6550/KT88 Monoblocks for Tube Stereo 70+70W

[Reeltarded]

I wonder why Dumble didn't use UL in his Steel String Singers/Dumblelands??

Because it's no good for guitar amps.

Cheers,
Ian

P.S. Ignore the folk who say Ultralinear is no good for guitar amps.

Cheeky!

[David Root]

Interesting stuff! beautifully done too. It seems it's mostly point to point layout with the one board. Maybe it's my guitar amp upbringing but I wouldn't mount tubes anywhere but thru the chassis.

Leo, I didn't see anything on Bob's site about selling the transformers, did I miss it? IIRC the Mk III OT was 4K3. I'm looking at a 4K2 or 5K from Edcor so it's in the ballpark.

I looked up triodeelectric, they sell Dynaco OTs but they want almost 50% more than Edcor for a 60W Mk. III OT, with the same published bandwidth (20 to 20KHz -1 dB) as a 100W Edcor. No contest I think. I've used Edcor before, they are tough to beat.

I also looked up the original specs of the A431 Dyna OT. 6-60KHz +/-1dB, weight 14 lbs. which is a horse of a different color. That doesn't square with the triodeel replacement spec but I see no weight on the replacement. The Edcor weighs 9.75 lbs. Is the triodeel A431 really 14 lbs? If so it's worth the money.

[Leo_Gnardo]

Leo, I didn't see anything on Bob's site about selling the transformers, did I miss it? IIRC the Mk III OT was 4K3. I'm looking at a 4K2 or 5K from Edcor so it's in the ballpark.

I looked up triodeelectric, they sell Dynaco OTs but they want almost 50% more than Edcor for a 60W Mk. III OT, with the same published bandwidth (20 to 20KHz -1 dB) as a 100W Edcor. No contest I think. I've used Edcor before, they are tough to beat.

I also looked up the original specs of the A431 Dyna OT. 6-60KHz +/-1dB, weight 14 lbs. which is a horse of a different color. That doesn't square with the triodeel replacement spec but I see no weight on the replacement. The Edcor weighs 9.75 lbs. Is the triodeel A431 really 14 lbs? If so it's worth the money.

Whoops you're right. I was thinking of the OT's Bob Latino uses on his ST-120. Which seem at least from specs to be a good match to the MkIII output. You could email him for a quote. I'm sure they're available ex-kit.

Sunn used the MkIII OT in their PA120, simply doubled up the drive tubes and halved the output impedances. Probably lost some bandwidth. But I did rebuild one of those amps @ 2years ago and it delivered full power with 4 x KT88. I did a spot measurement @ 200 Hz so cannot speak for bandwidth specs.

Had a look at the Triode Elec. A431S also, yes no mention of weight but again, an email will get you an answer. Whether any of these replacements would put up the treatment Sunn gave the A431 in the PA120 - who knows. After all this the Edcor may wind up being the one for you.

Just noticed, you're in Canada. Is there no Hammond iron that would suit your needs? I'm thinkin' the import duty on anything USA would put a dent in your wallet. Plus the shipping companies like to tag you extra for cross border shipments.

[David Root]

Thanx Leo. Yes I'm in Canada where everything costs you more except health care.

The Hammond equivalent of the Edcor 100W CXPP100-MS-5K or -4K2 is the 1650R at $173. The Edcor is $93.

To be fair to Hammond the 1650R weighs 2.25 lbs more than the Edcor, 12 lbs vs 9.75. The 60W 1650N, at 8 lbs, is $155. Prices from Parts Connexion in Canada, in US$. Maybe there is a Hammond source in Canada for less, I've not found any.

No duty into Canada (NAFTA) but there is 12% sales tax.

The last time I bought an Edcor the shipping was $28, so even if Parts Connexion shipped free within Canada, Edcor is still way cheaper.

[Leo_Gnardo]

I had a peek at Mouser who now list many but not all Hammond transformers. Mouser AFAIK has a presence in Canada. They didn't list the 1650R but you could ask. Also try asking Hammond, who knows, they may cut you a deal. One thing about H's secondaries, they're arranged in a sort of hinky way which requires a special switch to access all 4, 8 & 16 choices handily. I used one of their elephant size transformers a couple years ago & didn't know this until I got it. Luckily the owner of the amp it went into needs only 4 & 8 ohm taps. (And gets a healthy 120-130W from a quad of KT88.) After all this, I can see the attraction of the Edcor transformers.

[David Root]

Hammond has several distibutors in the Vancouver area but the only audio specialist doesn't cut anyone any deals.

I checked Mouser, Digikey, Newark and Allied, all within a few bucks of each other, some even higher than Parts Connexion. All from US stock, these outfits are all US based with no actual presence in Canada outside of their websites.

Hammond's audio transformer biz is a teeny teeny part of their overall biz and it seems to me that in recent years they have increased their prices, I think because the audio crowd is used to paying thru the nose for everything, and Hammond is taking advantage of that.