Most excelent 7Limit. First time I've heard you play, despite reading your posts for a while now. I've always liked your signature line re. holes. I watched a few of your band's youtubes after watching this and you play true to your motto. You've got great timing (leaving holes where they oughta be left) good taste and killer tone. Are you a 100% TBer? - May I ask what element you have in your bullet ? I sure your tone is fat even without an amp - but I'm curious about all the kit noe the less.
I appreciate the amp project - it sounds great - I built the lone wolf se6 kit myself. I've got a cute little gibson br9 that I just screwed up by running without the speaker connected - DUH! I'll be gat at the soldering table again soon - it may need a new output transformer and I don't know what . . .
The element is a Shure R7 crystal. With a 5 megohm volume pot with .001 mfd bypass cap. It sounds good with any mic, just a wee bit better with the R7.
On myspace its a Shure CR mic with a Kendrick Bassman linked with another 1w amp mic'd into seperate channels,then mixed. The videos use a Mojo kit Bassman with a CR mic
Very nice! A Shure crystal? Can't say I have ever heard anyone mention a crystal by Shure, since the CM/CRs get all the attention, but it sounded great. ---------- Todd
"I'm really not a real big crystal mic fan, mainly because they're so darn fragile and most aren't known for their big fat tone, and the fact that I'm content with my collection of CR's and CM's. Shure introduced one of the best, if not the best crystal mic ever made in 1940. The 707A. It was first introduced in 1940 and was identical to the 520 green bullet physically, but the shell was painted grey and was slightly smaller than the 520. It did not have any vent holes in it like the 520, which had 2 small holes drilled in the bottom side of the shell. It came with a chrome plated grille and a Bimorph Rochelle Salt crystal. It has a frequency response of 30 to 7,000 Hz, and output rated at 50db below 1 volt per microbar! In other words, some serious output! These mics had the biggest, fattest tone you'll ever hear from a harp mic although it wasn't made to be a harp specific microphone. It was made for the same uses that the 520 was made for but it was a stronger, louder mic, and needed an input impedance of at least 1 meg ohms, but preferably higher like 3 to 5 meg ohms. The elements that came in the 707A in the 40's were model #99-131. Over the years, Shure changed the shape of the element but used the same bimorph rochelle salt crystal. They were made up until 1970 before being discontinued."
I've got 3 R7's 1 is broken 1 has no top end The last is excellent.
They are not cheap and you need luck to get a good one.
I have a couple of Shure CR and CM that are very close to the R7, but they need a tight cup to work at their best. I find a crystal (the Astatic 151 included) are loud even when using only one hand. They are better for chromatic too. ---------- The Pentatonics Myspace Youtube
"Why don't you leave some holes when you play, and maybe some music will fall out".
Have you done anything to the harp because it seems really loud or are they just like that. I thought they were supposed to be quite dark and muted because of the plastic?
I am just getting into the chrom 3rd position stuff looking at Greasy Gravy by Bill C.
I would like to know what keys you have other than C and Bb? and what songs you were drawn to when you first got into the chroms.
Great playing. Very cool sound from the CX12. I love that little amp! Is the schematic for the amp online or does Mark sell them in a kit form? What kind of price?
7LimitJI's amp was a conversion from a Torres Tweed Boxer (6V6 Champ style amp)...new OT, new tube, basically move a few wires around & change a handful of parts. This is probably the cheapest route. Check Torres website for special offer models, they often come up cheap. The prototype that I built was built in to a 5F1 chassis, good quality transformers & parts...so, not surprisingly, mine costs about the same as a good quality 5F1...about £100 less than a Victoria 5F1 at £850GBP.
But I'm a practical kind of guy and appreciate that not everyone wants to spend >£2K per Watt (funny that!), yes, the hand drawn schem schem is at my myspace "half watt practice recording amp" with transformer specs (the 6SL7 version needs a different OT to that on the schem however). Though push pull, it basically uses the same amount of parts as a tweed Champ/princeton & I'm happy to advise anyone on how to go about building one. Feel free E-mail me at markwjburness@btinternet.com I have a bill of materials, would be happy to draw out a layout based around existing boards - don't expect any CAD designs though ;-)
Versions using 1x6SL7 can be built into 5F1/5F2A style chassis easily, a two channel, 2x6SL7 (one tube at either end of the primary) version can be built into a tweed 5E3 Deluxe Chassis easily...this route frees up transformer choices as a multitap 4/8/16ohm 6V6/EL84 OT can be used with a higher speaker load to bump up reflected impedance (blog at Myspace goes into this).
300-340vdc on the power tube plate seems to work nicely, so a power transformer should be rated at around 250-0-250VAC. Torres just happen to have PTs that work well & a suitable OT for the 2x6SL7 version (this is not, however a Torres design nor is it an amp that they sell).
I have 2 of these types of amps, I've tried 12AY7, 12AT7, 12AU7, 12BH7, 6SN7 & 6SL7 as power tubes...so far the 6SL7 is the sweetest, but not the loudest. With a transformer tap, or speaker change a 6SN7 is a replacement that will give volume about half that of a SF Champ...which is still surprisingly loud.
Last Edited by on Apr 13, 2011 2:34 PM
Its a CX12. I've got them in Bb, C, F and G They're easy to play and loud. Amped up the tone is phat.
They are standard apart from my special tuning!! 7limit on the blow notes set to the root of the harp.eg C. 0 -14 +2 5limit on the draw set to the 3rd pos root. eg D 0 -2.5 +2 +6 This tuning gives really nice sounding chords. It sounds complicated,but its not.
Have a read of this thread if you're interested in the tuning. http://www.modernbluesharmonica.com/board/board_topic/5560960/585951.htm
I still prefer the tone of the wooden bodied chroms. But the CX's just work straight OOTB so are a great purchase.They are my gigging tools apart from a heavily modded, old, wooden bodied 64
Rod Piazza, William Clarke and George Smith are the guys I listen to.
Regarding the amp. Its an easy mod to a ready built Champ style amp.Also a very good first amp build from a Torres kit.
But I must warn you! Building tube amps is very addictive. You'll be forever modding too! ---------- The Pentatonics Myspace Youtube
"Why don't you leave some holes when you play, and maybe some music will fall out".
That's a great sound for blues. Personally I thing that tune would have benefited from a cleaner sound. ---------- "Come on Brackett let's get changed"
Last Edited by on Apr 13, 2011 12:55 PM
