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Post by myles on Aug 28, 2012 8:36:02 GMT -7
Matt,
5751s in V1 and V2 will increase clean headroom a bit but be sure to use real (NOS) 5751 tubes not current production ones which are just out of spec 12AX7s.
Output tubes ... EL84 tubes that you prefer for their tonal qualities but assure they are of proper spec on plate current output. Weak tubes will break down earlier.
There is no difference between black and gray plates, that is an old myth. It was the overall construction not the black finish in some models that made them sought after pieces.
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Post by Matt on Aug 28, 2012 8:55:20 GMT -7
Matt, 5751s in V1 and V2 will increase clean headroom a bit but be sure to use real (NOS) 5751 tubes not current production ones which are just out of spec 12AX7s. Output tubes ... EL84 tubes that you prefer for their tonal qualities but assure they are of proper spec on plate current output. Weak tubes will break down earlier. There is no difference between black and gray plates, that is an old myth. It was the overall construction not the black finish in some models that made them sought after pieces. Which NOS 5751 tubes are you referring to? What kind of construction should I be looking for? There's such a large disparity in price among NOS 5751 tubes that I'm at a loss for which ones to purchase. Ideally I want ones that will give the most clarity and definition with a robust low end but not sound brittle on the high end. Thanks again, Myles, I really appreciate your help! |
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Post by myles on Aug 28, 2012 8:58:22 GMT -7
Matt, 5751s in V1 and V2 will increase clean headroom a bit but be sure to use real (NOS) 5751 tubes not current production ones which are just out of spec 12AX7s. Output tubes ... EL84 tubes that you prefer for their tonal qualities but assure they are of proper spec on plate current output. Weak tubes will break down earlier. There is no difference between black and gray plates, that is an old myth. It was the overall construction not the black finish in some models that made them sought after pieces. Which NOS 5751 tubes are you referring to? What kind of construction should I be looking for? There's such a large disparity in price among NOS 5751 tubes that I'm at a loss for which ones to purchase. Ideally I want ones that will give the most clarity and definition with a robust low end but not sound brittle on the high end. Thanks again, Myles, I really appreciate your help! Talk to Mike at www.kcanostubes.com or Doug at www.dougstubes.comI have a lot of 5751 info on my blog as well. |
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Post by Matt on Aug 28, 2012 10:57:41 GMT -7
Which NOS 5751 tubes are you referring to? What kind of construction should I be looking for? There's such a large disparity in price among NOS 5751 tubes that I'm at a loss for which ones to purchase. Ideally I want ones that will give the most clarity and definition with a robust low end but not sound brittle on the high end. Thanks again, Myles, I really appreciate your help! Talk to Mike at www.kcanostubes.com or Doug at www.dougstubes.comI have a lot of 5751 info on my blog as well. I emailed both of them and both said that they couldn't describe the differences in words, just something you have to hear. I get that tone is subjective but I just need a little direction to know where I'm heading. I'll check out your blog though. Thanks again! |
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Post by myles on Aug 28, 2012 12:41:05 GMT -7
Matt,
What is the difference between red and green?
Yes, it is totally subjective.
Just stick with proper spec tubes or your judgement is highly compromised. Compare apples to apples. That means compare tubes of proper spec. Not weak ones to strong ones. You can only do this if you have a trusted vendor that properly tests their product.
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Post by electricflag on Sept 6, 2012 9:33:37 GMT -7
Myles,
I'm user of 12AY7 tubes for their musical character and low noise. Surprisingly, there isn't much history written about it. The golden era Europeans manufactures never produced any to my knowledge.
So, a questions: Was the 12AY7 developed for a particular application?
-Rick
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Post by myles on Sept 6, 2012 12:05:28 GMT -7
Myles, I'm user of 12AY7 tubes for their musical character and low noise. Surprisingly, there isn't much history written about it. The golden era Europeans manufactures never produced any to my knowledge. So, a questions: Was the 12AY7 developed for a particular application? -Rick Rick, The 12AY7 was a small signal tube. It has a gain of about 40 compared to the 12AX7 gain of about 100. It is a very smooth tube that is great in front ends as a tone generator. It is the front end tube in some great classics such as the Fender tweed deluxe, super, pro, bandmaster and bassman to mention a few great amps. On my website and blog there are data sheets available if you want more technical info. |
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Post by electricflag on Sept 6, 2012 13:22:37 GMT -7
Myles,
Thanks for the information!
Will check out more at your Guitar Amplifier Blueprinting site.
-Rick
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Post by myles on Sept 6, 2012 15:49:00 GMT -7
Rick,
You are quite welcome.
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Post by sacklg on Oct 1, 2012 0:58:38 GMT -7
Myles, I have a ri Ampeg J12 2 el 84 and 2 12ax7 with no guitar plI ugged in turning the vol. Once I start to turn it up the noise comes on before I reach one justo retubed it with jj' s
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Post by myles on Oct 1, 2012 8:40:54 GMT -7
Myles, I have a ri Ampeg J12 2 el 84 and 2 12ax7 with no guitar plI ugged in turning the vol. Once I start to turn it up the noise comes on before I reach one justo retubed it with jj' s Just because you put in new tubes it does not mean they were good tubes. It it worked better before you did the retube that tells you a lot. Put things back. Did the problelm go away? |
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Post by sacklg on Oct 1, 2012 12:37:47 GMT -7
thanks for the reply Myles, but still noisy with old tubes.
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Post by myles on Oct 1, 2012 16:32:24 GMT -7
thanks for the reply Myles, but still noisy with old tubes. It could be many things. The resistors and caps in these amps are as cheap as can be purchased. Same for sockets and other components. This is time for an amp tech with a scope that can trace the noise back to the source. Could be a noisy resistor, bad ground etch, noisy cap or over a dozen other things. These amps are sort of like some cars .... once you have a problem it is very likely that you will have problems more often as the years pass. These Hot Rod series amps definitely have something of a shelf life and operational life. Output sockets that are PCB mounted holding very hot tubes have a MTBF that drops with each hour the amp runs. These amps are also not happy with vibration such as riding down the road and the bumps they are subjected to. One year I supported a tour from June through October. We went through nine Hot Rod amps during the tour, as in, nine of these amps failed. Good luck. |
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Post by lowbudget on Oct 9, 2012 6:30:40 GMT -7
Hi Myles,
I have a fairly new Vintage Sound 112P, which is a AA1164 clone but with a 20 watt OPT and a 12" speaker. It developed a minor issue and rather than ship it back for warranty repair I took it to a very respected amp tech locally. He questioned why an amp designed for 6V6s was running 6L6s, and I told him that the builder of these amps (also highly regarded) built them with a stout enough OPT to be able to switch at will with just a rebias. I had specified max headroom so that's the way mine was set up from the builder.
The local tech then went off on a bit of a rant about how this practice was a pet peeve of his because rebias notwithstanding, going from 6L6s to 6V6s or the other way around changed the impedance seen by the speaker. He showed me specs in the tube manual that basically said the 6L6s wanted to see a 4 ohm speaker while the 6V6s wanted to look at 8 ohms.
I'm just curious: who's right here? I trust this tech very much but the amp builder has been around a long time and he knows his stuff too.
And if I do need to go back to 6V6s to better match the 8 ohm Weber Cali, do you know of a 6V6 out there that will provide good headroom yet still retain that Princeton Reverb "sweetness"?
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Post by myles on Oct 9, 2012 8:15:07 GMT -7
Hi Myles, I have a fairly new Vintage Sound 112P, which is a AA1164 clone but with a 20 watt OPT and a 12" speaker. It developed a minor issue and rather than ship it back for warranty repair I took it to a very respected amp tech locally. He questioned why an amp designed for 6V6s was running 6L6s, and I told him that the builder of these amps (also highly regarded) built them with a stout enough OPT to be able to switch at will with just a rebias. I had specified max headroom so that's the way mine was set up from the builder. The local tech then went off on a bit of a rant about how this practice was a pet peeve of his because rebias notwithstanding, going from 6L6s to 6V6s or the other way around changed the impedance seen by the speaker. He showed me specs in the tube manual that basically said the 6L6s wanted to see a 4 ohm speaker while the 6V6s wanted to look at 8 ohms. I'm just curious: who's right here? I trust this tech very much but the amp builder has been around a long time and he knows his stuff too. And if I do need to go back to 6V6s to better match the 8 ohm Weber Cali, do you know of a 6V6 out there that will provide good headroom yet still retain that Princeton Reverb "sweetness"? A lot of amp builders advertise or state that output tubes can be swapped at whim with nothing more than a bias change. Some amps are biased so cold that a bias change is not even necessary for the amp to continue to operate. The output transformer for 6V6 and 6L6 tubes is very different on the primary side, the side that sees the tubes. a 6V6 and EL84 are close in plate impedance but a 6V6 and 6L6 are not. There is also an issue of filament current on the power transformer. A 6L6 draws twice the current of a 6V6, almost one amp per output tube for a 6L6 versus .45 amps for a 6V6. Headroom is a factor of many things and not just output tubes. Power supply, gain structure, phase inverter etc. The designer is correct in the fact that amp will probably work. Will it sound right, work well and be balanced? Not to my ears. Bottom line .... your amp tech is correct and the designer is better at marketing than he is at amp design. Listen to your amp tech. |
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Post by lowbudget on Oct 9, 2012 9:35:29 GMT -7
Hi Myles, I have a fairly new Vintage Sound 112P, which is a AA1164 clone but with a 20 watt OPT and a 12" speaker. It developed a minor issue and rather than ship it back for warranty repair I took it to a very respected amp tech locally. He questioned why an amp designed for 6V6s was running 6L6s, and I told him that the builder of these amps (also highly regarded) built them with a stout enough OPT to be able to switch at will with just a rebias. I had specified max headroom so that's the way mine was set up from the builder. The local tech then went off on a bit of a rant about how this practice was a pet peeve of his because rebias notwithstanding, going from 6L6s to 6V6s or the other way around changed the impedance seen by the speaker. He showed me specs in the tube manual that basically said the 6L6s wanted to see a 4 ohm speaker while the 6V6s wanted to look at 8 ohms. I'm just curious: who's right here? I trust this tech very much but the amp builder has been around a long time and he knows his stuff too. And if I do need to go back to 6V6s to better match the 8 ohm Weber Cali, do you know of a 6V6 out there that will provide good headroom yet still retain that Princeton Reverb "sweetness"? A lot of amp builders advertise or state that output tubes can be swapped at whim with nothing more than a bias change. Some amps are biased so cold that a bias change is not even necessary for the amp to continue to operate. The output transformer for 6V6 and 6L6 tubes is very different on the primary side, the side that sees the tubes. a 6V6 and EL84 are close in plate impedance but a 6V6 and 6L6 are not. There is also an issue of filament current on the power transformer. A 6L6 draws twice the current of a 6V6, almost one amp per output tube for a 6L6 versus .45 amps for a 6V6. Headroom is a factor of many things and not just output tubes. Power supply, gain structure, phase inverter etc. The designer is correct in the fact that amp will probably work. Will it sound right, work well and be balanced? Not to my ears. Bottom line .... your amp tech is correct and the designer is better at marketing than he is at amp design. Listen to your amp tech. Ahh, I see. Thanks as always Myles! |
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Post by rbushee on Oct 12, 2012 8:22:17 GMT -7
Hey guys, What are those little rubber 0-rings on the tubes for? Are they just shipping protection?
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Post by myles on Oct 12, 2012 8:59:00 GMT -7
Hey guys, What are those little rubber 0-rings on the tubes for? Are they just shipping protection? They are vibration dampers that will reduce some forms of physical microphonics. |
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Post by boptometrist(david) on Oct 12, 2012 8:59:19 GMT -7
They dampen vibration to reduce microphonics and perhaps prevent the tube from becoming microphonic.
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Post by highwayman (Dave) on Oct 29, 2012 9:37:55 GMT -7
Here is a question that some may find a bit odd, but I figured if anyone would have the answer and insight it would be Myles. A friend and I were experimenting with some signal path variations and decided to put the pedals through the effects loop to hear the pedals better rather than hearing them pounding on the pre-amp tubes. We found that some of the better pedals, Wampler, Zendrive, etc. seem to be fuller and smoother with respect overdrive in the effects loop. Then he posed this question...how could you run the pedals thru the FX loop in a stereo set up. So we quickly figured that you could run the second out from a stereo/chorus pedal into the output-in tap on a second amp with an FX loop. My question is, what is happening to the front end of the second amp with no signal from a guitar running through it? I assume it is just sitting there at an idle and I am not sure that would be a good thing for a gig setting playing say 2 - 75 minute sets. Any thoughts on the effect on the pre-amp section of the second amp? Thanks!
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Post by myles on Oct 30, 2012 8:37:31 GMT -7
Here is a question that some may find a bit odd, but I figured if anyone would have the answer and insight it would be Myles. A friend and I were experimenting with some signal path variations and decided to put the pedals through the effects loop to hear the pedals better rather than hearing them pounding on the pre-amp tubes. We found that some of the better pedals, Wampler, Zendrive, etc. seem to be fuller and smoother with respect overdrive in the effects loop. Then he posed this question...how could you run the pedals thru the FX loop in a stereo set up. So we quickly figured that you could run the second out from a stereo/chorus pedal into the output-in tap on a second amp with an FX loop. My question is, what is happening to the front end of the second amp with no signal from a guitar running through it? I assume it is just sitting there at an idle and I am not sure that would be a good thing for a gig setting playing say 2 - 75 minute sets. Any thoughts on the effect on the pre-amp section of the second amp? Thanks! It is a matter of personal taste. There is no right or wrong. High output pedals can squash the input to a dual triode easily (12AX7). Then again, some folks like this. Some folks like delay devices in a loop and distortion devices in the front end. Again, a matter of personal taste and preference. |
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Post by highwayman (Dave) on Oct 30, 2012 9:50:16 GMT -7
Thanks, Myles. Totally agree it is a taste thing.
I didn't describe the set-up very well. We want to run the pedals in the FX loop such that the chain would be pre-amp out (on amp #1) - pedal one, pedal two, stereo pedal with one out back to power amp in of amp #1 and the second (stereo) out to another power amp in on amp #2.
Is it OK to have the front end of the second amp sitting at what I can only assume to be an idle with no input while one of the stereo pedal outs is plugged into only the power amp in section of its FX loop?
Dave
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Post by myles on Oct 30, 2012 14:39:36 GMT -7
Thanks, Myles. Totally agree it is a taste thing. I didn't describe the set-up very well. We want to run the pedals in the FX loop such that the chain would be pre-amp out (on amp #1) - pedal one, pedal two, stereo pedal with one out back to power amp in of amp #1 and the second (stereo) out to another power amp in on amp #2. Is it OK to have the front end of the second amp sitting at what I can only assume to be an idle with no input while one of the stereo pedal outs is plugged into only the power amp in section of its FX loop? Dave Draw me a diagram. |
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Post by Matt on Nov 15, 2012 10:07:18 GMT -7
Hi Myles,
What NOS tubes would you recommend for V1, V2, V3 (PI) and the rectifier tube for a Dr Z Maz 38 NR head if I want to maintain the same stock tone it came with but want the reliability of NOS tubes?
Thanks for the help!
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Post by myles on Nov 15, 2012 12:57:54 GMT -7
Hi Myles, What NOS tubes would you recommend for V1, V2, V3 (PI) and the rectifier tube for a Dr Z Maz 38 NR head if I want to maintain the same stock tone it came with but want the reliability of NOS tubes? Thanks for the help! Any change will make the amp tone change. More definition, articulation etc. What tubes are currently in those positions now? |
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Post by boptometrist(david) on Nov 15, 2012 14:14:05 GMT -7
Hi Myles, I have a fairly new Vintage Sound 112P, which is a AA1164 clone but with a 20 watt OPT and a 12" speaker. It developed a minor issue and rather than ship it back for warranty repair I took it to a very respected amp tech locally. He questioned why an amp designed for 6V6s was running 6L6s, and I told him that the builder of these amps (also highly regarded) built them with a stout enough OPT to be able to switch at will with just a rebias. I had specified max headroom so that's the way mine was set up from the builder. The local tech then went off on a bit of a rant about how this practice was a pet peeve of his because rebias notwithstanding, going from 6L6s to 6V6s or the other way around changed the impedance seen by the speaker. He showed me specs in the tube manual that basically said the 6L6s wanted to see a 4 ohm speaker while the 6V6s wanted to look at 8 ohms. I'm just curious: who's right here? I trust this tech very much but the amp builder has been around a long time and he knows his stuff too. And if I do need to go back to 6V6s to better match the 8 ohm Weber Cali, do you know of a 6V6 out there that will provide good headroom yet still retain that Princeton Reverb "sweetness"? A lot of amp builders advertise or state that output tubes can be swapped at whim with nothing more than a bias change. Some amps are biased so cold that a bias change is not even necessary for the amp to continue to operate. The output transformer for 6V6 and 6L6 tubes is very different on the primary side, the side that sees the tubes. a 6V6 and EL84 are close in plate impedance but a 6V6 and 6L6 are not. There is also an issue of filament current on the power transformer. A 6L6 draws twice the current of a 6V6, almost one amp per output tube for a 6L6 versus .45 amps for a 6V6. Headroom is a factor of many things and not just output tubes. Power supply, gain structure, phase inverter etc. The designer is correct in the fact that amp will probably work. Will it sound right, work well and be balanced? Not to my ears. Bottom line .... your amp tech is correct and the designer is better at marketing than he is at amp design. Listen to your amp tech. Myles, does what you are saying here apply to amps like Fargen Mini Plex which can use different power tubes in it's parallel single ended design? Maybe you were just talking about fixed bias designs. Thanks for clarifying. -David |
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Post by Matt on Nov 15, 2012 15:42:45 GMT -7
Hi Myles, What NOS tubes would you recommend for V1, V2, V3 (PI) and the rectifier tube for a Dr Z Maz 38 NR head if I want to maintain the same stock tone it came with but want the reliability of NOS tubes? Thanks for the help! Any change will make the amp tone change. More definition, articulation etc. What tubes are currently in those positions now? Currently I have a the following in the amp: NOS Sylvania 5751 Gold Brand in V1 NOS JAN GE 7025 in V2 NOS JAN GE 5751 in V3 (PI) NOS JAN Philips 5AR4/GZ34 rectifier I had wanted to get more headroom out of it which my current tube choices certain have done. It certainly doesn't sound bad now but it's lost that certain something that made it special when I first got it. Thanks for the help, Myles! |
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Post by myles on Nov 16, 2012 14:40:49 GMT -7
Any change will make the amp tone change. More definition, articulation etc. What tubes are currently in those positions now? Currently I have a the following in the amp: NOS Sylvania 5751 Gold Brand in V1 NOS JAN GE 7025 in V2 NOS JAN GE 5751 in V3 (PI) NOS JAN Philips 5AR4/GZ34 rectifier I had wanted to get more headroom out of it which my current tube choices certain have done. It certainly doesn't sound bad now but it's lost that certain something that made it special when I first got it. Thanks for the help, Myles! If it has lost "something" that could be less of an aggressive nature with the 5751 in the PI position. Pull that tube and put in a decent 12AX7 and tell me if you like it more or less. We will go from there. |
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Post by BritInvasion on Nov 25, 2012 12:21:44 GMT -7
Hi Myles- I have a question about tube shields , like the ones that cover pre-amp tubes. I've heard for a long time that an amp is better off without them , supposedly sounds "better" that way. Is there any truth to that , is it one of those urban legends? Appreciate any insight!
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Post by myles on Nov 25, 2012 17:00:20 GMT -7
Hi Myles- I have a question about tube shields , like the ones that cover pre-amp tubes. I've heard for a long time that an amp is better off without them , supposedly sounds "better" that way. Is there any truth to that , is it one of those urban legends? Appreciate any insight! Actually, there is some truth to that. Tube shields are basically there to help keep the tube in place for more reason than anything else. You rarely see them in studio gear or hifi gear. The path of the electrons from the anode to the cathode is actually slightly bent by tube shields as they are grounded to the chassis at a different potential than either the anode or cathode and this adds one more factor into the mix which is not desired. Some very clean design amp will allow you to hear the difference with and without the devices. |
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