a gap and then the RCA jack for what I believe is the reverb return (a black RCA plug connected to the right side of the reverb tank). To the immediate right of that is another 12AX7 (SOVTEK). In front of them are two more output valves marked HARMA 5881.

Still moving to the right is what I reckon to be the output transformer.

In the space between that transformer and the right hand end of the chassis are two more small valves: a Philips 12AT7 and an Electro-Harmonix 12AX7. To emphasise - the 12AT7 you mentioned in your email is located almost in line with the MIDI In socket on the back face of the chassis.

So neither tube near what I think is the reverb send is a 12AT7 - they are both 12AX7 and the 12AT7 is way down the other end at the right.

Can you please confirm whether the positioning of the valves that I've described is correct? I would kinda' help if there was a diagram of what should go where in the PDF manual...

Thanks and regards,

Dave

PS I'm still keen to know the in's and out's of sending the chassis back to you for an upgrade.

From: dave@dave.st
Subject: Trying again with my 18 Mar email re: Valve positioning affecting Superfly Combo reverb problem?
Date: 25 March 2007 16:14:47 BST
To: zinky@zinky.com

I sure would like to know if the right valves are in the right place.

Regards,

Dave

From: dave@dave.st
Subject: Trying a second re-send of my 18 Mar email re: Valve positioning affecting Superfly Combo reverb problem?
Date: 1 April 2007 18:42:00 BST
To: zinky@zinky.com, info@zinky.com

Perhaps someone reads your "info" mailbox more often?

I'm still hoping for a reply to my email. I've scoured the Web for just a simple list or diagram of which tube goes where with no luck.

Regards,

Dave

I was confused because looking at the valves in the amp, the 12AT7 did not appear to be in the right place. It should be the small valve right next to the red RCA plug in the attached picture I think!, but there was a 12AX7 there. Although I'd got a PDF of the Superfly user guide, for some reason it did not include a simple diagram of the valve placement.

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Zinky Superfly Blog - Part 10: Check The Reverb Valve

From: zinky@zinky.com
Subject: Re: March 14 email about frustrating Superfly Combo reverb problem
Date: 15 March 2007 23:34:01 GMT
To: dave@dave.st

Hi Dave;

The Reverb tube (small tube nearest the large transfomer and near the RCA jack for Reverb Send) should be a 12AT7 type. a 12AX7 used here might exhibit intermittent behavior. Also, it COULD be a faulty 12AT7. Check that and let me know. If it were something like a bad Reverb transformer, that is covered under warranty and would mean no charge (other than shipping) for the complete upgrade.

BZ

Bruce's reply gave some more information on which tube sent the signal to the reverb, but nothing about the time required to do the upgrade once he'd got the amp.

I went back to the amp, took the back grille off (remember, all this time I'm still using the amp for weekly band rehearsals) and tried to match up his description with the positioning of the valves. See part 11 for my findings.

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