18w Modern Classic Build

[Bieworm]

yesterday my mod classic started to give light popping sounds. Obviously tube related. Then there was suddenly no sound anymore. The PI tube was a goner. White powder inside the bottle. After replacing that tube and checking voltages everything was crisp and fine again.

1. I hope it was a tube flaw
2. It was a JJ 12AX7 S..
3. I put the same type JJ as a replacement

Now let's wait and see...

I've been avoiding JJs since I had all those troubles with their EL84s. If the top of the tube turns white instead of silver/grey then that usually means the tube is cracked and lost its vacuum seal.

Interesting.. I always loved the JJ for its mellow sound but the quality is less than it used to be. With sovteks you loose finesse, but they sure are sturdy tubes.. always have been very reliable

[JMPGuitars]

Interesting.. I always loved the JJ for its mellow sound but the quality is less than it used to be. With sovteks you loose finesse, but they sure are sturdy tubes.. always have been very reliable

I usually stick with the new production tung-sol and mullard tubes. They sound better than the JJs ever did, and I've never had issues with them.

[Bieworm]

Interesting.. I always loved the JJ for its mellow sound but the quality is less than it used to be. With sovteks you loose finesse, but they sure are sturdy tubes.. always have been very reliable

I usually stick with the new production tung-sol and mullard tubes. They sound better than the JJs ever did, and I've never had issues with them.

I can vouch for that. My TMB tremolo carries those and I'm really really pleased. Compared the classic to the TMB tremolo again today. For me there is no contest.. the TMB is the fav in every way

[colossal]

I can vouch for that. My TMB tremolo carries those and I'm really really pleased. Compared the classic to the TMB tremolo again today. For me there is no contest.. the TMB is the fav in every way

I like the Tung-Sols as well.

FWIW I run mine also on a higher B+ and I like it. It has more headroom that way. In my band I can hardly get any dirt from my classic 18 watt. It's just not happening yet at that volume.
I play my TMB tremolo at practice. Has dirt in abundance...
But I like having a cleaner amp on the side when necessary

Is it the tone of the TMB Trem that you prefer and/or that there is more gain compared to the dual-triode Normal channel? Better suited to your music, guitars, and playing style? Just wondering...

Also, what output transformer did you use in your Classic and what is your EL84 plate voltage?

[Bieworm]

I can vouch for that. My TMB tremolo carries those and I'm really really pleased. Compared the classic to the TMB tremolo again today. For me there is no contest.. the TMB is the fav in every way

I like the Tung-Sols as well.

FWIW I run mine also on a higher B+ and I like it. It has more headroom that way. In my band I can hardly get any dirt from my classic 18 watt. It's just not happening yet at that volume.
I play my TMB tremolo at practice. Has dirt in abundance...
But I like having a cleaner amp on the side when necessary

Is it the tone of the TMB Trem that you prefer and/or that there is more gain compared to the dual-triode Normal channel? Better suited to your music, guitars, and playing style? Just wondering...

Also, what output transformer did you use in your Classic and what is your EL84 plate voltage?

The tonal difference is more appealing on the TMB... more glassy and cardboard like.. more jimi...more crisp. Maybe it's because I can dial in that mid more..
The TMB is raw and raunchy the classic is mellow and smooth. I like that nasty sound more..
On both I use the hammond 1750PA
Plate voltage modern classic is 345V and on the TMB tremolo 358V

[colossal]

Is it the tone of the TMB Trem that you prefer and/or that there is more gain compared to the dual-triode Normal channel? Better suited to your music, guitars, and playing style? Just wondering...

Also, what output transformer did you use in your Classic and what is your EL84 plate voltage?

The tonal difference is more appealing on the TMB... more glassy and cardboard like.. more jimi...more crisp. Maybe it's because I can dial in that mid more..
On both I use the hammond 1750PA
Plate voltage modern classic is 345V and on the TMB tremolo 358V

Interesting. Thanks for the reply. I know what you mean. I built a two channel 18; one side the parallel-triode Normal voicing (might have a couple of tweaks), and the other based on the Lite IIb cascade (similar to the Superlite sans TMB tone stack). The second, cascaded channel is glassy and more "present" in its way. However, I just keep coming back to that Normal channel! There is a throatiness and depth to it, that works so well.

As for the output transformer, the reason I ask is because of some thinking about why some amps have crossover distortion issues and others don't.

[JMPGuitars]

As for the output transformer, the reason I ask is because of some thinking about why some amps have crossover distortion issues and others don't.

Personally I think that comes down to the inconsistency in transformer manufacturing. It has to be a statistics game of what minor variation in the build process makes one OT more sensitive than another. If any manufacturer makes 1000 of a specific OT, how many of them are actually perfect? What do they actually test before releasing them? Just resistance?

We should move this conversation to its own thread though, we've hijacked the OPs thread a bit.

[Bieworm]

Is it the tone of the TMB Trem that you prefer and/or that there is more gain compared to the dual-triode Normal channel? Better suited to your music, guitars, and playing style? Just wondering...

Also, what output transformer did you use in your Classic and what is your EL84 plate voltage?

The tonal difference is more appealing on the TMB... more glassy and cardboard like.. more jimi...more crisp. Maybe it's because I can dial in that mid more..
On both I use the hammond 1750PA
Plate voltage modern classic is 345V and on the TMB tremolo 358V

Interesting. Thanks for the reply. I know what you mean. I built a two channel 18; one side the parallel-triode Normal voicing (might have a couple of tweaks), and the other based on the Lite IIb cascade (similar to the Superlite sans TMB tone stack). The second, cascaded channel is glassy and more "present" in its way. However, I just keep coming back to that Normal channel! There is a throatiness and depth to it, that works so well.

As for the output transformer, the reason I ask is because of some thinking about why some amps have crossover distortion issues and others don't.

I would agree to some point on the use of the normal channel, but only for home use and playing alone. In the band situation it don't deliver like the TMB tremolo. The TMB cuts like a knife and takes over some space in the mix. For me, playing the leads, it's essential. And a big + for the natural OD. I did not use a single OD pedal since I have the TMB tremolo ... big surplus for a lazy dude like me

[Atomicmod]

Is anyone here running NOS vintage tubes in an 18w Modern Classic? I’ve got a complete set of truly NOS vintage Mullards waiting to go in mine...

[JMPGuitars]

Is anyone here running NOS vintage tubes in an 18w Modern Classic? I’ve got a complete set of truly NOS vintage Mullards waiting to go in mine...

Do you also have new production Mullards? I would LOVE to hear a comparison demo.

[Atomicmod]

Do you also have new production Mullards? I would LOVE to hear a comparison demo.

I actually do have a set of the new Mullards... I lucked out about ten years ago and was able to buy up a large quantity of tubes from a retired stereo repair tech. That has allowed me to use vintage tubes in every amp I own. I’ve done lots of comparisons between new and old production for both hifi and guitar use, and the NOS tubes have always been far superior. I’ll post up some photos to show the differences between the internals on the new and vintage Mullards. They are the same tubes in name only. There’s also a good comparison that I found online that goes into great detail about those extreme differences... I’ll hunt that down and post it here...

[Atomicmod]

Here’s that in-depth physical comparison between a modern and a vintage Mullard 12AX7:

https://www.effectrode.com/knowledge-ba ... omparison/

[JMPGuitars]

I actually do have a set of the new Mullards... I lucked out about ten years ago and was able to buy up a large quantity of tubes from a retired stereo repair tech.

I'm definitely looking forward to hearing your comparison demo when your Modern Classic amp is done, and in spec. Don't put those NOS tubes in until the amp is 100%.

[Atomicmod]

I'm definitely looking forward to hearing your comparison demo when your Modern Classic amp is done, and in spec. Don't put those NOS tubes in until the amp is 100%.

No worries there - that exactly why I have some JJs and new Mullards on hand!

[Atomicmod]

Here’s a few you don’t see every day...

[zaphod_phil]

Do you also have new production Mullards? I would LOVE to hear a comparison demo.

I’ll post up some photos to show the differences between the internals on the new and vintage Mullards. They are the same tubes in name only. There’s also a good comparison that I found online that goes into great detail about those extreme differences... I’ll hunt that down and post it here...

Yes, the "new Mullards" are actually relabeled Russian tubes.But they still sound great to me! And I've always been a big fan of NOS tubes (when I can get them at a decent price).

[Atomicmod]

I believe the new Mullards are actually the standard Sovtek tubes relabeled as Mullard.

As an interesting aside, Groove Tubes had an exact copy of the original Mullard EL34 produced for a short period of time in the mid 2000s. Since I work in the guitar industry I spoke at length with a few people in the know about this particular tube - the only reason it’s not being made to this day is that the Chinese factories just will not stick to the design they are being hired to produce. Slowly but surely, the quality starts to drop and within about a year and a half, they are substituting in their own cheaper design. But, if you managed to get some of those first few runs of that particular EL34, you had a true modern reproduction of the classic Mullard.

[JMPGuitars]

I believe the new Mullards are actually the standard Sovtek tubes relabeled as Mullard.

I don't believe that. While I hear a difference which is subjective, I can also consistently measure a difference as well. See my comparison: viewtopic.php?p=243739#p243739

It's possible they're all made in the same place, but they're certainly not the same.

Thanks,
Josh

[Atomicmod]

I don't believe that. While I hear a difference which is subjective, I can also consistently measure a difference as well. See my comparison: viewtopic.php?p=243739#p243739

It's possible they're all made in the same place, but they're certainly not the same.

Thanks,
Josh

It’s my understanding that the Mullard branded versions have tighter tolerances and would represent the cream of the crop of those tubes.

Did you happen to take a look at the physical tear down comparison between a vintage Mullard and a reissue that I posted a few days ago?

[JMPGuitars]

It’s my understanding that the Mullard branded versions have tighter tolerances and would represent the cream of the crop of those tubes.

Did you happen to take a look at the physical tear down comparison between a vintage Mullard and a reissue that I posted a few days ago?

Subjectively (based on personal bias only) I could believe the cream of the crop thing, but the statement is wrong. If you look at my tests, you can see that the Sovteks are actually closer to spec than the Mullards.

I didn't watch the tear down. I'll check it out when I have time. I understand they're not the same, but I like the way the new ones sound, so it doesn't concern me much. I hate the overpriced NOS market. I need an AC701k for a microphone, but I'll never buy one because that $10 tube is $1500 to $2000. "F" that.

Thanks,
Josh