Feel free to ask Myles

[Sauce]

Ah thanks for clearing that up. You're the man Myles! So I guess now I gotta decide between the Celestion blue or one of the Weber offerings...

[myles_rose]

Ah thanks for clearing that up. You're the man Myles! So I guess now I gotta decide between the Celestion blue or one of the Weber offerings...

 

Very hard call .... Ted Weber makes some really stellar stuff. Just trying to pick one of HIS speakers would be hard enough but with Weber you can always talk to the man himself and he will steer you in the right direction. Really a great guy, builder, engineer and human being.

 

Actually ... go the Weber route ... great customer service and great products and I always prefer supporting non-mega companies over big corporations. Then again ... it's your $$$$ and your ears thus it is your choice

 

 

 

[Sauce]

Sounds good to me, I like supporting the smaller guys too and the Weber is significantly cheaper. So now I'm thinking a Weber blue 50 watt but I think I might take your advice and ask the big guy himself...

[myles_rose]

Sounds good to me, I like supporting the smaller guys too and the Weber is significantly cheaper. So now I'm thinking a Weber blue 50 watt but I think I might take your advice and ask the big guy himself...

 

Sounds good to me

[Sauce]

Much appreciated Myles, thanks again.

[Junior 1]

Hi Myles,

I just picked up a Crate V18. It has a tube compliment of 3 12AX7A preamp tubes and 2 EL84 power tubes. I would like to have less gain and was wondering what preamp tubes I could use to accomplish that. Less volume would be ok too. Any suggestions?

Thank You

Anthony

[myles_rose]

Hi Myles,

I just picked up a Crate V18. It has a tube compliment of 3 12AX7A preamp tubes and 2 EL84 power tubes. I would like to have less gain and was wondering what preamp tubes I could use to accomplish that. Less volume would be ok too. Any suggestions?

Thank You

Anthony

 

Anthony,

 

For less gain and more clean headroom replace V1 (most close to the input jack) with a 5751. Get those from Mike at www.kcanostubes.com as you want an NOS one, not a new one. All new ones are is weak 12AX7s and are not real 5751s. If you like what that does (it is an old SRV trick by the way), and want to do even more of what you are hearing then replace V1 with a 12AY7 (the first gain stage of some great classic amps ... Fender tweed Bassman as one example).

 

Happy playing.

 

[Junior 1]

Thanks Myles.

[myles_rose]

Thanks Myles.

 

You are quite welcome

 

 

[Zephyr]

Hey Myles, would you happen to have any recommendations for soldering iron kits for amps and tube testers?

[BCorbett]

Hey Miles, I have mid 80's fender deluxe reverb black face. It has a boost pull knob for the reverb channel. I recently had it modified so that the volume knob for channel one is Now a Master volume Knob - no more channel one. I just put in an 12AT7 in the pre amp and love the clean sound with a mellow distortion.

 

Here is the question: Could the boost function by used to kick in the pre amp (V1) in series with (V2) for more distortion ?

 

My local Amp tech said this would be a major mod and would not sound good and I would be better off just buying a different amp. So I would have to learn to do this myself if it was at all posible. The boost function is just too sharp, bright and harsh and does not get used in the 20 years I have had the amp. I am thinking maybe 2 12AT7's might be sweet and if i could use the two Tone knobs for the BOOSTED tone this could be all the more better. Thanks, Brendan

[myles_rose]

Hey Myles, would you happen to have any recommendations for soldering iron kits for amps and tube testers?

 

Soldering irons .... something like a Weller solder station ... any electronics supply house.

 

Tube testers .... look on ebay .... not a lot of them made today. The ones that are made today are quite pricy if they are any good.

 

 

[myles_rose]

Hey Miles, I have mid 80's fender deluxe reverb black face. It has a boost pull knob for the reverb channel. I recently had it modified so that the volume knob for channel one is Now a Master volume Knob - no more channel one. I just put in an 12AT7 in the pre amp and love the clean sound with a mellow distortion.

 

Here is the question: Could the boost function by used to kick in the pre amp (V1) in series with (V2) for more distortion ?

 

My local Amp tech said this would be a major mod and would not sound good and I would be better off just buying a different amp. So I would have to learn to do this myself if it was at all posible. The boost function is just too sharp, bright and harsh and does not get used in the 20 years I have had the amp. I am thinking maybe 2 12AT7's might be sweet and if i could use the two Tone knobs for the BOOSTED tone this could be all the more better. Thanks, Brendan

 

You can do this but I do not believe in modding amps ... if you want something more agressive buy something more agressive.

 

12AT7s in a tone generation stage to my ears sound terrible ... if you want that same gain structure use a 5751 instead, an NOS one ... www.kcanostubes.com is a good source.

 

A 12AT7 also has ten times the plate current as a 12AX7 or 5751 so that is one more reason to avoid them in places they were not intended. They are also harsh sounding and abrupt .... 5500TC vs 1200 for a 12AX7 or 1000 for a 5751.

 

 

Myles .... not Miles as a side note.

 

[Dave da Dude]

Myles, next week I will be picking up a lightly used Epi Galaxie 10 Combo practice tube amp.

 

It has a 10" Celestion speaker in it, I'm not clear if that is stock or not. Originally it was suppled with a 12AX7 PreAmp tube and a 6L6 Power tube.

 

The guy I'm buying it from has retubed it with a Groove Tube 12AU7 (to get "more headroom") and a RCA 6L6. The amp tends to be bright and trebly to begin with (by reputation) and most definitely was when I tried it out. The B, M, T controls do take much of it out. And I do have an EQ and Genesis 3 that I could take even more out, but it is very... "brittle"... until the gain is up past "7". It doesn't get loud at all until the gain is at, or past, "5", not much breakup until "7" or more.

 

Is that PreAmp tube the best choice for this amp?

[WaterMan]

Hey Myles,

 

I run a couple overdrive pedals and an Eventide delay into my 65 Amps London. Will I benefit much from installing an effects loop in the London? That is: will it make much difference tonally to run the delay (and possibly modulation) through the loop instead of in front of the amp? It costs about $200 to add the series loop. Thanks.

[BCorbett]

Myles,

Thanks for the advice, on the 12AT7's. I am still trying out different tubes and the Tung Sol 12AX7 may be all the Agression I need.

Brendan

[myles_rose]

Myles,

Thanks for the advice, on the 12AT7's. I am still trying out different tubes and the Tung Sol 12AX7 may be all the Agression I need.

Brendan

 

Brendan,

 

The current batch of Tung Sol reissues are great tubes and some of the most consistently high in gain of today's production tubes. The rightmost column is true, actual gain. Most of today's tubes are 75-85, most around 80 actually, so these are a great batch. Having a tube 5 points in gain lower than another in V1 will make a difference most folks can hear easily. Having a tube with plate current output down 20% from spec (spec is 1.2mA) as a phase inverter will also impact things a lot in most amps:

 

Design spec is:

 

1600 TC

1.2mA plate current

100 gain

 

Plate

Current TC Gain

 

1.0 1470 0.0155 94.8

1.4 1840 0.018 102.2

1.1 1320 0.015 88.0

1.1 1510 0.016 94.4

1.1 1560 0.018 86.7

0.9 1490 0.016 93.1

0.8 1340 0.015 89.3

1.0 1560 0.018 86.7

1.1 1630 0.0175 93.1

1.3 1740 0.0185 94.1

1.2 1650 0.018 91.7

1.0 1540 0.017 90.6

1.0 1400 0.015 93.3

1.2 1670 0.018 92.8

1.4 1730 0.018 96.1

1.5 1910 0.019 100.5

 

[myles_rose]

Myles, next week I will be picking up a lightly used Epi Galaxie 10 Combo practice tube amp.

 

It has a 10" Celestion speaker in it, I'm not clear if that is stock or not. Originally it was suppled with a 12AX7 PreAmp tube and a 6L6 Power tube.

 

The guy I'm buying it from has retubed it with a Groove Tube 12AU7 (to get "more headroom") and a RCA 6L6. The amp tends to be bright and trebly to begin with (by reputation) and most definitely was when I tried it out. The B, M, T controls do take much of it out. And I do have an EQ and Genesis 3 that I could take even more out, but it is very... "brittle"... until the gain is up past "7". It doesn't get loud at all until the gain is at, or past, "5", not much breakup until "7" or more.

 

Is that PreAmp tube the best choice for this amp?

 

A 12AU7 is a good phase inverter but a poor tone generator. Grab a 12AY7 ... the front end of a tweed bassman. Much nicer tone and very smooth.

 

 

[myles_rose]

Hey Myles,

 

I run a couple overdrive pedals and an Eventide delay into my 65 Amps London. Will I benefit much from installing an effects loop in the London? That is: will it make much difference tonally to run the delay (and possibly modulation) through the loop instead of in front of the amp? It costs about $200 to add the series loop. Thanks.

 

This is a personal preference item. I'd talk to Sam Austin at 65amps at 818-760-5089 on Monday.

 

 

[JoeInOttawa]

Hi Myles!

 

Newbie alert! I have recently purchased a Rivera K-Tre 55-watt combo purely on the basis of the spectacular clean channel. When I got the amp home, I discovered it actually had a dirty channel too -- one for which I hold no particular love. I've tried a number of things with greater or lesser success:

 

 

 

- I returned the combo to a near-original tube setup (12AX7WBs across the board), and the clean was great, but the dirt was staccato as opposed to smooth

 

-I replaced the tubes with 12AX7EHs across the board, and the whole thing went dark

 

-I put back the 12AX7WBs and added a 12AX7EH in position 1. It all got better, but I still find it a bit staccato-sounding

 

For what it's worth, my other rig is driven by a JMP-1 in which the dirty preamp is run through a 12AX7LPS. It is by far (to my ears) the smoothest gain/overdrive I've heard so far, and is more or less the quality I'm going for in the drive side of the Rivera. Alas, the LPS does not do particularly well in combos.

 

I'm about to order another raft of tubes (probably just in pairs for position 1 and 2) and I'm looking for advice. I'm considering Tung-Sols, JJs, and in an interesting twist, 5751s.

 

Anything else I might like to try?

 

Joe

 

[myles_rose]

Hi Myles!

 

Newbie alert! I have recently purchased a Rivera K-Tre 55-watt combo purely on the basis of the spectacular clean channel. When I got the amp home, I discovered it actually had a dirty channel too -- one for which I hold no particular love. I've tried a number of things with greater or lesser success:

 

 

 

- I returned the combo to a near-original tube setup (12AX7WBs across the board), and the clean was great, but the dirt was staccato as opposed to smooth

 

-I replaced the tubes with 12AX7EHs across the board, and the whole thing went dark

 

-I put back the 12AX7WBs and added a 12AX7EH in position 1. It all got better, but I still find it a bit staccato-sounding

 

For what it's worth, my other rig is driven by a JMP-1 in which the dirty preamp is run through a 12AX7LPS. It is by far (to my ears) the smoothest gain/overdrive I've heard so far, and is more or less the quality I'm going for in the drive side of the Rivera. Alas, the LPS does not do particularly well in combos.

 

I'm about to order another raft of tubes (probably just in pairs for position 1 and 2) and I'm looking for advice. I'm considering Tung-Sols, JJs, and in an interesting twist, 5751s.

 

Anything else I might like to try?

 

Joe

 

Joe,

 

The biggest problem in swapping preamp tubes is one does not know what an off the shelf preamp tube is doing. Trying to compare a 12AX7EH to a 12AX7WB will yield untrue results if the WB is close to design spec and the EH is not close. You need to compare tubes that have their specs close .... transconductance, true gain, plate resistance and current output.

 

You said that the EHs made the amp dark and this tells me you had some weak ones as the EH is brighter and more articulate than a WB.

 

A recent test of a lot of EH's showed this:

 

1.0 1160 0.014 82.9

1.1 1430 0.016 89.4

1.1 1510 0.017 88.8

1.3 1610 0.018 89.4

0.8 1260 0.014 90.0

0.8 1120 0.013 86.2

1.3 1580 0.0165 95.8

1.3 1560 0.0165 94.5

1.1 1540 0.017 90.6

1.1 1540 0.017 90.6

0.8 1310 0.015 87.3

1.2 1570 0.0165 95.2

1.3 1540 0.017 90.6

0.9 1370 0.015 91.3

1.1 1470 0.017 86.5

1.2 1590 0.017 93.5

0.6 1160 0.014 82.9

0.8 1280 0.014 91.4

1.0 1430 0.0155 92.3

1.4 1670 0.018 92.8

0.8 1200 0.014 85.7

0.9 1290 0.014 92.1

1.1 1480 0.0165 89.7

1.2 1490 0.016 93.1

0.8 1340 0.015 89.3

1.0 1540 0.0165 93.3

1.0 1370 0.015 91.3

1.3 1620 0.018 90.0

0.8 1300 0.0145 89.7

0.6 1170 0.013 90.0

1.0 1500 0.017 88.2

0.9 1370 0.0155 88.4

 

Output TC Gain

1.0 1418 90.09

84.9% 88.6% 90.1%

 

 

1610 100.6%

1120 70.0%

30.6%

 

1.4 116.7%

0.6 50.0%

66.7%

 

95.8 95.8%

82.9 82.9%

12.9%

 

This might not make a lot of sense but the important factor here is that these vary 66.7% in regard to spec current and the average tube is down 15% from spec and that is like turning a 50 watt amp into a 30 watter depending on position in the circuit.

 

Transconductance has a 30% spread and this is not good either.

 

You need to be able to compare apples to apples as today's production preamp tubes are a crap shoot and the odds are NOT in your favor.

 

Due to the inconsistent nature of tubes 65amps has me blueprint every amp that goes out. Here is an example ... I am sure the formatting will get hosed up but maybe you will get the idea:

 

Monterey

S/N M2H 809089

 

Current TC Gain Ref number

 

1.7 1720 0.004 43.0 917-17 Dario EF86

1.1 1610 0.0175 92 917-26 JJ803S

1.2 1770 0.019 93.2

1.1 1320 0.015 88 919-18 Tung Sol 12AX7

1.1 1510 0.016 94.4

36.1 JJ 6V6S

37.1 JJ 6V6S

 

[JoeInOttawa]

Hey Myles,

 

What do you suggest? I seem to remember seeing a suggestion that the Tung-Sols are consistent. I have five EHs, perhaps I should swap a few others in? Hopefully, with the admission that I REALLY like the Sovtek LPS, you have some idea what I'm going for here. Any thoughts?

 

Joe

[BCorbett]

Hey Myles,

I have just been putting in tubes and hoping I don't blow things up.

Do you have any books you could recomend on guitar amp basics, modification and so forth ? Is this something someone with no electrical training can pick up or best left to people that know what they are doing ?

Brendan

[myles_rose]

Hey Myles,

 

What do you suggest? I seem to remember seeing a suggestion that the Tung-Sols are consistent. I have five EHs, perhaps I should swap a few others in? Hopefully, with the admission that I REALLY like the Sovtek LPS, you have some idea what I'm going for here. Any thoughts?

 

Joe

 

Joe,

 

The Tung Sols are not consistent. Their gain is 15% down from spec on average and their transconductance is also low.

 

They have a 50% variance on plate current and their average plate current is 75% of what is expected as per 12AX7 design.

 

The LPS will be a bit darker over the Tung Sol and this is a personal preference matter.

 

mA actual TC (gm) actual gp Gain

1.2 1600

 

0.9 1250 0.015 83.33

1.1 1540 0.018 85.56

0.9 1230 0.015 82.00

0.9 1340 0.016 83.75

0.9 1500 0.016 93.75

1.0 1490 0.017 87.65

1.2 1650 0.019 86.84

0.9 1400 0.016 87.50

0.8 1230 0.014 87.86

0.6 1110 0.013 85.38

 

Output TC Gain

0.9 1374 86.36

76.7% 85.9% 86.4%

 

 

1650 103.13%

1110 69.38%

33.8%

 

1.2 100.0%

0.6 50.00%

50.0%

 

93.75 93.75%

82.00 82.00%

11.8%

 

[myles_rose]

Hey Myles,

I have just been putting in tubes and hoping I don't blow things up.

Do you have any books you could recomend on guitar amp basics, modification and so forth ? Is this something someone with no electrical training can pick up or best left to people that know what they are doing ?

Brendan

 

Go get this book ... best on the planet....

 

http://www.amazon.com/gp/product/087930863X/sr=8-2/qid=1155070110/ref=pd_bbs_2/002-7905940-9844816?ie=UTF8

 

 

 

 

[JoeInOttawa]

Didn't I just read "...The current batch of Tung Sol reissues are great tubes and some of the most consistently high in gain of today's production tubes"?

 

Okay, so they're a crapshoot too. What about the LPS? Is that a problem tube? Do you have any suggestions? I'm really looking for a smooth tube. What about maybe going to something lower-gain, like a 5751?

 

Thanks,

 

Joe

[myles_rose]

Didn't I just read "...The current batch of Tung Sol reissues are great tubes and some of the most consistently high in gain of today's production tubes"?

 

Okay, so they're a crapshoot too. What about the LPS? Is that a problem tube? Do you have any suggestions? I'm really looking for a smooth tube. What about maybe going to something lower-gain, like a 5751?

 

Thanks,

 

Joe

 

Joe,

 

It is more complicated than that when it comes to a "smoother" tube. If I say "burnt sienna" or "burnt umber" when you have a box of 64 crayons they are different but hard to define.

 

I have no idea what is in your amp now, your guitar, playing style and other factors. I have no idea of the specs of your tubes and two tubes of the same make and type can and will sound and feel very different depending on their specs and condition.

 

As far as a 5751 ... less gain, more clean headroom in most cases but DO NOT use any new 5751 as they are nothing more than out of spec low gain 12AX7s. For a real 5751 hit www.kcanostubes.com or another vendor you can trust. I use Mike at KCA for my own NOS stuff.

 

[JoeInOttawa]

Okay, thanks!

 

Joe

[JoeInOttawa]

What is considered NOS in the 5751? The pair I have purchased are both dated 1984.

[myles_rose]

What is considered NOS in the 5751? The pair I have purchased are both dated 1984.

 

Go to www.kcanostubes.com