5670 driver tube rolling options

[fritzthecat]

just researched a little bit regrading the 5670 driver tubes - actually they are very cheap and I asked myself what the impact of these regarding the sonic performance of the whole Kaiju amplifier is? I never heard of these tubes before. If I'd like to do some tube rolling here - would it actually be worth it at all and if, which producers and which types to go after?

I am aware that the impact of the in-/output caps is much bigger - but nevertheless I am just interested to get to know more for the sake of it....;o)

[Paul Joppa]

The original Paramount used a 12AT7 driver. With the soft-start circuit I needed to make the driver plate voltage trimmable, which required a tube with a bit less gain. Of the ones I looked at, the 5670 was the most linear so I chose it. As a plus, it is usually a premium tube with high reliability and good cathode metallurgy. Second best was the 5965.

Don't let the price fool you, this is an excellent tube. If you want to spend more, you can find some WE 396 types which was the original version of this type. The Type 2C51 is another version, and I think there's a Russian version as well. Doc B has tried many, and the last I heard he did not think any of the others sound as good as the GE 5-star 5670. That's what I have in my personal Paramounts.

The design is flexible enough to substitute many other possible drivers; several people have even put in 6SN7s, which have 6dB less gain but are well liked for audio purposes. You may find some more information on the Paramount forum, under the Legacy Products sub-forum.

[fritzthecat]

Great! I am not that experienced yet with tube circuits - still very basic but it is really amazing how interesting this all is and I want to learn as much as possible about tube circuit design. thank you for aanswering all my questions, I'll keep on asking...:-)

[fritzthecat]

The original Paramount used a 12AT7 driver. With the soft-start circuit I needed to make the driver plate voltage trimmable, which required a tube with a bit less gain. Of the ones I looked at, the 5670 was the most linear so I chose it. As a plus, it is usually a premium tube with high reliability and good cathode metallurgy. Second best was the 5965.

Don't let the price fool you, this is an excellent tube. If you want to spend more, you can find some WE 396 types which was the original version of this type. The Type 2C51 is another version, and I think there's a Russian version as well. Doc B has tried many, and the last I heard he did not think any of the others sound as good as the GE 5-star 5670. That's what I have in my personal Paramounts.

The design is flexible enough to substitute many other possible drivers; several people have even put in 6SN7s, which have 6dB less gain but are well liked for audio purposes. You may find some more information on the Paramount forum, under the Legacy Products sub-forum.

Hi Paul - that's what I learned so far regarding tubes and pricing - as you say - don't let the price fool you...;o) I have some GE 5-star 5687 in my ANK L4 preamp and they sound great. What do you think would be an appropriate price for GE 5-Star 5670 tubes?

Regarding the GE 5-star tubes there are at least white and red labelled versions - I do have the white 5687 - do you know if there is any difference? I only heard, that the red ones have been origninally produced for the miilitary while the white ones are selected versions from the normal production and just labelled 5 star.

A question regarding the paramount monos: Why did BH decide to discontinue these? Shame I did not know about Bottlehead when it still was available. But I guess the Kaijus are a good choice as well.

I am planning to replace the L4 preamp with a Bee preamp - how is the situation regarding the tubes - do you as well recommend the EH 300b for these as the best sounding ones? What else could one try with the Bee pre? I am looking for a new home for my PSVane 300b-N (I think they should work as they meet the original specs - but am not sure - so I rather ask...;o)

[Paul Joppa]

I'm the wrong person to answer such detailed tube-rolling questions. Hopefully someone more up-to-date will join the conversation.

The Paramount first appeared in 2005, and we had a collection of things we wanted to change. Most are minor; the big audible change is the larger plate choke and output transformer. One motive for going to a stereo amp is that they can be bridged to make a 16 watt monoblock. Many other changes are small, for example replacing some capacitors that were in a discontinued format.

[bombay317]

I came across some WE 396A / 2C51 that I plan on rolling through my system.  I am looking forward to see how they sound in comparison to the stock ones shipped with the unit.

[Adrian]

I use WE 396s in my Paramounts and find these to be a very nice substitute.

[Paul Birkeland]

I only use the WE tubes when I have someone coming over who loves all things WE.  TBH, the GE 5 star 5670s are very nice sounding tubes.

[Doc B.]

I'm with PB on this. In general WE tubes have a house sound that is slightly mid-centric. In my limited experience this is true for 300Bs, 417As, 437As, 396As, etc.,etc. If that is where you live they are great, vocals can be wonderful. My preference tends towards a bit more neutral presentation - not that that is better or worse. For that the GEs and other 5670s as well as Soviet 2C51s can be pretty nice. It's not too expensive an experiment to try both and see which you prefer.

[Raymond P.]

Resurrecting this thread to give my brief thoughts on the 5670 vs WE 396A tubes which I recently compared.


Between the two I much prefer the 5670. My main objection to the 396A is it has a "shouty-ness" nature, especially in female vocals. That characteristic is very difficult to listen to. In the bass region, the 396A is lacking there, even in the upper bass, which might contribute to its shouty-ness. The treble seems fine to me, although it doesn't have that bit of "airiness" the 5670 can create with some songs.


Like Doc said, the 5670 has a more neutral presentation. Bass is tight and hits fast (at least in my setup.) Treble is detailed, but not shrilling. Vocals sound natural with a  nice bit of richness.


I have a pair of 6N3P's coming in, and I'll give an update on that after some listening.

[Paul Joppa]

Be aware that the maximum plate voltage rating of the 6n3p is 160v, whereas the 5670 is rated for 330v. In Kaiju, the regulator section runs at 300v, and the amplifier section at 175v. Use of the 6n3p will risk failure of the tube and collateral damage to other parts of the amp.

Corrected - see the posts below.

[Raymond P.]

Be aware that the maximum plate voltage rating of the 6n3p is 160v, whereas the 5670 is rated for 330v. In Kaiju, the regulator section runs at 300v, and the amplifier section at 175v. Use of the 6n3p will risk failure of the tube and collateral damage to other parts of the amp.

Thanks for that critical piece of info, PJ. I thought the 6n3p was just a Russian copy of the 5670, but maybe not.

[Raymond P.]

Did some googling and found that there are variations of the 6n3p - 6n3p, 6n3pi, and 6n3pe. 6n3p and 6n3pi have max plate voltage ratings of 300V, while the 6n3pe has a rating of 160V. So now I need to double check which is the version I bought.

[Paul Birkeland]

Just rub the "E" off the glass if you happen to have them.   

[Paul Joppa]

Did some googling and found that there are variations of the 6n3p - 6n3p, 6n3pi, and 6n3pe. 6n3p and 6n3pi have max plate voltage ratings of 300V, while the 6n3pe has a rating of 160V. So now I need to double check which is the version I bought.

Good lord - that possibility never even occurred to me!