Feel free to ask Myles

[shortyprs]

Hey Miles,

 

First off, I appreciate that you are so willing to share information when this stuff is your living. It really helps those of us who are so far away. Without it, experimenting to find the perfect tone is just too expensive.

 

I just traded in most of my gear to get a Carr Slant 6v. After comparing with several amps, including my highly modified HR Deluxe, I just loved the sound of this amp. Couldn't resist it. Had to have it. I probably would have gone for the Rambler, which is more up my blues alley, but the versatility of the Carr as a sole performing amp tipped the balance. So, you wonder, what is the question...

 

Have you experimented with retubing this amp? I am addicted to tinkering with NOS tubes to get "the perfect" sound. Adding a Celestion Vintage 30, a Mullard Ecc83, a Mullard cv4004 and a Jan Phillips 12at7 (V1, V2 & V3) plus Jan Phillips 6L6's to my HR Deluxe made a huge difference. Have you tried any retubing on the Carr? What have you tried? Did you like it? Do you have a personal favorite? Any and all feedback is helpful.

 

By the way, I've already put 4 Mullard cv4004's and 2 Mullard cv4024's in the amp. The 4024's were too punchy in my Deluxe, but are like butter in the Carr. I had to back the reverb way down. The quality of the reverb like playing in an almost perfect hall. So, I guess I'm asking mostly about power tubes..6v6's. Any experience you can share is appreciated.

[johnny5]

i actually have 2 questions. one i think might be easy and the other, maybe not.

 

1)i noticed that my idle bias current was changing from place to place (studio to home) by about 10 mili amps. i couldn't figure it out and figured the trim pot was moving during transport. but i recently checked the wall voltage at both places and were;

home: 119VAC, about 72mA for 2 KT66

studio: 125VAC, about 82mA

is it the wall Voltage making this change? i don't know if i should set it so things will run alittle cooler at home or hotter at the studio. help?

 

2) the amps preamp is loosely based on the Bassman. are there any simple tricks / tweaks to get a little more preamp gain / compression? like an easy cap or resistor change? i have tried some different pre-tubes and it does something but i am looking for more.

 

thanks,

john

[myles_rose]

Originally posted by Speedy'sComing:

I should have said at the AES Show.

I was at AES at the GT booth both days this last weekend.

[myles_rose]

Originally posted by shortyprs:

Hey Miles,

 

First off, I appreciate that you are so willing to share information when this stuff is your living. It really helps those of us who are so far away. Without it, experimenting to find the perfect tone is just too expensive.

 

I just traded in most of my gear to get a Carr Slant 6v. After comparing with several amps, including my highly modified HR Deluxe, I just loved the sound of this amp. Couldn't resist it. Had to have it. I probably would have gone for the Rambler, which is more up my blues alley, but the versatility of the Carr as a sole performing amp tipped the balance. So, you wonder, what is the question...

 

Have you experimented with retubing this amp? I am addicted to tinkering with NOS tubes to get "the perfect" sound. Adding a Celestion Vintage 30, a Mullard Ecc83, a Mullard cv4004 and a Jan Phillips 12at7 (V1, V2 & V3) plus Jan Phillips 6L6's to my HR Deluxe made a huge difference. Have you tried any retubing on the Carr? What have you tried? Did you like it? Do you have a personal favorite? Any and all feedback is helpful.

 

By the way, I've already put 4 Mullard cv4004's and 2 Mullard cv4024's in the amp. The 4024's were too punchy in my Deluxe, but are like butter in the Carr. I had to back the reverb way down. The quality of the reverb like playing in an almost perfect hall. So, I guess I'm asking mostly about power tubes..6v6's. Any experience you can share is appreciated.

shortyprs

 

First off back your way, you are more than welcome.

 

Second off, I think you will be pretty happy with your Slant 6V. They are amazing amps, right down to the end of the power cord! Look at the plug he uses .... amazing.

 

The Rambler is also a darn amazing amp, but you amp is more versitile. You can do the class A or class A/B thing ... I love four 6V6's in that amp together, and your amp, no matter what it's rating, puts out over 50 watts on the bench, more than what Steve Carr claims.

 

I have done a lot of tube stuff on these amps, and NOS stuff is nice, but to tell the truth, the 6V6EH's are terrific in them. The center set (the ones for class A/B) are very happy when biased at 27.5 milliamps. The Carr is happy with a wider range of tubes than a Blackface Deluxe reverb.

 

Hope that was of some help.

[myles_rose]

Originally posted by johnny5:

i actually have 2 questions. one i think might be easy and the other, maybe not.

 

1)i noticed that my idle bias current was changing from place to place (studio to home) by about 10 mili amps. i couldn't figure it out and figured the trim pot was moving during transport. but i recently checked the wall voltage at both places and were;

home: 119VAC, about 72mA for 2 KT66

studio: 125VAC, about 82mA

 

is it the wall Voltage making this change? i don't know if i should set it so things will run alittle cooler at home or hotter at the studio. help?

 

2) the amps preamp is loosely based on the Bassman. are there any simple tricks / tweaks to get a little more preamp gain / compression? like an easy cap or resistor change? i have tried some different pre-tubes and it does something but i am looking for more.

 

thanks,

john

John,

 

O.K. .... let me see if I can help at all here ...

 

1)i noticed that my idle bias current was changing from place to place (studio to home) by about 10 mili amps. i couldn't figure it out and figured the trim pot was moving during transport. but i recently checked the wall voltage at both places and were;

home: 119VAC, about 72mA for 2 KT66

studio: 125VAC, about 82mA

 

First off, you will see changes. Any voltage change makes a difference. I typically use a variac set to 120 VAC.

 

These variances are normal, and there is not much that can be done about it. Fortunately, as voltage goes up current will go down, and visa versa. There will always be a relationship.

 

I like 30-34mA per tube on KT-66's at about 450 plate volts myself.

 

The best way to easily get more front end gain is to get a preamp tube in V1 that has the gain character you seek by ordering these tubes where they are checked and rated.

 

We do this at Groove Tubes (look on the GT website at the SAG Special Applications group ... my group actually) in the preamp tube area. Bob Pletka at Eurotubes, also does this.

 

Hope this was of some help.

[shortyprs]

Thanks Miles, Its nice starting with an amp that I'm very happy with. No urgency. No Hurry, No Necessity. All is very good. I may try the Brimar 6v6's. I've read of a guy only using the Brimars in two slots. Know anything about this? I assume in the fixed bias position.

 

With my pedals, I've tried and discarded everything but an MJM bluesdevil to get a little scream out of the clean channel and a Teese Picture Wah, to do that picture wah thing. When I use all 4 6v6's, the Zvex 2 in 1 adds a nice bright boost at times, but is largely unnecessary.

 

As always, you are very appreciated.

[Gabriel E.]

Miles:

 

I've got a Fender "red knob" Champ 12. It's single-ended with cathode bias. Runs two 12AX7s and a 6L6.

 

My questions:

 

Can I replace the shitty 6" reverb tank with a full-size accutronics unit? What other changes would I need to make?

 

Since it's cathode bias, it's self-biasing right? What tubes can I safely swap? I'd like to try a 6V6 (I have a couple NOS JAN Phillips 6V6s) and maybe an EL34. Would I need to install an additional filament tranny?

 

Thanks,

 

Gabriel

[myles_rose]

Originally posted by shortyprs:

Thanks Miles, Its nice starting with an amp that I'm very happy with. No urgency. No Hurry, No Necessity. All is very good. I may try the Brimar 6v6's. I've read of a guy only using the Brimars in two slots. Know anything about this? I assume in the fixed bias position.

 

With my pedals, I've tried and discarded everything but an MJM bluesdevil to get a little scream out of the clean channel and a Teese Picture Wah, to do that picture wah thing. When I use all 4 6v6's, the Zvex 2 in 1 adds a nice bright boost at times, but is largely unnecessary.

 

As always, you are very appreciated.

shortyprs....

 

The Brimar's are pretty nice. I also like most of the NOS stuff over any of the new stuff, especially in these amps or tweeds.

 

I have a few sets of NOS Mazda's that I found and stuck over on ebay to blow them out and make some room. They work pretty well too.

 

The outer slots are fixed (cathode) biased, while the two inside slots are adjustable bias. You can run a duet of NOS 6V6's in the two outer slots, and then just hit the 1/2 power class A setting, and you are in business. They do not have to match the inner pair, as these are biased for class A/B (27.5 mA in your amp by the way is what you want) and then work super with even a different tube type for the center pair.

 

Its a slick amp to say the least.

[myles_rose]

Originally posted by Gabriel E.:

Miles:

 

I've got a Fender "red knob" Champ 12. It's single-ended with cathode bias. Runs two 12AX7s and a 6L6.

 

My questions:

 

Can I replace the shitty 6" reverb tank with a full-size accutronics unit? What other changes would I need to make?

 

Since it's cathode bias, it's self-biasing right? What tubes can I safely swap? I'd like to try a 6V6 (I have a couple NOS JAN Phillips 6V6s) and maybe an EL34. Would I need to install an additional filament tranny?

 

Thanks,

 

Gabriel

Gabriel ....

 

On the reverb tank, you are sort of stuck, as the reverb transformer and cables (cables corrected for the tank), are part of the circuit. It may work, but you may love or hate the sound if it does work. What you might try is to borrow a 9" tank, plug it in, and see if you like it.

 

If you call Magic Parts (ask for Tom) or Antique Electric Suppy (ask for Steve Martin) and mention you are one of my (Guitar Amplifier Blueprinting) clients, they may give you even more of a price break on an accutronics reverb tank.

 

On the 6V6 idea ... it's a no-go. The 6L6 circuit has too much plate voltage, and you will fry a 6V6 in short order.

 

On the EL-34 idea .... they have too much heater current for your power transformer, and there is a pretty severe impedance mismatch between the output transformer and the plate impedance of an EL-34.

 

Try an NOS Tung Sol 5881 if you can find one. They are amazing in your amp.

[Gabriel E.]

Thanks Miles. I appreciate it.

 

I'll try a Tung-Sol 5881.

 

While I'm at it, I have another question: It's getting about time to do a cap job. Do you think Solen fast caps would be worth the extra $$? Or should stick to Spragues or Mallorys?

 

THX

[myles_rose]

Originally posted by Gabriel E.:

Thanks Miles. I appreciate it.

 

I'll try a Tung-Sol 5881.

 

While I'm at it, I have another question: It's getting about time to do a cap job. Do you think Solen fast caps would be worth the extra $$? Or should stick to Spragues or Mallorys?

 

THX

Gabriel....

 

The best deal now on great 5881's are from Mike at KCA. Last time I heard he had a few Tung Sol 5881's at $60 each in singles, no matched duets though, unless life has changed over at his place. In any case, even $60 for one of these is pretty nice, as in your amp they will sound GREAT and last FOR YEARS. His phone number over there is 703-430-3645.

 

Charlie Kittleson, over at Vacuum Tube Valley has this:

 

RCA/Tung Sol 5881 1960s-70s Actually a Tung-Sol with an RCA label and box. The ultimate for Fender tweed amps and other vintage amps as well as original equipment in many 1950s tube hi-fi amps. $75 each or $200 matched pairs.

 

At VTV, the minimum order use to be $100, so KCA may be the route here.

 

Over at Tube World, they have:

1 Platinum Pair) JAN-CTL-6L6WGB=5881 Tungsol NOS original boxes $180/pair 1) 1963 (58.2ma) (1) 1967 (58.7ma)

 

1) 1954 light brown base $85 (71ma)

1) 1962 dark brown base $80 (55.9ma)

1) 1963 dark brown base with "broken guide pin" $60 (60.5ma)

 

.... as you can see, the KCA price is nicer by quite a bit.

 

http://www.tubeworld.com/5881TS.jpg

 

As far as caps .... the more pricy ones last longer, but some like to stay with the originals. I can save you at least 50% on caps .... if you call me here at GT toll free at 1-800-459-5687, I will give you the number of one of my suppliers and what to tell them so you can set up an account with them and purchase stuff like this direct at cost. I do this for a lot of forum folks in this forum, which I don't do over at Harmony-Central.

 

Hope this was of some help.

[WDC]

Hello Myles,

 

I have a curious thing happening with my Pro Reverb. The amp is about 7 months old and is run through a 8 Ohm THD HotPlate. For the past 7 months, I typically run with the clean volume at 4 and adjust volume with the HotPlate as the situation warrants. Lately when I play with 0 attenuation, I can hear a hum coming from my amp. The hum is there when nothing is plugged in and the volume is turned to zero. I can't tell if the sound is coming from my output tubes or from some sort of low-level feedback coming from the speaker. In addition, at ¼ power mode, the hum goes away.

 

Here's another odd thing. I was poking my head behind the amp yesterday. The amp is on an old church pew so I needed to move the amp a little to fit my head behind. As I moved the amp forward in the pew, the front feet (not casters) slipped over the edge of the pew seat. The slip was not enough to crash the reverb tank, but enough to make the hum go away for a moment. This leads me to believe that my output tubes could be going. How far off base am I on this one?

 

Ive been waiting to re-tube this amp for a while. Is it time?

 

Best Regards,

WDC

[myles_rose]

Originally posted by WDC:

Hello Myles,

 

I have a curious thing happening with my Pro Reverb. The amp is about 7 months old and is run through a 8 Ohm THD HotPlate. For the past 7 months, I typically run with the clean volume at 4 and adjust volume with the HotPlate as the situation warrants. Lately when I play with 0 attenuation, I can hear a hum coming from my amp. The hum is there when nothing is plugged in and the volume is turned to zero. I can't tell if the sound is coming from my output tubes or from some sort of low-level feedback coming from the speaker. In addition, at ¼ power mode, the hum goes away.

 

Here's another odd thing. I was poking my head behind the amp yesterday. The amp is on an old church pew so I needed to move the amp a little to fit my head behind. As I moved the amp forward in the pew, the front feet (not casters) slipped over the edge of the pew seat. The slip was not enough to crash the reverb tank, but enough to make the hum go away for a moment. This leads me to believe that my output tubes could be going. How far off base am I on this one?

 

Ive been waiting to re-tube this amp for a while. Is it time?

 

Best Regards,

WDC

WDC ....

 

It sounds like your output tubes are getting a bit old and out of match at the least. One of the simptoms of mismatch is added hum.

 

Your amp is one that is easy to check the bias on. Look at one tube, then the other, and record the output. They should both be at about 30mA (or .03 volts) in your amp.

 

When you put in new ones and rebias, check this and record this. Check after a week or so after playing and rebias. With the exception of GT tested tubes, most will have the bias change quite a bit due to low vacuum, as most tube vendors do not check for this.

 

Let me know what you find, as there are a few other things it could be, such as V1 is starting to go ... not from age, just because they did not put great tubes in there from the start at the factory.

[Gus1234]

Hi Myles ,

 

I own a twin reverb ( silverface - 1972 )

It has a master volume option. plus , a pull option to crank the second channel .

 

It's time to change the valves . What do you recommend me ?

 

Thanks ,

 

Gus

[Dave da Dude]

Myles,

 

A quick and easy one for you. I'm just confused.

 

I've got a '93 Randall Tube Pro II amplifier that takes either (2) 6L6's or (2) EL34 power tubes (switchable bias). I've been under the impression that it is a "50" Watt amplifier.

 

I was at the Ampage site and saw their reference section on tubes, so I took a look.

 

They show the 6L6 in an AB1 amp to be 26.5 (or 19) watts for two (2) tubes and the EL34 in an AB1 amp to be 40 watts for two (2) tubes. Either I was misinformed about my amp's power, or if the data is for one (1) tube it would make my amp a 53 W (6L6's, or 38 W) or 80 W (EL34's)

 

Is this info at Amapage a typo? Am I wrong about my amplifiers wattage? What's going on?

 

Just curious, I love the amp, thanks, Dave.

[Gabriel E.]

Thanks Myles:

 

After X-Mas, I should have some extra cash so I'll definitely get a Tung-Sol.

 

I have some questions regarding the Trainwreck Express semi-clone that I'm planning to build and about power transformers in general

 

Is there such thing as a too large PT? I know how much current I need for the tubes and filaments. I also know I want to put about 410 Volts on the plates. And I will be using a 6K6 plate-plate OT (maybe a Hammond P-T1650H).

 

1)Will using a larger-than necessary PT affect the tone?

2)How do I fugure out how much voltage I will need for the bias supply?

3)I can't seem to find any well-written information on choosing a PT. Any good books on this?

 

Thanks in advance, Gabriel

[myles_rose]

Originally posted by Gus1234:

Hi Myles ,

 

I own a twin reverb ( silverface - 1972 )

It has a master volume option. plus , a pull option to crank the second channel .

 

It's time to change the valves . What do you recommend me ?

 

Thanks ,

 

Gus

Gus,

 

This is mostly a matter of personal preference, but my favorite Fender Amp tube for any of the 6L6 amps, is by far the KT-66.

 

From part of an article I just published (where this part is also in some forum posts):

 

.... One tube I use in almost all 6L6 type amps of my own, is the KT-66. This is one tube that loves current more than voltage. The "KT" stands for kinkless tetrode. Tubes in the 6L6 family have a characteristic kink, or non-linearity in their response curve. The KT-66 was developed to get rid of this, that that it did quite nicely. The KT-66 is more linear than the other 6L6 / 5881 tubes, and this is part of the reason it sounds so much larger in some amps than it's brothers (6L6 / 5881). The KT-66 was the Clapton Bluesbreaker sound of the 60's in the model 1962 Marshall combo and JTM-45. The linear nature of this tube means smooth and touch sensitive volume changes, whether it be via guitar volume pot or your playing touch. In any case, this is one tube that likes current more than voltage.....

 

This tube, after folks hear it when I let them try it in their amps, generally stays in their amp. If you want more of the original Fender sound from the 60's and 70's, then the other choice is the Groove Tubes USA 6L6GE ( http://www.groovetubes.com/product.cfm?Product_ID=1714 ) which is a pretty terrific tube that we can't keep in stock a lot of the time. By the way, at the bottom of that link are photos of the production of that tube.

 

The GE is a very long lasting tube, and 50% higher in cost than the KT-66. I still personally prefer the KT-66 in most Fender or other 6L6 amps applications.

 

For your V1 and V2, the original Fender sound was from the 7025. These sound different than other 12AX7 types.

 

V6 should be a matched phase inverter. MPI's are critical in these amps. A few folks offer these, including Watford Valves in the U.K., where they are referred to as "balanced valves". Bob Pletka at Eurotubes also has a super way of matching the two sides of the triodes for these, as does GT, where I actually am the one who does this, but do this on a vacuum tube curve tracer, so both the output and the time base are aligned ( http://www.groovetubes.com/product.cfm?Product_ID=1722 ) and if you want to see a photo of a vacuum tube curve tracer, on one of my links at GT, there is a photo ( http://www.groovetubes.com/product.cfm?Product_ID=1773 )

 

In any case, the 12AT7 in these amps used for the phase inverter, should be changed when the output tubes are changed.

 

Hope this was of some help.

[myles_rose]

Originally posted by Dave th Dude:

Myles,

 

A quick and easy one for you. I'm just confused.

 

I've got a '93 Randall Tube Pro II amplifier that takes either (2) 6L6's or (2) EL34 power tubes (switchable bias). I've been under the impression that it is a "50" Watt amplifier.

 

I was at the Ampage site and saw their reference section on tubes, so I took a look.

 

They show the 6L6 in an AB1 amp to be 26.5 (or 19) watts for two (2) tubes and the EL34 in an AB1 amp to be 40 watts for two (2) tubes. Either I was misinformed about my amp's power, or if the data is for one (1) tube it would make my amp a 53 W (6L6's, or 38 W) or 80 W (EL34's)

 

Is this info at Amapage a typo? Am I wrong about my amplifiers wattage? What's going on?

 

Just curious, I love the amp, thanks, Dave.

Dave,

 

It is not a typo. First of all, in the case of 6L6 / 5881 / KT66 tubes, there were tubes than ranged from 19 watts to 30 watts at max output. It is dependant on many factors.

 

Generally, an EL-34 is considered a 25 watt tube. There is an exception, the E34Ls, which is a new design 30 watt tube.

 

The way amps are set up and designed, is so they run a set of tubes to not exceed by design, the maximum rating of the tube. When we do, this is where output distortion comes into play. Generally a "50 watt amp" will produce about 50 watts at say 5% distortion or some % figure.

 

Hope this was of some help.

[myles_rose]

Originally posted by Gabriel E.:

Thanks Myles:

 

After X-Mas, I should have some extra cash so I'll definitely get a Tung-Sol.

 

I have some questions regarding the Trainwreck Express semi-clone that I'm planning to build and about power transformers in general

 

Is there such thing as a too large PT? I know how much current I need for the tubes and filaments. I also know I want to put about 410 Volts on the plates. And I will be using a 6K6 plate-plate OT (maybe a Hammond P-T1650H).

 

1)Will using a larger-than necessary PT affect the tone?

2)How do I fugure out how much voltage I will need for the bias supply?

3)I can't seem to find any well-written information on choosing a PT. Any good books on this?

 

Thanks in advance, Gabriel

Gabriel,

 

This is a very involved subject, and trying to even start it here would be a book in itself

 

There are many good books on transformer design and theory. I would first check over at www.tubesandmore.com which is Antique Electric Supply. If you really want the hard core info, then contact Mercury Magnetics and ask for Sergio. They are possibly the best transformer folks on the globe.

[Gabriel E.]

THX Miles. I appreciate it.

[dnnythms]

Miles, I heard you are the man regarding questions about tubes. As for my query...

 

my marshall dsl401 came stock with ei el84 power and ei 12ax7 preamp tubes. since i bought the amp over ebay (it plays great, no problems whatsoever, ebay rules) i don't know for sure how long the tubes have been played on. so, i'm gonna decide to change them before something unexpected happens at a gig. i've read about ei el84's and things i've seen was that it is modeled from a Telefunken, and that the ei el84 is primarily used for it's cleaner sound. I play with distortion most of the time, and although these ei tubes sound good to me, i have not had experience with any other varieties.

as for a replacement, what do you suggest for an excellent distorting power/preamp tube (modern rock). As for cleans, it has to be at least ok, not breaking up too early.

 

thanks

[Gus1234]

Hi Myles .

 

Really thanks 4 your words .

 

Gus

[myles_rose]

Originally posted by dnnythms:

Miles, I heard you are the man regarding questions about tubes. As for my query...

 

my marshall dsl401 came stock with ei el84 power and ei 12ax7 preamp tubes. since i bought the amp over ebay (it plays great, no problems whatsoever, ebay rules) i don't know for sure how long the tubes have been played on. so, i'm gonna decide to change them before something unexpected happens at a gig. i've read about ei el84's and things i've seen was that it is modeled from a Telefunken, and that the ei el84 is primarily used for it's cleaner sound. I play with distortion most of the time, and although these ei tubes sound good to me, i have not had experience with any other varieties.

as for a replacement, what do you suggest for an excellent distorting power/preamp tube (modern rock). As for cleans, it has to be at least ok, not breaking up too early.

 

thanks

dnnythms ....

 

Marshall is using a lot of Ei tubes these days. It actually goes back to a relationship Marhall and the Ei factory have had for years. A lot of folks don't know that Ei was the OEM for many of the Telefunken, Mullard at times, and Siemens tubes in the past.

 

The EL-84 Ei tube is one I am still testing. We have that tube at Groove Tubes as one of the EL-84's we sell. I still prefer the JJ version, the EL-84S, in most any EL-84 based amps. I have about 12 sets of the Ei EL-84 tubes out there with folks (some from here) for feedback. When this comes back, I will post some results.

 

The tooling for this tube was not "modeled" from the Telefunken tooling ... it WAS the Telefunken tooling originally. The differences these days are the cathode material formula, the purity of the cathode coatings, the degree of vacuum, the material of the grids, and the plate material. If the original recipe was the same, and the oven this was baked in, so to speak (the tooling), then we'd have the same tube.

 

A EL84S in a #6 will have a cleaner sound and more output. It will be a more articulate tube also. It is also a much more expensive tube in bulk than the Ei tube, hence it's use. The GT version of this tube (EL-84S) is at:

 

http://www.groovetubes.com/product.cfm?Product_ID=1687

 

The Ei version is at:

 

http://www.groovetubes.com/product.cfm?Product_ID=1689

 

There is also the Russian (Sovtek) EL-84, that sounds like a felt blanket was thrown over your amp, but is a sturdy tube for the most part. These are what are used in most amps as stock, and the Ei tube is better than these from my point of view.

 

Matching of these is critical, even more so in class A amps. A properly matched set gives a lot more sustain and will drop your output transformer temperature by a lot.

 

Ei preamp tubes are great fi you like their tone, when they are tested properly. They vary widely! VERY WIDELY! In these amps, I prefer the 12AX7C or the 12AX7R3. The Ei version is brighter, and to some, sound a bit brittle or harsh.

[myles_rose]

Originally posted by Gus1234:

Hi Myles .

 

Really thanks 4 your words .

 

Gus

Gus,

 

You are more than welcome.

[myles_rose]

Originally posted by Gabriel E.:

THX Miles. I appreciate it.

Gabriel ....

 

You are more than welcome

[ManInTheBox]

Hey Miles, I did it again, I messed up my amp.

I am always hearing that you can't play a bass through a guitar amp. And I wanted to find out why, so I did it, and I heard a loud pop. Then there was no sound for a few minutes. I turned it off, and back on, then I heard sound, but it was real thin, and low sounding.

I pulled it out of the chasis(Crate BV6212) and checked all the voltages at the various test point(which appeared to be at the output stage of each tube. All checked correct. I plugged it back in, and it got a little louder, but still not good. I looked at all my tubes, and they weren't glowing, so I changed them. They glow now, the tone is back, but the volume is still really low. I changed the output tubes with an old set, and I had the same problem. Sounds to me like none of this is even related. I am sure the bass didn't ruin my tubes.

I saw a little tag on the bigger of the two transformers on my amp, and it says there is a resettable fuse inside the transformer. I think some how the bass blew that, but when it reset, I lost something some how. Any idea what I should check?

[myles_rose]

Originally posted by tundrkys:

Hey Miles, I did it again, I messed up my amp.

I am always hearing that you can't play a bass through a guitar amp. And I wanted to find out why, so I did it, and I heard a loud pop. Then there was no sound for a few minutes. I turned it off, and back on, then I heard sound, but it was real thin, and low sounding.

I pulled it out of the chasis(Crate BV6212) and checked all the voltages at the various test point(which appeared to be at the output stage of each tube. All checked correct. I plugged it back in, and it got a little louder, but still not good. I looked at all my tubes, and they weren't glowing, so I changed them. They glow now, the tone is back, but the volume is still really low. I changed the output tubes with an old set, and I had the same problem. Sounds to me like none of this is even related. I am sure the bass didn't ruin my tubes.

I saw a little tag on the bigger of the two transformers on my amp, and it says there is a resettable fuse inside the transformer. I think some how the bass blew that, but when it reset, I lost something some how. Any idea what I should check?

tundrkys ....

 

If you run a bass at high levels through a guitar amp, usually the worst that will happen is the speaker may blow.

 

Your output tubes were worked harder (as an amp must produce more wattage at low frequencies for for same sound level) and this may have impacted the output transformer.

 

Crate amps don't use very robust transformers ... they can't, and still sell their amps for the price they sell them for.

 

In any case, check your tubes (output tubes) and their bias. Then swap one of the other 12AX7 preamp tubes with V1, as this guy may have been weak to start with, and the bass blew it over the line.

 

If that does not work, it's bench time, to check the output transformer.

 

Good luck

[Bassman59]

Hi Myles

 

I have a 59 Fender Bassman RI,and would like to swap the Solid State rectifier to a Tube Rectifier.

 

What tube rectifier do you recommend,and if i swap them will i have to re-bias the amp?

 

Thank you

 

Bassman59

--------------------------------------------------------------------------------

[myles_rose]

Originally posted by Bassman59:

Hi Myles

 

I have a 59 Fender Bassman RI,and would like to swap the Solid State rectifier to a Tube Rectifier.

 

What tube rectifier do you recommend,and if i swap them will i have to re-bias the amp?

 

Thank you

 

Bassman59

--------------------------------------------------------------------------------

Bassman59 ....

 

That is one of the best changes you can make to that amp.

 

I always use a GZ34 / 5AR4.

 

You can use any of the others too, you can always go down, but not the other way in a lot of cases, such as putting a 5AR4 or 5U4 in an amp designed to run off voltages from a 5Y3.

 

I have a lot of rectifier info on my personal website at:

 

http://www.guitaramplifierblueprinting.com/rectifiers.html

 

I generally do like to rebias the amp after changing to a tube rectifier, as the voltages are generally lower on the output tube plates, and you can then run higher current to compensate. Tubes prefer current over voltage, one of the reasons the tweed amps sounded and felt like they did.

 

For a new rectifier:

 

http://www.groovetubes.com/product.cfm?Product_ID=1182

 

These are Russian, and much more reliable than the older Chinese rectifiers.

 

If you have the money:

 

Mullard GZ34/5AR4 (used) Used, but tested in excellent shape for long life. The best sounding GZ34. Why settle for Chinese when you can have the best? $65 each

 

Mullard GZ34/5AR4 NEW The best sounding for vintage hi-fi and various guitar amps. Lasts forever and is the best there is. New in box and getting rarer. $145 each

 

These above are from Vacuum Tube Valley ( http://www.vacuumtube.com )

 

Another great rectifier source is KCA ( http://www.kcanostubes.com )

 

They have:

 

NOS VALVO (Made by Mazda)------------------------------------------------$ 80 Each

Made in western Europe. Same high quality as Mullard 5AR4s. Will last 10 times as long as the Chinese 5AR4s available today.

 

NOS Mazda GZ34/5AR4s-------------------------------------------------------$ 70 Each

Excellent western European rectifiers with 1960s datecodes. These will outperform and outlast the low quality Russian and Chinese rectifiers at least 10:1. Most users notice a tonal improvement. Excellent buy for NOS GZ34s! Large bottle similar to Sylvania 5AR4s. Limited quantity.

 

NOS Sylvania 5AR4/GZ34 (Large bottle, US)---------------------------------$ 85 Each

One in stock.

 

Rectifiers .... if they work for a month, will last almost forever. I cannot begin to count how many vacuum tube rectifier amps I have worked on, but I bet I have replaced less than 2-3 rectifiers that were worn out.

 

The main reason they are not used today is cost ... a different power transformer, a rectifier socket, and the associated wiring. It was a cost issue. Amps over 50 or so watts also required more than one rectifier in most cases, so that was another factor.

 

On your Bassman, be sure to replace V1 and V2 with some decent tubes. The stock ones are quite awful, and if you like the sound and feel of the stock tubed amp, you will go nuts over it's change getting rid of the stock tubes.

 

Power tubes, if you can find them, are great if they are Tung Sol 5881's or GT 6L6GE, or RCA Black or Gray plates.

 

Use a matched 12AT7 phase inverter. The stock phase inverters are so unmatched in 85%+ of the cases, that it is just silly. You will have a lot more sustain, even at low levels, linear volume all up and down your fretboard, and your output transformer temperature will drop at least 15 degrees (and the entire inside of the chassis will run cooler and age slower too).

[Bassman59]

Thank You Myles

 

I really appreciate your help..

 

Man i wish you were in Boston