[Happy Camper]

There is a real need for us new to the SP amps to have a tube and adapter guide for each lineup. Nothing comes with the amps. I suppose you call SP for information but this seems wasteful on SPs time and our phone bills. Earl and others are very helpful but they are doing SPs job of educating us.

The adapters are ECC 1,2, which one is for the 2c51? If head-fi is the school of tubes for SP, can we get a good definition page? I know this is a whine, but it's frustrating to want to try different tubes but afraid to damage the amp because of ingorance. Consider it a cry for help. I believe more would try these wonderful amps if there were better sources of education from SP.

Here is the Extreme ad:

In addition to the stock driver, you can also use a NOS 6SN7, 6SL7, 6188, 6SU7GTY. With optional ECC type 1 adapters you may implement the 12AT7, 12AU7, 5814, 5965, 6414, 6829, and 7062. Or, our ECC type 2 adapters are also available for the 6ES8, 6DJ8, 6922; 6DJ4, 6DJ8, ECC189, ECC88, E88CC; and Osram PCC88. Our third adapter type will allow for the implementation of the 5687, ECC182, and 7119. Other adapters available include 6CG7/6FQ7, 6GU7, and another for the 6350 and 6463.

Output tubes

The following NOS output tubes are available additionally for purchase: Raytheon 6080; GE 6080; Bendix 6080, 7802; RCA 6AS7; Tung-Sol 6080, 7236, 2399; IBM 5998(straight bottle), and Tung-Sol 5998(shoulder type).

Perhaps one for the MPX, PPX, Supra, etc.

These amps are top tier and should be heard if possible when deciding on a purchase. There are few equals.

 

[Skylab]

Quote:

Originally Posted by Von Soundcard /img/forum/go_quote.gif But can it be used for this headphone amp ? And if so is it practical with most good phones (Senn, AKG, AT etc.) ? Perhaps variants of the tube that are more powerful (6SN7xxx or equivalents) ? If so you could have and all round 6SN7 MPX3 (input and output), which is a musical idea That is unfortunate. I would still like to know what are the differences between the Extreme's families of tubes (like the 6AS7, 5998, 7236) and MPX's tubes (5687, 6bl7, 6bx7).

Indeed, unless I am mistaken, the MPX comes with 6SN7GTB's as both the driver and output tubes, so you can have an all 6SN7 line-up in that amp. Some headphones might require more output, I suppose, but I have not tried an MPX so I cannot say. The Extreme using 6AS7's or 5998's certainly has more output power than one could ever need - I cannot even get to 9:00 on the volume pot with 600 ohm DT990's

 

[hailmetal]

enjoy!

 

[fongalv]

Hi,

I too have recently been lucky enough to come into the possession of a MPX3 Slam from a fellow Head-fier, tho due to some unforseen circumstances, it has been sitting there unused until I can break open the worn out and rusty screws to remove some loose nuts inside the enclosure.

My set came with a LARGE bunch(~30) of tubes too, and while I was reading up on the 6SN7 variants, came across this: Translated version of http://www.avclub.gr/forum/showthread.php?t=4376

It might be an old thread, but it offers quite a bunch of information on the "main" tubes for the MPX3 Slam, the 6SN7 and its varients, which you can use as reference.

As for the various adapters you have, the "slam" ones should be the ones which have 9pins on the topside meant for the the 5687.

 

[sacd lover]

Here you go....

Base PPX3-6CG7

Gain tube 6CG7/ Output tube 6CG7

Main Substitute: 6GU7

PPX3 SLAM

Gain tube 9 pin mini socket:6CG7 .... some versions have an upgraded octal socket and use the 6SN7GT.

Main Gain tube Substitute: 6GU7

Output tube: 5687

Main Output tube Substitues .... 6900 (extremely expensive and not really designed to work well at 300 volts) and the 7044 /7119.

Gain tube adapters for octal tube socket version ....

Loctal 7N7 .... replaces 6SN7GT with 7N7 (three construction types) or 7AF7 short bottle round plate.

ECC type#1: replaces 6SN7GT with 12AU7/ 5814A etc...,12AV7/ 5965/6414/6829/7062, 12AT7/6201 and 12AZ7A. There are other tubes that have this pinout but most have to much voltage gain.

ECC type#2: replaces 6SN7GT with 6CG7/6GU7/6DJ8/6922 and several others like the 6BK7/ 6BZ7/6BZ8/6FW8 etc....

2C51 adapter .... replaces 6SN7GT with the 2C51/ 5670/ WE396A/ 6385/ 6854

MPX3-6SN7

Gain tube: 6SN7GT/ Output tube 6SN7GT

Main Substitute ....ECC32 (hard to find and expensive) and 7N7 using an adapter.

This amp will do fine with 7N7's or ECC32's in either position. Some of the higher VOLTAGE gain input tubes used in the ECC type #1 and #2 may have to much gain and cause low level hum when the signal is muted. 6BL7GT/A and 6bx7gt tubes will work for output duty .... but they will not be optimally biased and will not perform at anywhere near their potential. These 6BL7GT/A types do work ok, not great, for low impedence headphones due to their lower output impedence.

MPX3 SLAM

Gain tube:6SN7GT

Output tube: 5687 .... some have 9 pin mini sockets and you can use only 5687's. Some with octal sockets use adapters for the 5687's and allow you to use

Main Output tube Substitues .... 6900 (extremely expensive and not really designed to work well at 300 volts) and the 7044 /7119.

Gain tube adapters ....

Loctal 7N7 .... replaces 6SN7GT with 7N7 (three construction types) or 7AF7 short bottle round plate.

ECC type#1: replaces 6SN7GT with 12AU7/ 5814A etc...,12AV7/ 5965/6414/6829/7062, 12AT7/6201 and 12AZ7A. There are other tubes that have this pinout but most have to much voltage gain.

ECC type#2: replaces 6SN7GT with 6CG7/6GU7/6DJ8/6922 and several others like the 6BK7/ 6BZ7/6BZ8/6FW8 etc....

2C51 adapter .... replaces 6SN7GT with the 2C51/ 5670/ WE396A/ 6385 and 6854.

MPX3 SLAM SE

Gain tube:6SN7GT

Output tube: 6SN7GT @ LOW VOLTAGE, 5687 with adapter @ LOW VOLTAGE or 6BL7GT/A and 6BX7GT @ HIGH VOLTAGE. Some later MPX3 SLAM SE's can accept either tube and do not have a high/ low voltage switch because of a "universal bias (my term).

Gain tube adapters ....

Loctal 7N7 .... replaces 6SN7GT with 7N7 (three construction types) or 7AF7 short bottle round plate.

ECC type#1: replaces 6SN7GT with 12AU7/ 5814A etc...,12AV7/ 5965/6414/6829/7062, 12AT7/6201 and 12AZ7A. There are other tubes that have this pinout but most have to much voltage gain.

ECC type#2: replaces 6SN7GT with 6CG7/6GU7/6DJ8/6922 and several others like the 6BK7/ 6BZ7/6BZ8/6FW8 etc....

2C51 adapter .... replaces 6SN7GT with the 2C51/ 5670/ WE396A/ 6385 and 6854.

Supra-6SN7GT/ Supra SLAM / Supra SLAM SE

All the same configurations listed for the MPX3 work with the Supra. Again, some Supra's are setup for 6SN7GT X3, some using 6SN7GT/ 5687 with adapters .... and some with the high voltage option will use 6BL7GT/A and 6BX7GT's. Just understand what version you have.

Gain tube:6SN7GT

Output tube: 5687 with adapter @ LOW VOLTAGE or 6BL7GT/A and 6BX7GT @ HIGH VOLTAGE. Some later MPX3 SLAM SE's can accept either tube because of a "universal bias (my term).

Gain tube adapters ....

Loctal 7N7 .... replaces 6SN7GT with 7N7 (three construction types) or 7AF7 short bottle round plate.

ECC type#1: replaces 6SN7GT with 12AU7/ 5814A etc...,12AV7/ 5965/6414/6829/7062, 12AT7/6201 and 12AZ7A. There are other tubes that have this pinout but most have to much voltage gain.

ECC type#2: replaces 6SN7GT with 6CG7/6GU7/6DJ8/6922 and several others like the 6BK7/ 6BZ7/6BZ8/6FW8 etc....

2C51 adapter .... replaces 6SN7GT with the 2C51/ 5670/ WE396A/ 6385 and 6854.

The gain tubes you can use will again depend on the amp vintage and gain structure. Some higher voltage gain input tubes may overdrive the output stage and cause hum in older units.

Extreme

Gain: 6SN7GT

Output tube:6AS7G/5998/6080 and some rare types like the 2399. Some Extremes are set up to use higher power tubes like the 6528. The higher power tubes use tubes with much higher heater current draw, example 6AS7G =2.5 amps vs the 6528 = 5.0 amps of heater current draw. Make sure you know what type of Extreme you have. The newer Extreme's have a seperate power supply for the high power tubes.

Gain tube adapters ....

Loctal 7N7 .... replaces 6SN7GT with 7N7 (three construction types) or 7AF7 short bottle round plate.

ECC type#1: replaces 6SN7GT with 12AU7/ 5814A etc...,12AV7/ 5965/6414/6829/7062, 12AT7/6201 and 12AZ7A. There are other tubes that have this pinout but most have to much voltage gain.

ECC type#2: replaces 6SN7GT with 6CG7/6GU7/6DJ8/6922 and several others like the 6BK7/ 6BZ7/6BZ8/6FW8 etc....

2C51 adapter .... replaces 6SN7GT with the 2C51/ 5670/ WE396A/ 6385 and 6854.

The Extreme's 6AS7G type output tubes have a very low mu/ gain of 2. I find the higher voltage tubes seem to bring the amp to life dynamically. But the ECC32 and 6GU7 are lower gain and work very well.

I wrote this of the top of my head so excuse any omissions. I realized right away I didnt mention any Russian tubes. The best examples are PROBABLY the 6N1P subbing for the 6CG7/6GU7 .... and the 6N3P subbing for the 2C51.

 

[Voltron]

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
That was really cool of you to do that Earl. Nice, concise work that will really help people and prevent a lot of searching.

Cheers.

 

[Von Soundcard]

Very nice of you SACD to impart on us some of that substantial wisdom

However could you elaborate on these issues for the MPX3 SE (also relevant for the other models):

Quote:

Originally Posted by sacd lover /img/forum/go_quote.gif MPX3 SLAM SE Gain tube:6SN7GT

Does this mean that practically all 6SN7 equivalents (which are a lot) can work as a gain tube ?

Quote:

Originally Posted by sacd lover /img/forum/go_quote.gif Output tube: 6SN7GT @ LOW VOLTAGE, 5687 with adapter @ LOW VOLTAGE or 6BL7GT/A and 6BX7GT @ HIGH VOLTAGE. Some later MPX3 SLAM SE's can accept either tube and do not have a high/ low voltage switch because of a "universal bias (my term).

Is that the "12 V option" or some other upgrade from SP ? Can it be implemented on older MPXes ?
Quote:

Originally Posted by sacd lover /img/forum/go_quote.gif Gain tube adapters .... Loctal 7N7 ... ECC type#1 ... ECC type#2 ... 2C51 adapter

You only mention adapters for gain tubes. However since the gain tube is supposedly compatible with the output tube do these adapters also work in the output tube position ? That is to say, does the MPX SE allow for the same diversity of output tubes as for the input ?
(If not by standard perhaps with some minor upgrades from Singlepower ?)

 

[vberch]

Earl, I am going to print it out and make a poster out of it!

Thanks!!

Quote:

Originally Posted by sacd lover /img/forum/go_quote.gif Here you go.... Base PPX3-6CG7 Gain tube 6CG7/ Output tube 6CG7 Main Substitute: 6GU7 PPX3 SLAM Gain tube 9 pin mini socket:6CG7 .... some versions have an upgraded octal socket and use the 6SN7GT. Main Gain tube Substitute: 6GU7 Output tube: 5687 Main Output tube Substitues .... 6900 (extremely expensive and not really designed to work well at 300 volts) and the 7044 /7119. Gain tube adapters for octal tube socket version .... Loctal 7N7 .... replaces 6SN7GT with 7N7 (three construction types) or 7AF7 short bottle round plate. ECC type#1: replaces 6SN7GT with 12AU7/ 5814A etc...,12AV7/ 5965/6414/6829/7062, 12AT7/6201 and 12AZ7A. There are other tubes that have this pinout but most have to much voltage gain. ECC type#2: replaces 6SN7GT with 6CG7/6GU7/6DJ8/6922 and several others like the 6BK7/ 6BZ7/6BZ8/6FW8 etc.... 2C51 adapter .... replaces 6SN7GT with the 2C51/ 5670/ WE396A/ 6385/ 6854 MPX3-6SN7 Gain tube: 6SN7GT/ Output tube 6SN7GT Main Substitute ....ECC32 (hard to find and expensive) and 7N7 using an adapter. This amp will do fine with 7N7's or ECC32's in either position. Some of the higher VOLTAGE gain input tubes used in the ECC type #1 and #2 may have to much gain and cause low level hum when the signal is muted. 6BL7GT/A and 6bx7gt tubes will work for output duty .... but they will not be optimally biased and will not perform at anywhere near their potential. These 6BL7GT/A types do work ok, not great, for low impedence headphones due to their lower output impedence. MPX3 SLAM Gain tube:6SN7GT Output tube: 5687 .... some have 9 pin mini sockets and you can use only 5687's. Some with octal sockets use adapters for the 5687's and allow you to use Main Output tube Substitues .... 6900 (extremely expensive and not really designed to work well at 300 volts) and the 7044 /7119. Gain tube adapters .... Loctal 7N7 .... replaces 6SN7GT with 7N7 (three construction types) or 7AF7 short bottle round plate. ECC type#1: replaces 6SN7GT with 12AU7/ 5814A etc...,12AV7/ 5965/6414/6829/7062, 12AT7/6201 and 12AZ7A. There are other tubes that have this pinout but most have to much voltage gain. ECC type#2: replaces 6SN7GT with 6CG7/6GU7/6DJ8/6922 and several others like the 6BK7/ 6BZ7/6BZ8/6FW8 etc.... 2C51 adapter .... replaces 6SN7GT with the 2C51/ 5670/ WE396A/ 6385 and 6854. MPX3 SLAM SE Gain tube:6SN7GT Output tube: 6SN7GT @ LOW VOLTAGE, 5687 with adapter @ LOW VOLTAGE or 6BL7GT/A and 6BX7GT @ HIGH VOLTAGE. Some later MPX3 SLAM SE's can accept either tube and do not have a high/ low voltage switch because of a "universal bias (my term). Gain tube adapters .... Loctal 7N7 .... replaces 6SN7GT with 7N7 (three construction types) or 7AF7 short bottle round plate. ECC type#1: replaces 6SN7GT with 12AU7/ 5814A etc...,12AV7/ 5965/6414/6829/7062, 12AT7/6201 and 12AZ7A. There are other tubes that have this pinout but most have to much voltage gain. ECC type#2: replaces 6SN7GT with 6CG7/6GU7/6DJ8/6922 and several others like the 6BK7/ 6BZ7/6BZ8/6FW8 etc.... 2C51 adapter .... replaces 6SN7GT with the 2C51/ 5670/ WE396A/ 6385 and 6854. Supra-6SN7GT/ Supra SLAM / Supra SLAM SE All the same configurations listed for the MPX3 work with the Supra. Again, some Supra's are setup for 6SN7GT X3, some using 6SN7GT/ 5687 with adapters .... and some with the high voltage option will use 6BL7GT/A and 6BX7GT's. Just understand what version you have. Gain tube:6SN7GT Output tube: 5687 with adapter @ LOW VOLTAGE or 6BL7GT/A and 6BX7GT @ HIGH VOLTAGE. Some later MPX3 SLAM SE's can accept either tube because of a "universal bias (my term). Gain tube adapters .... Loctal 7N7 .... replaces 6SN7GT with 7N7 (three construction types) or 7AF7 short bottle round plate. ECC type#1: replaces 6SN7GT with 12AU7/ 5814A etc...,12AV7/ 5965/6414/6829/7062, 12AT7/6201 and 12AZ7A. There are other tubes that have this pinout but most have to much voltage gain. ECC type#2: replaces 6SN7GT with 6CG7/6GU7/6DJ8/6922 and several others like the 6BK7/ 6BZ7/6BZ8/6FW8 etc.... 2C51 adapter .... replaces 6SN7GT with the 2C51/ 5670/ WE396A/ 6385 and 6854. The gain tubes you can use will again depend on the amp vintage and gain structure. Some higher voltage gain input tubes may overdrive the output stage and cause hum in older units. Extreme Gain: 6SN7GT Output tube:6AS7G/5998/6080 and some rare types like the 2399. Some Extremes are set up to use higher power tubes like the 6528. The higher power tubes use tubes with much higher heater current draw, example 6AS7G =2.5 amps vs the 6528 = 5.0 amps of heater current draw. Make sure you know what type of Extreme you have. The newer Extreme's have a seperate power supply for the high power tubes. Gain tube adapters .... Loctal 7N7 .... replaces 6SN7GT with 7N7 (three construction types) or 7AF7 short bottle round plate. ECC type#1: replaces 6SN7GT with 12AU7/ 5814A etc...,12AV7/ 5965/6414/6829/7062, 12AT7/6201 and 12AZ7A. There are other tubes that have this pinout but most have to much voltage gain. ECC type#2: replaces 6SN7GT with 6CG7/6GU7/6DJ8/6922 and several others like the 6BK7/ 6BZ7/6BZ8/6FW8 etc.... 2C51 adapter .... replaces 6SN7GT with the 2C51/ 5670/ WE396A/ 6385 and 6854. The Extreme's 6AS7G type output tubes have a very low mu/ gain of 2. I find the higher voltage tubes seem to bring the amp to life dynamically. But the ECC32 and 6GU7 are lower gain and work very well. I wrote this of the top of my head so excuse any omissions. I realized right away I didnt mention any Russian tubes. The best examples are PROBABLY the 6N1P subbing for the 6CG7/6GU7 .... and the 6N3P subbing for the 2C51.

 

[guzziguy]

Hey Earl, thanks. This is a very useful piece of work that really isn't available anywhere else. It's too bad that it's not on the SP web site (along with other updated information

). I quickly made a Word doc and attached.

 

[Skylab]

Agreed, incredibly helpful!

Note that for the SP Extreme, as listed above, the Driver tube can be 6SN7, ECC32, 6SL7, 6188, or 6SU7GTY, and the Output tube can be 7236's in addition to the 6AS7/6080/5998. Those are the available choices on the stock Extreme, with no adapters.

 

[sacd lover]

Quote:

Originally Posted by Von Soundcard /img/forum/go_quote.gif Very nice of you SACD to impart on us some of that substantial wisdom Does this mean that practically all 6SN7 equivalents (which are a lot) can work as a gain tube ? Is that the "12 V option" or some other upgrade from SP ? Can it be implemented on older MPXes ? You only mention adapters for gain tubes. However since the gain tube is supposedly compatible with the output tube do these adapters also work in the output tube position ? That is to say, does the MPX SE allow for the same diversity of output tubes as for the input ? (If not by standard perhaps with some minor upgrades from Singlepower ?)

1) Thank you!

2) Yes .... the 6SN7GT/6SN7GTA/6SN7GTB and the loctal 7N7+ adapter, which is essentially a Sylvania VT-231 or early 1950's 6SN7GT or 6SN7GTA/B (depending on the 7N7's vintage) .... will all work.

3) No that is different. The 12 volt option has an added 12 volt transformer + outboard power supply that powers the 12 volt heaters so you can use 12SN7GT's. Why 12SN7GT's? Because they are the identical tubes to the highly sought after and expensive 6SN7GT's .... but they cost pennies on the dollar. With adapters @ 12 volts I also use 12FQ7's and 14N7's for gain. Plus, I have some 5687 adapters wired for 12 volts to run the 5687's @ 12 volts. Why run the 5687 @ 12 volts? My original amp had all three sockets wired for 6 or 12 volts .... you cant mix and match the voltage .... so all three tubes have to operate at the same voltage. Some newer amps allow mixing the gain and output tube voltages (6 or 12 volts) by using two outboard power supplies.

Moreover, DC heaters like the SP's use are quieter with higher voltage / lower current operation.

6SN7GT: 6.3 volt operation / 0.6 amps heater current
vs
12SN7GT: 12.6 volts operation / 0.3 amps heater current

.... see the relationship?

Beware complicated answer.

The SLAM SE originally had a high 400 volt/low 300 volt switch to set the amps high voltage B+ supply. The 6BL7GTA will run at voltages/ plate current that will burn up a 6SN7GT or 5687 in a few minutes. SP then found an auto-bias setting that would allow any of those three tubes to work in the most recent versions. My first production amp ran the 6BL7GTA @ 425 or 300 volts and had a switchable manual bias to select 30/40/55 or 70 ma's plate current. The new version limits the amp to a single voltage of around 350-370 volts and 20 something ma plate current .... and there is no switching.


4) Some gain tubes are compatible as output tubes; not all.

The gain tubes that are not compatible dont have enough power to effectively drive headphones. The current output is to low and the impedence to high for those tubes.

Examples: 2C51/5670, 12AV7/5965/6414/6829/7062, 12AZ7, 6BZ7/6DJ8 etc...

5) Output Tubes that can do both gain or output duty are .... 6CG7/ 6GU7/ 6SN7GT-A-B / 7N7 / 12BH7 / 5687 / 6350 / 7119. 6463's and 7044's will work but both tubes are typically very microphonic for gain use.

 

[Von Soundcard]

Thanks again for the in-depth and very informative answer. I was about to mention that we need a MPX tuberolling thread and you've pretty much covered the basics

From no. 3 I gather that practically high and low voltage will work on output for any version, either by auto-bias or by (adding) a switch in older models. Which is good...
Also 4 says that practically all 6sn7 work on output, it's just that some are not up to the task. But they will not blow the thing up or anything... Which is also good

Another thing, considering these options would it be fair to say that generally while the Extreme may have more punch, guts, raw and 'pure' power (as it were) the MPX is more refined, offers more nuances and possibly a more complete sound (when using the best tubes) ?

 

[sacd lover]

Quote:

Originally Posted by Von Soundcard /img/forum/go_quote.gif Another thing, considering these options would it be fair to say that generally while the Extreme may have more punch, guts, raw and 'pure' power (as it were) the MPX is more refined, offers more nuances and possibly a more complete sound (when using the best tubes) ?

I dont know I would go as far as to say more complete; generally more refined yes. Conversely, I also dont know I would say the Extreme has more punch. The bass weight of the MPX3 assisted by the MPX3's richer tonality can be very impactful. Given you want a richer sound, between the two, I suspect you would prefer the MPX3. The problem giving you an answer here is the tubes in use can make such a big difference with the tonality.

You can tube an Extreme to sound quite rich. But, so far, I have never had a tube set in the Extreme sound as rich as the MPX3 when the MPX3 is also using warmer sounding tubes.

If you want rich, the MPX3, with good 6SN7GT's x 3 and the Senn 580/600/650, is rich, atmospheric and tubey sounding. Furthermore, 6SN7GT's have plenty of power/ voltage for the high impedence Senns. I would not recommend 6SN7GT's for output tubes, with low impedence headphones, especially if you like to juice the volume.

 

[sacd lover]

Quote:

Originally Posted by guzziguy /img/forum/go_quote.gif Hey Earl, thanks. This is a very useful piece of work that really isn't available anywhere else. It's too bad that it's not on the SP web site (along with other updated information ). I quickly made a Word doc and attached.

You know what, I have answered these questions many, many times .... and I agree the info always seems to get buried. So, I sent SP an email with this info to use for their website.

 

[Von Soundcard]

Is the MPX3 (SE or not) close to the Extreme in terms of flexibility, meaning the differences in sound you can obtain by changing tubes ? I ask this because I read the Extreme is a very flexible amplifier which can supposedly alter its sound greatly with different tube sets.