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Post subject: Re: '68 Bassman Piggyback - 2x12 speakers (Oxfords)
Posted: Thu Aug 29, 2013 10:39 am
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shimmilou wrote:
All-in-all, I'm very pleased with the sound, but can't help wonder if I should convert it from the AC568 to an AB165 to get better clean. Any thoughts?


The AC568 revision was intended to produce a cleaner signal than the circuit it replaced. It's been my observation that it didn't quite work out that way though -- most Bassman's will compress and distort when dimed, regardless of which revision it happens to be (the ultra-linear's are the exception). And both the AB165 and the AC568 use the same bias-balance system so there's little to be gained there. I think you've optimized the amp and speaker array to the extent possible (and a nice job too).

Play and enjoy!

8)

Arjay

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Post subject: Re: '68 Bassman Piggyback - 2x12 speakers (Oxfords)
Posted: Thu Aug 29, 2013 10:48 am
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Shimmy, great job on the redo. Bet those Celestion V30 sound great. Interesting how the 10/500 F&T is bigger than the 20/500 cap.

You still interested in 12AY7/6072 tubes?


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Post subject: Re: '68 Bassman Piggyback - 2x12 speakers (Oxfords)
Posted: Thu Aug 29, 2013 10:55 am
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Runnerman wrote:
...I believe it's Realistic Liefting...


Well......maybe this is a cheap knockoff?

Image
Image[/quote]

Shimmy, this is a made in Korea (1970s vintage) 6L6GC. They made two types. One based on a pretty good Shuguang tooling. And one on a 1960s Reflektor (USSR)tooling (pre-Gorbachev era). The Shuguang knock-off (thin, straight glass envelope one) can't take the current a good US NOS one can handle. And the Russian knockoff (fat bottle) can take the current, but not high (~ 500VDC) plate voltages. Very characteristic of Chinese and Russian output and rectifiers tubes of this era.

FWIW... :D


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Post subject: Re: '68 Bassman Piggyback - 2x12 speakers (Oxfords)
Posted: Thu Aug 29, 2013 12:30 pm
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phansford wrote:
Shiimilou - Buddy Roger is still in business in Cincy. :lol:

https://www.buddyrogers.com


Amazing! Thank you for that. And he still has one store in the same location with the same phone number. I am going to send him an email with the picture and ask him about the warranty. :lol:

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Post subject: Re: '68 Bassman Piggyback - 2x12 speakers (Oxfords)
Posted: Thu Aug 29, 2013 12:45 pm
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Retroverbial wrote:
shimmilou wrote:
All-in-all, I'm very pleased with the sound, but can't help wonder if I should convert it from the AC568 to an AB165 to get better clean. Any thoughts?


The AC568 revision was intended to produce a cleaner signal than the circuit it replaced. It's been my observation that it didn't quite work out that way though -- most Bassman's will compress and distort when dimed, regardless of which revision it happens to be (the ultra-linear's are the exception). And both the AB165 and the AC568 use the same bias-balance system so there's little to be gained there. I think you've optimized the amp and speaker array to the extent possible (and a nice job too).

Play and enjoy!

8)

Arjay


Thanks! I'll leave well enough alone. I don't really appreciate how clean and loud it really is until I quit using it for a few days and go back to it. Now, to get that JX-2 Pro Switchbone, so I don't have to keep unplugging from one channel and plugging into the other, then jumpering channels, then back......... 8)

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Post subject: Re: '68 Bassman Piggyback - 2x12 speakers (Oxfords)
Posted: Thu Aug 29, 2013 12:58 pm
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BMW2002Ti wrote:
Shimmy, great job on the redo. Bet those Celestion V30 sound great. Interesting how the 10/500 F&T is bigger than the 20/500 cap.

You still interested in 12AY7/6072 tubes?


That is an anomaly in the picture, the 10 is slightly smaller than the 22, but the 10 just looks bigger in the picture. Note that the first 80 looks bigger than the second 80, and they are both the same size.

Perfect timing, send me a PM! :D

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Post subject: Re: '68 Bassman Piggyback - 2x12 speakers (Oxfords)
Posted: Fri Aug 30, 2013 7:22 pm
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Very nice job, shimmy!!! Bet that guy rattles the windows!!! Just wondering, if you're thinkin' about a 12AY7 in the V2 slot ? Art

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Post subject: Re: '68 Bassman Piggyback - 2x12 speakers (Oxfords)
Posted: Sat Aug 31, 2013 3:54 am
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Before recapping, I tried a 12AY7 in V3 to reduce the gain of the normal channel, but it lost too much sound. After replacing the bypass caps, the signal was cleaner all around, and now the Bass channel is pretty clean and solid, while the normal channel has some grit when pushed. Although I haven't tried it, I think that a 12AY7 in V2 would be too much cut in the sound, as V2 does affect both channels. I'm confident now that the amp is at it's best as-is, so I really need to try some different speakers. I think that I'll take the head to a buddy's house and try some Marshall cabs with it. He has a couple of 2x12s and a couple of 4x12s with various speakers. If my hunch is correct, a 4x12 will sound awesome. :D

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Post subject: Re: '68 Bassman Piggyback - 2x12 speakers (Oxfords)
Posted: Sat Aug 31, 2013 7:38 pm
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"Back in the day" I played my old AB165 Bassman through a big-box enclosure converted by a dealer to a 4 x 12 configuration. Even with a quartet of crappy Realistic (nee Utah) pie plates it sounded pretty beefy.

Arjay

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Post subject: Re: '68 Bassman Piggyback - 2x12 speakers (Oxfords)
Posted: Sun Sep 01, 2013 12:21 am
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Realistic!?!? :o :lol:

Yeah, I've used some of my other heads with the Marshall cabs and they all sounded beefier than the cab with the V30s.

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Post subject: Re: '68 Bassman Piggyback - 2x12 speakers (Oxfords)
Posted: Sun Sep 01, 2013 12:53 am
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Shimmy, I remember loading a cab with Realistic/Utah 12-inchers. At the time Radio Shack had them in different "wild-& crazy" colors --- as if anyone could see them. Mine was bright canary yellow basket.

Three outta the four blew at the same time. Note the starting price of this gem:

http://www.ebay.com/itm/VINTAGE-REALIST ... 9463869%26


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Post subject: Re: '68 Bassman Piggyback - 2x12 speakers (Oxfords)
Posted: Sun Sep 01, 2013 1:02 am
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Here's the 75-watt version, in all its glory......

Image

Image

Image

Image

The manufacturer's name was concealed in a valiant-but-vain attempt at innocence but the EIA code clearly indicates the "guilty" party.

:mrgreen:

Never seen them in yellow though -- only the orange and later, all black.

Arjay

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Post subject: Re: '68 Bassman Piggyback - 2x12 speakers (Oxfords)
Posted: Sun Sep 01, 2013 1:05 am
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BMW2002Ti wrote:
Shimmy, I remember loading a cab with Realistic/Utah 12-inchers. At the time Radio Shack had them in different "wild-& crazy" colors --- as if anyone could see them. Mine was bright canary yellow basket.

Three outta the four blew at the same time. Note the starting price of this gem:

http://www.ebay.com/itm/VINTAGE-REALIST ... 9463869%26


That's the 40-watt version, Steve......roughly equivalent to Fender P/N 081810 (a Bandmaster or Pro Reverb speaker). These speakers were sold initially with a "Lifetime" warranty.

Arjay

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