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pcrecord 2 June 2015

Hi there,

I'm starting to check for a place I can thrust to buy tube kits for my 2 x LA-610.
Affordable and good sounding (dreaming here ;))
They are both mk1 and were buildt around the same year but actually don't sound the same.
I guess they have different tubes or different wear on them.

Any suggestions ?

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DonnyThompson Wed, 06/03/2015 - 06:16

LOL... truthfully, If was in your situation, and I'd had this same question, I would have been asking you ... :)

That being said, considering his extensive background in electronics design and development for audio, I think you should probably page Boswell on this one. ;)
( Boswell )

I could give you suggestions, but they wouldn't really carry much weight - first of all, because I don't have an LA610 - and second, while I've experimented with different tubes in tube mics, I don't really know all that much about the individual characteristics of the different tube types; like what "starved" voltage will result in sonically, or how using a tube that is perhaps under or over biased will affect the sound...

;)
d.

pcrecord Wed, 06/03/2015 - 06:25

I've been suggested Tungsol tubes which are affordable but some says the Electro-harmonics perform better.. I'm a bit lost too Donny ;)
The last thing I want is to spend 500$ of tubes and end-up hating the sound of my LA-610s !!
And I don't want to spend more than what the preamps are worth either, it's for a home studio after all...

Boswell Wed, 06/03/2015 - 07:13

pcrecord, post: 429540, member: 46460 wrote: 12AX7 and 12AX7
I read that the output tube 12AX7 can be replaced with a 12AU7 to get cleaner sound and more headroom but I haven't decided if I'm gonna test that yet..

Well, I don't know about "cleaner sound" and "more headroom", but the one thing that you can guarantee is that it will make a difference, either subtle or gross.

Bear in mind that the amplifier designer will have purposely chosen a valve (tube) for each position in the unit, and will have done the calculations of voltage swings and current flows for that device. If he is worth his fee, he will have taken account of the differences between the same nominal device from a range of manufacturers. However, putting a different device in there will cause different operating conditions, and while, for example, you might perceive it having a sweeter sound for low-amplitude signals, you may find that you get overload distortion at half the output levels you had previously. Of course, that may be what you want for something like a guitar amplifier, but for an LA610, probably not.

Myself, I would not go spending large amounts of hard-earned cash on bucketfuls of different devices from around the world when I have a working known standard design, but if other tube-rollers say they get certain effects by swapping them out, you might feel it's worth some limited experimentation.

audiokid Wed, 06/03/2015 - 08:06

Boswell, post: 429544, member: 29034 wrote: Myself, I would not go spending large amounts of hard-earned cash on bucketfuls of different devices from around the world when I have a working known standard design, but if other tube-rollers say they get certain effects by swapping them out, you might feel it's worth some limited experimentation.

Words of advice.

pcrecord Mon, 03/21/2016 - 07:13

It's an old thread but I thought it would be important to write how this turned up

Initially the installed tubes were all GE and while sounding ok, I found the sound to be a bit nazal and easy to saturate. Altought usable, I wanted to see if I could make it cleaner in the HF and a bit warmer sounding.

I recently bought these :
3 of Mullard 12AX7 / CV4004 Tube
1 Genalex Gold Lion 12AT7 Tube
1 Tung-Sol 6005 / 6AQ5 Black Plate TGS

I chose those tubes by analysing there sonic properties on tubedepot.com with their guide list (very nice descriptions) and checking availibility in Canada.
After a few week of tests and breaking them up, I can say I'm very impress with the difference.
I get more defined HF warmer LF and the mids are well balanced now.
Now I'm debating myself if I'll order the same kit for my second LA-610 or I keep them sounding different.
But I'm very happy with the results !

rmburrow Fri, 04/08/2016 - 20:36

12AX7's have high gain and some brands are notoriously microphonic. Look for Telefunken ECC83 or ECC803, especially for the input stage. Amperex "bugle boy" 12AX7's should also work.... or RCA 7025's...I ordered some EF806's for a microphone the other year from JJ Electronic...they were quiet. You should select the most quiet tubes if you have several to try. Your ears will help you find the best choice. I don't have the Urei preamp, but have used the Altec 1567A units that use 12AX7's...

pcrecord Sat, 04/09/2016 - 05:23

I used Tubedepot comparaison tool to help me choose : https://www.tubedepot.com/tube-comparison-tool

Yes the JJ12AX7 are quiet but they have less headroom and are less sentitive. For the use that I make (mainly vocal) The mullard made more sens even if a bit less quiet.
I bought some JJ in the past and I found them to be less detailed. Of course every units is different ! ;)

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