which 6v6's

musicegbdf

Ok I replaced the JJ 's when one blew with some cheap russian vallves . Not tnat good , not as clean as I like. Before I buy some JJ's any ideaks for a nice valve that has good clean headroom. The amp is a 15w Ashdown Essex blonde

ICBM

Just get the JJs - they have the most headroom of any modern 6V6, possibly of any including old-production ones - almost 'halfway to a 6L6'.

The only ones I can think of which might have more would be the ones Groove Tubes sold as 'heavy duty 6V6s' in the 90s, and they were actually just relabeled low-quality 6L6s.

musicegbdf

Thanks , so 6L6's would have even more headroom...
Though must admit the JJ's are what came in it and have a nice bright sound . So will check them and the Groove to see which are around
Thks again

Van_Hayden

Yep. Go with @ICBM Either JJs for clean, Russian black cheapos for dirt. Dave G likes both. Is it an Ashdown built one or a Matamp built one?

ICBM

musicegbdf said:

Thanks , so 6L6's would have even more headroom...

Yes - in theory. You should be able to fit them in a cathode-biased 6V6 amp. But... you first need to check whether the components (transformers and cathode bias network in particular) will handle the increased current draw and higher cathode voltage; and secondly in order to make it worthwhile you need to reset the amp's output impedance relative to the speaker (halving the relative speaker load, so if the speaker is 8 ohm you need to connect it to the 16-ohm tap) or you won't get more power or headroom, and possibly even slightly less since the amp will then effectively be mismatched.

musicegbdf

Van_Hayden;49982" said:

Yep. Go with @ICBM Either JJs for clean, Russian black cheapos for dirt. Dave G likes both. Is it an Ashdown built one or a Matamp built one?

It is a Matamp one. Think I will stick to the JJ's

In the handbook it says I can use 6L6 without a problem or rebiasing , but going to stick to 6v6's . What is the difference between GT S. And GT C ? I seem to recall it came with GT S's in it.
My amp is serial number 5 of the first 50 made , and has a plate on the back saying it was made by Matamp.

musicegbdf

Ok seems hot rox is the cheapest , but Karltone for a couple of quid more say they have "burned them in" before grading and pairing ... Is this snake oil , or worth paying a small premium for . I know hot rox has a good rep , but don't know Karlton

ICBM

Karltone beats Hot Rox hands down in my experience.

Burn in before grading is essential, it's more or less pointless trying to match valves otherwise.

musicegbdf

Great tks Karltone it is then

Van_Hayden

Doesn't make bugger all difference in that amp. Individual cathode resistors so you don't need matching. They just need to work!

guitargeek62

musicegbdf said:

Great tks Karltone it is then

He's an ex-forumite iirc?

McToot

guitargeek62 said:

musicegbdf said:

Great tks Karltone it is then

He's an ex-forumite iirc?

 

He is - lovely bloke too.  He did me some nice EL34s last year.  I've been trying to find his email actually as I too need some new 6V6s... I'm guessing he didn't make it across to the new hangout. 

musicegbdf

Van_Hayden said:

Doesn't make bugger all difference in that amp. Individual cathode resistors so you don't need matching. They just need to work!

You lost me there.


Though interesting to know they don't need matching

Van_Hayden

I helped design it...

ICBM

Van_Hayden said:

I helped design it...

I hope you didn't have anything to do with the 8W one and how you have to get the chassis out!

I've never seen the 15 so I'm hoping it isn't the same...

Van_Hayden

Well - depends, at that time I was play testing for Matamp. Now I get to mend them.... There's quite a lot of compromises. Like the reverb. And the box - bit of a running joke at the factory that. Dave had some strange ideas, like running the reverb drive off the cathode.....

jpfamps

Van_Hayden said:

Well - depends, at that time I was play testing for Matamp. Now I get to mend them.... There's quite a lot of compromises. Like the reverb. And the box - bit of a running joke at the factory that. Dave had some strange ideas, like running the reverb drive off the cathode.....

Running the reverb drive from the cathode isn't a totally daft idea as it's a low impedance output.

It does somewhat depend on how it's implemented though.

Van_Hayden

No the DC power supply for a 741

musicegbdf

Actually really easy to drop the chasis, I can'r recall exactly (at work) I think the plate on the back says "made in the Uk by Radiocraft Matamp.

It has a full spring reverb tank in the bottom, I think I paid £450 new from Coda. I understand the first 50 were made by Matamp and the ones the magazines got and reveiwed . They stopped making them under the Ashdown name very quickly and changed it to Hayden and doubled the price. I was told they lost money on the "Ashdown" ones.
Here are some photo's
http://www.flickr.com/photos/musicegbdf/8061877832/
http://www.flickr.com/photos/musicegbdf/8061873233/

Van_Hayden

Well they sold them to retailers for less than Matamp charged to build them. Killed off the C7 in the process.

ICBM

Ah, that's totally different from the 8W one I tried - with that, the cabinet is closed-back with a panel over the speaker and the back of the amp section is a non-removable part of the chassis (I wish I was kidding!). To even change a valve, you have to remove the back panel from the speaker section, then either reach up really awkwardly around the speaker magnet - or if you want to get the chassis out to make it easier, you have to prise off the handle ends, remove the handle and a daft cover plate on the top, then undo the chassis bolts which are under it... if you can manage to do it without chewing up the cover plate, you get bonus points.