[TippyAudio]

Hi All -

I just ordered my ZMF OTL a few weeks ago. I'm super excited to try it out. I have the Taboo MKIV so it feels a bit like Xmas waiting on it to arrive...

 

[goldwerger]

Hi All -

I just ordered my ZMF OTL a few weeks ago. I'm super excited to try it out. I have the Taboo MKIV so it feels a bit like Xmas waiting on it to arrive...

you have the triple threat.... the OTL as amp for the high impedance dynamics, the OTL/Taboo combo for the planars (love it with the Caldera), and the OTL as a pre to any other amp (changes character of chain)

congrats!! pls share impressiosn when you get it..

 

[goldwerger]

Rectifier tube rolling:

Western Electric 422A (gray plate 1953)
Got this legendary rectiifer today and spending my first few hours with it. It is definitely distinct and provides a different sound profile compared to the GZ34 I've had there for the past few months. My initial impressions:

1. Extended lower bass - there is a notable bit of extra extension and resolution at the very lowest reaches of the FR
2. More rounded/sweet/warm sound - neither a plus nor a minus, more of an overall feel of the notes be rounded off; it can be called sweetness, but it's also a bit of the opposite of air; presentation remains very holographic, but timbre is perhaps a bit more saccharine

Philips Miniwatt GZ34 (brown base Sittard factory 1968)
This is my reference point. In comparison, the GZ34 feels more open and resolving in the mids, with a bit more air and openness. They have great bass, but not that extra depth of the 422A. They present a more neutral timbre compared to the 422A warmer presenation.

This presents a great opportunity to roll to mood, overall preference, or depending on the rest of your chain. My impressions will likely also evolve, but sharing my intital take after a few hours of comparison (I'm still using the Tung-Sol 5687 and RCA 6BQ7A when testing the above).

Next - I plan to try the 422A in the Taboo (with the OTL as pre-amp)..

 

[ansel1]

Just picked up a used Decware ZMF Ref OTL. I heard this at Dallas Canjam, with an Atrium, and was immediately struck by how right and enjoyable it sounded. I listened to a lot of stuff at Canjam, much of which was great, interesting, unique, etc, but this combo was the one I just wanted to sit and listen to for the rest of the day.

Anyway, at the moment, I don't have an Atrium to pair with it. I have an HD6xx, which of course loves this amp, but my daily driver's are LCD-4's, which I figured wouldn't be a great match. I mean, Zach as a "No Planars" right on the amp's web page.

But the LCD-4's are 200 ohms. If I turn the pre-amp pots all the way, I get good volume at 12 on the volume. And it sounds pretty great to me. I've been A/B'ing with my GSX Mini, and it definitely a bit different in ways I haven't been able to put my figure on, but I feel like it's getting the great tube sound without sacrificing anything obvious. Maybe a bit of detail? Still figuring that out.

Is there any reason this *shouldn't* work? If the impedance is high enough, does it matter that its planar? Is it sub-optimal to have the pre-amp pots turned all the way up? Without that I definitely don't get enough volume.

 

[goldwerger]

Just picked up a used Decware ZMF Ref OTL. I heard this at Dallas Canjam, with an Atrium, and was immediately struck by how right and enjoyable it sounded. I listened to a lot of stuff at Canjam, much of which was great, interesting, unique, etc, but this combo was the one I just wanted to sit and listen to for the rest of the day.

Anyway, at the moment, I don't have an Atrium to pair with it. I have an HD6xx, which of course loves this amp, but my daily driver's are LCD-4's, which I figured wouldn't be a great match. I mean, Zach as a "No Planars" right on the amp's web page.

But the LCD-4's are 200 ohms. If I turn the pre-amp pots all the way, I get good volume at 12 on the volume. And it sounds pretty great to me. I've been A/B'ing with my GSX Mini, and it definitely a bit different in ways I haven't been able to put my figure on, but I feel like it's getting the great tube sound without sacrificing anything obvious. Maybe a bit of detail? Still figuring that out.

Is there any reason this *shouldn't* work? If the impedance is high enough, does it matter that its planar? Is it sub-optimal to have the pre-amp pots turned all the way up? Without that I definitely don't get enough volume.

So glad you had a chance to try it at Dallas and get a chacne to experience it.

Saw that unit for sale (think only one ever posted for resale), congrats getting it

The LCD-4 is a rather unusual planar being also high impedance. That means that it have a better damping with an amp that has a higher output impedance - OTL output impednaces vary but will be roughyl around 50ohm or in that neighborhood, which is where the Decware OTL is probaly. With a regular SS amp, you can have an output impedance of single digits. 200 ohm headphones may be over damped.

The Decware/ZMF OTL is not particularly powerful, as its main use case doesn't require it to be. So the LCD-4 fit will depend on your listening volume. I just plugged mine in as I was curious and, yea, it works great. But I'm a low volume listener, and if you listen at high volumes and to very dynamic music, you may find it lacks some headroom (as a contrast, the Glenn OTL has simlar damping, but uses more powerful output tubes).

In short - if it works and you enjoy it, consider youself double lucky! no rules, except your ears.. and no reason why it "shouldn't" work, since it does...!

 

[zach915m]

Have a 120V version and two 230V versions in stock: https://shop.zmfheadphones.com/products/decware-zmf-otl

More coming as well!

 

[busseysound]

Rectifier tube rolling:

Western Electric 422A (gray plate 1953)
Got this legendary rectiifer today and spending my first few hours with it. It is definitely distinct and provides a different sound profile compared to the GZ34 I've had there for the past few months. My initial impressions:

1. Extended lower bass - there is a notable bit of extra extension and resolution at the very lowest reaches of the FR
2. More rounded/sweet/warm sound - neither a plus nor a minus, more of an overall feel of the notes be rounded off; it can be called sweetness, but it's also a bit of the opposite of air; presentation remains very holographic, but timbre is perhaps a bit more saccharine

Philips Miniwatt GZ34 (brown base Sittard factory 1968)
This is my reference point. In comparison, the GZ34 feels more open and resolving in the mids, with a bit more air and openness. They have great bass, but not that extra depth of the 422A. They present a more neutral timbre compared to the 422A warmer presenation.

This presents a great opportunity to roll to mood, overall preference, or depending on the rest of your chain. My impressions will likely also evolve, but sharing my intital take after a few hours of comparison (I'm still using the Tung-Sol 5687 and RCA 6BQ7A when testing the above).

Next - I plan to try the 422A in the Taboo (with the OTL as pre-amp)..


I'

I'd be very interested to compare the 274B I just acquired to the 422A.

 

[Coran]

My amp arrived last week, and I was finally able set it up and start enjoying it this weekend. Right off the bat I can tell this is something special, even with the stock tubes. Most importantly, the VU meters make me irrationally happy.

I went ahead and rolled in my Emission Labs 5U4G, which is sounding very nice right now. Looking forward to trying some other rolls once things break in a bit more.

The input voltage adjustments are an interesting addition to this amp. How have other folks approached setting those? I think I have them roughly at 25%, but it's hard to tell what would be the most appropriate. I still have plenty of play with the volume knob so I'm probably ok.

A question for folks using Tung-Sol 5687 tubes: What kind of adapter are you using and where did you get it? I have those tubes around and would like to try those next.

 

[goldwerger]

My amp arrived last week, and I was finally able set it up and start enjoying it this weekend. Right off the bat I can tell this is something special, even with the stock tubes. Most importantly, the VU meters make me irrationally happy.

I went ahead and rolled in my Emission Labs 5U4G, which is sounding very nice right now. Looking forward to trying some other rolls once things break in a bit more.

The input voltage adjustments are an interesting addition to this amp. How have other folks approached setting those? I think I have them roughly at 25%, but it's hard to tell what would be the most appropriate. I still have plenty of play with the volume knob so I'm probably ok.

A question for folks using Tung-Sol 5687 tubes: What kind of adapter are you using and where did you get it? I have those tubes around and would like to try those next.

Congrats!

I’m still addicted to this amp. For any high impedance dynamics, it’s as good as I have it.

I simply set the gain knobs at a level that was both quiet and left enough headroom, somewhere probably around 1-2 o’clock. But frankly it doesn’t matter as much. I’d put it the lowest where you still get enough headroom with your dac and headphone.

Tung Sol 5687 remain my top choice. I found they make a big difference in clarity.

For adapters, note carefully that some are too wide to plug into the amp faceplate, so you need to stack them on top of a socket saver (building a mini babylon tower), but others fit just perfectly — get this one for easy fit: https://www.ebay.com/itm/195640874664

Also, with the above tubes, I’ve found the best synergy so far with RCA 6BQ7A as the gain tube. Just a touch more grab and definition. The combo is awesome. I still enjoy the GZ34 brown base. I tried a WE422A and was too sccharine for me so I’m back to the 34.

Keep us posted on your journey! Which headphones will you be using?

 

[Coran]

Congrats!

I’m still addicted to this amp. For any high impedance dynamics, it’s as good as I have it.

I simply set the gain knobs at a level that was both quiet and left enough headroom, somewhere probably around 1-2 o’clock. But frankly it doesn’t matter as much. I’d put it the lowest where you still get enough headroom with your dac and headphone.

Tung Sol 5687 remain my top choice. I found they make a big difference in clarity.

For adapters, note carefully that some are too wide to plug into the amp faceplate, so you need to stack them on top of a socket saver (building a mini babylon tower), but others fit just perfectly — get this one for easy fit: https://www.ebay.com/itm/195640874664

Also, with the above tubes, I’ve found the best synergy so far with RCA 6BQ7A as the gain tube. Just a touch more grab and definition. The combo is awesome. I still enjoy the GZ34 brown base. I tried a WE422A and was too sccharine for me so I’m back to the 34.

Keep us posted on your journey! Which headphones will you be using?

I'll be using both the Atrium Open and Closed. This is my first OTL amp, and I'm loving what I'm hearing so far.

I'd like to find a GZ34 at some point. I have the Emission Labs 5U4G as well as the Elrog 5U4G, both of which are really great and fun tubes. I'm grateful the NOS options for this amp aren't in the unobtainium range (unlike my WA22 which...oof). I might look to really maximize the "tubiness" of the amp overall, while still keeping a nicer neutral/detailed set on hand. Have you found any combinations that really work the soundstage magic with this amp?

 

[goldwerger]

I'll be using both the Atrium Open and Closed. This is my first OTL amp, and I'm loving what I'm hearing so far.

I'd like to find a GZ34 at some point. I have the Emission Labs 5U4G as well as the Elrog 5U4G, both of which are really great and fun tubes. I'm grateful the NOS options for this amp aren't in the unobtainium range (unlike my WA22 which...oof). I might look to really maximize the "tubiness" of the amp overall, while still keeping a nicer neutral/detailed set on hand. Have you found any combinations that really work the soundstage magic with this amp?

The stock 6N1P + 6N6P definitely has a “tuby sound and, as you notes, is great out of the box!

The 5687 + 6bq7a are a step up in clarity, resolution, and soundstage. They may be a little less tuby thick, but still have warmth and a very holographic presentation. For me, this is best so far.

Another great combo I tried was the 5687 + Philips ECG JAN 6922 (1987) - definitely a more “tuby” sound that’s thick and want and also very holographic

This amp is my favorite for the AC and AO! It’s also great with the ADX5000 and HD800s

 

[busseysound]

The stock 6N1P + 6N6P definitely has a “tuby sound and, as you notes, is great out of the box!

The 5687 + 6bq7a are a step up in clarity, resolution, and soundstage. They may be a little less tuby thick, but still have warmth and a very holographic presentation. For me, this is best so far.

Another great combo I tried was the 5687 + Philips ECG JAN 6922 (1987) - definitely a more “tuby” sound that’s thick and want and also very holographic

This amp is my favorite for the AC and AO! It’s also great with the ADX5000 and HD800s

Congrats Coran! I second the statments on the Tung Sol 5687 (I tried them after Goldwerger's suggestion). For the input tube after trying about 20 different types (because fortunately they're not expensive) I liked 2 the best: Siemens PCC189 and the Tungsram PCC189. Something about that model of tube just gave overall balance to me in the sound.

As for the rectifier I used the Elrog 5U4G originally but after saving up for the Western Electric 274B I'm REALLY thrilled with this amp. I'd like to try the WE 422A in comparison sometime. Good luck and keep us posted on your journey!

 

[goldwerger]

after saving up for the Western Electric 274B I'm REALLY thrilled with this amp. I'd like to try the WE 422A in comparison sometime.

Happy to swap and cross test.. pm me if u like

 

[Coran]

Congrats Coran! I second the statments on the Tung Sol 5687 (I tried them after Goldwerger's suggestion). For the input tube after trying about 20 different types (because fortunately they're not expensive) I liked 2 the best: Siemens PCC189 and the Tungsram PCC189. Something about that model of tube just gave overall balance to me in the sound.

As for the rectifier I used the Elrog 5U4G originally but after saving up for the Western Electric 274B I'm REALLY thrilled with this amp. I'd like to try the WE 422A in comparison sometime. Good luck and keep us posted on your journey!

I'd love to try the WE 274B, but those prices are a bit nuts for the time being.

I will look for those Siemens and Tungsram tubes though. I love all the experimentation with a new tube amp.

 

[Coran]

The stock 6N1P + 6N6P definitely has a “tuby sound and, as you notes, is great out of the box!

The 5687 + 6bq7a are a step up in clarity, resolution, and soundstage. They may be a little less tuby thick, but still have warmth and a very holographic presentation. For me, this is best so far.

Another great combo I tried was the 5687 + Philips ECG JAN 6922 (1987) - definitely a more “tuby” sound that’s thick and want and also very holographic

This amp is my favorite for the AC and AO! It’s also great with the ADX5000 and HD800s

I have both the 6BQ7A and 6922 on the way thanks to your posts. Very excited to try them out.

I'll admit, part of me wants to get my hands on an HD600 again now that I have an OTL amp on hand. My Caldera has been my go to since I got it, but this will really encourage many new hours on my AO and AC.