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Post by Deleted on Mar 26, 2008 11:24:43 GMT -7
I have a Maz 38 that I'd like to change the preamp tubes in. I don't really understand how it works. In the manual it states the following: V1-ECC83, V2-ECC83, V3-12AT7, V4 and V5 have 12AX7. Are these all the same or do I need different tube types for each position? Does anyone have any recommendations for a tube replacement for each position? I was looking at Tung sol 12AX7 reissue as one possiblilty. Would I put this in V1 for best results? I have heard some reliability issues with this particular tube. Does anyone have any experience to confirm or refute this?
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Post by Fender Bender on Mar 26, 2008 12:15:15 GMT -7
First of all, ECC83=12AX7. The tube positions have the following functions: V1 = Input driver. (Most will say this is the most important "toneshaping" tube) V2 = Tone stack driver V3 = Reverb driver V4 = Reverb recovery V5 = Phase inverter (long plate recommended by the experts...) In my Maz Jr (same lauout) I have the following tubes: V1: NOS RFT 12AX7 V2: Tung-Sol reissue 12AX7 V3: NOS Mullard CV4024/ECC81/12AT7 V4: NOS JAN GE 5751 (for testing) V5: Sovtek 12AX7LPS w/ balanced triodes V8(Retifier): NOS JAN Philips/Sylvania 5AR4 I have changed most preamp tubes, and also changed the tube type in V4 to a 5751 (5751 is a lower gain tube compatable with the 12AX7). Primary reasons are sound and feel. I have found tubes I like in this amp. You might have a very different taste, and the stock ones might be spot on for you. I would say using the same type tube for V1, V2, V4 (and probably V5) would be safe, but trying a few different ones won't hurt... V3 is a different tube. I have used the Tung-Sol in V1, and it was OK. I still use it in V2. I have had no issued with this tube. If you can describe what you wan't to achieve by changing the tubes I'm sure you will get alot of suggestions for tubes here. Hopefully I answered some of your questions
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Post by dixiechicken on Mar 26, 2008 12:15:51 GMT -7
DC here!
If you just replace each respective tube in the various positions with the same model you will be fine.
12AX7 tubes you replace with either 12AX7 or ECC83 - thats the same thing/tube. (ECC83 is just the European label for a 12AX7)
The 12AT7 you replace with another 12AT7 or ECC81 tube. (again ECC81 is just the European label for a 12AT7)
What you have to decide is whether you want to spend a lot of money on NOS tubes. (N-ew O-ld S-tock)
These old new tube generally meets all specs, they last much longer and many people also think they sound much better. YMMV
Cheers: Dixiechicken!
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Post by Deleted on Mar 27, 2008 6:28:41 GMT -7
Thanks for the info guys. This site helpful as always. I asked KCA for some help in recommendations for my preamp tubes. His suggestions were: V1 and V2 lightly used ANOS RCA 12AX7 for the other 12AX7s Tong Sol reissue and for the 12AT7s Mullard CV4024/12AT7s So I will give these a try and see what happens. Just wondering if there is any issue with using lightly used NOS? Should I expect a little shorter life span?
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Post by dixiechicken on Mar 27, 2008 8:37:00 GMT -7
DC here!
Yes you could expect a little shorter lifespan - but given the fact - that NOS preamp tubes can last as long as decades even, you shouldn't need to worry overly much on that "dept".
The ANOS tubes are a bit cheaper too - since they are not brand new.
Often - IF a tube will fail prematurely - that's most likely to hapen early/very early in a tube's lifespan.
So an ANOS tube may very well be a good safe bet - looked at this way.
And of course you should pose the question to Myles in the experts section - if he doesn't know - then nobody else here needs to know about it either - I'll wager. ;D
Cheers: Dixiechicken!
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Post by Deleted on Mar 27, 2008 8:57:21 GMT -7
DC here! Yes you could expect a little shorter lifespan - but given the fact - that NOS preamp tubes can last as long as decades even, you shouldn't need to worry overly much on that "dept". The ANOS tubes are a bit cheaper too - since they are not brand new. Often - IF a tube will fail prematurely - that's most likely to hapen early/very early in a tube's lifespan. So an ANOS tube may very well be a good safe bet - looked at this way. And of course you should pose the question to Myles in the experts section - if he doesn't know - then nobody else here needs to know about it either - I'll wager. ;D Cheers: Dixiechicken! What??? Are you saying I could get several years out of my preamp tubes? I though that I would have to change them every 1 to 2 years. Some are saying they change them every other time they change their power tubes. That would be around once a year.
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Post by dixiechicken on Mar 27, 2008 10:46:20 GMT -7
DC here!
Short answer is yes. Pre-amp tubes generally lasts much much longer than power tubes. Unless you have a very weird circuit layout in your amp. YMMV of course. Usually you change the preamp tubes when they fail or go microphonic on you.
I would suggest many of us here change the pre-amp tubes - more to change the sound in our amps - than anything else.
Rectifier tubes are another kind of tube that can last a long long time. A good NOS rectifier tube can last the lifetime of your amp if your lucky.
Cheers: Dixiechicken!
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Post by Deleted on Mar 27, 2008 13:14:09 GMT -7
I agree with DC.
I've had the same preamp tubes in my '73 Deluxe Reverb for about three years. I practiced with that amp weekly, and gigged with it at least once per month over the last 3 years, with no sign that anything needs to be changed (including my power tubes, but I understand 6V6's have a completely different life expectancy than EL84's).
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Post by Deleted on Mar 27, 2008 13:14:47 GMT -7
I'm just getting ready to order but these tubes have options and I'm not sure if I need the options or not.
The ANOS RCA 12AX7A for V1 and V2 have the option of Balanced Triodes. Do I need this?
For V4 and V5 I want the Tong sol reissues. The options are Balanced triodes, matched pair and high gain. I assume that high gain is a preference thing. What about the other 2 options?
For V3 the Mullard CV4024/12AT7. Options; Balanced triodes. Do I need this?
Also is there an explanation posted somewhere that explains what V1 thru V7 in my Maz 38 head are exactly. I know that V8 is my recto.
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Post by Fender Bender on Mar 27, 2008 13:39:57 GMT -7
I would get balanced triodes for V5. Alot of people seem to like the Sovtek 12AX7LPS for this position. This is to get a balanced signal feeding your power tubes. I don't think you'll need balanced triodes for the other tubes. For V4 I would personally not get a high gain tube. It would give you way to much reverb in my opinion.
I have explained V1-V5 functions above. V8 is the rectifier. The others are your power tubes (2 pairs of EL84s).
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Post by Deleted on Mar 27, 2008 14:10:49 GMT -7
I have explained V1-V5 functions above. V8 is the rectifier. The others are your power tubes (2 pairs of EL84s). Doh. I knew that. I even printed it out at home. I don't know what I'm thinking.
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Post by dixiechicken on Mar 28, 2008 5:30:38 GMT -7
I agree with "Fender Bender" - the only position you should ABSOLUTELY get a balanced tube is in the PI position. (Phase Inverter position).
Else it doesn't matter really - as stated you'll need a balanced double triode as a PI-tube to drive the output- tubes equally hard.
( simplified - half the the set of the power-tubes takes care of the negative part of the sine wave - the other half set of power-tubes takes care of the positive part of the sine-wave )
All music material our sound in general can be analyzed/broken down into sine waves of various frequencies and amplitudes - this is called Fourier-transformation. (Fourier = French dude - mathematician & scientist)
Cheers: Dixiechicken!
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Post by Deleted on Apr 1, 2008 13:28:42 GMT -7
Ok. I'm just getting ready to submit my order and I think I've got it straight what I'm doing.
V1 and V2 are going to get ANOS RCA 12AX7 V3 Mullard 12AT7/CV4024 V4 Tong sol Reissue V5 Ton Sol Reissue (Balanced Triode?) So if I have it right is it the Tong Sol Reissue that I will be putting in to V5 that will have the balanced triode? I thought I read somewhere that people were having balanced Triode in the V3 tube. I could be wrong. I just wanted to verify before I order. Also is the Mullard 12AT7/CV4024 an NOS tube?
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Post by dixiechicken on Apr 1, 2008 15:35:44 GMT -7
If position V5 in your Maz is PI-position/PI-tube - yes that's correct.
Cheers: Dixiechicken!
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Post by myles on Apr 1, 2008 19:16:30 GMT -7
Preamp tubes, especially ones made from 1950-1970 can outlive the player. I have tested uncountable preamp tubes from vintage amps that test better than new production tubes.
In an EL84 amp the phase inverter is not worked all that hard and can last years. In a 6L6 amps some folks change it every other output tube change but a good set of 6L6s can last over 6,000 hours. I test phase inverters before I install them and then look at them at the end of a long tour. When they have dropped 15-20% in current output I replace them. Phase inverters are the most hard worked preamp tube in the amp and the only one that "wears out" other than some new production 12AT7 tubes used for reverb drivers.
EF86 pentodes go microphonic long before they wear out but in some early sixties Vox AC15s I have found tubes from 1962 that test as new even today. New EF86s would not do anywhere this well. I only use NOS EF86 tubes in any amp with this tube as part of its tube compliment.
On some master volume amps, depending on the phase inverter being pre or post master you can eat phase inverters very fast if the master is turned way down and the volume way up as the phase inverter could be pushing its guts out only to have that signal turned into heat energy rather than allow it to push the output tubes. No worry on the MAZ in this respect.
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Post by Fender Bender on Apr 2, 2008 3:45:50 GMT -7
I thought I read somewhere that people were having balanced Triode in the V3 tube. I could be wrong. That would be in a Maz without reverb if I'm not mistaken...
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Post by myles on Apr 2, 2008 8:01:16 GMT -7
I thought I read somewhere that people were having balanced Triode in the V3 tube. I could be wrong. That would be in a Maz without reverb if I'm not mistaken... You are correct ... in the MAZ NR V3 is the PI
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Post by Deleted on Apr 2, 2008 8:33:27 GMT -7
Got my order in for my preamp tubes. This is all experimental to me so we will see how it goes. Got the ANOS RAC for V1 and 2 the NOS Mullard 12A7T for V3 and the Tong Sol Reissue for V4 and a Tong Sol Reissue balanced triode for V5. I get to do this all over again when I get my Stangray head in a couple of weeks. One question. If I like this combo in my Maz 38 should it work well for my Stangray? Or will it be a whole different ball game?
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Post by dixiechicken on Apr 2, 2008 9:41:34 GMT -7
DC here! The Stang Ray is very different - it has the EF86 tube as a V1 position - only one. It has the 12AX7 as PI tube. Thus the Stang Ray preamp tube complement is a lot like Z-28 or my Route66. For the EF88 preamp tube a NOS tube is more or less mandatory. Get one or two spares as well. (NOS) The rectifier tube is a GZ34/5ARA4 the same tube as in my Route and couple of other Z-as. Cheers: Dixiechicken!
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