Vintage Asylum

Classic gear from yesteryear; vintage audio standing the test of time.

Return to Vintage Asylum

Message Sort: Post Order or Asylum Reverse Threaded

Heathkit w-5M questions

38.100.231.18
Posted on June 19, 2015 at 13:48:14
daseman
Audiophile

Posts: 40
Location: Seattle
Joined: April 20, 2008
 I just acquired a pair of these and they sound great!

A couple of questions for those with knowledge:

(1) Can the Russian 6p3se/6n3ce tubes be used in these amps? If so, anyone have comments on how they sound in this application?

(2) For biasing ("bass-bal" on these amps) the tubes - can I do this while the amp is turned on but not connected to the preamp? Logistically it would be much easier for me to do it this way.

 

Hide full thread outline!
    ...
Great amps!!!, posted on June 19, 2015 at 18:20:43
Mossback
Audiophile

Posts: 1871
Location: Washington, the State
Joined: November 17, 2001
 No need to have a preamp connected in order to balance or bias the amps.
Vintage KT66 GEC gray glass brown base or the new reissue KT66 Gold Lion are the tubes to use.

 

RE: Great amps!!!, posted on June 19, 2015 at 21:34:54
daseman
Audiophile

Posts: 40
Location: Seattle
Joined: April 20, 2008
 Thanks!

 

RE: Great amps!!! 6P3S-E, posted on June 21, 2015 at 09:11:18
PeterI
Audiophile

Posts: 1432
Location: Colorado
Joined: October 17, 2006



The Russian 6P3S-E tubes were in them when I sold my W5Ms. They were great - stable in circuit, punchy and musical. Bias balance easy to adjust.

Pete

 

Rebuild or rethink?, posted on June 23, 2015 at 16:46:52
Timbo in Oz
Audiophile

Posts: 23221
Location: Canberra - in the ACT - SE Australia
Joined: January 30, 2002
 these are nice amps.

IMO the VR holds any PP power amp back due to PIV limits. Even if it has a choke in the PSU.

More thoughts? Ask?


Warmest

Tim Bailey

Skeptical Measurer & Audio Scrounger


 

RE: Heathkit w-5M questions, posted on June 24, 2015 at 15:22:11
daseman
Audiophile

Posts: 40
Location: Seattle
Joined: April 20, 2008
 Great responses, guys. While I have your attention, I thought I'd ask what 12AU7s y'all liked best in these amps. Mine currently have some old Sylvanias. Everything is sounding great, but would appreciate knowing if you had a favorite 12AU7 in this application.

The 5R4GYs are also currently Sylvanias. I just happen to have a very nice pair of 1940s CRC dark brown base double-getter RCAs. But I'm waiting to get fully acclimated to the sound before plugging these in.

Cheers,
Blake

 

All 12AU7s are deficient. Try 12BH7s?, posted on June 25, 2015 at 15:52:03
Timbo in Oz
Audiophile

Posts: 23221
Location: Canberra - in the ACT - SE Australia
Joined: January 30, 2002
 The only job I will use U7s for is cathode-followers where they are blameless. ? The 12AU7 has the highest distortion of all the 12A_7 family. And, I don't know of any noval twin-triode audio valve that is worse.

As drivers for power tubes they might be slightly ahead of the prevalent use of 12AX7s as drivers, which IMO don't have enough gm (grunt) for that job.

So, IF the PTs have sufficient filament/heater-current reserves replace them with 12BH7s. IIRC these are drop-ins, so you may not need to change any of the surrounding components. But, lowering the NFB around the input and driver stages is worth considering.

The originalists might bitch but they are your amps. Vintage PP valve amps with decent iron offer the opportunity of high-end sound for not much money, if you give them a lot more PSU storage in the PSU, decent driver tubes, and less total/loop NFB.

Increasing the storage will require; replacing the Valve Rectifier diode, or paralleling it with soft recovery HV SS diodes. That idea will keep the amps looking original. There are a few threads at 'Tubes' here on this latter idea with Eli Duttman contributing. I used the socket hole for another big capacitor.

Chokes in PSUs have advantages.

Bypassing the last two caps in the PSU with 10% styrene or polypropylene film caps can't hurt.

You should be able to get a few dbw more power / headroom for peaks as your B+ voltage will be a bit higher. In any case the power bandwidth can be a bit wider. NFB bandwidth components will need to be adjusted.

LBNL double the wattage of all the small-signal Rs, if it uses cathode-bias use the best low inductance Rs that you can afford. Less noise.


















Warmest

Tim Bailey

Skeptical Measurer & Audio Scrounger


 

RE: All 12AU7s are deficient. Try 12BH7s?, posted on June 26, 2015 at 08:41:52
daseman
Audiophile

Posts: 40
Location: Seattle
Joined: April 20, 2008
 Timbo in Oz:

Thanks for the detailed message, but I don't have the technical ability/interest/time to modify my gear.

Would appreciate any 12AU7 suggestions from current or former Heathkit w5m users.

Cheers,
Blake

 

RE: Heathkit w-5M questions, posted on June 26, 2015 at 12:30:41
Barney's Beanery
Audiophile

Posts: 1191
Location: Twin Cities Area...MN
Joined: March 24, 2001
 I have a pair in my main system, I like em a lot.
The other poster is correct, you don't need the preamp connected to bias these guys.


The Russian tubes should be fine (I like the KT66 tube in these amps, for whatever that is worth).


Concerning the comment "but I don't have the technical ability/interest/time to modify my gear."
It is completely understandable.... I would just make a suggestion, check out this site...it talks about the W5-M (Williamson Amplifier) and the 12AU7 tube used in the circuit......just a suggestion.
If nothing else, it is an interesting read about your new amps!

These are excellent tube amps, excellent.

Enjoy the sound of tubes though one of the best tubes amp they made, in my opinion.

Barney


music has the power to make you happy

 

RE: All 12AU7s are deficient. Try 12BH7s?, posted on June 26, 2015 at 12:41:08
Crazy Dave
Audiophile

Posts: 14371
Location: East Coast
Joined: October 4, 2001
 There does not seem to be a lot love for the 12AU7 around here, but it does seem to be used a lot in vintage euipment. I have never used it, but I have used the similar 6SN7, and thought highly of the equipment it was in. Why is the 12AU7 so popular in commercial gear?

Dave

 

RE: All 12AU7s are deficient. Try 12BH7s?, posted on June 26, 2015 at 20:01:44
Steve O
Audiophile

Posts: 12383
Location: SE MI
Joined: September 6, 2001
 Just a guess as to why the 12AU7 was so popular back then was that it was similar enough to the octal 6SN7 that it could be adapted to previous 6SN7 circuit designs with little if any change.....at least for audio apps. Unfortunately, the 12AU7 is really a dual 6C4, not very linear and more at home in RF apps. A little after the intro of the 12--7 series of tubes came the 6CG7, a near exact duplicate of the 6SN7 but in the more compact 9 pin noval format. By this time momentum was probably with the 12AU7.

A common "upgrade" for the W5 and Mac amps using the 12AU7 is to convert them to the 6CG7/6FQ7. Requires some wiring changes at the sockets because the pinouts are different but usually no other changes necessary.

 

RE: Heathkit w-5M questions, posted on June 26, 2015 at 21:34:19
daseman
Audiophile

Posts: 40
Location: Seattle
Joined: April 20, 2008
 Cool, thanks!

 

RE: All 12AU7s are deficient. Try 12BH7s?, posted on June 29, 2015 at 13:57:31
Crazy Dave
Audiophile

Posts: 14371
Location: East Coast
Joined: October 4, 2001
 Of course Marantz 8/8B doesn't need to be modified because he used the 6CG7 for the long tailed pair.

Dave

 

RE: Heathkit w-5M questions, posted on June 30, 2015 at 08:52:45
Crazy Dave
Audiophile

Posts: 14371
Location: East Coast
Joined: October 4, 2001
 That was quite an interesting link. Thank you!

Dave

 

RE: All 12AU7s are deficient. Try 12BH7s?, posted on August 17, 2015 at 12:15:01
daseman
Audiophile

Posts: 40
Location: Seattle
Joined: April 20, 2008
 Follow up: I ended up with a quad of Amperex (made in Holland) 12AU7s and they sound mighty fine to me.

Rest of the tubes are (reissue) Gold Lion KT66s and dual bottom getter RCA 5R4GYs.

Very pleased with the sound of these W5Ms in my system.

 

Page processed in 0.026 seconds.

[ Top Top of Page ] [ Contact Us ] [ Support/Wish List ] [ Copyright © 2024, Audio Asylum, all rights reserved ]
[ General ] [ Speakers ] [ Tubes ] [ Vinyl ] [ Digital ] [ Hi-Rez ] [ Video Asylum ] [ Cables ] [ Tweaks/DIY ] [ Music ] [ Films ]