Preamp Tubes? - Who, What, When, Where, Why, and How? - Page 21

rockinr0ll · 07-08-2009, 10:36 AM

I'm going to watch that video right after I finish with this CD I'm listening to.

rockinr0ll · 07-08-2009, 11:06 AM

Funny interview!

"It's Tight."

lol love the accent...

RiverRatt · 07-08-2009, 02:17 PM

Quote:

Originally Posted by MartyStrat54

A 12BZ7 will always provide more gain than a 12AX7. This has been discussed many times in this forum. A 12BZ7 has half the plate resistance of a 12AX7. However, some guitar amp circuits do not like a 12BZ7. Excessive gain sometimes isn't a good thing. I sent Josh a 35-35 tube and he sent it back. He went with a 7025 in V1 and an Amperex 12AX7 in V2. So far, based on my experiments and those by Joe and Josh, the 7025 is the key to having great overall Marshall sound. Pairing a 7025 up with a high gain (30-30) tube is what everyone is settling on, so there must be something to it.
Marty

So you think I'd be better served with a 7025 in V1 than, say, that RFT that I've been planning to buy? I've never been 7025 shopping. What do I look for (or avoid)?

joshuaaewallen · 07-08-2009, 02:54 PM

Quote:

Originally Posted by solarburnDSL50

Looks like 1 12AX7 comes out to about $70. Someone buy one so we can hear the verdict...

I would but my money is tied up in 2 RFT EL34's.

Live rates at 2009.07.08 18:51:54 UTC

30.00 GBP = 48.0490 USD

United Kingdom Pounds United States Dollars 1 GBP = 1.60163 USD 1 USD = 0.624363 GBP

+Shipping...

MartyStrat54 · 07-08-2009, 02:55 PM

Quote:

Originally Posted by RiverRatt

So you think I'd be better served with a 7025 in V1 than, say, that RFT that I've been planning to buy? I've never been 7025 shopping. What do I look for (or avoid)?

If it was me, I would take the 7025 over the RFT in V1. However, a 7025 in V1 and an RFT in V2 would certainly be a sweet pair. The whole concept we have discovered revolves around a 7025 being matched up to a high gain quality NOS tube like a Amperex, Mullard or RFT. Another choice would be an RCA or Raytheon Black Plate in V2.

We have also found that the 7025 does not have to be a high gainer. It can test 25-26 and be a perfect match up against a 29-30 tube in V2. By keeping the 7025 at a medium gain, it provides a very controlled and clear clean channel. The rocket in V2 provides all the necessary gain for the crunch and/or lead channels if you happen to own a TSL.

There are many 7025's for sale on EBAY. A good deal is a GE Black Plate. You can get one of these for under $30. The fact is, single tubes for sale can go one of two ways. They can go real cheap, or they can go real high. The best thing to do is position yourself in several auctions and then you can determine which auction you will have the best luck in. An RCA 7025 is the standard. You can't go wrong with one of them.

If you can't get one on your own, I might be persuaded to let one of mine go.

Marty

MartyStrat54 · 07-08-2009, 03:20 PM

I looked over the data and there are some pro's and con's. I don't know if you read about the heater circuit resistance. It is different than a 12AX7. What this means is that you will need to replace all four tubes with the E813CC to prevent any early tube failure. Also, depending on how your amp gets its heater voltage, you may actually have to change a rail resistor (part of the heater supply circuit) in your amp. I think most modern Marshall's get their 6.3 volts through a bridge rectifier, so this wouldn't be a problem. However, having to replace all of the tubes is a necessity. Read the spec sheet all the way through to the bottom. If I'm wrong, please correct me.

Yes the tube is a completely different design with a gain factor of 90. It almost looks like two cowbells suspended on wires. From the specs, there are several areas were this tube varies from a 12AX7. They do not list the Rp (Plate Resistance), or I did not see it.

So the bottom line (unless I am wrong) is you can't just try one. It's all or nothing. That's sort of a bummer. Plus it takes away the ability to roll tubes.

If it comes down to these being available ten years from now, then it will be the tube of choice, because this is a quality product that is years ahead of anything from Russia or China.

Marty

MartyStrat54 · 07-08-2009, 03:51 PM

JOSH-By the time you read this, you will probably already know that JohnH left a link to the "other" Marshall forum regarding signal path through the tubes.

It is: The Marshall Amp Forum: • View topic - Preamp Tube Functions

The only thing is it combines the DSL with the TSL and speaks of the two DSL channels. Now I know we had the discussion on whether or not a TSL was a three channel amp or a glorified two channel amp. The crunch and lead channel share a lot of circuitry, so maybe in reality it is just a two channel amp that can act like a three channel.

Anyway, it is interesting and I was only partially correct. However, it proves that V1 and V2 are the real money makers in either one of these amps.

Marty

joshuaaewallen · 07-08-2009, 06:03 PM

Quote:

Originally Posted by MartyStrat54

JOSH-By the time you read this, you will probably already know that JohnH left a link to the "other" Marshall forum regarding signal path through the tubes.

It is: The Marshall Amp Forum: • View topic - Preamp Tube Functions

The only thing is it combines the DSL with the TSL and speaks of the two DSL channels. Now I know we had the discussion on whether or not a TSL was a three channel amp or a glorified two channel amp. The crunch and lead channel share a lot of circuitry, so maybe in reality it is just a two channel amp that can act like a three channel.

Anyway, it is interesting and I was only partially correct. However, it proves that V1 and V2 are the real money makers in either one of these amps.

Marty

Good link. Thanks Marty. It does kinda make it look like the TSL is a three headed toad that was the result of a nuclear accident involving a DSL...

So would you read that as indicating that the "Ultra Gain" channel is the "same" as the "Lead" channel on a TSL?

joshuaaewallen · 07-08-2009, 06:10 PM

Quote:

Originally Posted by MartyStrat54

I looked over the data and there are some pro's and con's. I don't know if you read about the heater circuit resistance. It is different than a 12AX7. What this means is that you will need to replace all four tubes with the E813CC to prevent any early tube failure. Also, depending on how your amp gets its heater voltage, you may actually have to change a rail resistor (part of the heater supply circuit) in your amp. I think most modern Marshall's get their 6.3 volts through a bridge rectifier, so this wouldn't be a problem. However, having to replace all of the tubes is a necessity. Read the spec sheet all the way through to the bottom. If I'm wrong, please correct me.

Yes the tube is a completely different design with a gain factor of 90. It almost looks like two cowbells suspended on wires. From the specs, there are several areas were this tube varies from a 12AX7. They do not list the Rp (Plate Resistance), or I did not see it.

So the bottom line (unless I am wrong) is you can't just try one. It's all or nothing. That's sort of a bummer. Plus it takes away the ability to roll tubes.

If it comes down to these being available ten years from now, then it will be the tube of choice, because this is a quality product that is years ahead of anything from Russia or China.

Marty

The stat sheet sure seems like they want to cover their butts if people do mix-n-match these w/ traditional 12AX7's...

MartyStrat54 · 07-08-2009, 06:24 PM

You're probably right. As I look at it, I think the TSL has two channels, but you can alter the volume of the second channel to make it become the lead channel. In other words, you can be going through the same tube path, but you have independent volume controls that alter how loud the crunch and lead channels will be based on manual selection or through the footswitch.

The crunch/lead channels share a lot of internal circuitry, so I think I will have to change my mind and say the three-headed toad only has two heads and a big lump. The funny thing is that they put the DSL401 in a group by itself and it uses its four preamp tubes in a different manner of say a DSL50 or 100.

Hell, you can go nuts trying to figure all of this stuff out.

Marty

solarburnDSL50 · 07-08-2009, 08:36 PM

Quote:

Originally Posted by joshuaaewallen

Live rates at 2009.07.08 18:51:54 UTC

30.00 GBP = 48.0490 USD

United Kingdom Pounds United States Dollars 1 GBP = 1.60163 USD 1 USD = 0.624363 GBP

+Shipping...

They gave me a price of 42.39 in GBP. Maybe I will check it again later. I can't wait to hear how these sound.

Edit: Includes shipping.

solarburnDSL50 · 07-08-2009, 08:47 PM

Quote:

Originally Posted by RiverRatt

So you think I'd be better served with a 7025 in V1 than, say, that RFT that I've been planning to buy? I've never been 7025 shopping. What do I look for (or avoid)?

I would get the RFT and the 7025. That way you could use either in those 2 positions V1& V2. The RFT sounds awesome in V1 and it pairs up nice with the 7025 in V1 & RFT in V2 in my DSL. A worth while investment IMO.

joshuaaewallen · 07-08-2009, 08:54 PM

Quote:

Originally Posted by MartyStrat54

I looked over the data and there are some pro's and con's... So the bottom line (unless I am wrong) is you can't just try one. It's all or nothing. That's sort of a bummer. Plus it takes away the ability to roll tubes...

I wonder just how prematurely the tube's life would come to an end?

MartyStrat54 · 07-08-2009, 09:11 PM

Quote:

Originally Posted by joshuaaewallen

I wonder just how prematurely the tube's life would come to an end?

Well the funny thing about heaters is they last forever, even outlasting the life of the tube...as long as the voltage and current are within a specific range. A tube heater can only vary + or - 10 per cent. If it goes outside of its working parameter, the heater will fail, sometimes very quickly, especially if the voltage is on the high side. Plus the heater needs to be stable, or else the tube will perform badly. The inner workings of the tube all rely on the heater being stable. Most heaters are rated at +5000 hours of life. Military versions like JAN or JRC exceed this rating. I would assume by the way they keep bringing up this fact, their tube must fail rather quickly if the amp is not running all of the same tubes.

Marty

joshuaaewallen · 07-08-2009, 09:12 PM

so it's any one's guess?

joshuaaewallen · 07-09-2009, 07:30 AM

Quote:

Originally Posted by joshuaaewallen

Awesome. Thanks for the heads up Marty! I am subscribed to the new thread (TSL Signal Path-Engineers and Repairmen Only) and eagerly anticipating some feed back. Sadly, the TSL is rather maligned in the forum and I fear the response may be more negative than useful...

Quote:

Originally Posted by MartyStrat54

Well the funny thing about heaters is they last forever, even outlasting the life of the tube...as long as the voltage and current are within a specific range. A tube heater can only vary + or - 10 per cent. If it goes outside of its working parameter, the heater will fail, sometimes very quickly, especially if the voltage is on the high side. Plus the heater needs to be stable, or else the tube will perform badly. The inner workings of the tube all rely on the heater being stable. Most heaters are rated at +5000 hours of life. Military versions like JAN or JRC exceed this rating. I would assume by the way they keep bringing up this fact, their tube must fail rather quickly if the amp is not running all of the same tubes.

Marty

Well... It may not be helpful to Blackburn's market share... Unless they release another "more traditional" version of the 12AX7... I mean... yeah their are those guys who replace all their tubes in one shot, but it seems to me that there are more guys who don't. I mean the logic is pretty simple. It's like replacing every single light bulb in your house just because the one out in the garage burned out. You just wouldn't do that. And if you get a lot of folks buying one or two of these at a time, throwing them in their amps and saying, "Boy these sound good but don't last worth crap!" I think it'll bite Blackburn in the butt sooner or later... Anyhoo... Just thinking...

I'm gonna be out of town until late Sunday night. Ya'll take care!

solarburnDSL50 · 07-09-2009, 02:21 PM

Check this out about the new TubeTech from the GP:

The Gear Page - View Single Post - TechTube to Start Manufacture of Tubes at Old Mullard Plant!

From about page 32 on for more input on these:

http://www.thegearpage.net/board/sho...438130&page=32

RiverRatt · 07-09-2009, 02:38 PM

Quote:

Originally Posted by solarburnDSL50

I would get the RFT and the 7025. That way you could use either in those 2 positions V1& V2. The RFT sounds awesome in V1 and it pairs up nice with the 7025 in V1 & RFT in V2 in my DSL. A worth while investment IMO.

Yikes! I just did some checking on prices. If I go with the 7025/RFT 12AX7 combo and the RFT EL34 pair, I'm going to have to hatch some cash. That's almost half what I paid for the DSL! I don't have the patience to snipe on eBay, either. I want it NOW. I even hate waiting for shipping.

solarburnDSL50 · 07-09-2009, 02:46 PM

Quote:

Originally Posted by RiverRatt

Yikes! I just did some checking on prices. If I go with the 7025/RFT 12AX7 combo and the RFT EL34 pair, I'm going to have to hatch some cash. That's almost half what I paid for the DSL! I don't have the patience to snipe on eBay, either. I want it NOW. I even hate waiting for shipping.

What is the price on the RFT 12AX7 and the 7025?

RiverRatt · 07-09-2009, 02:55 PM

Looking at retail, as you know the RFT 12AX7 is around $40 at the best price. I've seen 7025's from $50 to $150, and I don't know enough about them to tell which is the better deal. I don't think I would go wrong with an RCA, but they are some of the most expensive. The RFT EL34s' are going to be at least $90 to $100.

solarburnDSL50 · 07-09-2009, 03:14 PM

Quote:

Originally Posted by RiverRatt

Looking at retail, as you know the RFT 12AX7 is around $40 at the best price. I've seen 7025's from $50 to $150, and I don't know enough about them to tell which is the better deal. I don't think I would go wrong with an RCA, but they are some of the most expensive. The RFT EL34s' are going to be at least $90 to $100.

Yes to both RFT's. Marty will know about the 7025's so definitely ask him.

The RFT 12AX7 sounds good 2 ways that I've found.
1. V1 and a lower gain tube in V2.
2. The opposite. Lower gain(7025...)and then the RFT in V2.

In my amp the RFT had the biggest impact in V1. If you have to choose between the 2 you can't go wrong with either. If you can't find a good 7025 for under $40 then I would get the RFT. The EL34's are going to cost either way. To me its a win/win even if you have to give up a 12AX7.

Prolly come down to what you really need right now. Just remember to watch the RFT 12AX7's cause when they are gone, that's it. They are hard to find and they are getting more expensive because of it.

Now you know I'm just think'n with you here. Do it how you want and what's best for you. Marty can help you work out which 7025's to get. He majorly hooked me up and man I have so many great combination's its hard to pick one for very long.

Do not buy any Raytheon 12AX7 Black Plates. They are horrible...

If you find some let me know though.

RiverRatt · 07-09-2009, 03:24 PM

Well, I took the plunge and bought a couple of RFT 7025A's. This sounded like a good deal, so I grabbed them. I hope they are what they claim to be - the writing is about gone, but the seller has 100% positive. See what you think.

2 Matched E. Germany RFT 7025-A Tubes

solarburnDSL50 · 07-09-2009, 03:32 PM

Quote:

Originally Posted by RiverRatt

Well, I took the plunge and bought a couple of RFT 7025A's. This sounded like a good deal, so I grabbed them. I hope they are what they claim to be - the writing is about gone, but the seller has 100% positive. See what you think.

2 Matched E. Germany RFT 7025-A Tubes

I don't see any info on them...

solarburnDSL50 · 07-09-2009, 03:35 PM

This is what I have:

1.7025, RCA, Date ?, Short gray plates, Test 30-27 (High Gain)
2.7025 RCA?, Date ?, Medium gray plates, Test 22-24.
3.7025 RCA, 196X, Short gray plates, Test 22/23.

MartyStrat54 · 07-09-2009, 04:32 PM

Wow! Things are heating up like a backyard B-B-Q. RFT 7025A's. If you got them for the $31 something, that's pretty good. Based on the sort of tester used, they are still in the usable range. I think they should sound really phat in your amp. Sort of took care of the RFT/7025 problem didn't you?

Joe-Your thread from the Gear Page stated:

[I added my comments within the brackets. Marty]

I was able to test the transconductance of my two E813CC tubes, and confirmed what I heard in my initial amp testing. Holy b'zeejus, these tubes are beyond "strong," and way out of the top end of the 12AX7 spec.

[But as you will see it is not a good thing.]

I tested both sections of these two valves in my B&K 707 tube tester, where acceptable transconductance values begin at 22, and I measured four reference 12AX7s (Mullard I63 type, '50s CBS, '50s Ken-Rad, and '60s short-plate RCA 12AX7A) that I keep for this purpose at about 33 per triode (as expected). These new TubeTech E813CC measured whopping values of 52&60, and 48&54. That is about 150% of "new"!!

[Hey, this guy knows a good tube tester, the 707 which we are all familiar with, but I hope he knows that CBS and Ken-Rad didn't make tubes. So look at these figures. We all know that too strong means the tube is unacceptable. It causes distortion.]

This does account for the extreme distortion that I experienced, even when turning my preamp "volume" down. With the tubes this far out of spec, it seems there was a QC problem. And there is no way a comparison test can be equal. I have contacted TubeTech/Blackburn Microtech, and am awaiting their response.

[This poor sap got a couple of Jupiter boosters. They make the original ICBM look like a bottle rocket, but at least you could use the ICBM. This guy has two new tubes that he cannot use. They are so stout, that they are distorting the front end of his Hi Fi gear. "And" he has no where to turn. I'll bet he doesn't get a reply back and if he does get some sort of return/refund it will take weeks to accomplish.]

Now I'm really concerned about these tubes. First, you can't just use one. Secondly, the quality control is not up to the Brit/Mullard standards of old and lastly, their customer service sounds like it is shaky.

You know, I had actually thought several months ago that Blackburn was going to reissue their original 12AX7. Maybe the QC would be better because of advancements in materials and such. They claimed the tubes would be made on original "Mullard" equipment. It all sounded really good at the time. Now it's like a wet dog in your lap. Doesn't sound good at all.

I hope that they get it all under control fast, because the HI FI crowd has a long memory and if your shit is no good, it gets around fast and no one is going to buy your stuff.

The original spec sheet listed the tube with a gain of 90 and I said this would be more than acceptable. However, based on the above readings, I would like to have say twenty of the tubes to measure and see how many are above/below the norm. I mean it would be just as big of a bummer if you got some of these tubes and they tested 14-16. I have a feeling that this has probably happened. Those buyers without a tube tester are having to rely on Blackburn to sell them a tube that meets all the requirements. Right now it looks like that isn't happening.

Marty

solarburnDSL50 · 07-09-2009, 05:19 PM

Quote:

Originally Posted by MartyStrat54

Wow! Things are heating up like a backyard B-B-Q. RFT 7025A's. If you got them for the $31 something, that's pretty good. Based on the sort of tester used, they are still in the usable range. I think they should sound really phat in your amp. Sort of took care of the RFT/7025 problem didn't you?

Joe-Your thread from the Gear Page stated:

[I added my comments within the brackets. Marty]

I was able to test the transconductance of my two E813CC tubes, and confirmed what I heard in my initial amp testing. Holy b'zeejus, these tubes are beyond "strong," and way out of the top end of the 12AX7 spec.

[But as you will see it is not a good thing.]

I tested both sections of these two valves in my B&K 707 tube tester, where acceptable transconductance values begin at 22, and I measured four reference 12AX7s (Mullard I63 type, '50s CBS, '50s Ken-Rad, and '60s short-plate RCA 12AX7A) that I keep for this purpose at about 33 per triode (as expected). These new TubeTech E813CC measured whopping values of 52&60, and 48&54. That is about 150% of "new"!!

[Hey, this guy knows a good tube tester, the 707 which we are all familiar with, but I hope he knows that CBS and Ken-Rad didn't make tubes. So look at these figures. We all know that too strong means the tube is unacceptable. It causes distortion.]

This does account for the extreme distortion that I experienced, even when turning my preamp "volume" down. With the tubes this far out of spec, it seems there was a QC problem. And there is no way a comparison test can be equal. I have contacted TubeTech/Blackburn Microtech, and am awaiting their response.

[This poor sap got a couple of Jupiter boosters. They make the original ICBM look like a bottle rocket, but at least you could use the ICBM. This guy has two new tubes that he cannot use. They are so stout, that they are distorting the front end of his Hi Fi gear. "And" he has no where to turn. I'll bet he doesn't get a reply back and if he does get some sort of return/refund it will take weeks to accomplish.]

Now I'm really concerned about these tubes. First, you can't just use one. Secondly, the quality control is not up to the Brit/Mullard standards of old and lastly, their customer service sounds like it is shaky.

You know, I had actually thought several months ago that Blackburn was going to reissue their original 12AX7. Maybe the QC would be better because of advancements in materials and such. They claimed the tubes would be made on original "Mullard" equipment. It all sounded really good at the time. Now it's like a wet dog in your lap. Doesn't sound good at all.

I hope that they get it all under control fast, because the HI FI crowd has a long memory and if your shit is no good, it gets around fast and no one is going to buy your stuff.

The original spec sheet listed the tube with a gain of 90 and I said this would be more than acceptable. However, based on the above readings, I would like to have say twenty of the tubes to measure and see how many are above/below the norm. I mean it would be just as big of a bummer if you got some of these tubes and they tested 14-16. I have a feeling that this has probably happened. Those buyers without a tube tester are having to rely on Blackburn to sell them a tube that meets all the requirements. Right now it looks like that isn't happening.

Marty

Yeah I noted they were too high and unusable. Expensive to boot! I thought I'd give ya a look at some of what's happening with them.

NOS for the win still.

MartyStrat54 · 07-09-2009, 05:31 PM

Hey Mr. Joe. ^^^Up There^^^ you told Ratt the following:

Do not buy any Raytheon 12AX7 Black Plates. They are horrible.

Correct me if I'm wrong, but I thought you liked them?

Yes, no? If no, please tell me why.

Marty

solarburnDSL50 · 07-09-2009, 05:40 PM

I got these for my Night Train:

Funkwerk RFT EL84 -1966-1970 M. Pairs MINT NOS NIB Welded Plate Tubes E. Germany.

I just put them in awhile ago. These are firecrackers with not much clean headroom at all hehe. Great overdrive and crunch though. Thick & syrupy. I'm going to have to try my strat with these and see how it sounds. Should be a good mix.

I still prefer the NOS Russian tubes Marty gave me cause they have lots of clean headroom and still a great overdrive. Not as gainy as the RFT but they sound good and make that nice clean to bite transition especially with guitar volume.

These RFT will be fun to mess with for edgier, aggressive tones. I got a wild hair and thought I'd try them out.

I've got RFT EL34's on the way ta boot! Man I got RFT addiction go'n.

solarburnDSL50 · 07-09-2009, 05:45 PM

Quote:

Originally Posted by MartyStrat54

Hey Mr. Joe. ^^^Up There^^^ you told Ratt the following:

Do not buy any Raytheon 12AX7 Black Plates. They are horrible.

Correct me if I'm wrong, but I thought you liked them?

Yes, no? If no, please tell me why.

Marty

Yeah I was using reverse psychology so he wouldn't buy my Raytheon BP's wherever they are. You know I wants more O dem.

Just me being selfish and protective of my little friends(Tony from Scarface voice).

MartyStrat54 · 07-09-2009, 06:34 PM

Quote:

Originally Posted by solarburnDSL50

Yeah I was using reverse psychology so he wouldn't buy my Raytheon BP's wherever they are. You know I wants more O dem.

Just me being selfish and protective of my little friends(Tony from Scarface voice).

Oh no! Don't tell me that! I just took all of mine and smashed them on the sidewalk and beat them with the wheels of a skateboard.

Oh the tragedy of it all. What have I done, what have I done?

An embarrassed Marty

07-08-2009, 10:36 AM	#601 (permalink)
rockinr0ll Senior Member Join Date: Feb 2009 Posts: 1,340	Re: Preamp Tubes? - Who, What, When, Where, Why, and How? I'm going to watch that video right after I finish with this CD I'm listening to.

07-08-2009, 11:06 AM	#602 (permalink)
rockinr0ll Senior Member Join Date: Feb 2009 Posts: 1,340	Re: Preamp Tubes? - Who, What, When, Where, Why, and How? Funny interview! "It's Tight." lol love the accent...

07-08-2009, 03:20 PM	#606 (permalink)
MartyStrat54 Senior Member Join Date: Feb 2009 Location: Formerly Phoenix, now north of KC Posts: 2,583	Re: Preamp Tubes? - Who, What, When, Where, Why, and How? I looked over the data and there are some pro's and con's. I don't know if you read about the heater circuit resistance. It is different than a 12AX7. What this means is that you will need to replace all four tubes with the E813CC to prevent any early tube failure. Also, depending on how your amp gets its heater voltage, you may actually have to change a rail resistor (part of the heater supply circuit) in your amp. I think most modern Marshall's get their 6.3 volts through a bridge rectifier, so this wouldn't be a problem. However, having to replace all of the tubes is a necessity. Read the spec sheet all the way through to the bottom. If I'm wrong, please correct me. Yes the tube is a completely different design with a gain factor of 90. It almost looks like two cowbells suspended on wires. From the specs, there are several areas were this tube varies from a 12AX7. They do not list the Rp (Plate Resistance), or I did not see it. So the bottom line (unless I am wrong) is you can't just try one. It's all or nothing. That's sort of a bummer. Plus it takes away the ability to roll tubes. If it comes down to these being available ten years from now, then it will be the tube of choice, because this is a quality product that is years ahead of anything from Russia or China. Marty __________________ MARTY 2009 Gibson Explorer-Hell Raising Machine 1989 Fender Strat Plus USA 2008 Fender Tele USA 2004 Schecter Elite w/DiMarzio's TSL100 with custom 4x12 cab. TSL122 with Man 'O War Speakers. TSL602 #1 with JBL D123 Speakers and 602 #2 with Altec 417 Speakers. "Oh so sweet my friends." DSL401 #1 with Red Fang Speaker and 401 #2 with JBL D123 Speaker. Tubes: Let's just say they are NOS that kick ass.

07-08-2009, 03:51 PM	#607 (permalink)
MartyStrat54 Senior Member Join Date: Feb 2009 Location: Formerly Phoenix, now north of KC Posts: 2,583	Re: Preamp Tubes? - Who, What, When, Where, Why, and How? JOSH-By the time you read this, you will probably already know that JohnH left a link to the "other" Marshall forum regarding signal path through the tubes. It is: The Marshall Amp Forum: • View topic - Preamp Tube Functions The only thing is it combines the DSL with the TSL and speaks of the two DSL channels. Now I know we had the discussion on whether or not a TSL was a three channel amp or a glorified two channel amp. The crunch and lead channel share a lot of circuitry, so maybe in reality it is just a two channel amp that can act like a three channel. Anyway, it is interesting and I was only partially correct. However, it proves that V1 and V2 are the real money makers in either one of these amps. Marty __________________ MARTY 2009 Gibson Explorer-Hell Raising Machine 1989 Fender Strat Plus USA 2008 Fender Tele USA 2004 Schecter Elite w/DiMarzio's TSL100 with custom 4x12 cab. TSL122 with Man 'O War Speakers. TSL602 #1 with JBL D123 Speakers and 602 #2 with Altec 417 Speakers. "Oh so sweet my friends." DSL401 #1 with Red Fang Speaker and 401 #2 with JBL D123 Speaker. Tubes: Let's just say they are NOS that kick ass.

07-08-2009, 06:24 PM	#610 (permalink)
MartyStrat54 Senior Member Join Date: Feb 2009 Location: Formerly Phoenix, now north of KC Posts: 2,583	Re: Preamp Tubes? - Who, What, When, Where, Why, and How? You're probably right. As I look at it, I think the TSL has two channels, but you can alter the volume of the second channel to make it become the lead channel. In other words, you can be going through the same tube path, but you have independent volume controls that alter how loud the crunch and lead channels will be based on manual selection or through the footswitch. The crunch/lead channels share a lot of internal circuitry, so I think I will have to change my mind and say the three-headed toad only has two heads and a big lump. The funny thing is that they put the DSL401 in a group by itself and it uses its four preamp tubes in a different manner of say a DSL50 or 100. Hell, you can go nuts trying to figure all of this stuff out. Marty __________________ MARTY 2009 Gibson Explorer-Hell Raising Machine 1989 Fender Strat Plus USA 2008 Fender Tele USA 2004 Schecter Elite w/DiMarzio's TSL100 with custom 4x12 cab. TSL122 with Man 'O War Speakers. TSL602 #1 with JBL D123 Speakers and 602 #2 with Altec 417 Speakers. "Oh so sweet my friends." DSL401 #1 with Red Fang Speaker and 401 #2 with JBL D123 Speaker. Tubes: Let's just say they are NOS that kick ass.

07-08-2009, 09:12 PM	#615 (permalink)
joshuaaewallen Senior Member Join Date: Jan 2009 Location: Minnesota Posts: 372	Re: Preamp Tubes? - Who, What, When, Where, Why, and How? so it's any one's guess? __________________ Josh 2004 PRS Custom 24 10 Top Dean Caddy w/ Bare Knuckles Nail Bombs (This One's For Sale, Just Let Me Know If You Are Interested) 1999 Marshall JCM 2000 TSL 122 - Power Tubes: JJ EL34L's - Assorted New & Vintage pre-amp tubes... I like to roll... HardWire DL-8 Delay/Looper http://irkinempire.spaces.live.com/ "... When you do things right, people won't be sure you've done anything at all." - Futurama

07-09-2009, 02:55 PM	#620 (permalink)
RiverRatt Senior Member Join Date: May 2008 Location: Between Memphis and Nashville Posts: 517	Re: Preamp Tubes? - Who, What, When, Where, Why, and How? Looking at retail, as you know the RFT 12AX7 is around $40 at the best price. I've seen 7025's from $50 to $150, and I don't know enough about them to tell which is the better deal. I don't think I would go wrong with an RCA, but they are some of the most expensive. The RFT EL34s' are going to be at least $90 to $100.

07-09-2009, 03:24 PM	#622 (permalink)
RiverRatt Senior Member Join Date: May 2008 Location: Between Memphis and Nashville Posts: 517	Re: Preamp Tubes? - Who, What, When, Where, Why, and How? Well, I took the plunge and bought a couple of RFT 7025A's. This sounded like a good deal, so I grabbed them. I hope they are what they claim to be - the writing is about gone, but the seller has 100% positive. See what you think. 2 Matched E. Germany RFT 7025-A Tubes

07-09-2009, 04:32 PM	#625 (permalink)
MartyStrat54 Senior Member Join Date: Feb 2009 Location: Formerly Phoenix, now north of KC Posts: 2,583	Re: Preamp Tubes? - Who, What, When, Where, Why, and How? Wow! Things are heating up like a backyard B-B-Q. RFT 7025A's. If you got them for the $31 something, that's pretty good. Based on the sort of tester used, they are still in the usable range. I think they should sound really phat in your amp. Sort of took care of the RFT/7025 problem didn't you? Joe-Your thread from the Gear Page stated: [I added my comments within the brackets. Marty] I was able to test the transconductance of my two E813CC tubes, and confirmed what I heard in my initial amp testing. Holy b'zeejus, these tubes are beyond "strong," and way out of the top end of the 12AX7 spec. [But as you will see it is not a good thing.] I tested both sections of these two valves in my B&K 707 tube tester, where acceptable transconductance values begin at 22, and I measured four reference 12AX7s (Mullard I63 type, '50s CBS, '50s Ken-Rad, and '60s short-plate RCA 12AX7A) that I keep for this purpose at about 33 per triode (as expected). These new TubeTech E813CC measured whopping values of 52&60, and 48&54. That is about 150% of "new"!! [Hey, this guy knows a good tube tester, the 707 which we are all familiar with, but I hope he knows that CBS and Ken-Rad didn't make tubes. So look at these figures. We all know that too strong means the tube is unacceptable. It causes distortion.] This does account for the extreme distortion that I experienced, even when turning my preamp "volume" down. With the tubes this far out of spec, it seems there was a QC problem. And there is no way a comparison test can be equal. I have contacted TubeTech/Blackburn Microtech, and am awaiting their response. [This poor sap got a couple of Jupiter boosters. They make the original ICBM look like a bottle rocket, but at least you could use the ICBM. This guy has two new tubes that he cannot use. They are so stout, that they are distorting the front end of his Hi Fi gear. "And" he has no where to turn. I'll bet he doesn't get a reply back and if he does get some sort of return/refund it will take weeks to accomplish.] Now I'm really concerned about these tubes. First, you can't just use one. Secondly, the quality control is not up to the Brit/Mullard standards of old and lastly, their customer service sounds like it is shaky. You know, I had actually thought several months ago that Blackburn was going to reissue their original 12AX7. Maybe the QC would be better because of advancements in materials and such. They claimed the tubes would be made on original "Mullard" equipment. It all sounded really good at the time. Now it's like a wet dog in your lap. Doesn't sound good at all. I hope that they get it all under control fast, because the HI FI crowd has a long memory and if your shit is no good, it gets around fast and no one is going to buy your stuff. The original spec sheet listed the tube with a gain of 90 and I said this would be more than acceptable. However, based on the above readings, I would like to have say twenty of the tubes to measure and see how many are above/below the norm. I mean it would be just as big of a bummer if you got some of these tubes and they tested 14-16. I have a feeling that this has probably happened. Those buyers without a tube tester are having to rely on Blackburn to sell them a tube that meets all the requirements. Right now it looks like that isn't happening. Marty __________________ MARTY 2009 Gibson Explorer-Hell Raising Machine 1989 Fender Strat Plus USA 2008 Fender Tele USA 2004 Schecter Elite w/DiMarzio's TSL100 with custom 4x12 cab. TSL122 with Man 'O War Speakers. TSL602 #1 with JBL D123 Speakers and 602 #2 with Altec 417 Speakers. "Oh so sweet my friends." DSL401 #1 with Red Fang Speaker and 401 #2 with JBL D123 Speaker. Tubes: Let's just say they are NOS that kick ass.

07-09-2009, 05:31 PM	#627 (permalink)
MartyStrat54 Senior Member Join Date: Feb 2009 Location: Formerly Phoenix, now north of KC Posts: 2,583	Re: Preamp Tubes? - Who, What, When, Where, Why, and How? Hey Mr. Joe. ^^^Up There^^^ you told Ratt the following: Do not buy any Raytheon 12AX7 Black Plates. They are horrible. Correct me if I'm wrong, but I thought you liked them? Yes, no? If no, please tell me why. Marty __________________ MARTY 2009 Gibson Explorer-Hell Raising Machine 1989 Fender Strat Plus USA 2008 Fender Tele USA 2004 Schecter Elite w/DiMarzio's TSL100 with custom 4x12 cab. TSL122 with Man 'O War Speakers. TSL602 #1 with JBL D123 Speakers and 602 #2 with Altec 417 Speakers. "Oh so sweet my friends." DSL401 #1 with Red Fang Speaker and 401 #2 with JBL D123 Speaker. Tubes: Let's just say they are NOS that kick ass.

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