Transformer options . . .

dboul · Post by **dboul** » Tue 02/03/04 12:02 am

Hey guys,

Just a note . . .

I've been talking with Mercury Magnetics about building a tranny set for the 4xEL84 version of this amp. I'll let you know what we come up with!

How many people are actually building a 4 tube version? I am and I'm very excited about it!

As some of you may remember, I used a JTM45 clone from Mercury on one of my 18 watters and it was amazing! I'm going to try that tranny in a 4xEL84 version. The JTM45 (RSDeLuxe) OT has taps for EL84's and I hoping that it will sound great.

Post by **Plexi** » Tue 02/03/04 12:31 am

Dan.. yes so many flavors out there that could work..
Maybe we can all post what we might be useing.. I'll be trying the heyboer AC30 tranny first. Its funny,i have an AC30 here needing a PT.
So when i treid to see what they had,that might fit the reissiue,they told me they had one that might fit.. So i told them to send it..if it don't fit, i'll use it.. I 've also got the heyboer AC30 PT..but its a huge monster..
They do have those Drake ,for the reissiue..but i don't like those..not very big,and they have lots of problems. Or i might have tried one of those..
It looks like it might fit ok,but haven't tried. I have to get a parts order going here in the next few days..

Richie

dboul · Post by **dboul** » Tue 02/03/04 12:36 am

Hey Richie,

Let me know if you would like to try any MM stuff. I can get it at a significant discount. I'd be happy to grab you some iron there and send it to you. They are about 5 minutes from my office. I run over there quite a bit. I have several projects going with them right now.

Have you come up with a layout yet?

Cheers buddy!

Post by **Plexi** » Tue 02/03/04 5:49 pm

Thanks Dan, I've got some trannys coming now, i'll try these and see how they do..
I would like to try the MM ..but they were always pretty pricy..

Richie

dboul · Post by **dboul** » Tue 02/03/04 7:15 pm

Plexi wrote:Thanks Dan, I've got some trannys coming now, i'll try these and see how they do..
I would like to try the MM ..but they were always pretty pricy..

Richie

No problem! I just thought I'd offer. I enjoy the MM stuff so much that I always want to share! I think you would enjoy it as well.

Indeed they are pricey but I can get them at a price that is more easy to stomach. I buy enough from them that their volume discount is automatically kicked in on my orders. Plus they're good guys and are extremely knowledgeable about amps. They're very happy to do custom winds to tweak your sound.

Standing offer for you and anyone else . . .

Post by **Plexi** » Tue 02/03/04 8:14 pm

One thing we might do is, maybe do some swaps,at least on the OTS..
We could try what we have..then whoever may want to do some swapping..mail the transformer to them,and they mail one back.. this way you could try different ones {before} to see which one you thought sounded best.. The first OT i'll be trying is the one i have from Heyboer..

As for PTs..i'll have 2 of those with chokes in about 3 weeks..

HAHA.. I also have to get a couple sets from Graydon for the 18 too
And A Vox AC30,and heyboer has an SVT OT i sent to them to build..

So i have alot coming and going..lol plus i've still got to go through my stuff,and Order abuch of stuff i need..

Richie

dboul · Post by **dboul** » Tue 02/03/04 8:16 pm

Plexi wrote:One thing we might do is, maybe do some swaps,at least on the OTS..
We could try what we have..then whoever may want to do some swapping..mail the transformer to them,and they mail one back.. this way you could try different ones {before} to see which one you thought sounded best..
Richie

I'm in!

I'll have a couple to try as well here within a few weeks. Great idea!

Post by **Plexi** » Tue 02/03/04 10:34 pm

I just remembered when Joe at OEI was proto typing his OTs..it was sent to quite a few people to put through the test..So he got quite a few good ears to hear it..Thought it was a great idea.. Its easier than buying a bunch of different ones..this way,with only the cost of shipping,you can try a few different types. I was never much of a hammond fan..but others like them very much.

Richie

HeeBGB · Post by **HeeBGB** » Tue 02/03/04 11:47 pm

Hi all,

About two years ago I picked this up off of ebay. I think the iron might make for a good 36watt. I have attached the Schem. The PT voltages are kind of hard to read but I think they are in the 265-0-265 range. I need to put a meter on it to make sure but otherwise seems to be a perfect candidate for a 36watt. Now if I could find the time to get it together. Oh BTW it's a Harmon Kardon A224 Integrated amp.

Greg

Post by **zaphod_phil** » Wed 02/04/04 6:48 am

The PT may work. But it has two separate OTs, each for one pair of EL84s, as you would expect with a stereo amp. SO you don't really have an OT there suitable for a 36W.

tubetek · Post by **tubetek** » Wed 02/04/04 7:19 am

Howdy All-
New to this list; been fixing / building tube equipment since the 70s.
Does anyone here remember West amps (think grand funk rr)
Dave west is online selling parts now. H purchased the entire last production run of PT / CHOKE / OT sets for Matchless 15 and 30 watt VoxClones.
These are really high quality and reasonably priced.
HTTP://westlabs.com Give 'em a look; they should be close to perfect for
this project...JAM!!
TT

HeeBGB · Post by **HeeBGB** » Wed 02/04/04 8:52 am

I know but I was thinking about two OT's like the first Marshall 100 watters. Anyone have any thoughts on this. How did they wire the OT's to an output? I assume they had one output jack for each OT. Put it in a BB cab with two Vintage 30's. It could work!

chrisCMWamps · Post by **chrisCMWamps** » Mon 07/26/04 10:49 am

HeeBGB wrote:I know but I was thinking about two OT's like the first Marshall 100 watters. Anyone have any thoughts on this. How did they wire the OT's to an output? I assume they had one output jack for each OT. Put it in a BB cab with two Vintage 30's. It could work!

If the pairs do feed one OT/pair of EL84s then you can parallel both secundaries. The 8ohms windings in parallel will give 4 ohms and two 16 ohms ones will give 8 ohms.

Hope I'm not mistaken, it's monday

)

Chris

toyota_tim · Post by **toyota_tim** » Mon 07/26/04 11:51 am

HeeBGB wrote:I know but I was thinking about two OT's like the first Marshall 100 watters. Anyone have any thoughts on this. How did they wire the OT's to an output? I assume they had one output jack for each OT. Put it in a BB cab with two Vintage 30's. It could work!

I'm working on a converstion of an old knight stereo power amp. It is almost the the exact same circuit as the one you posted. I left each pair of el84s independant as they were as a stereo amp and run one speaker off each OT. I used a couple of the existing DPDT switches to switch in and out each of the pairs off the same PI. Using two different speakers I can select either one at 18watts or both for 36watts. Running each pair off it's own PI I have a stereo guitar amp. As long as you keep all the impedances matched there is no reason you couldn't run in mono with the OTs bridged or paralleled.

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