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Inexpensive Used PP EL84 Recommendations, please [message #9296]

Mon, 24 October 2005 11:45

DrD
Messages: 19
Registered: May 2009

Chancellor

On the hunt for a good used, preferably vintage EL84 amp. Thinking about a 60's HH Scott, something like that. I have never heard one I didnt like. Thanks for your input.

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Re: Inexpensive Used PP EL84 Recommendations, please [message #9297 is a reply to message #9296]

Mon, 24 October 2005 18:24

PakProtector
Messages: 935
Registered: May 2009

Illuminati (2nd Degree)

Hey-Hey!!!,
aside from enjoying it...what are your plans for the piece? Also, will you be needing just an amp? like a ST35 Dynaco? or some sort of integrated style?

The Dynaco SCA35 fits the integrated category, has the same output Iron as the ST35 and can be modified( probably require some re-fit for reliable day-to-day use anyway ).

The Heath W2 is a 6L6 amp, but has a 10k a-a output TX, and a seperate power supply, so a bit of work would be needed to fit El84. Mostly PS building, and socket swapping. It probably has better output Iron, but I am just speculating there...

And then there are the Eico and Scott to consider...
cheers,
Douglas

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Re: Inexpensive Used PP EL84 Recommendations, please [message #9298 is a reply to message #9297]

Mon, 31 October 2005 12:07

metasonix
Messages: 103
Registered: May 2009

Viscount

let me see....you're telling this guy to get a Heath W-2 and hack it to take EL84s? Why? EL84s are lesser performers than 6L6s--higher distortion, lower power. And W-2s do have some collectible value--but not when they've been hacked.

He'd be better off just finding a Scott 222 or Heath AA-151. Or a long list of other vintage EL84 amps. Or far better, getting two W-2s and using them as-is.

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Re: Inexpensive Used PP EL84 Recommendations, please [message #9299 is a reply to message #9298]

Mon, 31 October 2005 15:30

PakProtector
Messages: 935
Registered: May 2009

Illuminati (2nd Degree)

Well, thanks for waiting to suggest all those other options. As a matter of fact, W2's turn up one-at-a-time fairly inexpensively, especially w/o the PS part.

Considering my experience with the big S265 Peerless output, I'd conclude that a single 16277 would be a similar performer. Better than the cheaper integrated options you mention I'll bet. Get one, unwind and make more. No big deal there, that's for sure. Probably ~$75 each to make as many as you want. Can't call that expensive...:) Or try building with a 16311, or 16309.

I would agree that the W2 would do quite well with its own 6L6's. I don't have much experience with EL84's. 6L6's, those I've built with and liked the result. I would say that the original front end can be improved upon easily. See Merlin V2 for an example. Getting rid of the global NFB path has always sounded better, assuming the rest of the amp could be brought to heel of course...:)
cheers,
Douglas

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Re:Say; anyone have an opinion on the Mullard 5-20? [message #9301 is a reply to message #9299]

Mon, 31 October 2005 19:33

Manualblock
Messages: 4973
Registered: May 2009

Illuminati (13th Degree)

Nice tube compliment but the power trans looks difficult. I wouldn't mind hearing one myself.

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Re:Say; anyone have an opinion on the Mullard 5-20? [message #9302 is a reply to message #9301]

Tue, 01 November 2005 03:28

Damir
Messages: 1005
Registered: May 2009

Illuminati (2nd Degree)

No, Merlin V2 has "ordinary" Raa=1ok PP OPT, just with two UL taps, on 20% and 30%. The "usual suspects" we can buy only have one UL tap, about 40%, and "Merlin" OPT must be custom ordered, but acc. to Doug - no big deal.
Nothing complicated in terms of Quad, McIntosh or new Plitron "Specialist" range, with various windings for cathodes and g2.

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Huh, sorry Manual... [message #9305 is a reply to message #9301]

Tue, 01 November 2005 04:12

Damir
Messages: 1005
Registered: May 2009

Illuminati (2nd Degree)

I just realized that you talked about Mullard 5-20 POWER transformer, and not about "Merlin" OPT...
Well, nothing complicated with PT - usual 5V rectifier winding, two 6,3Vct heater windings and 410-0-410V HV secondary, GZ34 rectifier, CLC "smoothing". OPT is UL, 2xEL34 cathode biased, input/driver EF86 to ECC83, high neg. feedback.
There`re a few pages of descriptions/comments in M. Jones book(s). Of course, the full schematic/descriptions/construction, measured performances...etc - in "Mullard Tube circuits for audio amplifiers" book.
IMO - go for "Merlin V2" :-).

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Re: Huh, sorry Manual... [message #9307 is a reply to message #9305]

Tue, 01 November 2005 06:33

Manualblock
Messages: 4973
Registered: May 2009

Illuminati (13th Degree)

Thanks Damir; let me say this; it is sometimes easier for us new guys to follow the older schematics in terms of the maths and the reasons for part choices than it is in the CCS models. Thats why I happened to look at the Mullard. I don't like the high feedback though.
Thanks for that tutorial earlier on the circuit math. The trouble with those posts for us is that by the time I have it sorted out you guys are long past that point and on to something else.
It is much easier to learn on the all tube models for me at this point.

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CCS [message #9308 is a reply to message #9307]

Tue, 01 November 2005 10:56

Damir
Messages: 1005
Registered: May 2009

Illuminati (2nd Degree)

"Active load" is not a new idea, it is mentioned many times in the book "Vacuum Tube Amplifiers" by Walley and Wallman, 1948.
You can ignore how SS CCS circuit works, you can just look at it like very high value resistor for AC, and with "adjustable" voltage drop for DC.