Modwright DM36.5 Tube Rolling

[Audiocom AV]

Any Modwright LS 36.5 or DM36.5 pre-amp owners here?

I have been using the DM36.5 two box pre-amp for the past few months and decided to try out some of the more esoteric tubes. For those not familiar with the design, the pre uses a pair of the 6H30’s and the dual mono power supply has 2x 5U4GB (rectifiers) and 6AE7’s (regulation).

Starting with the 6H30’s, the stock tubes are the Electro-Harmonix 6H30-Pi Gold. I exchanged these for a matched pair of the Reflektor 6H30-DR purchased from thetubestore.com (great service from Jon). Considering the near 10x price hike I had high hopes, and was not disappointed. The improvement is very impressive; improved bass, clarity, openness, dynamics, PRAT and punch.

Next is the 5U4GB’s, I have two different types to try here, a matched pair of Mullard GZ34 Metal Base, and Tung-Sol 5U4GB. This will all happen in the next few weeks if anyone is interested I will post my comments here.

Cheers,
Mark

[Pete]

Hi Mark,

I have the LS36.5 DM. I too have the 6H30-DRs and they are nice.

I just put in Sylvania 5U4GBs and they killed the two Mullard 5AR4 f32 that I had in there. And they cost about $15 ea NOS :) They are staying in. Not sure I would go back to any 5AR4 again, and not willing to spend a fortune for metal base 5AR4s to find out.

I would investigate a good power cable. Also Dan Wright does not recommend changing the 6AE7’s

Cheers
Pete

[Audiocom AV]

Hi Mark,

I have the LS36.5 DM. I too have the 6H30-DRs and they are nice.

I just put in Sylvania 5U4GBs and they killed the two Mullard 5AR4 f32 that I had in there. And they cost about $15 ea NOS :) They are staying in. Not sure I would go back to any 5AR4 again, and not willing to spend a fortune for metal base 5AR4s to find out.

I would investigate a good power cable. Also Dan Wright does not recommend changing the 6AE7’s

Cheers
Pete

Hi Pete

Thanks for sharing.

Did you also try tube dampers on the 6H30-DR?

The Mullard GZ34 metal base were very expensive, almost EURO 400.00. I heard that they were the best available so I will give it a shot, but would like to see the $50 a pair Tung-Sol get close.

Cheers,
Mark

[Pete]

Hi Mark,

I put Herbies Ultrasonic Rx dampers on the 6H30P-DRs and regular Ultrasonic dampers the 5U4GBs. I guess I need a set for the 6EA7s

Same dampers on my Modwright SWP 9.0SE Signature Phone preamp

No complaints.

I found the 5U4GBs got more 3d sound and depth and width.
The treble calmed down a hair and just sounds more natural.
Really spectacular sounding at this point.

I found the power chord really affects the sound.
Shielded pc seems to sound the best to me.

Cheers,
Pete

[Audiocom AV]

Hi Mark,

I put Herbies Ultrasonic Rx dampers on the 6H30P-DRs and regular Ultrasonic dampers the 5U4GBs. I guess I need a set for the 6EA7s

Same dampers on my Modwright SWP 9.0SE Signature Phone preamp

No complaints.

I found the 5U4GBs got more 3d sound and depth and width.
The treble calmed down a hair and just sounds more natural.
Really spectacular sounding at this point.

I found the power chord really affects the sound.
Shielded pc seems to sound the best to me.

Cheers,
Pete

Hi Pete

Thanks.

What were the stock tubes in the pre and power supply?

The version I have came with Electro-Harmonix 6H30Pi and General Electric 5AR4, do not know what brand the 6AE7's are.

I use an Abbey Road carbon fibre power cable with Furutech FI-50 & 1363 Rhodium connectors. I found this gave the best result, and some more expensive power cords with heavier gauge wire clogged, fattened the sound.

Dan Wright is working on a higher-end umbilical cord, should be ready in a few weeks.

Best,
Mark