Heathkit w5m Pros and Cons

[zackthedog]

It's a stereo amp and it appears the 807's are connected in UL.

I would check on that. The LS-35 and the LS-65 were UL transformers, but were not designed for 807's. Those were the only LS series UL transformers UTC made. It's possible the amp uses those, or employs a screen supply on the 807s to get more power, but if the amp uses LS-61s or 63s, there are no UL taps. Like I said, it's probably a very nice amp but I'd find out a bit more about which OPTs it uses and what the circuit is.

Now, the UTC "Linear Standard" circuit uses the LS-63 and a screen supply (on 5881s) for 20 wpc. The input and driver tubes are 12AX7 and 6AU6. That is a unique circuit with very, very low distortion. I have LS-63's and am trying to talk myself into building a pair of those. It's more complex than a Williamson so I'm hemming and hawing. ;-)

It would be interesting if you can get a pic of the amp or find out more about it. I use LS-57s with triode EL34's in an otherwise standard Williamson circuit for 16 wpc, and it is my favorite amp. The midrange in particular is just wonderful. So a UTC-based amp can offer a lot of pleasure if lower power is not an issue.

 

[zackthedog]

what do you mean by “bring out more” when you suggest KT66? I’m curious about your findings.

I just think the KT66 offers a bit more texture than 6L6 variants. It's also what the amp was designed for. I think it brings out the best in the amp.

 

[Kevdog]

I just think the KT66 offers a bit more texture than 6L6 variants. It's also what the amp was designed for. I think it brings out the best in the amp.

That’s good to know Zach, thanks for the input.

 

[nerdorama]

I have pairs of LS-57 and LS-63 in the raw but the thought of not having to build the amp from scratch is appealing at this point. Hurt my back several weeks ago and can't sit at the workbench.

 

[grindfix]

Hurt my back several weeks ago and can't sit at the workbench.

Ha! I can relate. I can't work sitting down. Back issues for the most of my life doing what I do every day plus started playing tennis at a wrong age.
My bench is made for working standup. I have a telescoping bar stool that I sometimes use if my legs get tired but if I need to focus, I get up.

 

[zackthedog]

I have pairs of LS-57 and LS-63 in the raw but the thought of not having to build the amp from scratch is appealing at this point. Hurt my back several weeks ago and can't sit at the workbench.

I understand. ;-) I will say that the EL34/LS-57 amp is pretty wonderful.

I can give you specifics about my build, which is very stable, if you're interested. I built monoblock versions with tube rectification.

But I'd also be interested in whatever you can find out about the stereo 807 amp.

 

[nerdorama]

Thanks. i've watched that video before.

 

[8xlaxx]

@zackthedog

Which Chinese tube version(s) are you suggesting for the W5M?

-Shuguang
-Shuguang Treasure
-Gold Lion

 

[zackthedog]

@zackthedog

Which Chinese tube version(s) are you suggesting for the W5M?

-Shuguang
-Shuguang Treasure
-Gold Lion

Depends on your preference. The Gold Lions are very open and on the "lush" side, the standard Chinese are tighter and punchier, a bit darker in the midrange. I've never bought Treasures. The Chinese I use are TAD (Tube Amp Doctor) matched. I find TAD selects their tubes well.

 

[8xlaxx]

Depends on your preference. The Gold Lions are very open and on the "lush" side, the standard Chinese are tighter and punchier, a bit darker in the midrange. I've never bought Treasures. The Chinese I use are TAD (Tube Amp Doctor) matched. I find TAD selects their tubes well.

Thank you for the recommendations.

 

[Primotubes]

Does it make much difference which output transformer? These have the smaller 309 version. From what I've read the main thing is that the amps are well restored and stable.

According to what i have read, the smaller 16309 output tranny is made with nickel laminations. The second type 16458 and larger OPT is made with regular steel lams. I am not positive but the larger OPT maybe rated for higher output as well. When I was trying to get my set of W5m I saw more amps with the large 16458 OPT for sale. So, my unofficial survey indicates that the 309 type is rarer. Also, Nickel lams are a step up in construction quality for output transformers.

 

[ScottFan355]

Thank you for the recommendations.

I run Gold Lions in mine and the amps sound fantastic.

 

[ScottFan355]

According to what i have read, the smaller 16309 output tranny is made with nickel laminations. The second type 16458 and larger OPT is made with regular steel lams. I am not positive but the larger OPT maybe rated for higher output as well. When I was trying to get my set of W5m I saw more amps with the large 16458 OPT for sale. So, my unofficial survey indicates that the 309 type is rarer. Also, Nickel lams are a step up in construction quality for output transformers.

Mine also have the 16309s. Apparently they’re more prone to failure but according to some sound sweeter. But if they’ve made it this long and the amps are well restored they should be fine.

 

[8xlaxx]

If you had to do it all over again on the resto, would one want to install the 16309s or 16458s? Have several of both OPTs in waiting for a restos.

16309 ----> nickel lamination, smaller, fragile (prone to failure), better sonics.

vs.

16458 ----> steel lamination, larger, durable, questionable sonics (?).

Interesting, because in my W5M hunt, the 16458 seemed rarer and more expensive.

 

[Pio1980]

I'd use the 16309 and derate the amp with lower B+.

 

[nerdorama]

Well, as life sometimes goes, I didn't get either the W5's or the local amp with the UTC transformers. I posted in BT a WTB ad for W5's and ended up with a very nice pair of W3's. Thank you to @warriorpoet777. I'm excited to dig into these and get them running. They are original and untouched inside so need a thorough redo.
Thanks for the advice.
John

 

[maxhifi]

I recently restored a pair to stock, with all new resistors and capacitors, the SDS Labs capacitor board, and a CL-90. I'm aware of the excellent modifications that have been done to these, but I wanted to hear them stock.

I'm not disappointed, they are among the best sounding vintage amps I've ever heard! Dead quiet too, you have to put your ear right up to the speaker to hear even a hint of hum.