Q&A on my 12AX7/EL34 SE Amp
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- เผยแพร่เมื่อ 12 ก.ย. 2024
- Thank you all for your comments and questions on my last video! I really appreciate your feedback and being an "external processor" type of person, it helps me a lot to be able to throw out ideas and get feedback on them. It may sound like I am all over the place on this, I just want to consider all the options so I get this right!
Thanks again for your comments and questions, and know I read all of them.
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KISS - Keep It Simple Stephe! First round, put out a product that you know is excellent. Two models at most: one with a volume pot and one without. No options. This will allow you to get your feet wet, iron out your production, supply chain / inventory management, shipping, etc. Later, after you find out if you really enjoy being in production / support and have recouped your initial outlay, expand the catalog. Maybe iron or cap options for the first models, an input selector box with volume control or other amps. My 2 cents freely given.
Two things come to mind to potentially save you a lot of time and headache: 1. The measuring and drilling takes a tremendous amount of time. Design a top plate and have it fabricated so all that you have to do is attach the parts. You could use the Hammond wood chassis or some other chassis that accommodates a top plate style design. 2. Begin without any options. Design, build, and test a nice feature set and sell that for a while. Then consider branching out into options.
Yes I have to admit I’ve used your business model before.
It turns into WORK very quickly plus all the different parts you have to stock.
Quote: Keep things as simple as possible until simple doesn’t work.
Albert Einstein
It turns into work, if you don't enjoy doing it :)
@@SkunkieDesignsElectronics I’m like electricity. Follow the path with least resistance :)
👍for the amp-only idea. Throwing input switching and volume control onto a user-provided preamp, a passive preamp, or maybe something more exotic or remote controlled makes good sense. Someone (me maybe) might even just plug a DAC directly into the amp and handle volume control upstream with software.
Side-mounted inputs, sufficiently rearward on your amp could be very tidy with shallow passive preamps like the Schiit SYS or small cabinet passive volume knobs. With such a layout, perhaps you might consider only producing the amp-only version, making it BYOP or BYOPP (Bring Your Own (Passive) Preamp) leaving the input processing up to the users needs and simplify things on your end by eliminating volume control variants of the amp.
Definitely because the The inputs on this type of amp never seem to have enough inputs and then it's sort of just a passive front end with a volume control. Would much much rather have a nice power amp that I could use with any of my preamps!
I think you’re 100% on point with your ideas. You’ve obviously thought about this. I think the amp which needs a preamp is a great idea. Giving people options to upgrade or get custom models is fantastic too, but within reason. Once you narrow things down, I’m sure the amps will be fantastic, and I guarantee you’ll get plenty of orders. Thanks, Stephe. 🔊😊🎶
Yeah, I'm trying to judge from comments which options resonate. I had a lot of comments about using a pre-amp so I think having a "power amp" with an optional volume control makes sense. If people need switchable inputs, they can use a preamp or a simple switchbox.
Super interested to hear your findings on the different transformers
PPS - Love your idea of an external switch box ... So One simple power amp only version with an optional switch box, perfect!
2 versions. Power amp, integrated amp. Same chassis with a different front plate and side plate to accommodate volume and RCA jacks. Top plate & back plate stay the same. Sign me up for two momo blocks please 😊 I’m really looking forward to watching you make your dreams come true. And hopefully ending up with 2 new, bare bones, low powered amps. Remember… have fun, and don’t let the knuckle heads rain on your parade. Do it the way it makes you happy. Peace out ✌️
I don't think these are going to be bridgeable and honestly if you need more power, run an amp with a pair of KT88 tubes. Unless you are using them with active crossovers bi-amping speakers.
Steph, most of your followers are DIYers. Perhaps use a chassis that is a little oversized. That way an attenuator can be added in the chassis DIY. There are stepped relay attenuators that are microprocessor controlled. And some of those come with remote control (and if you control at the amp, add momentary pushbuttons to control the microprocessor or a rotary encode).
if there is room in the chassis, then folks and DIY to their hearts desire.
Same for caps and other components - folks and replace, upgrade to their hearts desire.
You are 100 percent on track, power amp only.
Thanks again, I vote for a power amp with no volume control. If possible... A version which can be mono blocked would be awesome... I am running a three way fully active system with solid state below 200Hz and would love four mono block (is fully differential possible ? ) tube amps for the mid and tops. Thanks again for all your amazing work!
I think limiting yourself to three options of amplifier tier would be the best way to go especially production-wise. Example, these transformers with these capacitors. A bronze silver and gold level. It would also help if there are any warranty or return issues because you knew exactly what went in each amp. If a customer decided to change the output bypass capacitor then you would know immediately
We know the hustle…lol na. Keep doing you. Thanks for calculating Delta or at least mentioning it. Nice tube rectifier! Woot. You are doing so great. Keep it up.
Whatever you decide, I’m in!!
You’re the best.
In the past, there used to be cylindrical ceramic power resistors that were mounted vertically on the chassis. I don't know if these are a good option any more (they probably aren't) but they were less unsightly in a tube amp that the wire-wounds with an aluminium heat-sink enclosure.
Maybe another (better) option would be vitreous enamel wire-wounds on a ceramic former. These are certainly better looking and more in-place on a tube amp chassis.
The only objection I have over power resistors on the chassis is the exposed uninsulated leads. These of course can be covered with some insulating tubing but it will always be a risk factor.
My two cents. I think you have some great ideas. I would vote for an integrated version with a volume control and one or two sets of RCA inputs. Inputs on the side would be fine but in the front would be inconvenient. I have always preferred integrated amps to separates but keep it a simple design.
Thank you for addressing my concerns about the volume control (pot). Obviously you are
aware of what constitutes decent quality as you mentioned the Alps Blue Velvet. As I
commented on your previous intro video to this project: my biggest concern is how well
the amp delivers a balanced (full) sounding signal to high efficient speakers so that at lower
volumes both the top and lower frequencies do not diminish. I think this phenomena is called
the Fletcher Munson curve? In any case, I listen at mid to low volume and I hope that your
eventual creation (or optional variation(s) thereof) will be able to produce at these volumes
and present a good linear sound that is full, rich and not sibilant. Keep moving forward with
this project - I applaud your creativity and willingness to be open about what you will or will
not do. (yeah, I'm talking about the remote)..... can't wait for all up-dates🇨🇦
I think for this use, most folks are going to have a pre-amp they love. I feel like it's easy enough to have two versions, with and without a volume control.
Totally agree.@@SkunkieDesignsElectronics
Stephe, Gold Lion sells three different 12AX7 tubes. Here's the three Gold Lion 12AX7s with their SKUs from Viva Tubes:
1. Gold Lion 12AX7 NP-095-1 (Made in China) $32
2. Gold Lion 12AX7 / ECC83 / B759 NP-021-1 $60 (this is the one to get)
3. Gold Lion 12AX7/CV4004 NP-197-1 $60
yup, not using that cheap one. And yes the middle one is good.
I have an Elite 80 amp which uses Sylvania 6AV5GA tubes for push-pull output and 12 AX7s for preamp tubes. I bought enough of these tubes to last a lifetime but don't know how available they are now. This amp sounds awesome and way over-built.
Those nos 6AV5 GA tubes are almost identical to a 2A3 when connected in triode mode ..........
Super cool project. These little amps are purist pieces, so keeping it is simple is key (no remote, limited inputs, etc). Really like your design philosophy and thoughts around component selection...especially around limiting upgrades to just those critical areas that make a real difference like transformers and bypass caps. This is turning into a neat project. I hope it comes to fruition.
Miflex, Mundorf.. I think the system must be similar to the one used by Musical Paradise MP-701 MK2 Tube Preamp Pre Amplifier. You can see it in the image they share.
[ 5. Output coupling capacitors and power filtering bypassing capacitors are user changeable to further improve or customize the overall sound characteristics. No soldering is required. ]
I'm not going to do some no soldering solution but I do plan to make them easy to change.
Like your KISS approach and agree with single input on the side panel.maybe a multi input switching box could be an optional extra.only thing missing for tube neophytes like me is auto biasing.looking forward to seeing what the pricing will be.
It is "auto biasing", with cathode bias there is nothing to adjust.
Power amp sounds like a good idea. Regarding 7025’s. What I’m reading is it’s a fallacy they are quieter.💁 Enjoy your content very much😊
They absolutely have less noise in a high gain application. In my EAR834 phono-stage using 12AX7 tubes, there is a lot more hiss and general noise than using EH7025 tubes.
I’ll have to try them in my phono stage next time I replace then😊 your favorite source?@@SkunkieDesignsElectronics
Yeah, Stephe. I use a NOS Mullard 7025 in my V1 spot in my phono pre. It’s absolutely a quieter tube and works well in that position, as does a 5751.
for NOS Motorola also sound good. I wasn't crazy about the NOS RCA, the new production EH7025 sound better
I prefer the 7025’s which are quieter and better sounding in my amps, and I’ve made a number of stepped attenuators but none of them have lived up to dream of sounding better than a good quality potentiometer, at least in my amps to my ears, your results may vary!
Yeah if someone really wants something beyond something like an alps pot, they would get the pre-amp version.
I think, outputs for 4 and 8 Ohm speakers are enough! The possibility to connect a pre amplifier is important! And the optional features, you listened, are very good. Please don't oversaving for the output transformers. I think, they are very important for the quality of the amp. And, last but not least, excuse me for by bad American school English 😵💫🤭😵💫!
I agree, I want to keep this simple. And the more I think about it, I am going to make this based on what sounds good to me as my brand's "signature sound". Like Klipsch speakers, people will either like it or not.
Personally, I HATE remote controls! I always misplace them, and don't like the little buttons. I like front panels crammed with switches & knobs that I can tweak and diddle with to my heart's content! This is especially true regarding test equipment, like old Tektronix 'scopes, but applies to audio gear, too.
Side RCA inputs are your design signature, IMHO.
Plus I do like RCA away from speakers cables away from power cord, both on noise reduction and easy of use. Fingers crossed, hope it will work as you wish! 😊
Hmm true that is how I have built the vast majority of my amps... I'm starting to think I should build it the way I always have, function first. If someone REALLY wants them on the back I could move them there.
I think maybe you're trying to do too much in one go. Why not offer an SE EL34 power amp for starters and maybe offer a separate preamp in the future?
Amp with volume control only.
Another reason to use it amplifier only you can use your own remote control preamp with it That's what I would do
I think you have a great plan. One thing to consider when using customer provided parts, it might be a good idea to adjust your guarantee on the amp. It sounds like it's going to be a nice piece
Great point!
PS My active crossover is fully balanced so has balanced outputs. Thanks again.
Probably not going there on this initial product.
I wish designers would use the 12AT7 tube much more. True, it has a little less gain than the AX but NOS AT versions are usually far less expensive than AX and AU versions
I haven't ruled that out, but the 12Ax7 will likely be a drop in replacement in my 6SQ7 amp. It shouldn't be hard to adapt it to use a 12AT7 and I might do that in the future.
There is a reason they don't and why they are more plentiful and cheap: they aren't very linear and aren't great for audio use.
love the idea of no attenuator, and tube rectifier. simple. later-on have a 'build passive-pre kit that we build with video tutorial. something that fits neatly underneath. name them E-6 and C-41
Right do a project with a pot and relay switchable inputs AWAY from that high voltage AC and heater current.
i really like this amp. its gorgeous, just gorgeous.
12AT7 guy here again. 12AT7's are made by all the usual suspects from Europe (JJ), Russia and China but the real benefit is the low cost of truly excellent NOS options. Since the 12AX7 is used in a lot of guitar amps NOS options are much more expensive. With a Mu of 60 vs the 12AX7's 100 the 12AT7 should have plenty of gain to take lower voltage inputs with a lot more drive grunt due to the much lower plate resistance. I'll stop pestering you about it now. :) By the way, you're missing out on a really good 300B by not trying JJ's. I'm going to be building a pentode driven WE 91A derivative 300B amp using a 57 pentode driver (a 2.5V version of the 6C6 which was originally used by WE as a driver for the 300B) and the JJ 2A3-40, which is a 2.5V filament version of their 300B. Using the lower filament voltage should allow use of AC on the filament due to less hum. Since the 57 is indirectly heated I should be able to use it on the same 2.5V supply as the big triode, saving $. I'm also going to use TV damper diodes as rectifier tube to get a good slow start with low voltage drop and super low cost. Anyway, give the JJ 300B's a go!
I think the worst thing to do with these amps and especially the ACA is to try to run it directly from a DAC or a phone or with a passive preamp having a good solid preamp with plenty of game is key with these amps in my experience
My DIY amps run fine without a pre-amp, there is no need for one.
Make something that puts out about 6-7 watts for speakers and has a 1-watt headphone output that will run 100 ohms to 600 ohm headphones, that's what i would love to see, there hard to find a good one. There just aint enough amps that have a headphone jack and if they do most don't sound great, BUILD IT AND THEY WILL COME.
I could see a stackable headphone unit? Honestly I'm not a headphone user, don't have even decent ones to know if what I did "sounds good" and anything like that is a compromise. A real tube headphone amp would have output transformers made to feed headphones.
I like your videos. Kudos for building new equipment for the audio nuts out there. Curious if you have a preamp build in the future?
I do, see my color pre-amp video series.
Take a look at the lab 12 the mighty, power amp only nice form factor I think you're looking to come out at the same price point and I bet you could do it with much better parts selling direct to customers
I'll check it out
Tube amps seem to fall into three price categories: under $2k; $4k to $6k, and over $8k. There is a market for between $2k and $4-5k. I’ve been looking in that range and there isn’t a lot of choice. So I’d favor you pricing the base around $2350 and then allowing buyers to option items raising the final price to the $4-5k range. I love the psvane EL 34ph tube (pair about $225). What about auto biasing as an option? Sub woofer output option?
This design is "auto bias" using cathode bias so nothing to adjust. Sub out would be done in a preamp I would think.
You can run speaker level to a powered subwoofer as well (if it has such an input).
Hi Skunkie, what a cool idea that you can easily exchange the capacitors! I was wondering why you don't use the Edcor output transformer that you have used in the past? I'm curious about your choice
I may end up doing that, not sure yet which route I am going on the iron.
great thinking Skunkie. You are a gifted designer. Do you consider designing for other brands?
Well Willsenton acted interested but when they asked me what I wanted to get paid, I shot them a one time mid 4 figure number and they never replied back. IDK if they thought I would redesign their amps for $200 or what they were thinking. Seems pretty dumb, as if it saved 3 amps being returned they made their money back.
6sn7 would be great and sounds better than a 12ax7
6SN7 is a much lower gain tube...
How about a pair of 2A3 mono amps? Just a pair of amps-no volume control.
Possibly later, not for a first build. That is too limited a market and use given how low power a real 2A3 is.
I was wondering if you ever put out the schematic for the 6bq5 spud amp you built. I’m currently trying to find it but no luck.
Honestly, it was so underwhelming, I wouldn't recommend building it. The 6BM8 or the 6LU8 are much better options. I honestly may take down the videos about that other "spud" amp.
Here is a link to the final schematic since you asked :)
drive.google.com/file/d/1rOqn3OBkc1aVKTDRMgj-gYGIuNa3Oqo1/view?usp=sharing
@@SkunkieDesignsElectronics Thank you for the reply and the honesty, you shouldn’t remove it because it still has a lot of good information, maybe just add a disclaimer in the description. Either way I’ll probably just slap it together on a breadboard just for kicks. Thanks again.
It IS a good project to test pre-amps with as it need a lot more drive than line level, so it actually works a pre-amp.
what do you think of the GE 5670/6N3P/6N3/WE 396 tubes? Those ones are pretty cheap
Have never used them and I want to focus on easy to find tubes, like you can order these on amazon :)
@@SkunkieDesignsElectronics audio note cobra uses 4 GE 5670 at the input stage but I see they are not that expensive compared to regular 12ax7
Self bias PLEASE.
It is, it uses cathode bias, no adjustment needed.
i figured that was sa straight power amp with a volume knob--is it an integrated amp?
Not sure what the difference is. I mean it doesn't have a bunch of inputs or a phono-stage etc.
me, neither,@@SkunkieDesignsElectronics, but most power amps do have volume knobs--just not most hifi/home stereo power amps. i frequently use pro audio power amps.
i guess the difference would be is there a preamp section, driver and output or just a driver and output?
A pre-amp isn't needed with modern sources. Possibly people are thinking an "integrated" amp includes a phono-preamp?
i dunno. a preamp is a preamp and an integrated amp is an integrated amp whether or not theres a phono section in it.
i do frequently come across newbies on facebook hifi groups who dont know that a turntable needs a phono amplifier/phono stage/phono section/riaa amp.
how does musical power supplies compare with thermionic?
I've only used their cheap guitar ones, wasn't super impressed but they aren't sold as hifi transformers.
yea,@@SkunkieDesignsElectronics . they sell hifi transformers too,
I tried to email them in the past and never got a reply, I'll try again.
@SkunkieDesignsElectronics , i just bought a pair of 6BQ5PP OPTs w/o screen taps. i have no idea if theyre any good. a few folks on AK were interested in his ST35 TX so i headed over thataway. i dont know much but id like to try em out regardless.
ill message you on AK.
It would be great to see it with better specs than the competitors, and then test it side by side with a more expensive amp, don’t waste your time sending it to reviewers they all suck and are most likely paid off in hardware. Its a scummy world out there.
Look at Thomas & Stereo's "Galion" amp for features and ideas.
Hmm, not sure I want to follow his lead.
LOL, no thanks.