RustyShak51
New Member
Heathkit w5m 25 watt tube mono amp from 1957 what's the ins and outs and what's to know.
Heathkit w5m Pros and Cons
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RustyShak51
New Member
I just got a set over the weekend and am new to tube mono blocks I've always had stereo integrated amps.
Well, the first thing to determine is whether they've been restored with new power supply caps and coupling caps. The originals are somewhat under-spec'd and can lead to potential problems. If they have been nin storage for a long time, it would be best to bring them up slowly ovber a day or so on a variac. If they've been used recently or in guaranteed workingn order, they should be okay.
Another thing to determine is which output transformer they use, the 16309 or the 16548. The former was also a bit underspec'd and were prone to failure. Heatrhkit replaced the 16309 with the 16458, which is larger and more robust. They also recommended the addition of a thermistor atb the AC inpout to slow the turn-on surge.
If you can post pictures of your purchases, both inside and out, folks here can assess the condition and recommend some things to make sure they continue to work well for you.
All that said, they're beautiful amplifiers.
Another thing to determine is which output transformer they use, the 16309 or the 16548. The former was also a bit underspec'd and were prone to failure. Heatrhkit replaced the 16309 with the 16458, which is larger and more robust. They also recommended the addition of a thermistor atb the AC inpout to slow the turn-on surge.
If you can post pictures of your purchases, both inside and out, folks here can assess the condition and recommend some things to make sure they continue to work well for you.
All that said, they're beautiful amplifiers.
Not sure what to offer other than generic old tube amp advice. Don't just turn them on to see if they work without knowing they were restored properly. There were two versions of the output transformers. The model numbers should be on the sides of the cases. I think they were 16309 or 16458, or close to these numbers. Pictures of both top and the insides would the AK experts to give you more specific advice.
edit: Zack beat me to the punch. Enjoy.
John
edit: Zack beat me to the punch. Enjoy.
John
Have restored two. First, they sound great when properly restored and represent a pretty good value for vintage power amps IF the output transformers are good (one of the two had burned out OPT and had to scrounge up a new one--concur on zack and nerdorama's posts above--the 16309 seemed to be more vulnerable). Can be hard on the power transformers as well. Look for tarry leakage from the power trans.
Classis Williamson ultra-linear circuit, cathode biased, with added stability features. The electrolytic caps must be replaced and there may be a few out of spec resistors (cathode esp) as well. A careful going over is a must if they are stock, as per the above. Handy external test points for setting the bias.
So, before powering up ascertain if they have been restored already. If not, I would not power them up before at least replacing the can multi-section electrolytic caps and all the axial electrolytics underneath, AS WELL as all the molded paper capacitors, especially the two big 1 uF main couplers.
Dave
Classis Williamson ultra-linear circuit, cathode biased, with added stability features. The electrolytic caps must be replaced and there may be a few out of spec resistors (cathode esp) as well. A careful going over is a must if they are stock, as per the above. Handy external test points for setting the bias.
So, before powering up ascertain if they have been restored already. If not, I would not power them up before at least replacing the can multi-section electrolytic caps and all the axial electrolytics underneath, AS WELL as all the molded paper capacitors, especially the two big 1 uF main couplers.
Dave
8xlaxx
Have you ever seen a spleen that large?
If your amps have already been in service and restored, then you're probably good. If they've been sitting then you should pull the rectifier out and test for HV, with a DVM, in order to verify that the PT is good. Be warned that there is 900VAC+ present. Move on to the OPT and smaller trans to verify resistance. If those look good then check caps and resistors.
Post a few pics. Would enjoy seeing the tube compliment your amps might have.
There are many threads here on AK regarding the Heathkit W5M, it's nuances, pros, cons, and suspected modes of failure. A quick search will help.
Post a few pics. Would enjoy seeing the tube compliment your amps might have.
There are many threads here on AK regarding the Heathkit W5M, it's nuances, pros, cons, and suspected modes of failure. A quick search will help.
I have restored two. Both were completely original, with the original genelex tubes, 16309 transformers, and both worked fine after sitting for 60yrs! I went completely through them, all new caps and resistors, gold input jacks, SS rectifier, standby switch, upgraded speaker terminals and the sds labs cap board. I still use the original tubes, although I am considering new ones, with the old ones safely stored. They are really fantastic sounding amps, and are totally reliable, as far as my experience goes. They are easy to rebuild, and you could probably just replace the electolytics and be good to go. I bought some speakers from a really high end audio guy, and when I told him I was using those amps, he said I would have to spend many thousands to match the sound. Who knows, but they do seem a good bang for the buck if you’re willing to do a bit of work.
ScottFan355
Super Member
You’ll love them.
I’m a recent owner of W5M’s and mine were gone through by a good tech (w/previous owner) and I’ll tell you what… these are pretty fantastic amps! For what I got them for (well under a grand) I can’t believe how detailed they are, neutral sounding, and punchy. The highs are simply sweet but not syrupy, lows are neutral as well and very capable. I think they’ve gotten a bad rap for their lows, but mine are killing it so maybe I have good caps in comparison. I’m running RCA cleartops and GE 6L6 power tubes. I thought my McIntosh MC30’s were the cats meow, but I’m not so certain anymore.
ScottFan355
Super Member
I would love to do a w5m vs mc30 shootout!
Primotubes
Active Member
I bought 4 of them over the years, and found that you really need to thoroughly check the transformers. Some amps had bad outputs and some had bad power trannys. On the output tranny I found 2 had bad UL windings. One was tricky because the fault only showed up at high voltage. The original circuit is great sounding but the power supply is a bit complicated because of the high voltages. This requires series connected capacitors to cover the high voltage surge at turn on. This also means that one should stick with the 5R4 rectifier which has the required voltage drop suitable for the original design. People recommend the mil spec 5r4 "potato masher", with the ceramic base, which is designed for b52 bombers (among other uses). Other than that the rest of the amp benefits from the usual tube amp refurbishing.
So I did the comparo apples to apples tonight with my MC30’s Vs Heathkit’s. I’m not sure there’s a clear overall winner, but I will say the W5’s best the 30’s in upper/mid transparency/staging/and speakers simply disappearing. The sound is also incredibly lifelike. It’s quite an experience with all of this going on. Nothing stands forward and seems in its place. A very deep stage but not especially wide. The 30’s add syrup and a bit more weight to the low end giving expansiveness. The W5’s are punchy but not weighty which goes hand in hand with the sound previously mentioned; transparent and lighter overall. The 30’s aren’t nearly as “staged” as the W5’s front to back. There are forward voicing at times with the 30’s making for inconsistencies. The W5’s are extremely consistent with staging with all voices. The 30’s are very expansive sounding in width but they are more forward overall.
It sure was a great experiment and rather surprising. I hope to get the best of both worlds with the 30’s on the bottom and W5’s on the highs/mids. It will be very interesting to see if their differences in weight work well together. I suspect they will with this configuration. Overall… there is no comparison when listening to something like Ella Fitzgerald with piano with the W5’s as the staging, voice, and piano all sound perfectly in place behind the speakers and the most realistic I’ve ever heard. Heavy (big) stuff is more “felt” and impactful with the 30’s.
I run a McIntosh MX110z preamp and Snell CIV speakers with a powered sub.
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ScottFan355
Super Member
This all seems to verify more or less what I’ve heard.
ScottFan355
Super Member
I had a chance to buy a pair of mc30s for a fantastic price. One was restored with decent cosmetics but the other was ‘working’ but by far the worst basket case cosmetically of any amp I’ve ever seen. It looked like it had been submerged in saltwater for decades. Then I found a ridiculous deal on a pair of electronically and cosmetically altered/restored w5ms. I feel great about my purchase especially after reading threads like this.
You’re gonna love ‘em! Post your findings here as well please. I could live with these very easily over the 30’s.
ScottFan355
Super Member
Oh I know I’ve had them for two years now. Pretty much endgame for me.
