[Audiobliss2]

From the layout of the PCB, it looks like the two front tubes are the output tubes feeding the caps, and the back one is gain, is that correct?

 

[pythagore]

I thought of that , but felt for sure you had checked that. Anyway, good to hear it's fine.
Which one was blown, the one on the pcb, or the main.

The one on the PCB motherboard. What threw me off is the fact that all 4 tubes turned on fine, and the left channel was fine at low volume. I did a continuity test everywhere but the fuse.

 

[pythagore]

From the layout of the PCB, it looks like the two front tubes are the output tubes feeding the caps, and the back one is gain, is that correct?

Correct, the front two are the pre-amp tubes, the third is the gain.

 

[Bkido]

My two favorite tube combinations are Philips E80CC SQ with a Brimar 12AU7 as cathode follower and Sylvania 12SN7 Bad Boys with a GE 12SN7 as cathode follower. As caps I'm running Mundorf supreme aluminium oil 2.2. . Rectifier is a Emission Labs 274B mesh. Very happy with how it sounds.

 

[Audiobliss2]

Changed the feet. The other setup made the preamp prone to tilting in the rear.
I was pleasantly surprised to see that treaded holes were provided in the rear, although it came with just the one spike foot in the rear.
That rear one is sealed tight not to be removed it seems.

 

[pythagore]

I change all 3 signal tubes to the same Genalex Gold Lion 6922, the Voshkod 6H23n tube is too good of a tube on its own to be doing backup (singer ) for the 6922. Although I can put a different tube in the back, since the back tube is simply for the output gain/impedance stage, but I'll keep all three tubes the same.
One thing worth mentioning, when I was debugging my unit, I noticed that the 6.8uF power filter cap is in parallel with the big power supply electrolytic caps, which means this cap is actually being used as a bypass to the electrolytic caps.

 

[Bkido]

Changed the feet. The other setup made the preamp prone to tilting in the rear.
I was pleasantly surprised to see that treaded holes were provided in the rear, although it came with just the one spike foot in the rear.
That rear one is sealed tight not to be removed it seems.

I've got mine on 4 Isoacoustics Orea Indigo. They don't mount to the device, so I've not bothered with removing the stock feet yet.

 

[Audiobliss2]

My two favorite tube combinations are Philips E80CC SQ with a Brimar 12AU7 as cathode follower and Sylvania 12SN7 Bad Boys with a GE 12SN7 as cathode follower. As caps I'm running Mundorf supreme aluminium oil 2.2. . Rectifier is a Emission Labs 274B mesh. Very happy with how it sounds.

That's a big tube, it must light up the room. You definitely need a top shelf for that.

 

[pythagore]

Amazing how different two rectifiers can make this pre-amp sound.
Svetlana 5C3S: Extremely.... detailed sounding, huge(bowling alley-like) sound stage, beautiful and really forward mid-range, but light on bass a bit.
RCA 5U4G: Detailed but slightly warm sounding, a little bit recessed mid-range and sound stage compared to the Svetlana tube, excellent/tight bass performance. I love this tube, but I wish it had the mid-range and sound stage of the Svetlana 5C3S.

If I can find a way to solve the bass problem of the 5C3S, then that would be my rectifier of choice going forward. I will swap some Mundorf caps to see if that solves the bass problem.

 

[Audiobliss2]

So how are the Gold Lions 6922s doing ? Are they keepers. I thought I had a set but they are 12ax7s I had used in my last McIntosh preamp.

I also have a bunch of 5u4g , but they are just too tall for where I am using the preamp. I have some smaller 5u4gb, but from what I remember trying them in my other amps, they were very strong in the bass, which I also don't need.

 

[pythagore]

So how are the Gold Lions 6922s doing ? Are they keepers. I thought I had a set but they are 12ax7s I had used in my last McIntosh preamp.

I also have a bunch of 5u4g , but they are just too tall for where I am using the preamp. I have some smaller 5u4gb, but from what I remember trying them in my other amps, they were very strong in the bass, which I also don't need.

There are not much difference between the Gold Lion 6922s and the Voshkod 6H23s, I love both. They are very similar sounding. Extended clarity, sweet mid-range, and huge sound stage. However, the 6H23s provide slightly bit deeper lows, while the 6922s provide slightly bit higher, more shimmering highs.

 

[Yoram Diamand]

Hi, I have a question: There are Class A tube preamps, but nowhere I saw the class of the MP 701, if not A what do you have for preamps? If I'd compare the 701 with a WBA Blaze bird Class A preamp what would you expect? They are approximately in the same price group.

 

[jasonh33]

My two favorite tube combinations are Philips E80CC SQ with a Brimar 12AU7 as cathode follower and Sylvania 12SN7 Bad Boys with a GE 12SN7 as cathode follower. As caps I'm running Mundorf supreme aluminium oil 2.2. . Rectifier is a Emission Labs 274B mesh. Very happy with how it sounds.

My two favorite tube combinations are Philips E80CC SQ with a Brimar 12AU7 as cathode follower and Sylvania 12SN7 Bad Boys with a GE 12SN7 as cathode follower. As caps I'm running Mundorf supreme aluminium oil 2.2. . Rectifier is a Emission Labs 274B mesh. Very happy with how it sounds.

I really like what you've done with this.How did you get the signal tubes to be so much more visible?

 

[Bkido]

I really like what you've done with this.How did you get the signal tubes to be so much more visible?

Thanks. I'm using 6sn7 -> 6922 adapters (adapters on ebay) to go from 8 pin octal to 9 pin of the pre. This lifts the sockets. The adapter also work at 12v with my 12sn7 sylvania bad boys that i'm currently running.

 

[jasonh33]

Thanks. I'm using 6sn7 -> 6922 adapters (adapters on ebay) to go from 8 pin octal to 9 pin of the pre. This lifts the sockets. The adapter also work at 12v with my 12sn7 sylvania bad boys that i'm currently running.

Thanks for the reply.Will definitely look for those.